Muscle Physiology Flashcards
Type 1 Fibres
Slow Fatigue Resistant Aerobic/Endurance work Red, many mitochondria, capillaries, oxygen Low glycogen capacity Uses triglyceride energy Small
Type 2b Fibres
Fast Easily Fatigued Strength/Power work White, low mitochondria, aerobic capacity Creatine Phosphate and Glycogen as fuel Large
Type 2a Fibres
Fast Moderate Fatigue Muscle Endurance work White, high mitochondria and aerobic capacity Creatine Phosphate and Glycogen as fuel Large
Red Small Muscles
Type 1 Fibres / Slow Twitch
White Large(st) Muscles
Type 2b Fibres / Fast Twitch
Intermediate (white, medium size) Muscles
Type 2a Fibres
Majority Type 1 Muscles
Tonic Muscles
(Low intensity for prolonged time)
Eg - Calves, Spine
Majority Type 2 Muscles
Phasic Muscles
(Intermittent work - hard intensity for short time)
Eg - Biceps, Triceps
How does muscle size grow?
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)
Traits of Smooth Muscle
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
Traits of Cardiac Muscle
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
Parts of Muscle Fibre Ordered Big to Small
Muscle belly, muscle fibre bundle, muscle fiber, myofibril, sarcomere, myofilaments actin and myosin
Parts of A Sarcomere
Actin (thin) and Myosin (think)
Z disc - dark lines anchoring actin
H zone - bright area anchoring myosin
A band - overlapping disc and zone
Describe Sarcomere Contraction
ATPase on myosin crawls up the actin (H zone towards Z disc) when ATP is dephosphorelated
How do Sarcomeres attach (Simple explanation)
Z discs align serially, in-between fibrils (T tubule system and sarcoplasmic reticulum)
Shortening Muscle Action
Concentric
Lengthening Muscle Action
Eccentric
Holding Position Muscle Action
Isometric
Controlled rate muscle action
Isokinetic (joint controlled)
Controlled strength muscle action
Isotonic (resistance controlled)
Controlled length muscle action
Isometric
How do Sarcomeres attach (detailed explanation)
- Motor neuron synapse reaches threshold of depolarisation
- Calcium stores in sarcoplasmic reticulum releases in muscle fibres
- Myosin binding sites on actin are exposed, myosin ATPase activates
- Myosin crawls up the actin towards binding sites
How are muscles recruited
Size Principle (Type 1 first)
3 Mechanoreceptors
- Muscle Spindles
- Golgi Tendon Organs
- Joint Receptor
What are Muscle Spindles
Receptors in muscle belly, parallel to fibres
Coiled nerves, stretch as muscle stretches, send info to CNS
What do muscle spindles detect
changes in Length and rate of change
What are Golgi tendon organs
Woven into fibres of tendons sensing tension and sending signals to the spine to activate golgi tendon reflex which relaxes the muscle
What do Golgi tendon organs detect
Muscle stretching
What are joint receptors
Nerves in and around joints responding to pressure, acceleration and deceleration of joint movement
What do joint receptors detect
Positioning of muscles and bones by joints
Muscle Groups in the Upper Extremity
Shoulder, chest, neck, ribs, back, biceps, forearm, triceps
Muscle Groups in the Lower Extremity
Quads, Hamstrings, Glutes, Hip flexors, calves
Muscle Groups in the Trunk
Ab muscles, Erector Spinae
