physiology Flashcards
what is the function of skeletal muscles
maintain posture respiration heat production (shivering) metabolism movement
what are the 3 types of muscle
cardiac
skeletal
smooth
describe cardiac muscle
striated and involuntary
describe smooth muscle
non-striated and involuntary
describe skeletal muscle
striated and voluntary
what innervates cardiac muscles
ANS
what innervates smooth muscles
ANS
what innervates skeletal muscle
somatic nervous system,
what is the transmitter at the skeletal muscle neuromuscular junction
acetylcholine
what initiates skeletal muscle
neurogenic mechanism
what initiates cardiac muscle
myogenic (pacemaker potenital)
what is a motor neurone
a single alpha motor neurone and all the skeletal muscle fibres that it innervates
what does the number of muscle fibres per motor unit depend on
the function served by the muscle. if precision is more important than power then there will be fewer fibres and vice versa
how are skeletal muscles organised
whole muscle to muscle fibre to myofibrils to sarcomere which are made up of myosin and actin
what is a myofibril
a specialised intracellular structure
what is a functional unit
the smallest component capable of performing the functions of the organ
where is a sarcomere located
between two z-lines
what is a z-line
connects the thin filaments of two adjoining sarcomeres
what are the 4 zones of a sarcomere
A-band
H-zone
M-line
I-band
what is a A-band
thick filaments with portions of thin that overlap both ends of the thick
what is the H-zone
lighter areas within the middle of the A-band where the thin filaments don’t reach
what is the M-line
extends vertically down the middle of the A-band, within the centre of the H-zone
what is the I-band
consists of the remains portion of thin filaments that don’t project onto the A-band
how is muscle tension produced
the sliding of actin on myosin
what is ATP needed for in muscle contraction
contraction
relaxation
to release cross bridges
pump Ca2+ back into the SR
what is Ca2+ needed for in muscle contraction
switch on cross-bridge formation
what is excitation contraction coupling
the process where the surface AP results in activation coupling of the contractile structures of muscle fibres
explain muscle contraction
acetylcholine is released by the motor neurone
the surface AP spreads down the transverse T-tubles
this triggers the release of Ca2+ from the SR
Ca2+ binds to troponin which pulls the troponin-tropomysoin complex aside to expose the bind site
cross-bridge formation occurs
