muscle Flashcards
where does skeletal muscle occur
at the joints of a skeleton
what is the name of the pairs which muscles are arranged in
antagonistic pairs, when one contracts the other elongates
each skeletal muscle fibre is multinucleate, what does that mean
multinuclate- contains many nuclei
what is the name of the plasma membrane structure which surrounds the muscle fibres
sarcolemma
what is the muscle cytoplasm which is within muscle fibres called
sarcoplasm
what is held in the sarcoplasm
sarcoplasmic reticulum
many mitochondria
what are skeletal muscles arranged in
myofibrils
what are myofibrils divided into
sarcomere
what are the two protein filaments which allow muscle contraction
myosin
actin
what are the three types of muscle
smooth
cardiac
skeletal/ striated
is smooth muscle voluntary or involuntary
involuntary
describe smooth muscle contraction
slow contraction
regularly contracts
doesnt tire quickly
what nervous system controls smooth muscle
autonomic nervous system
is smooth muscle multinucleate
no it contains one nucleus for each muscle cell
where is smooth muscle found
digestive system
blood vessels
what does cardiac muscle form
the muscular part of the heart
describe cardiac muscle structure
corss bridges between fibres
intercalated discs to join muscle cells
contraction is a squeezing action
what do intercalated discs do and what muscle do they belong to
intercalated discs is a specialised plasma membrane which are fused to produce junctions which allow diffusion of ions between muscle cells.
Easy transmission of action potential along cardiac muscle fibres
does cardiac muscle fatigue easily
no
what controls the rate of contraction of cardiac muscle
SAN
what is the word used to describe cardiac muscle
myogenic- initiates its own contraction
how does cardiac muscle appear under a microscope
striated with gaps, not in straight lines, with gaps in between rows of striated muscle
what is the neuromuscular junction
the junction between the nervous system and a muscle is a neuromuscular junction
what is stimulation of contraction
1- action potential arrives at the end of the axon and calcium ion channels open in the membrane, calcium diffuses in.
2- acetylcholine vesicles move towards and fuse with the end membrane through exocytosis
3- acetylcholine molecules diffuse across the gap and fuse with sarcolemma receptors
4- sodium ion channels open and sodium ions and diffuse into the muscle fibre and depolarise the sarcolemma
5- wave of depolarisation spreads along sarcolemma and down tranverse tubules into muscle fibre
what is a transverse tubule
they are deep invaginations of the sarcolemma in muscle cells which facilitate transmission of action potential and muscle contraction.
what is a motor unit
when many motor neurones divide and connect to several muscle fibres, they then contract together and provide a stronger contraction
what are differences between a neuromuscular junction and a synapse
neuroM junctions-between a neurone and a muscle
A synapse is between neurone and neurone
neuromuscular junctions use t tubules to carry signals quickly, synapses dont
what are similarities between neuromuscular junction and cholinergic synpases
both use acetylcholine
both therefore use acetlycholinesterase to prevent constant impulses
both triggered by action potentials in presynaptic membrane
both use sodium ion channels and chloride ion channels
what muscle groups do myofibril belong to
skeletal
