organism response Flashcards

Question

structure of myelinated neuron…

Answer 1

cell body= protein and neurotransmitter production dendrites= carry action potential to surrounding cells axon= carries nerve impulse along neuron myelin sheath= doesn’t allow charged ions or the impulse to pass through

Answer 2

the difference in electrical charge between the outside and inside of the neuron when an impulse isn’t being conducted resting potential is about -70mV because there are more Na+ and K+ ions outside the neuron

Answer 3

by sodium-potassium pump, involves active transport and therefore requires ATP

Answer 4

chemical disturbance that is carried along the surface membrane of the axon when an impulse is received from receptors, sodium ion channels open so Na+ ions enter the neuron, causing depolarisation, so charge becomes more positive

Answer 5

voltage gated sodium ion channels are activated, leading to an even higher influx, causing an action potential (+40mV) voltage gated Na+ channels close, whilst voltage gated K+ channels open so depolarisation occurs as K+ ions leave the neuron causes hyperpolarisation, so the voltage gated K+ ion channels close sodium potassium pump returns neuron back to its resting potential

Answer 6

Once the threshold potential is reached, each action potential depolarises the con to the same voltage by voltage gated sodium ion channels

Answer 7

period in an action potential when the axon can’t be depolarised to imitate another action potential important because= limits frequency of action potential, ensures action potentials only travel in one direction and are discrete overshoot= voltage drops below -70mV, so ensures signal only goes one way, allow it to return to normal

Answer 8

non-myelinated= transmission acts like a ‘Mexican wave’ because when depolarisation occurs, voltage gated sodium channels open further down the axon, by the time depolarisation has spread, part of the neuron has already repolarised (Salvatore period) myelinated= action potentials only occur at the Nodes of Ranvier, so action potentials ‘jump’ from node to node, which is quicker and is called saltatory conduction

Answer 9

myelination= increase speed axon diameter= wider the axon, faster the impulse temperature= higher temps increase speed of impulse

Answer 10

axon terminal- synaptic gap- receptor

Answer 11

connect to a muscle instead of a post-synaptic neuron place where 2 neurons functionally meet

Answer 12

1. action potential arrives at the synaptic knob, depolarising it so voltage-gated calcium channels open and calcium ions diffuse into the synaptic knob 2. vesicles containing acetylcholine fuse with the pre synaptic membrane 3. acetylcholine is released into the synaptic cleft by exocytosis 4. acetylcholine diffuses across the synaptic cleft to the post-synaptic membrane, and binds to cholinergic receptors 5. Na+ channels on the post-synaptic membrane open and Na+ diffuse into the post-synaptic neuron, causing depolarisation 6. if the threshold is reached, action potential is formed 7. acetylcholine removed from synaptic cleft + degraded by acetylcholine esterase to prevent a continuous impulse 8. products are transferred into presynaptic neuron and Na+ channels close, allowing post-synaptic neuron to reach resting potential

Answer 13

chloride ions move into the post-synaptic neuron and potassium ions move out membrane potential reaches -80mV, causing hyperpolarisation, so an action potential would be very unlikely

Answer 14

rapid build up of neurotransmitters to help generate an action potential temporal summation= 1 neuron releases neurotransmitters repeatedly over a short time period do the threshold value is exceeded spatial summation= many neurons collectively stimulate an action potential by combining the neurotransmitters they release to exceed the threshold value

Answer 15

unidirectional as neurotransmitter receptors are only on the post-synaptic membrane only excitatory connects motor neurons and muscles end point of the action potential acetylcholine binds to receptors on muscle fibre membranes

Answer 16

mimic shape and action of neurotransmitter, so binds to post-synaptic receptors and causes action potentials (agonist) bind to receptor but to block it, so preventing action potentials. (antagonist) bind to acetylcholine esterase, so fewer t-s complexes formed with acetylcholine, causing a continuous impulse can cause the release or blocks release of neurotransmitters

organism response Flashcards

(40 cards)