Muscles Flashcards
What are the alternative names for each type of muscle?
smooth - unstriped/involuntary
skeletal - striped/voluntary
cardiac - heart
What are the three types of muscle?
smooth, cardiac, skeletal
Describe the contractions of each type of muscle
smooth - slow
skeletal - rapid
cardiac - rapid/myogenic
Describe the speed of the fatigue of the muscle types
smooth - slow
skeletal - rapid
cardiac - never/very slow
Describe the distribution of the different types of muscle
smooth - tubular organs
skeletal - attached to skeleton/bones
cardiac - heart
What is antagonistic muscle action?
muscle pairs that act in opposite directions, one contracts and the other relaxes
Give an example of antagonistic muscles?
bicep and tricep
How is skeletal muscle controlled?
-by the voluntary nervous system
-each muscle is controlled by a motor neurone
How do motor neurones interact with muscles?
at a neuromuscular junction (specialised synapse between a motor neurone and muscle fibre)
Explain the process at a neuromuscular junction
-an action potential arrives at the neuromuscular junction causing Ca2+ channels to open
-Ca+ diffuses into neurone
-this causes vesicles containing acetylcholine to fuse with the pre-synaptic membrane
-acetylcholine diffuses across the synaptic cleft and binds to sarcolemma receptor proteins on the post-synaptic membrane
-this causes Na+ to diffuse into the sarcolemma
-post-synaptic membrane depolarises and sends the an action potential along the sarcolemma and down T-tubules
-T-tubules channel the action potential towards the sarcoplasmic reticulum which releases Ca2+ ions into the cytoplasm
-increase in Ca2+ ions causes the muscle cell to contract
Compare the neurotransmitter, post synaptic membrane, type of movement, effect, number of receptors, type of response of cholinergic synapse and NMJ
neurotransmitter - CS is acetylcholine, NMJ is acetylcholine
post synaptic membrane - CS is a neurone, NMJ is the sarcolemma in a muscle cell
type of movement - diffusion
effect - CS - action potential, NMJ - muscle contraction
number of receptors - CS - fewer, NMJ - more
type of response - CS - excitatory or inhibitory, NMJ - excitatory
What are muscle fibres joined by?
tendons
What is a sarcomere?
the basic contractile unit
What is a muscle fibre?
a single muscle cell
How do myofibrils appear under a microscope?
banded structures
How are the insides of the myofibrils structured?
parallel filaments
What are the two types of filament in a myofibril?
thick - myosin
thin - actin
How are the two filaments linked?
intervals called crossbridges
Describe the structure of myosin
-two heads called myosin heads
-each head contains an ATPase
-the heads stick out from the crossbridge
Describe the structure of actin
contains a binding site for myosin heads