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human biology > A2- the nervous system > Flashcards

A2- the nervous system Flashcards

all flashcards for the nervous system topic

1
Q

what does the central nervous system consist of?

A

the brain and the spinal cord.

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2
Q

what does the central nervous system do?

A

it processes sensory information and decides what to do with it, then initiating a response.

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3
Q

what does the CNS contain, what type of neurones?

A

relay neurones

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4
Q

what is the role of relay neurones?

A

they carry signals across parts of the CNS, they can both transmit and receive messages
they also connect the sensory neurones to the motor neurones.

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5
Q

what are the characteristics of a relay neurone?

A

they have short axons and short dendrites.

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6
Q

what is the peripheral nervous system? PNS

A

the nervous system outside the spinal cord and brain, involvinf all other nerves in the body

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7
Q

what neurones is the PNS made up of and what do these then do?

A

made up of sensory and motor neurones, the sensory neurones bring information from receptors to the CNS.
motor neurones carry info from the CNS to effectors like muscles and glands.

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8
Q

what is the function of a sensory neurone?

A

they send info to the brain regarding the senses, keep the brain informed about the external and internal environment, can only transmit messages (one way street) e.g send the message that you just touched something too hot.

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9
Q

what are the characteristics of a sensory neurone?

A

they have long dendrites and short axons, cell body is to the side of the cell.

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10
Q

what is the function of a motor neurone?

A

they carry signals from the CNS towards organs and muscles in the body
work as a two way street like relay neurones as they can both transmit and receive info.

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11
Q

what are the characteristics of motor neruones?

A

they have short dendrites and long axons, can also be known as a motor end plate if it is connected to muscle.

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12
Q

what is conscious nervous coordination?

A

when an action is produced that involves thought, uses the brain and is voluntary.

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13
Q

what is unconscious nervous coordination?

A

it requires no thinking, uses the reflex arc and uses the spinal cord only, it is involuntary.

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14
Q

what are the four features of a neurone/ characteristics?

A

dendrites, cell body, axon, axon terminal

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15
Q

what are neurones?

A

they are nerve cells.

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16
Q

what is the function of a dendrite?

A

carries impulses towards the cell body.

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17
Q

what is the function of the cell body?

A

contains nucleus of the neurone

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17
Q

what is the function of the axon terminal?

A

it is the end of an axon, it is where the synapse is found connecting to the dendrite of the next neurone.

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18
Q

what is the function of the axon?

A

carries impulses away from the cell body.

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19
Q

what are nerve signals?

A

also known as action potentials

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20
Q

what is an action potential?

A

the change in electrical potential along the membrane of a nerve or muscle cell.

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21
Q

what are the 3 types of protein that neurone membranes contain?

A

sodium potassium pumps
sodium channels
potassium channels

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22
Q

what is the sodium potassium pump?

A

it is a transmembrane protein pump that transports sodium and potassium ions across the cell.

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23
Q

how does the sodium potassium pump work?

A

it moves sodium and potassium ions against large concentration gradients using carrier proteins.it moves potassium ions into the cell where potassium levels are high and sodium ions out of the cell and into the extracellular fluid. it uses active transport to pump ions across membranes

24
Q

how many potassium ions get pumped into the cell?

A

2 get pumped into the cell

25
Q

how many sodium ions get pumped out of the cell?

A

3 sodium ions get pumped out of the cell

26
Q

explain the 5 steps to the sodium potassium pump.

A

1 - 3 NA+ 9 sodium) from the inside of the cell bond with the enzyme/protein pump.
2 - the carrier protein then gets energy from ATP and changes shape.
3- this shape then allows for the sodium ions to be pumped out of the cell making this area more positive.
4- then 2 potassium ions from the outisde bind with their side of the protein pump and the process repeats.
5 - 2 potassium ions are transported into the cell.

27
Q

where can the sodium potassium pump be found?

A

in the plasma membrane of almost every human cell

28
Q

what does the sodium potassium pump help with?

A

to maintain cell potential and it regulates cellular volume

29
Q

what is resting potential in a nervous impulse?

A

when a neuron is not actively transmitting a nerve impulse, the sodium potassium pumps maintain a difference in charge across the cell membrane.

30
Q

what is the amount of mV in a resting potential nerve impulse?

A

-70mV or -60-80mV

31
Q

what is depolarisation?

A

when the sodium channels open, the ions diffuse into the neurone down the concentration gradient which causes it to depolarise. a neurone has to meet a certain threshold in order top begin depolarisation.

32
Q

what happens if membrane depolarisation does not happen?

A

an action potential will not happen.

33
Q

what is the mV needed to reach the threshold for depolarisation to occur?

A

it has to be -50mV

34
Q

what is repolarisation?

A

when the cell returns to a negative value jut after the depolarisation phase of an action potential, happens when positively charged potassium ion move out of the cell

35
Q

what is the process of repolarisation?

A

when the potassium ions leave the cell the membrane potential drops back down to 0mV as it becomes negative, the repolarization continues to drop below 0,until it reaches its resting membrane of -70mV.

36
Q

what is the stage after repolarisation?

A

hyperpolarization.

37
Q

what is hyperpolarisation ?

A

when the membrane potential becomes more negative spot on the neurones membrane.

38
Q

what are the three types of sodium ion channels?

A

stimuli-gated ,voltage-gated, ligand-gated

39
Q

what is the location and use of stimuli gated channels?

A

they are found in the dendrites of sensory neurones, and are used to create new action potential from stimuli-receptors.

40
Q

what is the location and use of voltage gated channels?

A

found along the length of dendrites and axons in all neurones, they are used to transmit waves of action potential.

41
Q

what is the location and use of ligand gated channels?

A

found in post synaptic membrane across the synapse, used to transmit action potential between neurones or motor neurones to muscle.

42
Q

what is myelination?

A

the formation of the myelin sheath around a nerve to allow for improved conduction. which helps to greatly increase the speed of signals transmitted between neurones.

43
Q

what is the myelin sheath?

A

it protects the axon and helps speed nerve transmissions.

44
Q

what are synapses?

A

they are the junctions between neurones. where information is transmitted from one neurone to another.

45
Q

what is a synaptic cleft?

A

the extra space between the presynaptic and postsynaptic membranes.

46
Q

what is synaptic transmission?

A

the way in which information is communicated between neurones through the synapse, this can either be chemical or electrical. But in the human body it is mostly chemical.

47
Q

what are neurotransmitters?

A

the chemicals that carry the signals across the synapse.

48
Q

what is the effect of myelination on transmission speeds?

A

as the current jumps from node to node, a process called saltatory conduction happens, which increases the nerve impulse transmission.

49
Q

in myelinated neurones where do action potentials occur?

A

where the axon is exposed at the nodes of Ranvier.

50
Q

describe the process of how information crosses the synaptic cleft.

A

when the nerve impulses reach the dendrites at the end of one axon, called the axon terminal, the neurotransmitters diffuse across the synaptic cleft and bind with receptor molecules onto the membrane of the next postsynaptic neurone.

51
Q

what is a presynaptic membrane?

A

it is the axon terminal membrane of the neurone carrying the impulse to the synapse.

52
Q

what is the post synaptic membrane?

A

it is the membrane of the cell body that carries the impulse away from the synapse, it contains a number of channels to allow ions to flow through.

53
Q

what is myelin made out of?

A

from flattened layers of specialised cells called Schwann cells, they wrap around the axon and form a lipid insulating layer.

54
Q

what is saltatory conduction?

A

it is the process of the signal jumping from node to node. ( one node of ranvier to another) this increases conduction velocity of action potentials.

55
Q

explain the steps of chemical transmission across the synapse.

A
  • the action potential arrives at the end of the axon (the presynaptic membrane)
  • the calcium ion channels open up and these ions diffuse across the presynaptic membrane because of the concentration gradient.
    -as this concentration increases vesicles containing neurotransmitters move to the membrane.
56
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57
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58
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human biology (6 decks)

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