Physiology Final

Front 1

4 types of locomotion

Back 1

1) Muscular contractions

2) Hydrostatic pressure/water vascular system

3) Cytoplasmic streaming

4) cilia and flagella

Front 2

Draw the net cost of locomotion graph

Label: x axis, x intercept, y axis, y intercept

What happens/when does the line peak?

Does the graph not start at zero?

Why is the graph nonlinear?

Back 2

X axis = speed (km/hr)

x intercept at peak = max aerobic speed

y axis = O2 consumption (ml O2/hr)

y intercept at peak= VO2 max

Standard MR is not zero

Organisms change their behavior with increased speed.

Front 3

Impact of body size on net cost of locomotion

4 Large

5 small

Back 3

Large:

1) lower mass specific NCT

2) greater weight = less O2 consumption/distance

3) can store more elastic energy during movement due to gravity.

4) greater muscle size = more elastic tension = more power

Small

1) more energetically expensive to move (steeper slope NCT)

2) need more economical fast-twitch fibers to move appendages faster

3) Water = increase SA to vol, small muscles cannot overcome drag

4) Terrestrial = decrease stride length = increase stride freq.

5) Smaller muscle = less elastic force= less powerful

Front 4

Impact of environment on net cost of locomotion

Back 4

Land = more energetically expensive due to gravity

Air = lift minimizes the effect of gravity

Water = most efficient, buoyancy

Front 5

Ecological cost of transport = ?

What factors effect ETC?

Mammals v reptiles

Back 5

DMD (km/day) x NCT (J/km) / DEE (J/day)

Increased body mass = increase DMD

largest DMD for carnivorous mammals

high DEE mammals = lower ECT

low DEE reptiles = high ECT

Front 6

5 properties of skeletal muscles

3 functions

Back 6

Voluntary, extend, elastic, excitable, contract

Produce heat, Movement, Posture/stability

Front 7

Composition of skeletal muscles

Back 7

Fascicles : bundles of muscle fibers

Myofibrils: individual fibers

held together by connective tissues

highly vascularized

Front 8

5 components of muscle cells

Back 8

1) Sarcoplasm

2) Sarcolemma

3) T-Tubules: conduct electrical charge

4) Sarcoplasmic Reticulum: store/release Ca+

5) Myofibrils: protein segments (sarcomeres alternating light and dark bands that give muscle its striated appearance)

Front 9

Myofibrils

Back 9

1) Myosin: thick filament, contractile protein, motor molecule, binds to actin, head with ATPase which hydrolyzes ATP, energy release allows head to swivel and bind to actin.

2) Actin: thin filament, contractile protein, 2 strings of G-proteins, 5-7 active sites for myosin.

3) Troponin: regulatory protein, binds to CA+ and pulls tropomyosin away from binding sites on actin

4) Tropomyosin: regulatory protein, woven around actin, covers the binding sites

Front 10

CNS

PNS

Motor/efferent (output)

Back 10

Brain and spinal cord

sensory input from the body

somatic NS (voluntary movement)

Front 11

Neuromuscular Junction

Back 11

somatic motor neuron (Presynaptic) innervates a skeletal muscle cell (Postsynaptic)

Front 12

sequence of excitation events btw a somatic motor neuron and a skeletal muscle fiber leading towards muscle contraction (9 steps)

Back 12

1) AP arrives at somatic motor neuron terminals

2) Voltage gated CA+ channels open, CA+ moves in via elecrochemical forces. Motor neuron depolarizes.

3) CA+ causes fusing and opening of vessicles, release of ACH, ACH diffuses into synapse

4) ACH binds to ligand gated receptors on motor end plate of a muscle cell

5) channels open, leading to influx Na+

6) NA+ depolarizes muscle, release of CA+ from the sarcoplasmic reticulum, AP propagates down muscle fiber via increased T-tubule SA

7) Muscle contracts

8) ACH reuptake by motor neuron, diffused out of synapse, BD by enzyme acetylcholineasterase.

9) Ligand gates receptors close, muscle relaxes, no more depolarization

Front 13

3 levels of how the CNS controls movement

Back 13

1) Spinal cord to brain stem (knee jerk)

2) brainstem, cerebellum to posture, hand/eye coordination

3) basal ganglia, cerebral cortex to voluntary movement (planning, initiation, execution, higher order processing)

Front 14

Sliding filament model

Back 14

muscle shortens as actin and myosin slide past each other

sliding filaments = crossbridge cycling = muscle contraction = increased shortening = increased contraction force

Front 15

Cross bridge formation

Back 15

CA+ binds ti troponin, causing tropomyosin to move away from myosin binding sites on actin

formation of cross bridge = muscle contraction

Front 16

4 steps that allow muscle to contract

Back 16

1) cross bridge formation

2) powerstroke (head swivel of myosin)

3) cross bridge detachment

4) reactivation of myosin head

Front 17

Calcium's relationship with Force?

Back 17

Force (%max) y axis

Myoplasmic CA+ concentration, x axis

Sigmoidal

Front 18

6 steps occurring at the level of Actin and Myosin during a muscle contraction

Back 18

1) CA+ binds to troponin

1a) ATP binds to myosin head, detaches from actin

2) Tropomyosin moves from active site

3) ATP Hydrolyzes, energy release causes the head of myosin to swivel

4) ADP and phosphate released, actin and myosin slide toward each other

5) Rigor: myosin remains bound

6) ATP rebinds, myosin detaches

Front 19

5 steps occurring at the level of Acting and Myosin during muscle relaxation

Back 19

1) ACH removed from synapse

2) Ca2+ removed actively via Calcium-ATPase pumps

3) Active sites on actin covered

4) No crossbridge interaction

5) Passive recoil of sarcomere to resting length (generate max. contractile force during subsequent contractions)

Front 20

Invertebrate muscles

Back 20

Asynchronous nerve signals (1 signal can produce multiple contractions)

oblique striation, thin and thick filaments connected to dense bodies

Stretch activation: myofibril is selective to ca2+ when muscles are relaxed. Once a contraction occurs, it becomes calcium insensitive. Intercellular calcium remains high.

Front 21

Nervous system

Back 21

control an communication of body systems

fast and short-term

movement of ions create electrical currents that are sent to specific target cells or release chemicals that interact with other cells

Front 22

Types of nerves present in the PNS and CNS

Back 22

PNS = sensory and motor neurons

CNS = brain and spinal cord, sensory, motor, and interneurons

Sensory = carries/compiles info to CNS

Motor = info away from CNS, cause response

Interneuron = connection btw neurons

Pathway = sensory cell to sensory neuron to interneuron to motor neuron to effector cell

Front 23

Neuron

Function

Structure

Back 23

functional unit of the NS, excitable, respond to and produce electrical signals via ion concentrations.

Dendrites: receive info/ AP

Cell body

Axon hillock: AP generated, highest density of voltage gated sodium channels, lowest threshold

Axon: nerve fiber that conducts an electrical signal, AP jumps from node to node (saltatory conduction) myelin keeps ions in.

Front 24

Resting membrane potential

created by?

GHK equation

Back 24

- 70mv

created by potassium leak channels (more than sodium accounts for negativity). always open, ion specific, ions driven by electrochemical gradients

K+ moves towards low concen. inside cell, excess negative charge.

depends on concentration gradient and permeability of ions

61 log PNa[Na+]o+PK[K+]o / PNa[Na+]i+PK[K+]i

Front 25

Nerst equation

Back 25

equilibrium potential: membrane potential necessary to balance the concentration gradient of a given ion. (concentration gradient = electrical gradient)

Eion = 61/z log [concen]ionOutside/

[concen]ionInside

Front 26

RMP mediated by

Back 26

Sodium-Potassium Pump

Active transport (use of ATP) to move 2 K+ in and 3 Na+ out against their concentration gradients

Front 27

Action potential

Back 27

uniform and propagated change in electrical/membrane potential across the cell membrane (result of permeability change)

easier to excite when a RMP moves towards its threshold

Front 28

Stages of an action potential

Back 28

1) RMP

2) Threshold: (-40mv) voltage gated sodium and potassium channels triggered. Voltage gated Na+ channels open

3) Depolarize: influx of Na+ (increased permeabiltiy of sodium)

4) Peak: timed closing of voltage gated sodium channels, voltage gated potassium channels open

5) Repolarize: efflux of K+ out of neuron, increase premeability of potassium

6) Hyperpolarize: below RMP VG K+ still active along with leak potassium and sodium-potassium pumps

7) Depolarize to RMP: VG K+ channels closed

Front 29

Voltage gated Sodium channels

Back 29

At rest: Inactivation gate open, activation gate closed

Depolarize: threshold stimulus opens both gates, influx sodium down electrochemical gradient

+30mv (timed) Inactivation gated closes, decrease sodium permeability

Repolarization (increased potassium) resets the gates to initial positions, no sodium movement, allows another action potential to be fired.

Front 30

Voltage gated potassium channels

Back 30

Threshold triggers delayed opening of gate until peak potential

Once peak occurs, the channel is open until hyperpolarization

Without this channel, the cell could repolarize due to leak channels, but

1) no hyperpolarization without the continued opening of VG K+ chennels

2) peak is higher (no counterbalance between Na+ and K+)

3) extended AP

4) Slower NS because fewer AP are sent over a given time

Front 31

Phases of AP are regenerated down the axon by

Back 31

local changes in the membrane potential propagated down the axon

sodium influx = depolarizes adjacent portions of the membrane, causing the neighboring areas to reach threshold

Front 32

Refractory period

(Absolute v relative)

Back 32

No backwards signalling because once an area experiences an AP it briefly enters an insensitive period, that lasts until the gates of the Voltage gated sodium channels are reset.

Absolute: cannot fire again until reset

Relative: cell is responsive and can fire again but requires a super stimulus.

Front 33

Size of action potential relative to stimulus

How do neurons send different messages

Back 33

all - or - none

independent of the strength of the stimulus, as long as the threshold is met the cell fires the same every time.

Vary frequency and number of action potentials occurring.

Front 34

Conduction velocity

Back 34

speed an AP propagates down an axon, depends on:

1) Diameter of the axon: increase diameter = increase conduction velocity. because there is more room for ions to move, less likely to impact cell membrane and less likely to leak out (largest diameter in sensory neurons, speed important for quick response)

2) Myelination: insulation of the axon. extended cell membrane and cytoplasm.

CNS= oligodendrocytes

PNS= schwann cells

Increases conduction velocity, allows Saltatory Conduction, prevents the movement of ions. maintains the depolarization.

Front 35

Saltatory conduction

Back 35

jumping of an AP from node of ranvier to node.

(number of nodes depends on the length of the axon).

Front 36

Synaptic transmission

Back 36

electrical signal/AP is converted to a chemical signal (neurotransmitters) that interacts with neighboring cells

Presynaptic: axon terminals before a synapse, releases the neurotransmitter.

Postsynaptic: receives message (effector cells)

Front 37

7 steps of synaptic transmission

Back 37

1) AP arrives at terminal, depolarizes presynaptic cell

2) VG CA2+ channels open

3) Influx Calcium down electrochemical gradient

4) Ca2+ influx causes vessicles to dock and release neurotransmitter into synapse

5) Neurotransmitter binds with ligand gated receptors on the post synaptic cell. causing ion/protein channels to open and ions move in or out

6) Movement of ions causes Excitatory Postsynaptic potential or an Inhibitory PSP

7) Receptors/ligand gated channels close, Neurotransmitter is diffused out of the synapse, BD by enzymes, or is reuptaken by the presynaptic cell

Front 38

GRADED POTENTIALS

Excitatory PSP

Inhibitory PSP

Back 38

Depolarization of the cell membrane, brings the cell closer to threshold, more likely to fire

Hyperpolarization, brings cell closer to RMP, less likely to fire

Front 39

Graded potentials

(how they differ from action potentials)

Back 39

1) small change in membrane potential
2) Occur at dendrites and cell body (less frequently near axon terminal)
3) Mechanically, chemically or VG channels
4) Movement of sodium, chloride, calcium
5) Na+ depolarizes, Cl- hyperpolarizes
6) Strength of signal depends on initial stimulus, can be summed! (rather than all or none)
7) Signal initiated by entry of ions through gated channels
8) No min. threshold required, no refractory period

- maintain threshold = continued firing

Front 40

Decremental

Back 40

charge of ions becomes weaker, having less effect in other areas of the postsynaptic cell, as it moves. Due to:

Dispersal, resistance, ions leaked out

EPSPs may be strong enough to cause a wave of depolarization to hit the axon hillock at threshold and cause an AP

Front 41

Neural integration

3 factors that effect potential for firing

Back 41

occurs at the axon hillock, determines whether a postsynaptic cell fires

1) Location of incoming messages: closer to hillock=more likely to change action potential. (less decremental effect)

2) Spatial summation: currents from nearly simultaneous graded potentials combine

3) Temporal summation: graded potentials occur close together in time