nervous transmission peq Flashcards
describe how the concentration of calcium ions around the myofibrils is controlled
calcium ions released from sarcoplasmic reticulum
in response to action potential at neuromuscular junction
calcium channels open to allow calcium ions to cross the membrane (enter the sarcoplasm)
calcium ions taken back up into the sarcoplasmic reticulum by active transport
explain the electrical changes in an axon that allow these nerve impulses to be detected
potential difference across axon changes
due to increased permeability to sodium ions
voltage gated sodium channels open
sodium ions move into the axon- causing depolarisation
followed by increased permeability to potassium ions/ K+ channels open
K+ ion move out of the axon causing the membrane to repolarise
sensory neurone structure
cell body in middle of axon
glycolipid structure
lipids attached to a chain sugar molecules joined by glycosidic link
describe the role of dendrites in a neurone
form synapses with other neuroens
receive impulses from other neurones
involved in summation
propagate a signal
initiate an action potential to the cell body/ axon
explain how a named drug causes an action potential in the post synaptic neurone
drug is a similar shape to acetylcholine
increases permeability of membrane to sodium ions
changes shape of receptors/ channel proteins
named drug causes the depolarisation of post synaptic membrane
depolarisation reaches threshold level
describe the process that occurs at a synapse that leads to habituation
repeated stimulus decreases sensitivity of pre synaptic membrane/ calcium channels not opening
fewer/no Ca2+ ions move in to pre synaptic neurone
fewer/ no vesicles move towards/ fuse with pre synaptic membrane
less/ no neurotransmitters are released and can diffuse across gap
action potential/ depolarisation less likely to occur in post-synaptic neurone
describe how ions and neurotransmitter molecules are involved in the transmission of an impulse
synapse formation/ process
calcium ions enter presynaptic neurone so vesicles with neurotransmitter can move towards/ fuse with presynaptic membrane
neurotransmitter molecules diffuse across the synaptic cleft
neurotransmitter binds with receptors on postsynaptic membrane on the brain cell
sodium ions diffuse into brain cell/ post synaptic neurone leading to action potential/ depolarisation
sensory vs motor neurone
both have cell body containing nucleis
both have axon
both have dendrites at one end and terminal branches at the other end
different location of cell body- MN at one end of axon, SN located along the axon
explain why inhibitors of acetylcholinesterase could be useful in preventing loss of neurones that produce acetylcholine
acetylecholinesterase breaks down acetylcholine
inhibitor prevents break down of acetylcholine
more acetylcholine will be available to bind to post synaptic membrane/ receptors
compensates for loss of acetylcholine producing neurones
