Muscle 2 Flashcards
Name the 2 types of twitch muscle
slow and fast-twitch
Describe how the slow-twitch contracts, its contractions, time period and where it is most common
Slow-twitch contract more slowly, provide less powerful contractions over a longer period common in the calf
Describe how the fast-twitch contracts, its contractions, time period and where it is most common
fast-twitch contracts more rapidly provide more powerful contractions over a short period common in biceps
How are slow-twitch muscles adapted for aerobic respiration?
Large store of myoglobin
Rich supply of blood vessels
Numberous mitochondria
How are fast-twitch muscles adapted for anaerobic respiration?
Thicker and more numerous myosin filaments
High concentration of glycogen
High con. of enzymes involved in anaerobic respiration
A store of phosphocreatine 4 energy 4 muscle contraction
What is a neuromuscular junction?
where motor neurone meets skeletal muscle fibre
What is a motor unit
multiple muscle fibres supplied by the motor
What are the similarities between synapses and neuromuscular junction
Both have neurotransmitter transported by diffusion
Have receptors causing an influx of Na+
Use Na/K pump to repolarise axon
use enzymes to breakdown the neurotransmitter
What are the differences between synapses and neuromuscular junction in relation to being excitatory or inhibitory
Neuromuscular junctions excitatory
Cholinergic synapse can be either excitatory or inhibitory
What are the differences between synapses and neuromuscular junction in relation to linking the neurone to ____
Neuromuscular junctions = motor neurone
Cholinergic synapse = motor/ sensory or intermediate
What are the differences between synapses and neuromuscular junction in relation to the state of the AP
Neuromuscular junctions = AP ends
Cholinergic synapse = A new AP may be produced
What are the differences between synapses and neuromuscular junction in relation to what the Acetylcholine binds to ?
Neuromuscular junctions = Muscle Fibre
Cholinergic synapse = post synpatic neuone
Skeletal muscles occur in ___ pairs
antagonist pairs
Name the mechanism for the contraction of skeletal muscle
Sliding Filament Mechanism
What happens to the —- during the sliding filament mechanism
I band
A band
Z-lines/ sarcomere
I band narrows
A band remains the same length
Sarcomere shortens
What evidence discounts the sliding filaments mechanism
The A band remains the same length
Describe how the muscle is stimulated
AP reaches many neuromuscular junctions so Ca 2+ channels open and then ions diffuse into the synaptic knob
Ion causes synaptic vesicles to fuse with the presynaptic membrane and release their acetylcholine into the synaptic cleft
Acetylcholine diffuses across cleft and binds with receptor and depolarise
Describe muscle contraction
AP travels into fibre via T-tubles which are in contact with the ER which AT ca2+from sarcoplasm.
AP opens Ca2+ channels so ions diffuse into sarcoplasm and cause tropomyosin to pull away from the actin-binding site they were blocking.
ADP attaches to myosin head which can bind to actin and form cross-bridges.
The head changes angle pulling actin along and releasing ADP
ATP attaches to myosin causing it to unbind to actin
Ca2+ activate ATPase to supply energy for myosin head to return to original shape
What are the T-tubules?
They are extensions of the cell-surface membrane and breach throughout the sarcoplasm
Myosin is joined _____ so can move in ____
Myosin is joined tail to tail so can move in opposite directions
Describe Muscle Relaxation
Nervous stimulation ceases
Ca2+ AT back to ER
Reabsorption of Ca2+ allows tropomyosin 2 block actin again
Myosin heads unable to bind to muscle relaxes
