neutral structure and neural communication

Question 1

what are the five features of a typical neuron?

Answer 1

dendrites, terminal buttons, myelin sheath, axon (inside myelin sheath), and soma (cell body)

Question 2

what is an action potential

Answer 2

• when a neuron fires and is caused by changes in low of charged molecules across the neuron’s cell membrane.
• term refers to rapid change in membrane potential of neuron

Question 3

what are the ions involved in action potentials

Answer 3

Sodium (Na+), chloride (Cl-), potassium (K+)

Question 4

what happens at rest membrane potential

Answer 4

neuron is polarised at -70mV

Question 5

what happens when the Na+ ions flow

Answer 5

membrane potential depolarises (moves from -70mV to 0mV)

Question 6

when will action potential be triggered

Answer 6

-50mV

Question 7

what happens when action potential is finished

Answer 7

• refractory period where membrane potential is hyperpolarised

Question 8

what does it mean for a membrane to be hyperpolarised

Answer 8

• it is even further from the threshold of activation and the neuron will be less likely to trigger another action potential untol the membrane potential has returned to the resting potential (-70mV)

Question 9

what does the influx of positive ions in action potential initiate?

Answer 9

• increases the charge within the neuron, reducing difference in charge between the inside and outside of the neuron (going from -70mV to -40mV)
• depolarisation

Question 10

what are the 6 steps of action potentials

Answer 10

1. Na+ channels open, Na+ begin to enter cell
2. K+ channels open, K+ being to leave cell
3. Na+ channels become refactory, no more Na+ enters cell
4. K+ continues to leave cell, causes membrane potential to return to resting level
5. K+ channels close, Na+ channels resent
6. Extra K+ outside diffuses away

Question 11

what is the propagation of action potentials

Answer 11

• ions are only able to flow in and out across the neuron membrane in the gaps between the myelin, causing the actions potential to move faster

Question 12

what is the rate law of action potentials

Answer 12

• neuron firing is “all or none” so frequency of firing determines the strength of the neural signal
• strong stimulus > leads to faster threshold for activation > more frequent action potentials

Question 13

what are the 5 key structural details of a synapse

Answer 13

• terminal button
• synaptic cleft
• pre and post synaptic membrane
• synaptic vesicles
• microtubles

Question 14

what do synapses enable

Answer 14

communications between neurons

Question 15

what are neurotrasmitters

Answer 15

chemicals that are synthesised within the brain/neurons and are often called “chemical messangers”

Question 16

where does the action potential stop and what does that mean

Answer 16

• stops at the end of an axon so the presynaptic neuron can only influence the post-synaptic neuron through the release of neurotransmitters across the synapse

Question 17

steps for the neurotransmitter

Answer 17

1. an action potential in the pre-synaptuc cell triggers synaptic vesicles to move toward the cell membrane
2. this is followed by a fusio of the two membranes
3. neurotransmitter molecules are then released
4. neurotransmitter then flows into the synaptic cleft where it is available to bind to receptors on the post-synaptic membrane

Question 18

what happens when the neurotransmitter releases

Answer 18

• when synaptic vesicles merges with the presynaptic membrane the contents are released into the synaptic cleft
• sometimes referred to as “kiss and run”

Question 19

what happens in the neurotransmitter reuptake

Answer 19

• synapse has the capacity to recycle and reuse neurotransmitter molecules after they have been released
• endocytosis

Question 20

what is the process of reabsorption into synapse

Answer 20

endocytosis

Question 21

what doe excitatroy postsynaptoc potentials (EPSPs) do

Answer 21

• depolarise the postsynaptic cell membrane
• increase likelihood that an action potential will be triggered in the postsynaptic neuron

Question 22

what is the primary excitatory neurotransmitter

Answer 22

glutamate

Question 23

what do the inhibitory postsynaptic potentials (IPSPs) do

Answer 23

• hyperpolarise the postsynaptic cell membrane
• decrease the likelihood that an action potential will be triggered

Question 24

what is the primary inhibitory neurotransmitter

Answer 24

Gamma-aminobutyric acid (GABA)

Question 25

what is the combined effect of EPSPs and IPSPs

Answer 25

neural integration

Question 26

how do neurotransmitters cause an effect on the post-synaptic neuron

Answer 26

• chemical message received by attaching to the binding site of a receptor sensitive to that neurotransmitter
• opening an ion channel is one example of the effect caused by neurotransmitter binding to the receptor

Question 27

what is the action of neurotransmitters at receptor

Answer 27

• receptors are very selective (lock and key)
• each receptor can generally only be activated by one neurotransmitter
• each receptor has a specific function/action
• when a neurotransmitter binds to the receptor this will trgger the same event each time

Question 28

what is the action of drugs on receptors

Answer 28

• drugs work by mimicking the chemical structure of the natural compound (perfectly or partially)

Question 29

what is the action of drugs at the receptor

Answer 29

• can act as antagonists - activating the receptor like the natural compound
• can act as an antagonist - blocking the receptor and preventing the natural compound from activating it

Question 30

drugs can only impact one function of the neurotransmitter. true or false

Answer 30

FALSE - they can impact every stage of neurotransmitter function from synthesis to release to receptor binding

Question 31

how do drugs work

Answer 31

• by mimicking/triggering the same biological responses triggered by naturally occurring substances

Question 32

do psychological events directly impact the biological processes

Answer 32

yes! Remembering things requires neurons to fire and chemical messages to be sent across neurons