the nervous system Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Why is it important that a neurotransmitter eg seretonin is transported back out of the synapse and explain why

A

if not removed, it will keep binding to the receptors on the post synaptic membrane and so would keep causing action potentials.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

suggests how cocaine leads to feelings of pleasure`

A

cocaine binding will lead to the shape of transporter changing so dopamine can not be removed. this builds up in the synapses leading to pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cannabinoid receptors are found in the pre-synaptic membrane of neuromuscular
junctions. When a cannabinoid binds to its receptor, it closes calcium ion channels.
Suggest how cannabinoids could prevent muscle contraction.

A

Prevents influx of calcium ions (into pre-synaptic membrane);
Need idea of moving into pre-synaptic membrane / synaptic
knob
Accept Ca++ / Ca2+
2. (Synaptic) vesicles don’t fuse with membrane / vesicles don’t release
neurotransmitter;
Accept vesicles don’t release acetylcholine
3. Neurotransmitter does not diffuse across synapse / does not bind to
receptors (on post-synaptic membrane);
Accept: sarcolemma / muscle membrane for post-synaptic
membrane
4. No action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how is a resting potential maintained

A

the membrane is more permeable to potassium ions less permeable to sodium ions
sodium ions are actively transported out and potassium in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain how applying pressure to the Pacinian corpuscle produces the changes in
membrane potential recorded by microelectrode P

A

pressure causes membranes to become stretched
sodium ion channels in membrane open
greater pressure means more channels open

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The membrane potential at Q was the same whether medium or heavy pressure
was applied to the finger tip. Explain why.

A

threshold has been reached so all or nothing principle causes maximal response as no aps generated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Multiple sclerosis is a disease in which parts of the myelin sheaths surrounding
neurones are destroyed. Explain how this results in slower responses to stimuli.

A

Less / no saltatory conduction / action potential / impulse unable to
‘jump’ from node to node;
2. More depolarisation over length / area of membranes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When DDT binds to a sodium ion channel, the channel remains open all the time.
Use this information to suggest how DDT kills insects.

Suggest how the KDR minus allele gives resistance to DDT

A

neurones remain depolarised
so not action potentials

(Mutation) changes shape of sodium ion channel (protein) / of receptor

(protein) ;
2. DDT no longer complementary / no longer able to bind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

speed of myelinated vs non

A

(In myelinated) action potential / depolarisation only at node(s);

  1. (In myelinated, nerve impulse) jumps from node to node / saltatory;
  2. (In myelinated) action potential / impulse does not travel along whole length

remember- say ap not impulse or depolarisation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why isn’t the whole length of the axon covered from beginning to end with myelin?

A

The axon has nodes on it that cause the electrical impulse to “jump,” if you will, from one node to another. This speeds up conductivity and allows impulses to travel faster. Most of the axon is covered in myelin anyway, but only a number of small portions on the axon have these nodes. They’re called nodes of Ranvier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The doctors used a statistical test to compare the results for AD and LD.
They obtained a value for P of 0.047.
What does this result show about the difference between the means for AD and LD?
Use the words probability and chance in your answer.

A

Probability of obtaining this difference by chance;
Reject ‘results’ once only
2. Is less than 5% / less than 0.05 / less than one in twenty;
Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047
Accept correct greater than 95% / greater than 0.95
arguments
3. Difference is significant;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Serotonin diffuses across the synaptic gap and binds to a receptor on the
post-synaptic membrane.
Describe how this causes depolarisation of the post-synaptic membrane

A

Causes sodium ion channels to open;

  1. Sodium ions enter (cell and cause depolarisation);
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Give one similarity and one difference between a taxis and a tropism.
Similarity
Difference .

A

Similarity − directional response (to a stimulus) / movement
towards / away from a stimulus;
2. Difference − taxis (whole) organism moves and tropism a growth
(response).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In each experiment, the biologist exposed the surfaces to light that was dim and
even, so he could see where the worms went.
Apart from seeing where the worms went, suggest two reasons why it was
important that the light was dim and even.

A

(Dim) worms live in soil / dark / affected by bright light / dim light is like
normal environment / what they are used to;
2. (Even) because worms might move towards / away from bright light / to
avoid creating light gradient / prevent worms showing phototaxis / all
parts of surface exposed to same light;
Accept to avoid kinesis due to light
3. (Dim light) ensures heat from light not a variable / heat from lamp could
kill / dry out worms;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe na ions and releasing them sybapses

A

once released, it diffuses across the synaptic cleft and it binds to receptors ont the sodium ion channels and this causes sodium ions to diffuse into the post synaptic neuonr depolarising the membrane causing the initiation of an ap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

GABA is a neurotransmitter released in some inhibitory synpapses int he brain, GABA causes negatively charged chloride ions to enter the post synatic neurone, explain how this inhibts post synaptic neurones

A

adding more negative= hyperpolarisation, lower than resting potential

cl- entering the post synaptic neurone causes hyperpolarisation, this means that more sodium ions have to enter the post synaptic neurone in order for the voltage to reach the threshold potential in order for depolarisation of the membrane initiating an ap

17
Q

How does temperature affect the speed of a nerve impulse? (5)

A
  1. The higher the temperature the faster the nerve impulse;
  2. Sodium-potassium pump uses active transport;
  3. Which requires energy from ATP from respiration;
  4. Respiration is enzyme-controlled;
  5. More kinetic energy so more enzyme-substrate complexes formed and faster diffusion
18
Q

how is the resting potential manintained

A

sodium potassium pump, k+ diffuses out whilst na+ diffuses in= actively transporte.d membrane is more permeable to k+.

19
Q

why is aps faster in myelinated neurone

A

nodes, aps do not need to be generated at all the nodes, non myelination across the entire length of the axon,
also say that
myelination provides electrical insulation

20
Q

why does an inhibitor result in an overall potential of 0

A

as there is less atp less active transport, electrochemical gradient is not maintained, same conc of na+ and k+ on either side

21
Q

pacinian corpuscle

A

membrane becomes deformed or stretched
sodium ion channels in membranes open and sodium ions move in
increase of channels open

22
Q

myelination depolarisation

A

only at nodes, jumps from node to node= saltatory conductionn.