Neuromuscular Physiology I Flashcards
Skeletal tissue - histology
- long, cylindrical fibre
- striated
- multinucleated
Cardiac tissue - histology
- short, branched
- striated
- single nucleus
Smooth tissue - histology
- short, spindle shaped
- not striated
- single nuclues
Skeletal tissue - function
- voluntary movement
- produces heat
- protect organs
Cardiac tissue - function
contracts to pump blood
Smooth tissue - function
- involuntary movement
- move food
- involuntary respiration
- secretions
- blood in arteries
Muscle layers
muscle -> fascicles -> muscle fibres -> myofibrils
4 steps of the myogenic pathway
- MITOSIS of additional satellite cells
- MYOTUBE formation
- TRANSLOCATION of myotube across sarcolemma
- FUSION of myotube withe existing myofibril
Thick filament contractile properties
- 6-subunit myosin protein
- 2 MHCs
- 2 MLCs
Thin filament contractile properties
- 2 twisted strings of spherical actin molecules
- tropomyosin on actin
- Troponin
Tropomyosin role
blocks binding site
Troponin role
moves tropomyosin out of the way to allow binding
3 sub-class of troponin
- troponin C
- Troponin I
- Troponin T
Troponin C role
calcium binding site
Troponin I role
Inhibitory
Troponin T role
binds troponin I to tropomyosin
How is myosin activated before binding to myosin?
ATP hydrolysis
Desmin
connects z-disk of sarcomeres from 2 myofibrils
Nebulin
bond actin, non elastic
Titin
connects m-line to z-disk. acts as molecular spring
a-actin
forms z-disk
what are the 4 main proteins in the cytoskeleton
- Desmin
- Nebulin
- Titin
- a-actin
white matter vs grey matter
White matter in the brain is myelinated, whereas grey is unmyelinated
Resting membrane potential value
-70mV
How does a muscle action potential happen?
transmission of nerve impulses by NT across synaptic cleft to post-synaptic motor end plate (nicotinic receptors). opens voltage gated Na+ channels and depolarizes the plasma membrane
What is the motor unit
the alpha motor neuron and muscles it innervates
Motor unit ratio for fine movement
Low motor unit ratio; 1:1
Motor unit ratio for gross movement
high motor unit ratio; 100:1
What does the max force of a muscle directly relate to?
its cross-sectional area; independent of size
What % of fibers are ‘slow twitch’?
45-55%
