key concepts

Question 1

contraction cycle - 6 steps

Answer 1

1) neuromuscular junction propagates signal
2) acetylcholine is released
3) Ca is released
4) T-tubules dive into muscle & relay action potential along t-tubule
5) Ca binds to troponin & releases tropomyosin for actin & myosin cross bridge
6) myosin heads pull thin filaments in user power stroke = contraction

Question 2

3 ways to produce ATP

Answer 2

1. creatine phosphate - fastest
2. anaerobic pathway- glycolysis
3. aerobic pathway- TCA - slowest

Question 3

3 ways ATP is metabolized

Answer 3

1. Na / K ATPase pump - uses ATP to pump 3 Na out & 2 K in
2. Ca ATPase pump- uses ATP to pump Ca back into cell / SR
3. ATP hydrolysis - during muscle contraction to release it for actin

Question 4

2 factors that influence amount of force control

Answer 4

1) increased frequency of stimulus
2) increased motor unit recruitment

Question 5

How does AChE cause paralysis

Answer 5

AChE breaks down acetylcholine which is needed for contraction cycle to occur - releases Ca needed for action potential

Question 6

2 reasons why action potentials are unidirectional

Answer 6

1) refractory period - prevents another AP
2) no sensor at pre-synapse so it can’t pick up a stimulus and transfer AP backwards

Question 7

muscle contraction in smooth vs skeletal muscle

Answer 7

1) smooth- uses myosin light chain - phosphorylated myosin which allows it to bind to actin
2) skeletal- troponin & tropomyosin cross bridge sites

Question 8

How does a neuron reset after an action potential

Answer 8

after depolarization, Na channels close so membrane can return to resting potential & neuron enters refractory period

Question 9

sliding filament mechanism

Answer 9

muscle fibers contract when myosin pulls actin closer & causes sarcomeres to shortn

Question 10

power stroke mechanism

Answer 10

myosin bends to pull thin filaments in, detaches and rebinds further on fibre to pull it more

Question 11

what is the function of troponin

Answer 11

exposes myosin binding sites

Question 12

what is the function of tropomyosin

Answer 12

blocks actin cross bridge sites & prevents interaction between myosin & actin for muscle contraction

Question 13

what is cross bridge cycling

Answer 13

repeated motions that drive thin filaments in towards each other

Question 14

3 mechanisms that influence NT concentration after release at synapse

Answer 14

1. diffusion
2. re-uptake
3. enzyme degradation

Question 15

contraction & relaxation of smooth muscle

Answer 15

contraction- increased calcium results in a chain of biochemical events & myosin becomes phosphorylated which allows it to interact with actin & produce movement

relaxation- myosin becomes dephosphorylated through the light chain and it follows biochemical reactions for calmodulin to unbind Ca and allow relaxation

Question 16

how is an action potential initiated & propagated

Answer 16

initiated by a stimulus that reaches threshold to open Na gates & cause depolarization where 3 Na enter the fiber -> dendrites receive signal & conducts the AP along axon to axon terminal where NT are released -> 2 K leave fiber to repolarize -> hyperpolarization allows return to resting state & gates are closed

Question 17

How is muscle fatigue affected by ATP metabolism

Answer 17

ATP concentration decreases as it is consumed by muscles -> favours transfer of phosphate to phosphocreatine from ADP -> forms ATP + creatine for contractions

drop in ATP-> cannot pump Na, K or Ca and cannot perform ATP hydrolysis b/c these metabolic mechanisms require ATP - without ATP = no mechanisms can occur = no ATP for muscle use = muscle fatigue

Question 18

temporal vs spatial summation

Answer 18

temporal- several inputs from 1 axon that stimulates another response

spatial- same synapse type with more than 1 input

Question 19

a decrease in pH leads to what shift?

Answer 19

right shift- bohr effecr

Question 20

2 concepts that give s shaped curve

Answer 20

1) sigmoidal curve- O2 drops very fast during 20-40 = steep increase = O2 drops off slower 60-100 =s shape

2) postage stamp hypothesis- takes more energy to make 2 cuts on the 1st O2 (steep curve section) and only 1 cut for the 2nd, 3rd & 4th O2 (flattens curve) = s shaped

Question 21

what produces EPO

Answer 21

kidneys

Question 22

inflammation mechanism (4 steps)

Answer 22

1) brings fluid to site of damage
2) macrophages recognize pathogen
3) mast cells release histamine to widen gaps
4) neutrophils & monocytes enter & fight

Question 23

hemostasis steps

Answer 23

1) vascular spasm: blood vessels constrict to prevent excess blood loss
2) platelet plug formation: platelets stick to collagen & secrete ADP to cause other platelets to stick to them
3) blood coagulation: fibrinogen is converted to fibrin which forms a clot & prevents platelet plug from moving

Question 24

why do you want low concentration of factor 12 in the blood?

Answer 24

factor 12- creates clot

want low concentration so there is no accidental clotting - especially in lungs so TPA is high to ensure no random clotting

Question 25

depolarization ions

Answer 25

Na enters

Question 26

repolarization ions

Answer 26

K leaves

Question 27

hyperpolarization ions

Answer 27

K leaves

Question 28

resetting phase ions

Answer 28

3 Na out & 2 K in

Question 29

2 things that slow down conduction speed

Answer 29

decreased myelination
decreased fibre diameter

Question 30

Rigor mortis

Answer 30

no ATP available to release cross bridges = stuck in contraction