1/31/12 12:15 AM I. Biodiversity A. Total of all living things on earth (organisms) B. 4 to 100 million species C. About 1.7 million species identified D. Classification 1. Communicate information 2. Learning 3. Preservation: reducing biodiversity species extinction a. conservation b. sustainable use E. Evolutionary Relationships evolution- accumulation of inherited changes w/in a population over time F. Systematics 1. Scientific study of the diversity of organisms & their evolutionary relationships 2. Taxonomy: evolutionary history II. Binominal System of Nomenclature A. species ? basic unit B. name species ? Carolus Linnaeus, 18th Century Unique 2 part name C. genus + specific epithet (name) D. Rules 1. Latin 2. Genus (capitalized) specific epithet (not capitalized) 3. Italics, or underline 4. Genus- abbreviated Ex. H. sapiens, E. coli 5. Genus- unique 6. Specific epithet not necessarily unique III. Classification Systems A. Aristotle 1. Scale of nature (ladder) a. most imperfect to most perfect b. inanimate objects/matter plants invertebrates vertebrates 2. No concept of evolution (change did not occur) B. Into 17th Century Simple to complex C. Carolus Linnaeus 1. System of classification 2. Species- basis of morphology grouped organisms on basis of structural similarities 3. Classification reflects God?s concept of nature ?God creates, Linnaeus arranges? 4. No evolution IV. Species Definition A. Morphospecies Species defined by anatomical features B. Biological species 1. Ernst Mayr 2. Members of the same species can produce offspring that can in turn reproduce 3. Meaningless a. asexual organisms ex. Prokaryotes, some protists, some fungi b. fossil morphospecies concept genotype phenotype V. Classification ? Heirarchy A. species ? basic level B. several levels above species level 1. Domain Kingdom Phylum Order Class Family Genus Species 2. Taxon- grouping of organisms at any one of these levels, taxa (pl.) C. each taxanomic level is more inclusive (has more species) than before it Ex: cats- Family Felidae: short face, modified teeth Order Carnivora: teeth, sheer meat Class Mammalia: hair + milk production D. Some levels are subdivided 1. Prefixes sub- or super- ex: subkingdom- division of a kingdom superfamily- grouping of several families 2. Species- divided a. subspecies- geographically different population b. strains- microorganisms c. varieties- plants IV. Phylogeny A. Characters- defined attributes of a species 1. Structural (anatomical) ex. Legs a character has states ex. Legs- long, short, absent 2. Physiological 3. Developmental 4. Behavioral 5. Molecular traits B. character states may be similar for 2 reasons 1. Homologous- characters inherited from common ancestor 2. Homoplastic- (exhibit homoplasty) independently acquired similar b/c of similar function (not b/c of CA) convergent evolution ex. Bones in human arm, cat forelimb, whale flipper, bat wing [fig 18-10] similar in bone, muscle, and nerve arrangement all inherited from CA = homologous ex. Wings of birds & butterflies no shared CA of birds & butterflies similar b/c of conforming aerodynamic principles = homoplastic C. group together organisms that have homologous characters Molecular traits: protein sequences, DNA/RNA sequences D. Phylogentic traits 1. Geographical representation of evolutionary history of a group of species 2. Common ancestor: species from which all species of a group are descended LUCA- Last Universal Common Ancestor Most recent organism from which all organisms now descended 3. Branches 4. Nodes- branch points 5. Extant species- species currently living at tips of branches E. 3 Types of Taxanomic groups- based on character data 1. Monophyletic- includes a common ancestor & all its descendants a. all members of group share CA b. natural grouping c. true evolutionary relationship 2. Paraphyletic- contains CA & some but not all its descents a. unnatural grouping b. misrepresents evolutionary relationships VI. Tree of Life Lecture 1: Classification 1/31/12 12:15 AM I. Protists- Ch 26 A. ?very first? ~1.5 ? 1.6 bya B. Excavates 1. Characteristics a. flagella b. excavated oral groove c. anaerobic d. many endosymbionts 2. Diplomonads a. 1 or 2 nuclei b. ex. Giordia intestinalis- parasite, in small intestine, ?backpackers diarrhea?, water bourne diarrhea 3. Parabasalids a. ex. Trichonymphs- mutualism w/ termites, have endosymbiotic bacteria digest cellulose b. ex. Trichomonads ? Trichomonous vaginalis- parasitic, STD, causes trichomoniasis 4. Trypanosomes a. ex. Tripanosoma brucei- [fig 26-5c] parasitic, African Sleeping Sickness, Tsese fly, nervous disorders, fatigue, coma, death C. Chromalveolates 1. 2 main groups a. alveolates- dinoflagellates, apicomplexans, ciliates b. stramenophiles- last semester 2. Alveolates a. alveoli- flattened vesicles, lie just inside plasma membrane support membrane b. apicomplexans i. apical complex- microtubules, attach to & penetrate into host cells, ii. Parasitic iii. Locomotion- flexing iv. Plasmodium- malaria, complex life cycle [fig 26-7] in vertebrates, attacks liver cells & RBCs, ~300 million infected, 1-3 million deaths per yr c. ciliates [ fig 26-8] i. pellicle- flexible outer covering, formed by alveoli ii. Cilia- extend through pores in pellicles locomotion & feeding iii. Tricocysts- organelles in pellicle, form toxic filaments to sting & tray prey iv. 2 nuclei- macronucleus metabolism & growth; micronucleus sexual reproduction v. reproduction- asexual & sexual conjugation- opposite mating types exchange micronuclei vi. Most free-living D. Rhizarians 1. Tests- hard outer shell, cyctoplasmic projections, extend through pores 2. Foramniferans- forams [fig 26-13a] a. test- calcium carbonate, many small pores b. cytoplasmic projections- locomotion & feeding c. marine environment- die thick marine sediments formed, geological uplifting land forms ex. White Cliffs of Dover, England 3. Actinopods-[fig 26-13a] a. axopods- cytoplasmic projections, locomotion & feeding b. radiolarians- glassy shells silica c. marine plankton E. Unikonts 1. Ameobozoa a. pseudopodia- temporary cytoplasmic projections (movement), lobose, rounded & wide b. Amoebas [fig 26-18] i. free-living ii. Parasitic- Entamoeba histolytica: causes amoebic dysentery, lives in intestine fulminating diarrhea iii. Opportunistic- normally free-living, but parasitic if in a host ex. Nagleria fowleri: intro nose of swimmers olfactory nerve brain death in 3 days 2. Choanoflagellates- [fig 26-21] a. free-living b. collared flagellates: single flagellum, surrounded by collar of microvilli c. related to ancestor of animals II. Kingdom Animalia (Ch. 30, 31, 32) A. Unikont B. Characteristics 1. Multicellular, eukaryotic 2. Heterotrophs- ingest food, digest 3. All animals have differentiated cells specialized- specific functions most have differentiated tissues groups of cells w/ common structure & function higher forms have differentiated organs tissues adapted to perform specific function(s) 4. Lack cell wall 5. Locomotion 6. Most have sense organs & nervous systems: muscle tissue movement 7. Reproduction- usually sexual, diploid stage dominant a. meiosis b. fertilization genetic recombinant C. More than 1.5 million animal species identified ~ 35 Phyla D. major branches in evolution of animals 1. Animal kingdom is monophyletic, ancestor- choanoflagellate (protist) 2. Differentiated cells, tissues, and organs 3. 1st major division between organisms a. Subkingdom Parazoa ?beside the animals? do not have clearly differentiated tissues & organs b. Subkingdom Eumetazoa ?true animals do have clearly differentiated tissues & organs III. Phylum Porifera ?pores? sponges A. Structure 1. Least complex animal 2. ~10,000 species 3. Multicellular 4. Symmetry: arrangement of body structure in relation to body axis, sponges are asymmetrical 5. No nervous system 6. Asexual reproduction 7. Larvae- flagella, swim, attach to substrate adults are sessile B. simple sponge 1. Sac-like body holes 2. Spongocoel- central cavity, passage for water, not digestive chamber 3. Osculum- open end 4. Choanocytes- flagellated collar of microvilli, lines spongocoel 5. Suspension feeders [fig 31-1] water enters pores particles trapped by choanocytes water enters spongocoel digestion in choanocytes intracellular water exists via osculum IV. Among Eumetazoa, major branch defined by symmetry of body & embryonic tissue development A. 2 Types of symmetry [fig 30-3] 1. Radial- Branch Radiata, wheel or cylinder, multiple planes divide animal into mirror images 2. Bilateral symmetry- Branch Bilateria, only 1 plane through midline right & left mirror images, adapted for locomotion cephalization: development of a head region, end of animal that encounters things, bilateral animals B. Embryonic Tissue Development: eumetazoan embryos- layered 1. Concentric layers of embryonic tissue germ layers a. ectoderm- inner outer covering & nervous system b. endoderm- inner lining digestive tract & other organs c. mesoderm- middle most of the other body structures (muscle, skeleton) 2. Diploblastic organisms- only ectoderm & endoderm layers, Radiata 3. Triploblastic organisms- all 3 layers, Bilateria V. Branch Radiata A. Phylum Cnidaria [fig 31-2] marine >10,000 species Ex. Jelly fish, coral, sea anemone, radial symmetry 1. Diploblasts- ectoderm epidermis- outer layer endoderm gastrodermis- lines gut 2. Hollow sac- mouth & tentacles at one end 3. Mouth- only opening, ingestion of food, expulsion of wastes 4. Gastrovascular cavity- digestive compartment B. Phylum Ctenophora [fig 31-7] 1. Comb jellies 2. 8 rows of cilia on outer surface 3. Marine 4. 100 species Lecture 2: Animal Diversity (Ch. 26) 1/31/12 12:15 AM I. Bilateria A. type of coelom 1. Coelom- body cavity, fluid-filled space between body wall & digestive tube, only in triploblastic organisms 2. 3 types ?[fig 30-4] a. acoelomate: body-solid, lack a blood vascular system b. pseudocoelomate: body cavity not completely lined with mesoderm c. coelomate: true coelom, body cavity completely lined with mesoderm coelom/pseudocoelom a. hydrostatic skeleton b. circulation- not needed to be flat B. Early Development 1. Cleavage- succession of mitotic cell division that occur in the zygote [fig 30-5] a. protostomes i. spiral cleavage- planes of cell division are diagonal to vertical axis of embryo ii. Determinant cleavage- developmental fate of each embryonic cell is rigidly set very early in development, if a cell is removed adult lacks parts b. deuterostomes i. radial cleavage- planes of division parallel or perpendicular to vertical axis of embryo ii. Indeterminant cleavage- each cell retains capacity to develop into a complete embryo 2. Fate of blastopore- early development, embryo-ball of cells blastula a. group of cells in blastula move inward form blastopore; blastopore- opening into primitive gut (digestive system) b. protostome- ?mouth? blastopore develops into mouth c. deuterostomes- ?two mouths? blastopore anus, 2nd opening forms later mouth Protostomes ? Ch. 31 Lophotrochozoa A. Phylum Platyhelminthes ?flat worms? 1. Characteristics a. triploblastic b. acoelomate c. 1st bilateral symmetry d. 1st organs, digestive tract, reproduction, monecious, male & female in 1 individual, nervous system, & excretory system e. 1st cephalization, ganglion- simple brain sense organs 2. Classes a. Turbelleria- free-living ex. Planaria b. Cestoda- tapeworms, parasitic, gastrointestinal tract, no mouth or digestive tract absorb ex. Taenia saginata [fig 31-11] c. Trematoda- flukes, parasitic, gastrointestinal tract, urinary system ex. Genus Schistosoma [fig 31-9] blood fluke, 200 million people infected B. Phylum Molluska [fig 31-13] and [Table 31-3] 1. >80,000 species- snails, slugs, oysters, clams, octopi, squid 2. Structure a. soft body- may be covered by a dorsal shell calcium carbonate b. foot- muscular structure, ventral side, locomotion, tentacles c. visceral mass- viscera (internal organs) d. mantle- thin sheet of tissue; covers visceral mass e. radula- belt of teeth in mouth area scrape up food, not in bivalves 3. 4 Major Classes a. Polyplacaphora: ?many plates? = chitons marine, oval, shell-8 parts, foot- broad & muscular b. Bivalvia: marine & freshwater, clams mussels, oysters scallops, shell-2 parts, hinged, secreted by mantle no distinct head, radula, suspension feeders trap food particles in water can extend foot- dig, anchor c. Gastropoda: snails-shell, slugs & nudibranches-no shells, distinct head area-tentacles & eyes torsion- twisting of visceral mass during growth anus above head d. Cephalopoda: marine, squid & octopus, predatory, mouth radula 2 beaks, foot-tentacles, brain-learn & remember, eyes, closed circulatory system C. Phylum Annelida ?little rings?- segmented worms [Table 31-4] & [Table 31-18] 1. Segments: body wall, coelom, main internal organs divided into segments metamere 2. Classes a. Polychaeta: ?many bristles?- each segment has pair of parapodia ?almost feet? locomotion many setae on parapodia: bristle-like structures, anchor, marine & fresh water ex; sandworms, tubeworms b. Ogliochaeta: no parapodia, but have setae ex. Earthworms c. Hirodinea: no parapodia, not setae, leeches fluid-filled feeders, ~75%- blood D. Phylum Rotifera [fig 31-22] ?wheel animals? Crown of cilia- anterior end, fresh water II. Ecdysoza- ecdysis= process of molting A. Phylum Nematoda [fig 31-23] and [fig 31-24] 1. Intro a. roundwords b. bilateral symmetry c. psuedocoelomates d. cuticle- non-living outer surface prevents desiccation, molts as nematode grows 2. Habitats a. many free-living b. parasitic c. human parasites i. hookworm- lives in intestine, feeds on blood ii. Trichinella spiralis- causes trichinosis, pork iii. Pineworm iv. Heartworm- found in dogs, transmitted by mosquitoes B. Phylum Anthropoda ?joint-footed? 1. Intro- largest Phylum ~1 million species 2. structure a. jointed appendages: functions- walk, swim, sensory b. joined exoskeleton: chitin (polysaccharide, carb, sugar) & protein, covers entire body, advantages- protection, limits water loss, points of attachment for muscles, disadvantages-limits growth must molt c. segmented body- basic body plan i. head ii. Thorax- middle, bears legs/wings iii. Abdomen- posterior d. open circulatory system- fluid e. brain & vental nerve & sense organs 3. 5 Subphyla a. Trinlobitomorpha: extinct, 250 mya b. Myripoda [fig 31-27] i. Class Chilopda: centipedes, each segment 1 pair of legs, carnivores-poison claws ii. Class Diplopoda: millipedes, each segment 2 pairs of legs, no poison claws, herbivores, scavengers c. Subphylum Chelcerata i. Cephalothorax: head & throat fused ii. Chelicerae: anterior to mouth manipulate food iii. Class Merstomata: most extinct, horseshoe crabs iv. Class Arachnida: spiders, ticks, mites, scorpions d. Subphylum Crustacea: marine ex. Class Malacostraca crabs, lobster, shrimp e. Subphylum Hexapoda: Class Insecta [Table 31-6] >1 million species identified actual number about 30 million species 6 feet hexapoda wings- cuticle only flying invertebrates advanced compound eyes tracheal system: chitin-lined tubes, branch exchange gas Deuterostome Phylum (Ch. 32) I. Phylum Echinodermata ?spiny skin? [fig 32-1] A. Characteristics 1. Marine 2. Larvae- bilaterally symmetrical adults- pentaradial symmetry (5) 3. Endoskeleton- made up calcium carbonate, spines- project through epidermis 4. No brain- nerve ring w/ nerves extending out 5. Water vascular system: fluid-filled canals & chambers feeding & gas exchange, tube feet- branches, adhere to surfaces, locomotion B. Examples 1. Class Asteroida: sea stars, central disc w/ 5 arms, carnivorous predators, feed on mollusks, eversible stomach- projects out of mouth 2. Class Echinoidea: sea urchins, sand dollars, no arms, tube feet 3. Class Holothuroidea: sea cucumbers, tube feet II. Phylum Chordata A. Intro: deuteron, coelomate, triploblastic B. 4 chordate characteristics 1. Notochord- firm, but flexible longitudinal supporting rod located between gut & nerve cord, internal skeleton- in all embryos & some adults forerunner of the backbone 2. Dorsal tubular nerve cord- develops into central nervous system other animals- solid nerve cord, ventral 3. Pharyngeal slits- ancestral trait, suspension feeder 4. Muscular post-anal tail- extends posterior, beyond anus C. Subphylum Vertebrata 1. Chordate characteristics- mostly in embryo 2. Adult vertebral column- bone or cartilage 3. Endoskeleton 4. Highly developed brain- skull 5. Sensory organs D. Classes of Vertebrates 1. Fish a. jawless- lack jaws ex. Lamprey b. chondrichthyes- cartilagous, skeleton is cartilage ex. Sharks, rays, skates c. bony- skeleton bone, calcium phosphate, hardens cartilage ex. Perch, salmon, trouty tuna 2. Tetrapods- land vertebrates a. Amphibia- 1st tetrapods, eggs- laid in water or in damp environment, thin, moist skin ex. Frogs, toads, salamanders b. amniodes- amniotic egg egg contains amnion-membrane that forms fluid-filled sac around embryo i. Reptilia- hard, dry scales, protect from drying out & from predators ectodermic- temperature fluctuates w/ environment ii. Aves- birds, feathers, wings, light skeleton, endothermic, use metabolic energy to maintain constant body temperature iii. Mammalia- hair, mammary glands, live young, endothermic Lecture 3: Animal Diversity II 1/31/12 12:15 AM I. Nervous System A. compartments 1. Central nervous system (CNS) brain, spinal cord 2. Peripheral nervous system (PNS) sensory receptors & nerves B. Functions 1. Process information & make appropriate response 2. Respond to stimuli- changes w/in or outside body, can be detected C. Response to Stimuli 1. Sensory reception- detecting stimulus, specialized sense organs ex. Eyes, ears, skin 2. Transmission- process of sending messages along a neuron a. afferent= sensory neuron, receive stimuli & conduct into towards CNS b. efferent= motor, info from CNS to effectors effector- part of an organism that produces response to stimulus ex. Muscles, glands 3. Integration- sorts & interprets info interneurons= association neurons (in CNS), 99% of all neurons 4. Response/motor output sense organ afferent neuron interneuron efferent neuron effector II. Neuron A. Intro: basic unit, conduct messages, electrical signals [fig 41-2] B. Cell Body C. 2 Types of Cytoplasmic Projections 1. Dendrites- receive info from environment of from other neuron sends neural impulse to cell body most neurons- many short, branched dendrites 2. Axons- transmits neural implse away from cell body usually only 1 axon branches axon collaterals branch into 100?s -1000?s axon terminals at tips of axon terminals synaptic terminals nerve- collection of axons of many neurons bound by connective tissue D. Morphology 1. Multipolar- single axon & many dendrites integrate information from other neurons motor neurons & interneurons 2. Bipolar- axon & single dendrite on opposite sides of cell body specialized sensory neurons- transmission of special tissues ex. Smell, taste, sight, hearing, touch E. Synapse 1. Junction between synaptic terminal & other neuron or effector 2. Space between membranes 3. 2 types a. electrical: presynaptic & postsynaptic terminals very close electrical signal passes unchanged b. chemical: synaptic cleft >20nm wide electrical signal does not pass neurotransmitters- chemicals released by presynaptic terminal diffuses across cleft to specific receptors on post-synaptic terminal ex. Acetylcholine- released from motor neurons dopamine- level in brain, affects in mood endorphins- pain regulation glutamate- amino acid, major excitatory neurotransmitter in brain F. Summary- 3 Types of neurons 1. Sensory = afferent 2. Interneurons = association, never connect to sensory organs or effectors 3. Motor = efferent III. Glial Cell A. Intro: do not transmit B. Types [Table 41-1] 1. Microglia- in CNS, near blood vessels, phagocytic cells clean up after injury/infection 2. Astrocytes- in CNS, provide neurons w/ glucose regulate composition of CNS fluid remove excess potassium & neurotransmitters stimulate endothelial cells in blood vessels to form tight junctions 3. Oligodendrocytes- in CNS, cell membrane, myelin- lipid, form myelin sheath around neurons electrical insulation 4. Schwann cell- in PNS, form myelin sheath each associated w/ region of axon overlapping layers series of Schwann cells lines up around axon internodes- regions in myelin sheath between Schwann cells myelinated fiber- white matter, unmyelinated fibers/cell fibers- gray matter IV. Transmission A. neural impulse- electrical signal Electrochemical process- flow of ions in a neuron cell membrane B. all animal cells have a selectively permeable cell membrane 1. Allows certain ions to cross 2. Results in a polarity between outside & inside of cell ?(charge) membrane is polarized 3. Charge difference is negative- inside of cell is negative compared to outside C. Membrane Potential 1. Potential to do work 2. Only excitable cell have the ability to generate rapid changes in membrane polarity neurons & muscle cells 3. Voltage- measurement of charged particles to flow between 2 points voltmeter- reference electrode put on outside 2nd electrode inside see charge differences 4. Resting potential cell membrane at rest -70 mV [fig 41-4a] D. Charge Difference 1. Sodium potassium pump [fig 5-17a] membrane protein moves 3 Na+ out for every 2 K+ in inequality of positive charges pumps against concentration gradient active transport ATP membrane is less positive (more negative) on inside than outside inside-less positive outside-more positive 2. Ion channels a. passive [fig 41-4b]- specific ions i. energy of concentration gradient ii. K+ channels most common membrane, is 100x more permeable than to Na+ iii. Any K+ that is pumped into cell can easily pass back out iv. But Na+, once outside, it is stuck there b. voltage-activated ion channels [fig 41-7] i. membrane proteins ?gates? ii. Changes in voltage open/close iii. Regulated by changes in voltage change shape of protein iv. Facilitated diffusion v. K+ and Na+ bind to voltage-activated Na+ channels block vi. Can?t open no pain impulse ex. Novocain E. Neural States 1. Resting potential (RP) -70 mV potential energy voltage-activated Na+ channels closed RP- can be change by stimulus environmental factor that can induce change in membrane potential 2. Hyperpolarization: membrane potential moves below RP more negative IPSP- inhibitory postsynaptic potential neuron away from firing 3. Depolarization: membrane potential become more positive EPSP- excitatory postsynaptic potential 4. Threshold: positive ions have moved inside when threshold reached results in action potentials -55 mV V. Action Potential [fig 41-8b] and [fig 41-9] Transmission of nerve impulse Electric excitation- down axon to synaptic terminals Depolarization action wave (more positive!) A. Chain of Events 1. Stimulus 2. Depolarizes membrane a. voltage-activated Na+ channels open i. Na+ enter axon ii. Membrane potential becomes more positive (less negative) b. maginitude of change depends on strength of stimulus i. small- few channels will open membrane will not reach threshold (stays at rest) ii. Strong- many channels open produce large change in permeability reaches -55 mV 3. Membrane suddenly very permeable to Na+ a. Na+ rush down gradient & into cell b. changes polarity c. inside- more positive than outside 4. Spike of +35 mV a. voltage-activated Na+ channels close b. membrane- impermeable to Na+ c. absolute refractory period d. no other action potential can be generated e. relative refractory period i. voltage-activated Na+ channels have been reset ii. can transmit action potential, but threshold is higher 5. Voltage-activated K+ channels- also being opening when a. threshold is reached, but slowly K+ slowly move out b. fully open at peak depolarization c. membrane repolarates back to more negative i. overshoots RP -90 mV ii. hyperpolarization- membrane potential more negative than RP iii. K+ channels close 6. Channels & pumps -70 mV B. Summary [fig 41-8a] 1. Neurons at rest (RP) 2. Stimulus 3. Membrane depolarization (Na+ in) 4. Threshold 5. Rapid depolarization (Na+ rushing in) 6. Spike 7. Repolarization (K+ out) 8. Hyperpolarization 9. Overshoot 10. Resting potential C. Action Potential- 2 Properties 1. All-or-none a. above -55 mV action potential will happen b. intensity of sensation depends on number of neurons stimulated c. frequency of stimulation 2. Self-propogating- as voltage shift in one region, spreads to voltage-activated Na+ channels further along action potential wave of depolarization D. Wave of Depolarization 1. Unmyelinated axons- continuous conduction every location, depolarization & repolarization 2. Myelinated axons a. internodes- covered in myelin no depolarization b. nodes of Ranvier- no myelin i. concentration of Na+ & K+ channels ii. Depolarizes action potential (only at nodes) iii. Impulse ?leaps? from node to node salutatory conduction (jumps from one to another) iv. Transmission much faster myelinated axons 50x faster more energy efficient Lecture 4: Nervous System I (Ch. 41) 1/31/12 12:15 AM c. multiple sclerosis: degenerative, myelin sheaths deteriorate, disruption of transmission loss of coordination Nervous System II (Ch. 42) arrangement of nervous systems I. Nerve Net A. Simplest- Cnidarians ex. Hydra [fig 42-1] B. Structure 1. Interconnected neurons 2. No central control organ 3. Response in one neuron spreads both directions stronger stimulus, further it gets II. Bilaterally Symmetrical A. Increased number of nerve cells B. Centralization of nerve cells ex. Brain C. Specialization of function in nerve cells D. Increased complexity- interneurons, synaptic contacts E. Cephalization- concentrate nerve cells at front end III. Invertebrata A. Flatworm (Platyhelminthes) ex. Planaria [fig 42-2] 1. Central ganglion at anterior end primitive brain 2. Ladder- type neuron systems a. 2 solid ventral longitudinal nerve cords form cerebral ganglion to posterior end of body b. transverse nerves connect 2 nerve cords B. Annelids & Arthropods [fig 42-3] 1. Ventral longitudinal nerve cord 2. Larger anterior brain 3. Specialization of function, especially in insects IV. Vertebrates [fig 42-4] A. CNS 1. Brain 2. Spinal cord- dorsal, tubular, inside vertebral column (spine) B. PNS 1. Sensory receptors 2. Nerves- cranial & spinal V. Peripheral Nervous System A. sensory receptors Detection of stimuli (auditory, visual, etc.) B. Nerves 1. Spinal- 31 pairs, originate in spinal cord, innervate body 2. Cranial- 12 pairs, originate in hind part of brain, innervate head & upper body C. PNS- 2 components 1. Somatic- nervous system a. external environment b. components i. sensory receptors ii. Afferent neurons- from receptors to CNS iii. Efferent neurons- from CNS to skeletal muscles c. function i. most ?voluntary? movement ii. Involuntary reflexes involving skeletal muscles 2. Autonomic nervous system a. signals that regulate internal environment (non-conscious) b. components i. receptors- internal organs ii. Afferent- from receptors to CNS ii. Efferent neurons- from CNS to glands or involuntary muscles (smooth, cardiac) c. function- control & coordinate systems not normally under conscious control ex. Breathing, heart beat d. 2 divisions of autonomic 2 types of efferent pathways i. sympathetic- ?flight or fight? ?fight or frolic? prepare body for action (stressful situations) increase in heart rate, respiration, metabolic rate dilates air passage slows down digestive processes ii. Parasympathetic vegetative/restful(conserve energy) VI. Central Nervous System [fig 42-8] A. Spinal cord Link between brain & rest of nervous system 1. Structure a. small central canal b. gray matter surrounds canal (unmyelinated) non-myelinated axons, cell bodies, dendrites, glial cells c. white matter surrounds gray- myelinated axons 2. functions a. transmits to & from brain b. control reflex actions fixed response patter to a simple stimulus ex. Withdrawal reflex [fig 42-9] touch-hot pain receptors signal to sensory neuron transmitted to association neuron in spinal cord response transmitted to motor neuron transmits to skeletal muscle move away B. Brain 1. Vertebrate embryonic development a. neural tube- single tube of tissue anterior brain posterior spinal cord b. brain always develops into hindbrain, midbrain, and forebrain 2. Subdivisions hindbrain- myelencephalon and metoncephalon midbrain- mesencephalon forbrain- diencephalon and telencephalon VII. Brain Structures A. Hindbrain 1. Myelencephalon medulla- posterior part of brain on top of spinal cord that connects to autonomic nervous system control center- respiration, heart beat, BP, swallowing, coughing, vomiting, etc 2. Metencephalon a. pons- large mass of fibers at top of brain stem connects spinal cord & medulla with upper parts of brain respiration & sleep centers b. cerebellum- back of brain coordinates muscle activity size= extent & complexity of muscle activity medulla + pons = brainstem B. Midbrain = mesencephalon 1. Info between hindbrain & forebrain 2. Major association area receives sensory info integrates response w/ motor nerve 3. Mammals a. inferior colliculi- auditory reflexes b. superior collicuili- visual reflex (i.e. pupil constriction) C. Forebrain ?higher? function Complex neural processing 1. Diencephalon a. thalamus- coordinate sensory input i. except olafactory- relays to cerebral ii. Component of RAS- reticular activating system interconnecting neurons from brain stem into thalamus maintenance of consciousness survey of incoming stimuli general level arousal of brain relaxed & few stimuli sleep (ex. in lecture) b. hypothalamus i. olfactory centers ii. regulates internal processes homeostasis coordinates autonomic & somatic senses receives sensory input from internal & external sources via the thalamus iii. Regulates basic drives- hunger, thirst, rage, sex iv. Link between nervous system & endocrine system 2. Telencephalon a. cerebrum- prominent, complex, deeply convoluted b. 2 hemispheres right and left- connect via corpus collosum band of white & gray matter c. inner portion = white matter = myelinated axons d. outer portion = cerebral cortex, gray matter- cell bodies, dendrites, convolutions- folds, sulci (fissures) e. cerebral cortex- functional divisions (areas) i. sensory cortex- infor from sense organs ii. Motor cortex- signals to skeletal muscles voluntary movement iii. Association cortex- links other 2 thought, learning, memory, language, personality, judgement f. cerebral cortex also divided into 4 lobes i. temporal- hearing ii. Occipital- visual iii. Frontal- prefrontal area sensory stimuli motor area- voluntary movement speech area- motor part of speech iv. Parietal- sensory stimuli from skin body awareness thought, learning, language & personality Lecture 5: Nervous System II 1/31/12 12:15 AM [fig 42-10] and [fig 42-2] I. Sensory System (Ch. 43) A. mechanism to gain info about external environment & internal state B. Types of Info 1. Quality/type of stimulus 2. Quantity C. Sensory receptors & sensory neurons II. Sensory Neurons Afferent neurons Info from receptors in CNS III. Sensory Receptors A. detect info about changes in environment B. neuron ending or specialized cells that in close contact w. neurons C. Transducer- converts energy into electrical energy (neural impulse) D. Sense organs- receptors & associated cells IV. Stimulation of sensory receptors A. unstimulated Receptor maintains resting potential B. stimulated 1. Receptors- depolarization more positive, Na+ move into cell 2. Receptor potentials- depolarizations 3. Amount of depolarization graded response receptor potential proportional to stimulus strength 4. When receptor potential reaches threshold action potential trigger in sensory neuron 5. The larger the receptor potential, the more frequent the action potentials C. Adaptation When stimulus applied continuously to receptor Receptor responds rapidly at first Eventually response slows and stops Decrease in action potentials in sensory neuron Reasons: 1. Receptor sensitivity decreases & produces smaller receptor potentials 2. Changes at synapse of sensory pathway release of neurotransmitters decrease adaption varies in how quickly it occurs touch-fast cold-slow V. Types of Sensory Receptors A. Stimulus Origin 1. Exteroreceptors 2. Interoreceptors B. Types of Energy 1. Touch/pressure- activated when shape changes ex. Merkel discs- skin, touch/pressure 2. Chemoreceptors- chemical compounds taste (gustuary) smell (olafactory) respond to similar chemicals receptors- embedded in liquid/mucus film, chemical dissolve in film ?wet sense?, regenerated a. taste- taste buds are organs of taste each ~100 receptor cells, molecules dissolved in saliva depolarization action potential receptors for specific tastes- salt, sweet, bitter, sour, umami(glutamate)-savory, meaty flavor- combinations of taste, temp b. smell- molecule breathed in, dissolved in mucus 100 million olfactory receptor cells, molecules bind to receptors depolarization action potential in olfactory nerve 10,000 different scents 3. Thermoreceptors 4. Electroreceptors 5. Photoreceptors VI. Human Ear A. function 1. Balance/equilibrium 2. Hearing B. balance/ equilibrium 1. Inner ear- contains organs of equilibrium labyrinth- comprised of interconnected canals & sacs all vertebrates have inner ear 2. Labyrinth- membranous labyrinth fits into bony labyrinth 3. Membranous labyrinth = vestibular apparatus a. saccule & utricle i. contain hair cells = sensory receptors function as mechanoreceptors (push/pull) otolithes- ?ear stones? grains of calcium carbonate = gravity receptors ii. Change tilt of head- otolithes shift & bends hair cells action potential iii. Allows awareness of position relative to the ground regardless of the position of the head b. 3 semicircular canals i. endolymph ii. Ampulla- base of each canal hair cells- sensory receptors iii. Head moves fluid moves in canals bends hairs in ampullae triggers action potential iv. Canals at right angles to each other allows detection of turning in any direction [fig 43-8b] [fig 43-9] [fig 43-10] VII. Hearing A. ability to sense changes in pressure 1. Sound- waves of air or water pressure 2. Frequency- # of waves/sec slow frequency low pitch high frequency high pitch 3. Amplitude- loudness B. Response to Sound 1. Ear- 3 chambers a. outer- pinna b. middle- auditory base c. inner- cochlea 2. Sound waves enter outer ear a. cartilage- asymmetrical, leads to ear canal b. ear canal = external auditory canal cylindrical, collects waves c. tympanic membrane = eardrum thin, membrane, separates outer from middle, vibrates from waves 3. Vibrates transmitted to middle ear a. air-filled b. connects to throat by eustacchian tube equalize pressure between middle ear & atmosphere c. ossicles- i. malleus = hammer, in contact with ear drum ii. incus = anvil, in contact with malleus + stapes iii. Stapes = stirrups, in contact with oval window membrane separates middle ear from inner ear d. middle ear amplifies sound transmits vibrations from eardrum into inner ear 4. Oval window- transmit vibrations to inner ear a. cochlea i. hearing ii. 3 chambers (canals) vestibular canal- pertilymph cochlear duct- endolymph tympanic canal ? perilymph iii. basilar membrane- separates cochlear duct from tympanic canal b. pressure from stapes causes window to go in & out P waves transmitted to fluid in vestibular & tympanic canals Causes round window at end of tympanic canal to bow in & out Vibrates basilar membrane up & down c. Organ of Corti i. within cochlear duct ii. Auditory region iii. receptor cells ~ 18,000 hair cells detect changes in P waves iv. Located between 2 membranes rests on basilar membrane tectorial membrane- overhangs hair cells in contact stiff [fig 43-11] d. translated into action potentials i. stereocilia- at tips of hairs, mechanoreceptors, in contact with tectorial membrane ii. Hair cells stimulated depolarize AP axon of hair cells join cochlear nerve iii. cochlear nerve = auditory nerve, sends message to brain e. different sounds i. one end of basilar membrane- narrow, stiff, more tension, vibrates high sounds ii. Other end- wider, flexible, less tension, vibrates low sounds iii. brain interprets different pitches p. 922- green summary box draw/write out! Sound waves enter external auditory canal tympanic membrane vibrates malleus, incus, and stapes amplify vibrations oval window vibrates vibrations are conducted through fluid basilar membrane vibrates hair cells in organ of Corti are stimulated cochlear nerve transmits impulse to brain VIII. Light Perception A. Intro Light sensitive receptor cells containing photosensitive pigment Pigment- chemical change receptor cell transmits nerve impulse Wave length: 430-750 nm B. Eye [fig 43-18] 1. Sclera- outer coat tough, opaque connective tissue protection 2. Cornea- front surface sclera- thinner transparent fixed lens- focuses light 3. Choroid- inner to sclera sheet of cells- block pigment & absorb light blood vessels 4. Ciliary body- anterior portion of choroid (where sclera becomes cornea) consist of: ciliary muscle- smooth muscle change shape of lens accommodation- change focus for near & far vision [fig 43-19] ciliary processes- secrete aqueous fluid 5. Iris- pigmentated anterior to ciliary body diaphragm- muscular regulates size of pupil 6. Pupil- in center of iris 7. Retina- covers inside of choroid light sensitive 2 types of photoreceptors- specialized neurons a. rod- detect shape & movement respond to low light levels night vision contain rhodopsin- photopigment that is activated by light, changes shape depolarization b. cones- color vision, photopigment- bright light & fine detail 3 types- sensitive to specific wavelengths (red, blue, green) 8. Macula- near center of retina, functions to absorb UV light 9. Fovea- center of macula, tightly packed with cone cells (no rod cells) region of high visual acuity image most clearly focused 10. Optic disc- (blind spot) where optic nerve fibers leave eye 11. Lens- attached to ciliary body by suspensory ligaments divides eye into 2 chambers a. anterior cavity between cornea & lens aqueous fluid (watery) b. posterior cavity between lens & retina contains vitreous fluid (viscous-thicker) fluids- act as lenses, help focus image on retina glaucoma- blockage of ducts that drain the aqueous fluid increasing pressure, compresses retina, causes blindness 12. Conjunctiva- anterior to cornea, maintains moisture 13. Optic nerve- [fig 43-21] rods & cones synapse with bipolar neurons bipolar neurons- ganglion cells unite to form optic nerve out of eyeball & into brain p. 930- green box summary draw/write out! Light passes through cornea through aqueous fluid through lens through the vitreous body image forms on photoreceptor cells in retina signal bipolar cells signal ganglion cells optic nerve transmits signal to thalamus integration by visual areas of the cerebral cortex I. Endocrine System (Ch. 49) A. characteristics 1. Slower 2. Longer term responses 3. Generalized, not so precise 4. Regulates- metabolism, growth & development, reproductive behavior 5. Cell, tissues & organs ? secrete hormones B. Hormones 1. Chemical messengers regulation 2. Secreted in body fluids 3. Specific actions on target tissues- contains specific receptors for the hormone C. Gland- specialized for secretions Exocrine gland- not part of endocrine system secrete substances via ducts that open into free surfaces duct- tubular passage ex. Sweat, mucus, digestive enzymes, etc endocrine system- ductless glands & tissues that release hormones works with nervous system to regulate metabolic activities II. Types of Endocrine Signaling [fig 49-3] A. endocrine signaling endocrine glands comprised of endocrine cells secrets directly into blood B. neuroendocrine signaling Neurons release neurohormones into capillaries or interstial fluid C. paraendocrine regulation Horomone secreted into interstitial fluid & acts on nearby targeted cells D. autocrine regulation Hormone acts directly on cells that produce it III. Hormone Chemical Groups [fig 49-2] A. fatty acid derivatives 1. Long hydrocarbon chains 2. Examples- a. juvenile hormone (JH)- insects, preserves juvenile structure during molting b. prostaglandins- involved in a variety of physiological functions B. Steroid Hormones 1. Lipids- from cholesterol 2. Examples- a. molting hormone- insect b. cortisol- stress c. estradiol C. Amino acid derivatives 1. Simplest 2. Ex. Adrenaline D. peptide & protein hormones 1. Peptide- short ~9 amino acids, largest hormone group ex. Neuropeptides- oxytocin, antidiuretic hormone(ADH) 2. Protein hormones- larger, 100s of amino acids ex. Insulin IV. Regulation of Hormone Secretion A. many hormones regulated by negative feedback gland receives info about amount of hormone/secretion & then responds to restore homeostasis effects- opposite (negative) to stimulus hormone level low hormone production increases hormone level high hormone production decreases B. ex. Ca^2+ regulation by PTH (parathyroid hormone) PTH-released by parathyroid gland PTH- increase concentration of Ca^2+ by kidneys If Ca^2+ levels high gland slows PTH output Lecture 6: Senses 1/31/12 12:15 AM If Ca^2+ levels low gland increases PTH output [fig 49-1] V. Action of hormones in target cells A. Regulation of gene expression 1. Circulator system 2. Small, lipid soluble pass through cell membrane 3. If enter target cell a. bind to receptors in cytoplasm hormone-receptor complex into nucleus b. hormone passes into nucleus binds to receptor hormone-receptor complex 4. Complex binds to some specific site of DNA 5. Binding caused conformational change in DNA mRNA transcription or repression protein synthesis of repression [fig 49-4] B. Signal Transduction 1. Does not enter cell effect through 2nd messenger 3. Example: peptide hormone a. hydrophilic b. bind specifically to receptor in cell membrane of target tissue c. once hormone is bound to receptor message relayed into cell by 2nd messenger 2nd messenger- chemical that is activated when hormone combines w/ receptor & triggers a response in cell effector molecules in cell 4. Example of 2nd messenger: cAMP (cyclic AMP) a. G-protein- transmembrane inactive- bound to GP (guanosine diphosphate) b. hormone binds to receptor on cell membrane c. hormone-receptor complex formed binds to G-protein d. G-protein releases GDP & binds GTP conformational change in G-protein e. G-protein binds to adenylyl cyclase (membrane-bound enzyme) f. adenylyl cyclase activated ATP cAMP cAMP 2nd messenger g. cAMP 2nd messenger h. cAMP levels high ? activates protein kinase add phosphate group to specific protein phosphorylation mechanism by which an enzyme can be activated post-transcriptional control [fig 49-5] VI. Invertebrate A. hormones- nerves B. neurohormones- regulate many functions Growth & development, reproduction, metabolism, behavior C. Insect Development 1. Environmental factor activates neuroendocrine cells in brain BH (brain hormone) 2. BH stimulates prothoracic gland in thorax (behind head) MH (molting hormone) = ecdysone 3. MH a. stimulates growth & molting b. in mature insect- stimulates metamorphosis ex. Caterpillar butterfly c. in mature insect i. corpora allata- pair of endocrine glands secrete JH (juvenile hormone) ii. JH- prevents metamorphosis increases JH levels MH stimulates increase in size?molt Maintains juvenile state At each molt, amount of JH decreases When JH levels decrease, MH metamorphosis iii. synthetic JH insecticide prevents maturation into reproducing adults VIII. Human endocrine system A. main endocrine glands [fig 49-7] and [Table 49-1] B. abnormal rates of secretion 1. Hyposecretion- decreased output 2. Hypersecretion- increased output Endocrine System II I. Hypothalamus A. intro 1. Regulatory structure 2. Neuroendocrine tissue neurohormone 3. Link between nervous & endocrine system 4. Connected to pituitary gland by pituitary stalk B. modes of action 1. Releasing Hormones (RH) & Inhibiting Hormones (IH) released into pituitary vein blood supply for pituitary gland directly bathes anterior lobe of pituitary 2. Production of oxytocin +antidiuretic hormone (ADH = resopression) peptide hormones produced by cell bodies of neurons in hypothalamus ? axon extend into posterior pituitary hormones stored in vesicles axon terminals until neuron stimulated hormone released II. Pituitary gland A. Into- 2 parts: just below hypothalamus B. Posterior Pituitary 1. Posterior lobe 2. Secretes ADH & oxytocin a. ADH- kidney-targeted tissue, released when body needs to conserve water makes collecting ducts of kidneys more permeable to water more water reabsorbed into blood (smaller volume of urine) b. oxytocin i. stimulates smooth muscle contractile of uterus Pitocin- initiate or speed up labor ii. Letdown reflex- stimulates smooth muscle surrounding alveoli of breast (sacs that produce milk) baby at breast sensory nerves at nipple, signal pituitary to release oxytocin stimulates muscle contradiction breastfeeding gets uterus back to non-pregnant size iii. stimulates smooth muscle contractions in male & female reproduction tracts [fig 49-8] C. Anterior Pituitary [fig 49-9] 1. endocrine gland- signals from blood, releases hormones into blood 2. Regulated by RH & IH stimulate or inhibit specific hormones from anterior pituitary 3. Hormones a. prolactin (PRC) b. growth (GH = somatotropin) tropic hormones- stimulate another endocrine gland c. thyroid-stimulating gland (TSH) d. adrenocorticotropic hormone (ACTH) d. gonadotropic hormone luteinizing hormone (LH) follicle-stimulating hormone (FSH) 4. PRL- action a. following birth- stimulates milk production target tissue- mammary gland b. testes function c. parental behavior d. non-human species ex. Birds-regulates fat distribution, fish- water balance 5. GH a. regulation i. secretion of GH regulated by GHRH and GHIH- released by the hypothalamus ii. If GH levels in blood high Hypothalamus GHIH anterior pituitary releases less GH iii. if GH levels low hypothalamus GHRH anterior pituitary releases more GH b. action i. provides tissue growth = anabolic hormone ii. Stimulates production of IGH (insulin-like growth factor) by liver iii. IGF-peptide, stimulate cartilage formation linear growth of skeleton stimulate tissue & organ growth by increasing uptake of amino actions and stimulating protein synthesis c. abnormalities i. hypothesecretion of GH pituitary dwarfism small, correctly proportioned, normal intelligence treatment- human GH- cadaver recombinant DNA technology- human GH gene inserted into bacteria ii. Hypersecretion of GH during childhood gigantism during adulthood acromegaly connective tissue thickens, abnormal growth of bones in hands, feet, & head 6. TSH (thyroid stimulating hormone) a. tropic- stimulates thyroid b. regulation of TSH [fig- 10a] i. thyroid hormone concentration in blood, below normal level stimulates anterior pituitary to secrete more TSH stimulates thyroid ii. Thyroid hormone concentration in blood above normal anterior pituitary secretes less TSH thyroid produces less hormone iii. exposure to cold temperature hypothalamus stimulated to secrete TRH (TSH- releasing hormone) stimulates thyroid to secrete more hormone increase metabolism raises body temperature 7. ACTH a. stress stimulates hypothalamus to secrete CRF (corticotropin-releasing factor) b. CRF- stimulates anterior pituitary to release ACTH c. ACTH acts on adrenal cortex 8. Gonadotropic hormones- LH & FSH a. regulation- controlled by GnRH (gonadotropin-releasing hormone) form the hypothalamus b. action i. LH- female- ovary ovulation male- testes produce testostersone ii. FSH- female- ovary stimulates follicle growth male- testes testosterone secretion & sperm level production IV. Thyroid Gland 2 lobes, on ventral surface of trachea secretes hormones- important in growth & development & metabolism A. TSH (anterior pituitary) Stimulates thyroid to secrete 2 hormones Derived from tyrosine & iodine 1. Triodothyronine- T3 & 3 iodines 2. Thyroxine- T4 & 4 iodines most of production, less active form in target cells T4 T3 (more active) B. Action of T3 and T4 1. Stimulate cell metabolism of body 2. Growth and development of CNS 3. Homeostasis C. Calcatonin Tagert tissue = bone Lowers blood calcium levels by inhibiting calcium levels Removal from the blood D. Disorders of Thyroid Gland 1. Cretinism- extreme hyposection a. childhood b. mental & physical development is delayed 2. Myxedema- hypersecretion a. adult b. decreased metabolic rate impairs physical & mental functions 3. Grave?s Disease- autoimmune a. abnormal antibodies b. bind to TSH receptors stimulate c. weight loss, high body temperature, exophathalmus 4. Goiter [fig 49-10b] a. dietary deficiency of iodine b. thyroid gland muscle unable to produce enough hormones c. anterior pituitary secretes large amounts of TSH d. causes thyroid gland to grow IV. Parathyroid Glands A. 4 Glands In connective tissue surrounding thyroid gland B. PTH- stimulates calcium release from bones increases blood calcium C. PTH works antagonistically to calcitonin [fig 49-11a] V. Pancreas A. Function 1. Exocrine- pancreatic juice digestive enzymes into small intestine 2. Endocrine- islets of Langerhans clusters of endocrine cells 2 types of cells ? ? glucagon and ? ? insulin regulate blood glucose levels B. Glucose Regulation 1. Glucose levels high insulin secreted a. target tissue- all cells in body except brain binds to receptor stimulates cells to take up glucose from blood b. brain- can take up glucose w/out insulin 2. Low glucose levels glucagon secreted a. target tissue- liver b. raise blood glucose levels stimulates glycogen glucagon stimulates gluconeogenesis [fig 49-13] C. Malfunction Diabetes mellitus- most common endocrine disorder Very high blood glucose levels Cause of blindness, kidney disorders, gangrene Type I = insulin-dependent (10%) Onset before age 30 Insulin deficiency Autoimmune ?- cells destroyed by antibodies Type II = non-insulin dependent Insulin resistance Receptors on target Cells don?t bind insulin VI. Adrenal Gland A. Intro 1. On top of each kidney 2. Adjust to stress [fig49-15] 3. 2 parts [fig 49-14] adrenal medulla- central adrenal cortex- outer B. Adrenal Medulla 1. Alarm reaction 2. Neuroendocrine gland 3. Continuously secretes a. epinephrine (adrenaline) b. norepinephrine 4. Stress- a. sympathetic nerves in nervous system send messages from brain to adrenal medulla release acetylcholine in adrenal medulla b. triggers adrenal medulla to release epinephrine & norepinephrine i. blood goes to organs essential for emergency action ii. Raises level of fatty acid & glucose in blood iii. increases metabolic rate iv. Increases oxygen delivery, heart rate, stroke volume dilates bronchioles in lungs used for asthma attacks C. Adrenal Cortex 1. Chronic stress 2. Responds to endocrine signals 3. ACTH (from anterior pituitary) stimulates adrenal cortex to produce 3 types of hormones corticosteroids (from cholesterol) a. glucocorticosteriods- promote glucose formation most (95%) of activity due to cortisol = hydrocortisone increases blood glucose levels b. mineralocorticoids- regulate mineral metabolism fluid balance aldosternone- principle mineralcorticoid c. sex hormone precursors- converted into testosterone, estradiol Lecture 7: Endocrine System I Continued 1/31/12 12:15 AM I. Modes of Reproduction in Animals A. Asexual 1. Single parent offspring offspring identical to each other & parents clones 2. No meiosis 3. No fusion of gametes 4. Various methods a. fission- division of a parent into 2 or more individuals of about equal size b. budding- small part of parent?s body separate to form offspring ex. Sponges & cnidarians c. fragmentation- parent body breaks into several pieces regeneration- each fragment produces missing pieces d. partheogensis- no gametes unfertilized egg develops into adult animal advantages- rapid B. Sexual 1. Gametes- meiosis a. sperm- male parent, small motile, flagellated b. egg(=ovum)- female parent, large & motile, contains nutrients 2. Fertilization- gametes fuse zygote (2n) fertilized egg 3. Advantages- genetic variation recombination 4. Disadvantages- if offspring not like parent may be less likely to survive, if sessile- difficult time finding a mate 5. Hermaphroditism a. each individual has male & female reproductive systems b. self-fertilization, meiosis & fertilization c. cross-fertilization d. sequential hermaphroditism individual reverses sex during lifetime protogynous- female first, and then male protandrous- male first, and then female ex. Wrasses (reef fish) largest & oldest female changes to male harem- lots of females, one male remove male, largest female becomes male II. Male Reproductive System A. Function 1. Spermatogenesis- process of sperm production 2. Deliver sperm into female reproductive tract B. Testes (sing. Testis) Male gonads (reproductive organ) Spermatgensis Source of sperm & testosterone 1. Semiferoustubules- very long, hollow, small diameter, spermatogenesis 2. Interstitial cells- scatter between semiferous tubules produce testosterone & other male sex hormones C. Epididymis 1. Coiled tail 2. Structure a. head- on top of testes b. body- along side testes c. tail- at base of testes 3. Functions a. transport sperm b. sperm maturation c. sperm storage- mostly in tail D. Scrotum 1. Skin-covered sac contains testes epididymis 2. Suspended from groin testes & epididymis a. sperm cells cannot develop at body temperature need 1-2º cooler b. temperature affects: sperm production sperm longevity in humans & other animals, but except in elephants b.c they have lower body temperature at 35.9ºC and 96.6º 3. Mechanism of temperature regulation a. external b. bloody supply pampiniformplexus- testicular artery (warm blood) & vein (cooler blood) coiled around each other for heat exchange c. muscles sensitive to temperature warm relax, testes descend cold contract, testes closer to body E. During Ejaculation Sperm from epididymis?propelled through vas deferus F. Vas Deferus 1. Sperm ducts- one from each epididymis 2. From scrotum to pelvic cavity 3. Vasectomy- ligation 4. Each vas deferus erupts into an ejaculatory duct G. Ejaculatory Duct Short Passes through prostate gland & then joins with urethra H. Urethra 1. Carrie urine & semen 2. Passes through penis I. Penis [fig 50-7] 1. Copulary organ delivers sperm into female reproductive tract 2. Urethra- down middle 3. Bulbourethral gland 2 small, round either side of urethra first gland to deposit secretion into urethra at time of arousal bulbourethral fluid mucous- lubricant some sperm released before ejaculation major reason for high failure rate of withdrawal method 4. Erectile tissue a. 3 parallel columns 2-carnervous bodies 1- spongy body b. sexual stimulation: parasympathetic nerves of autonomic nervous system release NO (nitric acid) smooth muscle in arterial walls of pelvis to relax arteries dilate blood in erectile tissue swells veins compressed blood comes in faster by artery than it leaves by vein Viagra- promotes action of NO 5. Glans penis- tip of penis that has sensory neurons 6. Prepuce- foreskin, removed in circumcism III. Semen A. Sperm & Fluid B. Seminal Vesicles 1. Pair 2. Fluid fructose- energy for sperm prostaglandins- stimulate contractions of female uterus 3. Secrete into vas deferens 4. ~60% of total volume of semen yellow pigment- fluoresces C. Prostate Gland 1. Alkaline fluid- neutralizes acidic vaginal environment 2. Cancer- ~1/3 of men over 50 have prostate cancer ~37& die, PSA test-prostate specific antigen D. Bulbourethral Gland Pathway for sperm Testes epididymis vas deferens ejaculatory duct urethra IV. Spermatogenesis [fig 51-4] and [fig 51-5] A. Spermatogonia Undifferentiated cells In walls of seminiferous tubules Diploid (2n) Divide by mitosis more spermatogonia Some enlarge become primary spermatocytes ~3 million spermatogonia differentiated into primary spermatocytes each day B. Primary Spermatocyte Diploid (2n) 1st division of meiosis secondary spermatocytes meiosis II 4 spermatids C. Mature Sperm Cell [fig 51-6] 1. Head a. nucleus- DNA b. acrosome- on surface of head, membrane-bound vesicle enzymes help sperm penetrate into egg 2. Midpiece- mitochondria energy (ATP) for movement of tail of sperm 3. Tail- flagellum 9x2 arrangement of microtubules E. Sertoli Cells In seminiferous tubules Functions: 1. Adjacent Sertoli cells form tight junctions areas of tight connections between membranes of adjacent cells form ring around lumen of tubule blood- testes barrier protection for developing sperm from toxins that may be in blood prevents sperm from getting into blood 2. During sperm development most of sperm cytoplasm discarded & phagocytized by Sertoli cells 3. Produce hormones 4. Provide nutrients to sperm ? ?nurse cells? V. Male Endocrinology [fig 50-8] and [Table 50-1] A. Androgens 1. Sex hormones in males 2. Testosterone most important B. Hypothalamus 1. Secretes GnRH into pituitary portal vein of anterior pituitary 2. GnRH- pulse-secreted every 2 hours 3. GnRH- stimulates anterior pituitary LH & FSH C. LH 1. Target tissue- interstitial cells of testes 2. Interstitial cells- produce & secrete androgens (testosterone) D. Testosterone 1. Level in tests has to be high 2. Stimulates puberty a. period of sexual maturation sex characteristics develop b. growth spurt c. primary male characteristics grow reproductive organs d. secondary sexual development deep voice facial hair & body hair muscle development E. FSH 1. Stimulates development of seminiferous tubules 2. Stimulates Sertoli cells to produce & secrete: ABP- androgen binding protein Binds to testosterone sequestered Maintain high levels Reproduction I & II (Ch. 50) 1/31/12 12:15 AM I. Development (Ch. 17) A. all changes that occur during entire life cycle of an individual Fertilization through birth/hatching B. Unicellular zygote multicellular organism 1. Cell division- mitosis increase in # of cells 2. Cell determination- molecular events activities of certain gens altered cause cell to become more committed to specific gene activation exception stem cells do not differentiate & they retain the ability to give rise to wide variety of cell types 3. Cell differentiate: final step specialization cell specialized biochemically & structurally 4. Morphogenesis- process by which cells organize themselves into a particular form & structure through pattern formation?organization of cells in 3D structures signaling between cells changes in cell shape cell migration apoptosis- controlled death of cells ex. Webbed fingers/toes & spinabifida C. Nuclear Equivalence 7200 different types of cells all came from same cell all nuclei all have same info that was in zygote D. Differential Gene Expression each cell type expresses subset of info II. Fertilization A. Sperm- flagellated, motile fuse with ovum- larger, immobile zygote- single cell (fertilized egg) B. Consequences of Fertilization 1. Restores diploid # 2. Determines sex 3. Stimulates reactions that lead to development C. 4 Steps in Fertilization 1. Contact & recognition 2. Sperm entry into egg 3. Egg activation & beginning of development 4. Sperm & egg nuclei fuse D. Sea Urchin (phylum Echinodermata) 1. Readily available 2. Easy to work with 3. Easy to obtain lots of gametes 4. Extremely fertilized E. Contact & Recognition 1. Oocyte surrounded by plasma membrane & various coverings functions of coverings: a. aid in fertilization by sperm of same species b. barrier to interspecific fertilization 2. Sea urchin a. egg coverings- internal to external i. plasma membrane ii. Uterine envelope?thin iii. jelly coat?think, glycoproteins b. sperm released w. water i. in same species of external fertilizers egg release chemicals into water that attract sperm chemotaxis OR ii. Other spp- chance c. sperm contacts jelly coat & undergoes acrosome reaction i. pores enlarge in membrane of acrosome ii. Calcium from seawater move into acrosome swells, release proteolytic enzymes digests path through jelly coat to vitelline envelope ii. Bindin: species-specific binding protein on acrosome if egg & sperm are same species bindin adheres to bindin receptors on vitelline envelope 3. Mammal a. egg enclosed by i. zona pellucida ii. Granulosa cells newly acquired sperm not ready to undergo acrosome reaction b. capacitation phase that occurs in female reproductive tract increase motility makes sperm capable of acrosome reaction something in seminal fluid inhibits capacitation once sperm are in female, seminal fluid diluted ~6 hours c. acrosome reaction- sperm bind to ZP3 (glycoprotein) in zona pellucida acrosomal & plasma membranes of sperm fuse pores- hydrolytic enzymes released enzymes help sperm get to egg F. Regulation of sperm entry into egg 1. Sea urchin a. acrosome- vitelline envelope binding enzymes dissolve small area of vitelinne envelope microvilli on egg plasma membrane elongate & surround the head of sperm egg & sperm plasma membranes fuse fertilization cone contracts draws sperm into egg plasmogamy b. prevention of polyspermy i. fast block- unfertilized egg polarized & cytoplasm negatively charged relative to outside after sperm fuses ions channels move in egg plasma membrane open calcium enter egg egg polarizes prevents fusion by sperm only lasts about 1 min (transient effect) ii. Slow block- cortical reaction sperm bind to receptors on vitelline envelope activates signal transduction pathway in egg release of calcium stored in ER into cytoplasm increase in calcium triggers cortical granules to migrate to plasma membrane & fuse w. plasma membrane exocytosis occurs releases enzymes & proteins into space between plasma membrane & vitelline envelope protein links broken space enlarges vitelline envelope forms fertilization envelope hardens ? prevents entry by additional sperm requires ~1 min complete block 2. Mammals- enzymes released by cortical granules after sperm receptors on zona pellucida no other sperm can bind hardening of zona pellucida no fertilization envelope forms G. Activation of Egg 1. Activation program- series of metabolic changes that occur in the egg trigger by an increase in calcium ions in cytoplasm 2. Increase in aerobic respiration maternal enzymes & proteins activated increased protein synthesis?maternal mRNA egg nucleus?secondary oocyte (stalled at metaphase II) fertilization triggers resumption of meiosis female protonucleus & 2nd polar body H. Fusion of sperm & egg prouclei 1. Occurs simultaneously w. egg activation egg- provides most of cytoplasm & organelles 2. Sperm nucleus guided to egg pronucleus by microtubules 3. Sperm nucleus swells male pronucleus 4. *Female & male pronuclei karyogamy (nuclear fission) zygote(2n) totipotent- potential to give rise to all cell types III. Cleavage A. 1st step in embryogenesis B. in zygote, immediately after fertilization Series of rapid mitotic divisions Not accompanied by significant cell growth Increase # if cells Embryo size doesn?t increase C. Stages Zygote(one cell) embryo(2 cells & more) blastomeres- cell Human- 1st division ~24 hours after cell membranes fuse morula- (?mulberry?) 32 cells, solid balls of blastomeres blastula- 64 to several 100 blastomeres, hollow ball, blastocoel fluid-filled cavity D. Yolk- affects patter of cleavage 1. Mixture of protein, fats, & phospholipids 2. Amount of yolk varies among spp a. macrolecithol- lots of yolk in egg until hatching ex. Birds, reptiles b. microlecithol- little yolk b.c they receive maternal support ex. Mammals 3. Distribution of yolk a. isolecithol eggs i. small amount of yolk uniformly distributed in a cytoplasm ii. Most invertebrates & simple chordates iii. holoblastic cleavage- cytokinesis completely separates cells during division iv. Either radial or spiral cleavage Radial- deuterostomes ex. Echinodermata & chordates Spiral- protostomes ex. Annelids & mollusks B. telolecithol i. yolk not distribute equally vegetal pole- end of cell w. large amounts of yolk animal pole- opposite end, more metabolically active ii. Some eggs are moderately telolecithol mesolecithol ex. Amphibians cleavage- holoblastic, radial vegetal hemisphere divisions slowed by yolk vegetal hemisphere- fewer but larger cells animal hemisphere- more, smaller cells blastocoel- located more toward pole [fig 51-6] iii. telolecithol- birds & reptiles large amount of yolk at vegetal pole?never cleave blastodisc- small disc of cytoplasm that?s located at the animal pole cleavage described as meroblastic restricted to blastodisc blastomeres- form 2 layers, epiblast-upper, blastocoel, hypoblast- lower [fig 51-7] E. Cytoplasmic Determinants 1. Proteins & RNA in zygote cytoplasm 2. In specific locations end up in specific populations of blastomeres 3. As a result, certain gene activities are going to triggered in certain blastomeres 4. Distribution in the cytoplasm varies a. mosaic development- determinants are not evenly distributed in the cytoplasm if 1 cell is removed/destroyed adult structures that would have developed are now missing b. regenerative development- uniform distribution cells produced by cleavage are equivalent Development I (Ch. 51) 1/31/12 12:15 AM I. Gastrolation A. morphological process by which a blastula becomes a gastrula B. Gastula- 3 layered embryo C. Changes in cell motility, cell shape, & cellular adhesion D. Sea Urchin- Isolecithol 1. Beings when a group of cells at vegetal pole flatten 2. Then move inward through invagination 3. Go to opposite wall obliterate blastocoel results in double-walled cup-shaped structure embryo lengthens ? no change in mass 4. Inner wall ? lines archenteron?newly formed cavity becomes digestive tract 5. Opening of archenteron is the blastopore deuterostome- anus 6. 2nd opening will form at the other end of archenteron mouth [fig 51-4] 7. 3 germ layers a. endoderm- cells lining archenteron b. ectoderm- outer wall c. mesoderm- buds off archenteron between ecto- & endo- E. Birds- telolecithol 1. Simple gastrulation can?t take place b.c. of yolk that?s in vegetal hemisphere 3. Epiblast cells- upper layer of cells at animal pole migrate toward midline form primitive streak, thickened cells constantly migrating from epiblast inward to primitive groove sink down, then move laterally [fig 51-10] 4. Henson?s node- thickened region at anterior end of primitive streak form notochord II. Mammalian Development A. Fertilzation- oviduct B. Cleavage- oviduct Primary division ~24 hours 1. Embryo- no obvious polarity Primary divisions are random until blastula 2. No yolk- division is holoblastic blastomeres are all equal size 3. Blastula blastocyst ~1 week C. Blastocyst 1. Trophoblast a. outer single layer of cells b. forms chorion & amnion- membranes that surround embryo c. when trophoblasts come in contact w. endometrium secrete enzymes penetrate endometrium d. trophoblast- thickens, finger-like projections into endometrium implantation e. placenta forms from the trophoblast & endometrium 2. Inner cell mass- cluster cells fetus in ~2 months sometimes divides 2 independent groups = monozygotic twins if mass does not separate = conjoined twins 3. Blastocoel D. Gastrolation 2nd & 3rd week 1. Takes ~1 week 2. Inner cell mass: epiblast- outer layer hypoblast- inner layer 3. Epiblast cells ? involution move inward, forms primitive streak some epiblasts mesoderm some epiblasts mix w. hypolast endoderm rest of epiblsat ectoderm 4. Gastrulation a. 3 germ layers b. extra- embryonic membrane i. choria- surrounds embryo & all other membranes ii. Amnion- encloses embryo in fluid-filled cavity iii. yolk sac-membrane blood cells iv. Allantois- develops from outpocketings of gut incorporated w. umbilical cord blood vessels E. Organogenesis Increase in size of embryo 1. *notochord, brain, spinal cord ~2 ½ weeks a. mesoderm notochord b. notochord sends signals to ectoderm thicken & form neural tube becomes nervous system induction cells stimulate other cells c. central cell of neural plate- move downward form depression neural groove d. cells on either side of groove roll up neural tube chordates- nerve chord is hollow [fig 51-11] e. neurua- embryo- neurulation occurs anterior portion- brain posterior portion- spinal cord f. birth defects i. anencephaly- neural folds fail to fuse at anterior end no forebrain ii. Spina bifida- neural folds fail to fuse at posterior end iii. neural tube defects- folic acid 2. Heart-beat 3 ½ weeks 3. Organs- development from 3 germ layers [Table 51-1] and [fig 17-1] Development II (Ch. 51) 1/31/12 12:15 AM F. Birth ~266 days (38 weeks, 9 months) [Table 51-2]
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