Physiology

Spans the field of anatamy, chemistry, and physics

A physiologist searches for ____________

the link between cause (independent variable) and effec (dependent variable)

Levels of Organization

Chemistry->Molecular Biology ->Cell Bology->Physiology->Ecology

Organ systems are integrated(work together) to ______________

maintain homeostasis

Nuitrients and wastes pass between blood and cells via ______________

interstitial fluid

Respitory system

Takes in oxygen and eliminates carbon dioxide

Digestive system

Takes in nuitrients, breaks them down, and eliminates unabsorbed matter (feces)

Integumentary system

Protects the body as a whole from the external environment

Cardiovascular System

Via the blood, distributes oxygen and nuitrients to all body cells and delivers wastes and carbon dioxide to disposal organs

Urnary System

Eliminates nitrogenous wastes and excess ions

Nevous tissue

Internal communication

- Brain, Spinal chrods, and nerves

Muscle Tissue

Contracts to cause movement

Muscle attached to bones(skelletal)
Muscles of heart(cardiac)
Muscles of walls of hollow organs (smooth)

Epithelial tissue

Forms boundaries between different environments, protects, secretes, absorbs, filters

Skin surface(epidermis)
Lining of GI tract organs and other hollow organs

Epithelial tissues are liners

Connective Tissue

Supports, protects, and binds other tissues together

Bones
Tendons
Fat and other soft padding tissue

Collagen fibers of tendon_________

are densely packed into parallel bundles

Lumen

Is a hollow center that forms in exocrine glands, creating a duct that provides a passageway for secretions to move to the surface of the epithelium

Endocrine Glands

lose the connecting brdge of cells that links them to the parent epithelium. Their secretoins go directly into the bloodstream

Ductless and they release their secretions, called hormones, into the bodys extracellular compartment

Some best known endocrine glands are the pancrease, theyroid gland, gonads, and the pituitary gland.

Isolated endocrine cells

Occur scattered in the epithelial linning of the digestive tract, in the tubules of the kidney, andi in the walls of the heart.

Exocrine Glands

null

Goblet cells

secrete mucus into the lumen of hollow organs such as the intestine

Serous Secretions

Are watery solutions, and many of them contain enzymes.

Tears, sweat, and digestive enzyme solutions are all serous exocrine secretions

Exocrine Glands

Release their secretions to the bodys external environment---This may be onto the surface of the skin or onto an epithelium lining one of hte internal passageways, such as the airways of the lung or the lumen of the intestine. In effect the exocrine secretion leaves the body ---> This explains how some exocrine secretions, like stomach acid, can have a pH that is incompatible with life

Most exocrine glands release their products through open tubes known as ducts.

Sweat glands, mammary glands in the breast, salivary glands, the liver, and the pancreas are all exocrine glands.

During development, the region of epithelium destined to become glandular tissue____________

divides downward into the underlying connective tissue

Simple squaumous epithelium

Single layer of flattened cells with disc shaped central nuclei and sparse cytoplasm ;the simpliest of the epithelia

It allows a passage of materials through diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae

Its located in the kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity

skeletal muscle tissue

Cells are long, cylindrical, striated, and multinucleate. Neurogenic only. Voluntary

Its combined with connective tissues and neural tissue in skeletal muscles

It moves or stabalizes the position of the skeleton; guards entrances and exits to the digestive , respiratory, and urinary tracts; generates heat; protects internal organs

cardiac muscle tissue

cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercallated discs. Myogenic only. Involuntary

Located in the heart

It circulates blood; maintains blood (hydrostatic) pressure

Smoth muscle tissue

Cells are short, spindle shaped, and nonstriated, with a single, central nucleus. Myogenic and neurogenic. Involuntary

Found in the walls of blood vessels and in digestive, respiratory, urinary and reproductive organs

It moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels

Skeletal characteristics

multinucleate
Cylindrical, extends muscle bundle
No gap junctions between cells
Striated
Contraction by sliding of thin/thick filaments
Voluntary
Neurogenic

Smooth muscle characteristics

Uninucleate
Tapered, does not extend length of muscle
Gap junctions present between some cells
Not striated
Contraction by sliding of thin/thick filaments
Involuntary
Neuro- & Myogenic

Cardiac characteristics

Uninucleate
Branched, does not extend length of muscle
Gap junctions present between cells
Striated
Contraction by sliding of thin/thick filaments
Involuntary
Myogenic

Homeostasis

'Fluid compartments,' and the exchange of substances between the compartments, is a fundamental property of homeostatic mechanisms

Is fundamentally a property of cells, but it operates across all organizational levels

Extracellular Fluid Compartment (ECF)

is subdivided into plasma and interstitual fluid . Material moving between cells and ECF must cross the cell membrane

Exchanges(transport)

must occur between fluid compartments of the body, and between the body and the external environment

Takes place along cell membrane

Leaky exchange epithelium

allows movement through gaps between the cells

Tight junctions in a transporting epithelium

prevent movement between adjacent cells.

Substances must instead pass between the epithelial cell, crossing two phospholipid cell membranes as they do so

All physiological variables are regulated homeostatically and use mechanisms that are____________

dynamic
stable
flexible
confer an integrated balance

Heat gain and heat loss must be ____________

balanced

When theres high environmental temperature.

Maximize heat loss:

Vasolilation of cutaneous blood vessels
Increased sweating
Behvioral response
- Use of fans to create convective heat loss
- Immersion of water to increase conductive heat loss
- staying out of sun to prevent radient heat gain
-Removing clothes

When theres high environmental temperature

Minimize heat production

Diminish food intake to lessen obligatory heat production

Behavioral response- decrease physical activity

When theres low environmental pressure

Minimize heat loss

Vasoconstriction of cutaneous blood vessels
Lack of sweating
Behavioral response- adding clothes, standing by heat source, etc...

When theres low environmental pressure

Maximize heat production

Shivering thermogenesis
Nonshivering thermogenesis(unproven in humans)
Behavioral response - increase physical activity

Negative feedback loops

are homeostatic
play a huge role in maintaining homeostasis - they reverse the direction of the variable

Elements

the simplest kind of matter

Atomic shells or 'orbitals

contain e's at different energies

Covalent bonds

shared electrons between atoms (H20)
involve electron sharing

Ionic Bonds

'electrical' bond between ions (NaCl)
involve an electron attraction between atoms after gaining/losing one or more electrons

ions

atoms which have completely lost or gained an electron

Hydrogen bonds

weak electrical attraction between H2O's
between water molecules also involve an electron attraction but this is due to unequal distribution of charge within a water molecule, rather then the gaining/losing of the electron

Atoms with unfilled outer orbitals are__________________

chemically reactive, they try to bond with another atom so that the outer orbital is filled up with electrons, either by sharing those electrons(covalent bonds) or by completely losing/gaining electrons (ionic bond)

Covalent bonds ________ electrons between outer orbitals

share

Atoms with filled outer shells are _______________

chemically unreactive

Shared electrons

form covalent bonds

H20 molecules exibit ____________

electrical polarity even though they are electrally neutral

Simple Diffusion

only uses the energy inherent in molecular movement.
It is a passive process even though it depends upon thermal energy to be present

Diffusion

Occurs 'down' a gradient, either a concentration gradient, or an electrical gradient

Diffusion of a substance

can occur only if there is no barrier, even if a gradient does not exist

Osmosis

Diffusion of water
Water moves by osmosis into the more concentrated solution
Osmosis involves H20 movement across the membrane permeable to water, but that is impermeable to solute
Osmosis is the movement of water down its (gradient); Osmosis could also be described as the movement of water against the (solute) gradient

Tonicity

refers to changes in cell volume as the result of differences in the ICF, and ECF, {solute}

ECF is Hypo if_____________

cells gain H20 when ECF is less than the ICF.
- ex. cell swells and cell membrane stretches

ECF is Hyper if_____________

Cell loses H20 when ECF is more than the ICF
- ex. the cell shrinks and the cell membrane wrinkles. Cells lose H20 through osmosis

More acidity=________

increased {H+}

Higher pH=________

less acidity

CHOs=__________

Monosaccharides

Lipids=___________

Fatty acids and monoglycerides

Proteins=

amino acids

Hydrophilic-

hates lipids, can be dissolved in water

The head of the cell membrane is____; Tails_______

charged; arent charged- these are phospholific molecules

Liposomes have an ______ center

aqueous

Transmembrane proteins:

carriers and channels
Cell membranes can act as a barrier

Transport proteins(carriers and channels) of membranes= ___________

integral proteins

Cell membranes are made up of ___________

double layer trigliceride fatty acid

Fascilitated diffusion

is like 'simple diffusion' except that it uses a carrier protein
Carrier- mediated transport of substances, if passive

Active=

some type of cellular energy needed

Carrier mediated transport may be passive as in __________

facilitated diffusion or active

Graded potential (GP's)

are variable- strength signals that travel over short distances and lose strength as they travel through the cell.
They are used for short-distance communication.
they are stimulated with ligand-gated channels are opened
GP's can be summed

What happens when a depolarizing graded potential is strong enough when it reaches an integrating region within a neuron?

The graded potential initiates an action potential

Action potential

are very brief, large depolarizations that travel for long distances through a neuron without losing strength.
Their function is rapid signaling over long distances

Graded potentials in neurons

are depolarizations or hyperpolarizations that occur in the dendrites and cell body or, less frequently, near the axon terminals
Their size or amplitude is directly proportional to the strength of the triggering event

Local current flow

The wave of depolarization that moves through the cell

The # of stimulus to the number of action potentials generated is

null

The initiation of an action potential from several nearly simultaneous graded potentials is an example of _________

spatial summation
- spatial refers to the fact that the graded potentials originate at different locations on the neuron

Postsynaptic inhibition

May occur when a presynaptic neuron releases an inhibitory neurotransmitter onto a postsynaptic cell and alters its response
The neurons fire, creating one inhibitory postsynaptic potential (IPSP) and two excitatory graded potentials that sum as they reach the trigger zone

Solutes

Substances that are dissolved

solvents

dissolves other substances

Solutions

solutes dissolved in a solvent

The pH scale

is a 'log' scale and is a measure of {H+}

A substance that gives up a H+ is a _______

acid

When H+ is bound to something, _____________

it does not contribute to acidity

A substance that binds free H+ is a _______

base

Polypeptides-> different shapes =

Proteins

In proteins: Amino acids=

the monomer

In Nucleic acids : nucleotides= ___________

monomer

In Nucleic acids: DNA/RNA=

nucleotide polymers

Simple diffusion only uses _______________

the energy inherent in molecular movement
It is a passive process, even though it depends on thermal energy to be present

Diffusion occurs __________ a gradient

down; either a concentration gradient or an electrical gradient

Diffusion of a substances can only occur if___________

there is no barrier, even if a gradient does exist

Before Osmosis

Two compartments are separated by a membrane that is permeable to water but not glucose

After osmosis

water moves by osmosis into the more concentrated solution

macromolecules are made up of

monomers linked by chemical bonds(covalent, ionic, hydrogen)

CHOs= monosaccharides
Lipids= fatty acids and monoglycerides
Proteins= amino acids

Phospholipids form lipid bilayers and micelles because __________

they have polar and nonpolar regions

Phospholipids arrange themselves _____________

so that their nonpolar tails are not in contact with aqueous solutions such as extracellular fluid

Phospholipid bilayers

Form a sheet

micelles

are droplets of phospholipids

Liposomes have an ________ center

aqueous

Substances can be transported across a

semipermeable cell membrane(i.e exchanges are made across a barrier between fluid compartments) by means of transmembrane channels

Transport proteins(carriers and channels) of membranes=

integral proteins

Open Channels

Have gates but spend most of their time in the open gate

Gated Channels

are usually closed. They open in response to chemical, mechanical, or electrical signals

As long as the lumen of a channel protein is open, ____________

substances specific to that channel traverse the cell membrane by diffusion according to the gradients involved

Diffusion through a cell membrane

pg 69

1. Simple diffusion of through the phospholipid bilayer
2. Carrier- mediated faciilated diffusion; binding of a substrate causes shape change in transport protein
3. Facilitated diffusion through a channel protein
4. Osmosis, diffusion of water into a high solute region

Na+ - K+ ATPase: an example of ___________

so is Na+ - K+ metabolic pump

Primary active transport

Primary Active Transport

requires energy, and results in the transport of substances against their gradient

The cell membrane allows a seperation of electrical charge between the fluid compartments of the body-->

membrane potential

The unequal distribution of charge only occurs _______________

immediately adjacent to the cell membrane/ This 'charge seperation' represents a form of potential energy that can be used to work (e.g. opening/closing/ gated channels and communication between neurons.)

Concentration Gradients

K+: very low in ISF, very high in ICF
Na+: very high in ISF, very low in ICF

Electrical gradients and {gradients}

may be in the same direction, or they may oppose eachother

Leak channels are __________

everywhere , V-g'd channels are on the 'transmitting' end of a neuron; L-g'd channels are on the receiving end of a neuron

All cells........Negative RMP

More K+ leak channels than Na+ leak channels
Na+/K" ATPase

Excitable cells........Negative RMP

More K+ leak channels than Na+ leak channels
Na+/K+ ATPase
Gated channels cause transient changes in MP

Depolarization

A small patch of the membrane has become depolarized

Spread of depolarization

The local currents that are created depolarize adjacent membrane areas and allow the wave of depolorization to spread

Graded potentials are stimulated with ___________

ligand-gated channels are opened

Convergence

is a common feature in neuronal pathways

No summation

Two graded potentials will not cause an action potential if they are far apart in time

Summation causing action potential

If two subthreshold potentials arrive at the trigger zone within a short period of time, they may sum and create an action potential

For the postsynaptic neuron to 'fire', most neurons.....

Require some form of summation to reach threshold and create an action potential

voltage gated channels dictate

the events of an action potential

The AP is a brief change in

volume in a membrane patch thats depolarized by local currents
- the AP is caused by permeablity changes in the plasma membrane

In an unmyelinated axon,

adjacent patches of membrane must reach threshold and fire an AP

In a myelinated axon,

nonadjacent patches of membrane reach threshold and fire an AP

Channel distribution dictates

neuronal function (e.g. APs are not generated without voltage gated channels present

EPSP need

Na+ or Na+ - K, ligand gated channels
Occur in postsynaptic membrane

IPSP need

K+ ligand gated channel
Occur in postsynaptic membrane

AP

require summation of GPs in order to reach threshold membrane potential
cannot be summed due to refractory periods
APs are all or none, and self generating

The difference between GPs and APs

reflects the difference in distribution between ligand-gated and voltage gated channels

Graded Potentials

Graded or gradual change in membrane potential; size of response varies with size of stimulus
Decremental conduction
Passive spread to adjacent membrane
No refractory period
Can be summed
Can be depolarization or hyperpolorization
Occurs in regions with high concentrations of ligand-gated channels

Action potentials

All or none response; size of stimulus is coded by frequency, not amplitude
Unchanged with distance
Self generating to adjacent areas
Refractory period
Cannot be summed
Always depolorization usually with charge reversal
Occurs in regions with high concentrations of voltage- gated channels

Despite large changes in Vm in a series of APs

, ion{gradient} remain virtually unchanged

Large changes in Vm

are due to small numbers of ions diffusing across the membrane

Gap junctions

Transfer both chemical and electrical signals
Can create an electrical synapse
Clusters of gap jxs can create cytoplasmic bridges between adjacent cells

A chemical synapse includes

1. Presynaptic membrane
2. a synaptic cleft(filled with ISF) and
3. postsynaptic membrane

Chemical synapse

transmits signals from one neuron to another using ntms

Presynaptic Neuron

1. AP arrives at axon terminal
2. Voltage gated Ca2+ channels open. Ca2+ enters the axon terminal
3. Ca2+ entry causes ntm- containing synaptic vesicles to release their contents by exocyytosis
4. Ntm diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane

Neurotransmitters (ntms)

1. can be returned to axon terminals for reuse or transported into glial cells
2. Enzymes inactive ntms
3. neurotransmitters can diffuse out of the synaptic cleft

Presynaptic inhibition

1. An exitatory neuron fires
2. An AP is generated
3. An inhibitory neuron fires, blocking ntm release at one synapse

Post synaptic inhibition

1.One exitatory and one inhibitory neuron fire
2. Modulated signal is below threshold
3.No action potential is initiated at trigger zone
4. No response occurs at any target cell

Presynaptic and Postsynaptic events are

'electrical' in nature with ions diffusing across the cell membrane, altering the membrane potential

Synaptic events are____________

chemical in nature: diffusion, inactivation, opening ligand gated channels, on the postsynaptic membrane

Autonomic Nervous Systems pathways use _______________

two neurons

The simplest neuronal pathways are ____________

reflex arcs

Preganglionic neurons use _______________ as their ntm

ACh

Postganglionic use __________ as their ntm

ACh and NE

Somatic Nervous System

Efferent(motor) pathways

All Reflex arcs have the basic components

Receptor
Sensory Neuron
Integration Center
Motor Neuron
Effector

A monosynaptic reflex has a ___________

a single synapse between the afferent and efferent neurons

Polysynaptic reflex __________

have two or more synapses

All autonomic reflexes are _____________

polysynaptic, with at least one synapse in the CNS and another in the autonomic ganglion

Sensory(afferent) and motor(efferent) information travel along

neuronal pathways (like reflex arcs) as action potentials

Motor pathways consist of_____________________

somatic and autonomic divisions(ex. somatic nervous system and autonomic nervous system) that innervate(ex. synapse with) effector organs

neuromuscular junction consists of ______________

axon terminals, motor end plates on the muscle membrane

Somatic motor neuron branches at its

distal end

The motor end plate

is a region of muscle membrane that contains high concentrations of ACh receptors

Neuromuscular junctions

are ALWAYS excitatory
require NO summation to trigger APs in the postsynaptic membrane

Two types of smooth muscle

single-unit smooth muscle- is connected by gap junctions and the cells contract as a single unit

Multi-unit smooth muscle cells - are not electrically linked and must be stimulated independently

Muscle cell characteristics

Skeletal

Multinucleate

Cylindrical, extends length of muscle bundle
No gap junctions between cells
Striated
Contraction by sliding of think/thick filaments
Voluntary
Neurogenic

Muscle cell characteristics

Smooth

Uninucleate
Tapered, does not extend length of muscle
Gap junctions present between some cells
Not striated
Contraction by sliding of think/thick filaments
Involuntary
Neuro- and Myogenic

Muscle cell characeristics

Cardiac

Uninucleate
Branched, does not extend length of muscle
Gap junctions present between cells
Striated
Contraction by sliding of thin/thick filaments
Involuntary
Myogenic

Organization of muscle bundles

Muscle Bundle-> multiple muscle fascicles -> multiple muscle fibers, or cells-> multiple myofibrils -> multiple sarcomeres -> cytoskeletal proteins

Neuron(chemical) synapses require summation

greater then 1:1; nmjs do not they are 1:1

Somatic motor neurons innervate ________

skeletal muscle, and always release ACh

Depolarization of an excitable cell membrane requires an influx of ___________

a cation( can be Na+ or Ca++); repolarization requires the efflux of K+ in all cases

The functional unit of skeletal muscle fibers is the __________

sarcomere(know organization); contraction requires rigorous organization of cytoskeletal proteins ( ex. actin myosin)

In sarcomere, Nebulin helps align

actin

In sarcomere, titan provides

elasticity and stabilizes myosin

Sarcomere organization

I band

thin filaments only

Sarcomere organization

H band

thick filaments only

In sarcomere organization

M line

thick filaments linked with accessory proteins

In sarcomere organization

Outer edges of A band

thick and thin filaments overlap

T- Tubules and SR

important for 'excitation'
T-Tubules bring action potentials into interior of muscle fiber

Excitation contraction coupling

Excitation part 1

transmission of APs to the NMJ

Excitation contraction coupling

Excitation part 2

Transmission of APs from the NMJ

Excitation contraction coupling

'coupling'

= Ca++ inducement of cross-bridge formation

Excitation parts 1 and 2

1. somatic motor neuron releases ACh at neuromascular junction
2. Net entry of Na+ through ACh receptor channel initiates a muscle action potential

Excitation parts

'coupling'

3. AP in t- tubule alters shape of DHP receptor
4. DHP receptors opens Ca++ channels in SR and Ca2+ enters cytoplasm
5. Ca2+ binds troponin -> actin-myosin binding
6. Myosin heads execute power stroke
Actin filaments slides toward sarcomere center

Regulatory proteins control ____________

the interaction of thick and thin filaments

Contractile proteins do not

contract, they slide past eachother

Binding between the myosin head, and the myosin binding site on the thin filament, triggers a __________

power stroke

Electrical excitation

precedes contraction( ex. thin and thick filaments sliding past eachother.)
Excitation refers to APs traveling down an excitable membrane; contraction refers to the shortening of the sarcomere

Ca++ couples

excitation to contraction

Length-tension relationships in contracting skeletal muscle

Tension developed by individual muscle fibers is a function of fiber length, specially, the amount of overlap of thick and thin filaments within a sarcomere

During single muscle twitches __________

the muscle completely relaxes between stimuli

Stimuli that occur close together

do not allow the muscle to relax fully-> summation

Fatigue causes muscle to ____

lose tension despite continuing stimuli

Stimuli leading to unfused tetanus:

Stimuli are far enough to allow muscle to relax slightly between stimuli

Summation leading to complete tetanus:

Muscle reaches steady tension

Summation of muscle fiber tension permits

increasingly heavy loads to be moved

Muscle fiber tension can be summed because

they develop and fade away over a much longer period than does the muscle AP

A motor unit consists of

a motor neuron and all muscle fibers it innervates

The corticospinal tract

is a 2 neuron pathway.
The output neuron from the CNS to the muscle bundle is the somatic motor neuron

There is no 'inhibition neuron' that

synapses on skeletal muscle fibers, causing them to relax

Extrafusal fibers=

skeletal muscle fibers

Muscle spindles send info to the CNS re:

muscle length and changes in muscle length

Muscle spindle function maintains

muscle tone using a monosynaptic reflex

spindles are firing even when

muscles are relaxed

muscle spindles prevent

overstretching

reflexes:

muscle spindle and golgi tendon

a knee jerk reflex is a

muscle spindle reflex

GTOs respond to muscle tension by

causing a relaxation effect(inhibiting the motor neuron, not the skeletal muscle fiber), and can prevent/minimize injury from an excessive contraction - this is the opposite of the muscle spindle which causes a reflex contraction

The output neuron of the corticospinal tract is a ____________. This output neuron and all muscle fibers it innervates compromise a ___________.

somatic motor neuron; Motor unit

One sensory mechanism(muscle spindle apparatus) acts to

maintain optimal length- tension in skeletal muscle bundles

Golgi tendon organ ensures

that the muscle is not torn from an excessive load

Physiology

Biology 246 with Johnson at University of Kansas

About this deck

About StudyBlue

Sign up (free) to study this.

About this deck

About StudyBlue