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The centralcavity of the gastrula stage of embryonic development that is lined withendoderm; the primitive digestive system.
a neuron conducting impulsesinwards to the brain or spinal cord
Example of a Trichonymph
o Triploblastic but have a solid body cavity
o They have to have a very simple body plan
Ex: Flatwormsand ribbon worms
The evolution of the head; concentrationof nervous tissue and sense organs atthe front end of the animal.
Evolved alongside bilateral symmetry
· Scientific Communication
the scientific study of the diversity oforganisms and their evolutionary relationships; employs two tools.
o Reconstruction of Phylogeny
The science of naming, describing, and classifyingorganisms; Species identification.
o Each species is assigned a two part name; thefirst part is the genus, and the second part is the specific epithet..
Proposed the separation of Fungi fromthe plant kingdom, and the addition of Prokaryotae to accommodatebacteria.
Proposed 3 domains based on rRNA 16S (ribosomalRNA)
1. Domain (broadest)
8. Species (most specific)
feature or characteristic in question.
Structural, physiological, developmental,behavioral, molecular traits (DNA, rRNA), fossils
the presentation of one alternative form of agiven character.
Ex: hair=Y/N;red hair, brown hair, hair, black hair
character derived from same structure in commonancestor; useful in creating a phylogenetic tree.
Example: vertebrate limbs, same bone structure used fordifferent purposes in different species
Similarfeatures even though not descendent from common ancestor; occurs via convergentevolution or reversal; not useful in constructing a phylogenetic tree.
Example: wings of birds and butterflies or ichthyosaurus and dolphins
The independent evolution of structural or functionalsimilarity in two or more distantly relates species, usually as a result toadaptations to similar environments.
features that were present in an ancestralspecies, and remain present in all groups descended from that ancestor
Example: vertebral column in sub-phylumVertebrata; indicate remote ancestry; the presence of a vertebra indicates acommon ancestor between species in the phylum
science that uses molecular structure to uncoverevolutionary relationships
Example: Aminiotes, develop through an embryo thatis enclosed within a membrane called an amnion.
Phylogenetic groups that includes SOME of the descendants of the recent commonancestor, but not all.
Example: reptiles, excludes birds even though theycame from a common ancestor as crocodiles, turtles, and lizards, etc.
Phylogenetic group in which members do not share the same recent ancestor.
Example: Warm blooded tetrapods; tetrapods that canregulate their own body temp; these are mammals and birds, they do not share acommon ancestor
Excavates, chromalveolates, rhizarians,archaeplastids, and unikonts
o They are made of unicellular eukaryotic cells,with the exception of animals which are multicellular
o They are heterotrophic
o They have flagella
Anaerobicflagellated excavates that often live in animals
Examples: Trichonymphs and Trichomonads
Parasitic T.vaginales (STD in humans)
§ Atypical Mitochondira
§ Crystalline rod in flagella
§ Many photosynthetic
§ Has onlyone mitochondrion
§ 1 Flagellum w/ crystalline rod
§ Parasitic forms (blood of vertebrates)
Trypanosomabrucei: cause of African sleepingsickness
Micronuclei (2n): reproduction
Macronucleus (polyploid): cell metabolism andgrowth
Conjugation in Paramecium (5)
Protists characterized by the presence of tests (shells), and are marine organisms; about the size of a grainof sand.
Two Clades: Forams and Actinopods
Beginning of specialized cells for a specificfunction, which is evolutionary stem to multicellularity
Cannot be divided onto equal parts by any plane
Bodyplan in which any section through the mouth and down the length of the bodydivides the body into similar halves.
Ex: Cnardians (jellyfish) and Adult Echinoderms (sea stars)
Body plan in which only two section can be madeto divide the body into similar halves.
Ex: ctenophores (comb jelly)
Body plan where the right and left halves of thebody of mirror images of each other; can be divided by only one plan to achieveequal halves.
Evolved alongside cehpalization
Most animals exhibit either ______ or __________ symmetry. The ______ symmetry is only seenin the sponge and ______ is only seen in the comb jelly.
Diploblastic Tissue Development
§ Has only 2 germ layers; the ectoderm andendoderm
§ Only in Phylum Cnidaria and Ctenophora
Triploplastic Tissue Development
§ Has 3 germ layers
§ Typically found in Bilateria
o Has a “false coelom”
o Body cavity that is not completely lined with mesoderm;the epithelium (endoderm) is not lined.
The zygote rapidly divides mitotically to make embryo; the resultingcells, blastomeres, become smallerand smaller in size, and form into a hollow ball-like structure. When there are 32 cells comprising the ballit is call a morula, and where thereare more than 64 cells, it is call a blastula. The blastula has a hollow fluid filled cavitycalled the blastocoele.
The primitive opening of the body cavity in an early embryothat may become the mouth or anus in the adult organism.
o Phylum Porifera: Sponges
o Phylum Placozoa: Trichoplax
Class Holothuroidea: SeaCucumber
Class Echinoidea: SandDollar
Class Asteroidea: Sea Star
Key Characteristics ofPhylum Nematoda
o Complete Digestive System
o Ecdysis (molt)
Main function of nervous system
Reception and response to stimuli
o Main regulatory system in animals
o Coordination, control and homeostasis
o Combination of electrical and chemical signals
o Fast response to stimuli—but short lived
Important to the blood brain barrier: they form tight junctions
o Line Cavities of CNS
o Important in the production and circulation ofcerebral spinal fluid (CSF)
o May function as neural stem cells
o Release signaling molecules that mediate inflammation
o Phagocytosis of Bacteria and debris
Two factors determine membrane potential
Selective Ion Channels (2 kinds)
§ Neuron becomes more positive
§ EX -70 mv to -50 mv
Neuron becomes more negative
o local axonal excitation—occurs in a specific spot on the membrane,but not across the whole membrane/neuron (not action potential)
Voltage activated Na and K channels closed
Activation threshold reached, Na rushes
Action potential Properties (2)
Presynaptic neuron is in contact with themembrane of the post synaptic neuron; the two neurons form gap junctions;cytoplasm of both neurons are in contact with each other
Trends in Evolution of Nervous System
· Nerve net
· Radial nervous system
· Bilateral nervous system
o Segmentation is present in the nervous system
o Alongl the ventral nerve cord are segmental ganglia
o Ventral nerve cord w/ concentration of nervecells froming asegmental ganglia
o The body is segmented into head, throrax, and abdomenthat are made of several segments
o Cerebral ganglia with specific functionalregions
o Anterior Nerve Ring
o Ventral Longitudinal nerve cords
o Brain + Spinal Cord (Dorsal)—a central nervoussystem
NOTE THAT THE CNS IS DORSAL NOT VENTRAL LIKE THEINVERTEBRATES
Evolution of nervous system
o Increase in the number and concentration ofcells:
o Specialization of function
o Increasing complexity
§ Receptors receive information from the externalenvironment
§ Afferent Sensory nerves transmit signals fromreceptors to CNS
§ Efferent nerves in CNS transmit signal from CNSto effectors; skeletal muscles and glands
§ Receptors receive from internal environment
§ Afferent nerves transmit signal from receptos ininternal organs to CNS
§ Efferent nerves transmit signals from CAN toeffectors; smooth muscle, cardiac muscle, glands, etc.
Functions of the Meninges
o Cushioning the brain and spinal cord
o Providing brain w/ nutrients
o Removing waste
o Transmits impulses to/from the brain
o Control reflex activities
decrease activity of inhibitory neuron thatsends messages to dopamine releasing neuron, thereby allowing the dopamineneuron to fire more rapidly.
stimulates dopamine- releasing neuron in thebase of the brain that in turn stimulates the cerebral neuron of the rewardsystem more rapidly.
Sensory receptors that transduce mechanical energy (change in shape),touch pressure, gravity, equilibrium, internal organs (like stomach)
o Muscle spindles (muscle movmt and tone)
o Golgi tendon organs (tension in contractingmuscle, and tendons)
o Joint receptors (mvmt in ligaments)
receptor cells; series of cilia (stereocillia) that have thelongest on one side and get steadily smaller (9+2); pushing the cilia one waytransmits signal, the other inhibits the signal
utricle contains the hair receptor cells; contains fluid w/otolith granuels in it that stimulate the hair cells as our orientation changes
§ secrete their products through a duct ordirectly onto the surface (sweat glands, gastric glands)
Four Types ofEndocrine Signaling
endocrine cells release hormones that atransported to target cells by the blood. They are then recognized by a target cell by binding to their receptors,specific to the hormone.
Neurons release neurohormones, secreted down theaxon. They are trans by the bloodstreamor diffuse into the interstitial fluid. They then bind to target cell on its specific receptors for the neurohormone