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Human Biology > Nervous System > Flashcards

Nervous System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What does a dendrite do?

A

Carries impulses towards the cell body

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2
Q

What does a cell body do?

A

Contains the nucleus of the neurone

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3
Q

What does the axon do?

A

Carries impulses away from the cell body

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4
Q

What does an axon terminal do?

A

A synapse is found connecting to the dendrites of the next neurone

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5
Q

What are sodium potassium pumps?

A

-carrier proteins
-they actively transport na+ ions out of neurones and k+ ions in
-they use ATP and work against concentration gradients

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6
Q

What are sodium and potassium channels?

A
  • channel proteins with specific tertiary structures which only allow ions of the right shape, size and charge to pass through
  • when open, they allow facilitated diffusion of either na+ ions or k+ ions in or out of the neurone
  • na+ ions and k+ ions are water soluble so cannot diffuse directly through the phospholipid bilateral of the neurone membrane expect through the channels when open
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7
Q

What happens during resting potential?

A

Neuron cell membranes are polarised.

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8
Q

What is resting potential?

A

The potential difference across the neuron membrane while the neuron is at rest 

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9
Q

What happens during polarisation?

A

This is about -70mv to -60mv inside the neuron compared to the outside. A neurone is more negative inside and outside because 3Na plus ions are pumped out of the neurone for every 2K plus ions pumped into it. And sodium and potassium channels are closed. So ions cannot get back in or out of the neurone once plant.

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10
Q

What is action potential?

A

It is the depolarisation of the neurone membranes inside is more positive on the outside 

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11
Q

What happens during depolarisation?

A

It is about +40mv inside the inside the neuron compared with the outside. And sodium channels open in response to stimulus and Na ions diffusefuse into the neuron down the concentration gradient created by the sodium and potassium pumps. This is the start of a nerve impulse. 

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12
Q

What is an all or nothing response

A

Stimulus is a set of an action potential, or it doesn’t
Once an action potential started, it is transmitted along neurons with the same value (40mV)
High intensity stimuli produce the same action potential as low intensity stimuli
However, action potentials are generated more frequently as stimulus intensity increases
The brain interprets a high frequency of nerve impulses as a more intense stimulus

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13
Q

What happens after an action potential has been created

A

Repolarisation

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14
Q

What happens during repolarisation?

A

Sodium channels close
Potassium, channels open
K+ ions diffuse out of the neuron down a concentration gradient created by the sodium potassium pump
The neuron repolarises inside of the neuron becomes negative compared to the outside once again 

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15
Q

What happens during hyperpolarisation?

A

Potassium channels are slow to close, so too many K plus ions diffuse out of the neuron and a potential difference over shoot slightly, making a neuron hyperpolarises, meaning it’s more negative inside than resting potential

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16
Q

How do you sodium potassium pump, restore resting potential?

A

By pumping NA, plus ions back out of the neuron and K plus ions back in 

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17
Q

What happens during the refractory period?

A

The refractory period is the time it takes for a membrane to recover from repolarisation and hyper polarisation of the neuron membrane. During this period the neuron cell membrane cannot be excited again. 

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18
Q

What is the function of the refractory period?

A

1) ensures action potentials don’t overlap by delaying time between them
2) limits the frequency of nerve impulse
3) ensures action potential are on directional


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19
Q

When is sodium channels open at the start of a neuron what happens?

A

NA plus ions diffuse in, and then the neuron depolarises, and then an action potential is set up 

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20
Q

The influx of an A+ ion sets of transmission of a nerve impulses along the neuron, describe how this works

A

1) increase in NA, plus ion concentration at the point of depolarisation, set up a local current of na+ ions
2) NA plus ions diffuse sideways along the side of the neuron away from the region of higher concentration
3) this causes sodium channels open further down the neuron, setting of another action potential
4) the local current move, some neuron as a wave of depolarisation, followed by a wave of repolarisation. This is the nerve impulse. 

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21
Q

What affect does myelination have on the speed of conduction?

A

Myelinated neurons conduct faster than nonmyelinated neurons
Mylan is a fatty substance, so ions are not lipid soluble, so cannot pass through it. This provides electrical insulation 

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22
Q

Why do myelinated neurons conduct faster than nonmyelinated neurons

A

Because in unmyelinated neurons the whole membrane must depolarise

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23
Q

Why does the myelin provide electrical insulation

A

Because in myelinated neurons depolarisation only occurs at the nodes action potentials leap along the neuron 

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24
Q

What is MS?

A

An autoimmune disease in which the myelin sheath is damaged, slowing down nerve impulses. Four motor neurons, disease, slower muscle contraction

25
Q

What is a synapse?

A

The junction between two neurons

26
Q

What is a synaptic cleft?

A

The gap between two neurons

27
Q

What is the presynaptic neuron?

A

The neuron before the synapse

28
Q

What is a postsynaptic neuron?

A

The new one after the

29
Q

What is the synaptic knob?

A

Swelling at the end of the presynaptic neurons, which makes and releases neurotransmitters

30
Q

What is a neurotransmitter?

A

Chemical that the fuses across the synaptic cleft to transmit a signal to the postsynaptic neuron.

This communication between cells is an example of cell signalling

31
Q

What is a cholinergic synapse?

A

A synapse, which makes and releases acetylcholine

32
Q

What are nerve impulses?

A

Waves of electricity (action, potentials) transmitted along neurons

33
Q

Nerve impulses cannot jump across synaptic cleft so how did they get across?

A

Neurotransmitter released by pre-synaptic knob allows nerve impulses to carry the cross in attic left. It does this by bring me about depolarisation of the postsynaptic membrane. This sets off a new nerve impulse in the postsynaptic neuron. 

34
Q

What happens during the first step of transmission of a nerve impulse across a membrane?

A

1) nerve impulse arise that synaptic knob causing calcium channels on presynaptic membrane to open.
Calcium ions diffuse into the synaptic knob
Calcium ions cause vesicles containing acetylcholine to migrate towards the presynaptic membrane

35
Q

What happens during the second stage of transmission of a neuron impose across a synapse?

A

2) vesicles containing acetylcholine fuse with the presynaptic membrane
Vesicles release acetylcholine into the synaptic cleft by exocytosis
Acetylcholine molecules diffuse across the synaptic cleft 

36
Q

What happens during the third stage of transmission of a nerve impulse across a membrane?

A

3) acetylcholine molecules bind to receptors sites on the postsynaptic membrane, causing sodium channels open
Sodium ions diffuse from the synaptic cleft into the postsynaptic neuron
The postsynaptic membrane, depolarises and nerve impulse is set up

37
Q

What happens during the final stage of transmission of a nerve impulse across a synapse?

A

4) acetylcholinesterase is released
This enzyme hydrolyses acetylcholine so sodium channels of the postsynaptic membrane close and impulse stops
This allows for membrane to repolarise ready for the next impulse

38
Q

NT released by excitatory synapsis causes what

A

Depolarisation so set up action potential in postsynaptic neurons

39
Q

NT released by inhibitory synopsis causes what

A

Hyper polarisation so prevent an action potential in postsynaptic neurons

40
Q

What do drugs do?

A

Drugs are chemicals which either mimic or block the action of specific neurotransmitters for particular effects. This is usually achieved by competing with the neurotransmitter for complimentary receptor in synapses.

41
Q

Drug which mimics in neurotransmitter is known as

A

An agonist

42
Q

A drug which blocks and neurotransmitter is

A

An antagonist

43
Q

Give some examples of agonistic drugs which impact on cholinergic synapses

A

Nicotine and muscurane

44
Q

Examples of antagonistic drugs, which impacts on cholinergic synapses

A

Atropine and curare

45
Q

What is an example of a voluntary response

A

1) stimulus (dropping £5 note)
2) Receptor (eye)
3) sensory neuron
4) relay neurone
5) CNS
6) motoneuron
7) effector (muscle contraction)
8) response

46
Q

An unconscious nervous communication is known as a simple reflex, because

A

It involves a rapid involuntary response to a stimulus because you do not think

47
Q

Describe the steps of a reflex arc

A

1) stimulus
2) Receptor
3) sensory neuron
4) relay neuron
5) motor neuron
6) effector
7) response

48
Q

Compare the signals from the nervous system and hormonal system

A

In the nervous system signals are electrical and electrolytes whereas in the hormonal system, signals or chemical

49
Q

Compare the target audience of the nervous system and hormonal system

A

In the nervous system has a specific target audience and in the hormonal system. It has a widespread target audience.

50
Q

Compare the transport in the nervous system and hormonal system

A

The nervous system contains transport of neurons where is the hormonal system contains transport of blood

51
Q

Compare the duration of effect of the nervous system and hormonal system

A

The nervous system has a short duration, and the hormonal system has a long lasting effect

52
Q

Compare the time to act of the nervous system and hormonal system

A

The nervous system has a fast acting time to act where is the hormonal system has a delayed time to act

53
Q

Compare the feedback of nervous system and hormonal system

A

The nervous system reacts to negative feedback, where is a hormonal system reacts to both positive and negative feedback

54
Q

Compare the response created from the nervous system and hormonal system

A

In the nervous system, CNS is in control of for processing and PNS is in control of muscle contraction and glandular secretion, whereas in a human or system, protein hormones also cell function of metabolism, as well as muscle, contraction, and steroid hormones or the gene expression

55
Q

Give examples of things involved with the nervous system and hormonal system

A

Examples of the nervous system of heart rate, breathing rate, digestion, Thermo regulation movements and reflexes
Examples of hormonal system, a menstrual cycle, blood, glucose regulation, protrusion, digestion, growth, puberty, metabolism, water, and ion balance

56
Q

Why does the hormonal system have a slow response from the nervous system?

A

It takes time for hormones to travel in blood. Where is nerve impulse travels quickly.

57
Q

Why does the nervous system have a localised effect and hormonal system have a widespread effect?Q

A

Hormones travel to all parts of the body and target cells are dispersed, where is neurons link directly to specific affecters

58
Q

Why does the nervous system of a short lived in fact, whilst the hormonal system has a long-lasting affect

A

Hormones are broken down slowly, whereas neurotransmitters are broken down quickly

Human Biology (12 decks)

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