Physiology Of Muscle Contraction

Question 1

In skeletal 4 Ca bind to?

Answer 1

Troponin C, but in heart 3 Ca, changes conformation, shuts off Tn1 tropomyosin- troponin leaves F-actin groove unmasks the myosin binding site on actin

Question 2

Troponin I is a marker for?

Answer 2

Total muscle breakdown

Question 3

Cardiac TnI is marker for?

Answer 3

Myocardial infarct

Question 4

Macro molecular contraction?

Answer 4

Contraction depends on myosin head binding to think actin filaments at specific binding sites.

Otherwise blocked by tropomysoin

Question 5

Cross bridge cycle?

Answer 5

1. To allow myosin head to let go, release ADP, require ATP to allow myosin to let go of actin
2. Myosin head cleaves ATP
3. Myosin binds actin, when moved tropomysoin out of way (ca was present)
4. Power stroke

Question 6

What is rigor mortis?

Answer 6

ATP is needed to pump ca in sarcoplasmic reticulum.

ATP deleted

Myosin stuck to actin,

Rigor mortis ends when muscle tissue degrades after 3 days

Question 7

How do you store ATP?

Answer 7

Creatinine is stored in muscle after phosphorylation

Question 8

How to get energy from. Muscles?

Answer 8

Creatine phosphate (in mitochondria) gives a phosphate group to ADP.

Question 9

Creatine phospho kinase does what?

Answer 9

Adds phosphate to creatine

Question 10

Phosphokinase is a marker of?

Answer 10

Muscle destruction

Question 11

Creatinine is?

Answer 11

Breakdown product of creatine, marker for kidney function

Question 12

Depolarisation allows influx of calcium?

Answer 12

Active nicotine cells acetylcholine receptor, net inward current.

Causing depolarisation spread via T-Tubules

Local action potentials trigger Ca2+ efflux from terminal cisternae
Across membrane of sarcoplasmic reticulum
into the fibre cytoplasm

Question 13

SERCA does what?

Answer 13

Puts ca back in the SR

Question 14

Ryanodine receptor does what?

Answer 14

Releases ca from SR, triggered by voltage sensor on ca channel

Question 15

Frequent APs cause complete tetany because?

Answer 15

Insufficient Ca resequestration so summation of contraction

Question 16

Slow twitch are?

Answer 16

Type 1 “red” oxidative small diameter

High myoglobin, many mitochondria

Question 17

Fast twitch have?

Answer 17

Type 2 white
Non oxidative wide diameter
Lower myoglobin
Energy requires from glycolysis

Question 18

Which muscle fibres are fatigue resistance?

Answer 18

Slow

Question 19

Soleus muscle has composition?

Answer 19

80% type slow

20% type IIA

Question 20

Vastus lateralis for running has composition?

Answer 20

Mixture of type I, IIA, IIX

Question 21

Long distance runner have?

Answer 21

Type 1 predominantly

Question 22

In type I what type of fuel as storage?

Answer 22

Triglycerides

Question 23

In Type II fibres the fuel for storage?

Answer 23

Creatine phosphate

Glycogen

Question 24

Motor unit is?

Answer 24

A single alpha motor neuron and muscle fibres it innervates

Question 25

Isometric?

Answer 25

Generates variable force while length of muscle remains unchanged

Question 26

Isotonic?

Answer 26

Generates a constant force while the length of muscle changes

Question 27

Eccentric contraction?

Answer 27

Force during muscle elongation

Question 28

Size principle?

Answer 28

as the initial isometric contraction occurs: more and more motor units are recruited starting with smaller ones and progressively adding larger ones

Question 29

Lower motor neuron disease?

Answer 29

Weakness | Muscle atrophy

Question 30

Upper motor neurone disease?

Answer 30

Spasticity, hypertonia

Question 31

Lack of patellar reflex is called?

Answer 31

Westphals sign

Question 32

Muscle spindle consists of how many intrafusal fibres?

Answer 32

3-12

Question 33

Sensors from muscle spindle are called?

Answer 33

Type 1a and Type 2

Question 34

Tendon reflex aim?

Answer 34

Protection from overloading

Question 35

Tendon reflex has how many synapses?

Answer 35

2

Question 36

Eccentric and concentric contraction?

Answer 36

Eccentric- force during muscle elongation Concentric- force during contraction

Question 37

Size principle?

Answer 37

Always start with small motor unit, as its going through feedback mechanisms, recruit bigger motor units to generate force

Question 38

Absence of Westphalia sign means there is?

Answer 38

Receptor damage Femoral nerve damage Peripheral nerve disease