name the physiological functions of skeletal muscle
movement/ respiratory movements
contributor to whole body metabolism
skeletal muscle is striated/non striated and voluntary/ non voluntary
striated and voluntary
which nerves innervate skeletal muscle?
somatic nervous system
skeletal muscle has _______ initaion of contraction
what is the transmitter at the neuromuscular junction of skeletal muscle
skeletal muscle fibres are organised into what?
motor units- single alpha motor neuron
muscles that allow for precise movements will have fewer/greater motor fibres per unit than for power?
sort into levels of organisation 1. muscle fibre 2. sarcomere 3. myofibril 4. actin/filamin 5. whole muscle
4. actin/filamin 2. sarcomeres 3. myofibrils 1. muscle fibre 5. whole muscle
define functional unit
smallest component capable of performing all the functions of that organ
sarcomere is found between what two lines?
what are the four zones of the sarcomere
describe the A- band
thick filaments with portions of thin filamwetns that overlap in both ends of thick filaments
describe the H- zone
lighter area of the A-band where thin filaments dotn reach
describe the M-line
extends vertically down A-band within the centre of H-zone
remaining portion of thin filaments that don't project in A-band
muscle contraction is caused by what?
actin filaments sliding on myosin filaments
force generation of muscle depends on what?
ATP- dependant interaction
in skeletal muscle fibres Ca2+ is released from where?
lateral sacs of the sarcoplasmic reticulum
the surface action potential of skeletal muscle spreads down what?
the transverse (T)- tubules (extensions of the surface membrane)
what allows simultaneous contraction of muscle fibres?
stimulating more motor units to achieve a stronger contraction is known as what?
motor unit recruitment
asynchronous motor unit recruitment during submaximal contractions helps prevent what?
tension developed by each contracting muscle fibre depends on what two things?
frequency of stimulation and summation of contractions
length of muscle fibre
the action potential in skeletal muscle is longer than the duration of the resulting twitch true/false
false- the AP is shorter
describe single twitch in skeletal muscle
the muscle fibre has completely relaxed before being restimulated
with single twitch the second twitch is the same/greater magnitude than the first twitch
what happens if a muscle fibre is restimulated before it has completely relaxed?
the second twitch is added to the first resulting in twitch summation
what is tetanus?
when a muscle fibre is stimulated so rapidly it doesn't have time to relax between stimuli- maximal sustained contraction
what type of muscle cannot be tetanised and why?
cardiac muscle- long refractory period
when is maximal tetanic contraction achieved?
when the muscle is at its optimal length before the onset of contraction