Nervous Coordination & Muscles Flashcards
Features of nervous control
Transmitted through the body along an electrical impulse
Rapid, short lived and localised response
Features of hormonal control
Transported in the bloodstream
Slow, long lasting and widespread response
What is happening at resting potential?
Potential difference of -70mv
Inside of axon negatively charged compared to outside
No voltage gated channels open
What occurs at depolarisation?
Na+ channels open and Na+ enters axon
Inside of axon becomes more positive
Potential difference is +35mv
What occurs at repolarisation?
Na+ channels close
K+ channels open
Inside of axon becomes negative as k+ diffuses out of axon
How does hyper-polarisation occur?
K+ channels remain open and inside of axon becomes too negative
What is spatial summation?
A number of neurones release enough neurotransmitters to exceed the threshold
What is temporal summation?
A single presynaptic neurone releases neurotransmitter many times in a short period
Mechanism of transmission across a synapse
Calcium ions enter presynaptic neurone through calcium ion channels.
Calcium fuses with vesicles containing neurotransmitter
Neurotransmitter diffuses across and binds to receptors
Na+ channels open and Na+ enters postsynaptic neurone
Features of slow twitch fibres
Adapted for aerobic respiration
Large store of myoglobin
Rich supply of blood vessels
Lots of mitochondria
Features of fast twitch fibres
Adapted for intense exercise:
Thicker and more myosin filaments
High conc. of glycogen
Store of phosphocreatine
Muscle contraction
Ca2+ move tropomyosin to pull away
Myosin heads bind to actin
Myosin heads change angle & pull, releasing molecule of ADP
ATP attaches to myosin so it detaches
Hydrolysis of ATP to ADP provides energy for myosin head to reattach
