Muscle Physiology

Question 1

Type 1 Fibres

Answer 1

Slow 
Fatigue Resistant 
Aerobic/Endurance work
Red, many mitochondria, capillaries, oxygen
Low glycogen capacity
Uses triglyceride energy
Small

Question 2

Type 2b Fibres

Answer 2

Fast
Easily Fatigued
Strength/Power work
White, low mitochondria, aerobic capacity
Creatine Phosphate and Glycogen as fuel
Large

Question 3

Type 2a Fibres

Answer 3

Fast 
Moderate Fatigue 
Muscle Endurance work 
White, high mitochondria and aerobic capacity
Creatine Phosphate and Glycogen as fuel
Large

Question 4

Red Small Muscles

Answer 4

Type 1 Fibres / Slow Twitch

Question 5

White Large(st) Muscles

Answer 5

Type 2b Fibres / Fast Twitch

Question 6

Intermediate (white, medium size) Muscles

Answer 6

Type 2a Fibres

Question 7

Majority Type 1 Muscles

Answer 7

Tonic Muscles
(Low intensity for prolonged time)
Eg - Calves, Spine

Question 8

Majority Type 2 Muscles

Answer 8

Phasic Muscles
(Intermittent work - hard intensity for short time)
Eg - Biceps, Triceps

Question 9

How does muscle size grow?

Answer 9

Ratio of Type 1 to Type 2 cannot change but
when muscles are fatigued type 2b converts to 2a as they are being used
During rest 2a changes back to 2b with overshoot so
More 2b compared to 2a (2b is bigger so growth)

Question 10

Traits of Smooth Muscle

Answer 10

Tracts + Vessels controlled by Autonomic NS
Single cell, single nucleus
Unorganised myosin and actin
No sarcomeres or myofilaments
eg - blood, lymph, respiratory etc tracts and iris of eye

Question 11

Traits of Cardiac Muscle

Answer 11

Individual cells very small
Organised myosin and actin in sarcomeres
Branch and attached by intercalated discs
Resistant to fatigue - many more mitochondria and capillaries
Fully dependant on aerobic metabolism

Question 12

Parts of Muscle Fibre Ordered Big to Small

Answer 12

Muscle belly, muscle fibre bundle, muscle fiber, myofibril, sarcomere, myofilaments actin and myosin

Question 13

Parts of A Sarcomere

Answer 13

Actin (thin) and Myosin (think)
Z disc - dark lines anchoring actin
H zone - bright area anchoring myosin
A band - overlapping disc and zone

Question 14

Describe Sarcomere Contraction

Answer 14

ATPase on myosin crawls up the actin (H zone towards Z disc) when ATP is dephosphorelated

Question 15

How do Sarcomeres attach (Simple explanation)

Answer 15

Z discs align serially, in-between fibrils (T tubule system and sarcoplasmic reticulum)

Question 16

Shortening Muscle Action

Answer 16

Concentric

Question 17

Lengthening Muscle Action

Answer 17

Eccentric

Question 18

Holding Position Muscle Action

Answer 18

Isometric

Question 19

Controlled rate muscle action

Answer 19

Isokinetic (joint controlled)

Question 20

Controlled strength muscle action

Answer 20

Isotonic (resistance controlled)

Question 21

Controlled length muscle action

Answer 21

Isometric

Question 22

How do Sarcomeres attach (detailed explanation)

Answer 22

1. Motor neuron synapse reaches threshold of depolarisation
2. Calcium stores in sarcoplasmic reticulum releases in muscle fibres
3. Myosin binding sites on actin are exposed, myosin ATPase activates
4. Myosin crawls up the actin towards binding sites

Question 23

How are muscles recruited

Answer 23

Size Principle (Type 1 first)

Question 24

3 Mechanoreceptors

Answer 24

1. Muscle Spindles
2. Golgi Tendon Organs
3. Joint Receptor

Question 25

What are Muscle Spindles

Answer 25

Receptors in muscle belly, parallel to fibres

Coiled nerves, stretch as muscle stretches, send info to CNS

Question 26

What do muscle spindles detect

Answer 26

changes in Length and rate of change

Question 27

What are Golgi tendon organs

Answer 27

Woven into fibres of tendons sensing tension and sending signals to the spine to activate golgi tendon reflex which relaxes the muscle

Question 28

What do Golgi tendon organs detect

Answer 28

Muscle stretching

Question 29

What are joint receptors

Answer 29

Nerves in and around joints responding to pressure, acceleration and deceleration of joint movement

Question 30

What do joint receptors detect

Answer 30

Positioning of muscles and bones by joints

Question 31

Muscle Groups in the Upper Extremity

Answer 31

Shoulder, chest, neck, ribs, back, biceps, forearm, triceps

Question 32

Muscle Groups in the Lower Extremity

Answer 32

Quads, Hamstrings, Glutes, Hip flexors, calves

Question 33

Muscle Groups in the Trunk

Answer 33

Ab muscles, Erector Spinae