Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A level Biology > Unit 3.8 - The nervous system > Flashcards

Unit 3.8 - The nervous system Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What kind of animals have nervous coordination?

A

Only higher animals (e.g - mammals) have developed it

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

Purpose of the nervous system

A

To respond to changes in the external or internal environment, and do something to respond to these changes

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

Name for the things we respond to with the nervous system

A

Stimuli
(Singular = stimulus)

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

How would the nervous system act when the sun comes through the window?

A

Receptor cells in the retina in the eyes convert the signal into an electrical signal that’s transmitted to the brain = react

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

What does the nervous system allow us to do?

A

Respond to changes in our environment

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

Stimulus

A

Any detectable change in the internal or external environment of the organism

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

What do receptor cells act as and how?

A

Transducers
They detect energy in one form and convert it into electrical energy

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

what act as transducers in the nervous system?

A

Specialised receptor cells

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

How does electrical energy travel along neurones?

A

As a nerve impulse

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

What is a nerve impulse?

A

Electrical energy travelling along neurones

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

Neurones

A

Nerve cells

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

What do nerve impulses do?

A

Initiate a response in an effector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an effector?

A

A muscle or a gland

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

What do muscles and glands do as part of the nervous system?

A

Act as effectors

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

What are the 2 main parts of the nervous system?

A

The central nervous system (CNS)
The peripheral nervous system (PNS)

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

What is the central nervous system composed of?

A

The brain and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the central nervous system do?

A

Processes information provided by a stimulus and coordinates a response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the peripheral nervous system made up of?

A

Neurones (nerve cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which part of the nervous system then has two further parts?

A

The peripheral nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

2 parts of the peripheral nervous system

A

The somatic nervous system
The autonomic nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The somatic nervous system:
What is it made up of?
What do these do?

A

Made up of pairs of nerves branching from the brain and spinal cord
These neurones carry impulses from receptor cells to the CNS and then from the CNS to the effectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the autonomic nervous system do?

A

Provides unconscious control of the internal organs (e.g -heartbeat and breathing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which part of the peripheral nervous system is made up of pairs of nerves branching from the brain and spinal cord?

A

The somatic nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which part of the nervous system is composed of the brain and spinal cord?

A

The central nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which part of the peripheral nervous system provides unconscious control of the internal organ?

A

The autonomic nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the nervous system made up of?

A

Neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What type of neurone is the one we have a detailed labelled diagram of?

A

A motor neurone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Which part of neurones contains the nucleus and most organelles?

A

The cell body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does the cell body of a neurone contain?

A

The nucleus and most organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What come from the cell body of a neurone?

A

Many extensions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Names for the extensions from the cell body of a neurone

A

Many extensions - dendrites
1 long extension - axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What do the dendrites of a neurone do?

A

Conduct nerve impulses towards the cell body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does the axon of a neurone do?

A

Conducts nerve impulses away from the cell body towards the axonal terminals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Name for the ends of the axonal terminals

A

Synaptic end bulbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What happens at the synaptic end bulbs of the neurone?

A

Where the neurone connects to another neurone or a muscle or a gland (effector)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What do Schwann cells form?

A

Form the myelin sheath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What form the myelin sheath?

A

Schwann cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Describe Schwann cells

A

Wrapped around along the axon many times in several layers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are Schwann cells wrapped around many times in several layers?

A

The axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Purpose of Schwann cells wrapping around the axon many times in several layers

A

Provide a form of electrical insulation for the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Why do Shwann cells need to provide a form of electrical insulation for the axon of a neurone?

A

The electrical insulation increases the speed of nerve impulses along the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Do Shwann cells form a complete sheath?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Gaps between Shwann cells

A

Nodes of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Why are nodes of Ranvier important?

A

Important in the way in which the nerve impulse propagates along the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Describe neurones

A

Highly specialised cells which carry nerve impulses in one direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How are nerve impulses carried?

A

In one direction by neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Three main types of neurones in a vertebrate

A

Sensory
Relay
Motor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What do sensory neurones do?

A

Carry nerve impulses from the receptor cells in the sense organ to the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What do relay neurones do?

A

Connect the sensory and motor neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Where are relay neurones found?

A

In the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What do motor neurones do?

A

Transport nerve impulses from the CNS to the effectors (muscles and glands)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Where are sensory, relay and motor neurones found?

A

In both the somatic and central nervous systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Another word for Shwann cells

A

Myelin sheath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What does the plasma membrane of a Shwann cell do?

A

Provides electrical insulation to the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Describe the plasma membrane of Shwann cels

A

Layers of membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Where is axoplasm in Shwann cells and what does it do?

A

Inside the axon
Contains organelles (e.g - mitochondria)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is the plasma membrane of Shwann cells made up of?

A

Phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Why is the plasma membrane of Shwann cells a good electrical insulator?

A

Phospholipids contain non-polar fatty acid tails, making the membrane a good electrical insulator (non-polar)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Between the membranes of Shwann cells

A

Myelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What does myelin do in Shwann cells?

A

Is a fatty substance that also acts as an electrical insulator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Reflex arc

A

A mechanism that controls a reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Describe the features of reflex responses

A

Unconscious (doesn’t go through the brain)
Innate (present in an individual from birth + not learnt)
Protects us from injury
Rapid, automatic, beneficial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

How come reflex responses are unconscious?

A

Don’t go through the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What does it mean that reflex responses are innate?

A

Present in an individual from birth and not learnt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Give 2 examples of reflex reponses

A

Hand moving away from a hot surface
Blink response when something approaches your eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What’s the purpose of the gaps between the vertebrae of the spinal cord?

A

Allow spinal nerves to branch off from the spinal cord and branch into the various parts of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

How many neurones make up the branches from the spinal nerves?

A

Thousands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What do reflex responses rely on?

A

The 3 types of neurones previously mentioned

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What’s the name for the region at the back of the spinal cord?

A

Dorsal region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What’s the name for the region at the front of the spinal cord?

A

Ventral region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Dorsal region of the spinal cord

A

Back of the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Ventral region of the spinal cord

A

Front of the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What are all of the different features that the transmission of a nerve impulse along a three-neurone reflex arc involves?

A

Stimulus
Receptor
Sensory neurone
Relay neurone (in CNS)
Motor neurone
Effector
Response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Explain exactly how a nerve impulse is transmitted along a three-neurone reflex arc

A

Stimulus
Receptor that initiates a nerve impulse to travel along the…
Sensory neurone. The axon of the sensory neurone enters the spinal cord via the dorsal root. It first enters the dorsal root ganglion, which is where the cell body of the sensory neurone is.
The axon of the sensory neurone then continues to the grey matter, where it forms a synapse with the…
Relay neurone (in CNS). The replay neurone then forms a synapse with the…
Motor neurone, which carries the nerve impulse to the…
Effector to give a response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Example of a receptor involves in a reflex response

A

Temperature receptors in the skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What initiates the nerve impulse that travels along the sensory neurone?

A

Receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

How does the axon of the sensory neurone enter the spinal cord?

A

Via the dorsal root

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Where is the cell body of the sensory neurone?

A

The dorsal root ganglion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What is in the dorsal root ganglion?

A

The cell body of the sensory neurone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Where does the sensory neurone form a synapse with the relay neurone?

A

In the grey matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Where does the relay neurone form a synapse with the motor neurone?

A

In the grey matter in the spinal cord

82
Q

Which neurone carries the nerve impulse to the effector to give a response?

A

The motor neurone

83
Q

Why is the great matter in the spinal cord grey?

A

Lots of relay neurones and cell bodies (cell bodies of both relay and motor neurones)

84
Q

The cel bodies of which neurones are in the grey matter of the spinal cord?

A

Relay and motor neurones

85
Q

Explain why white matter in the spinal cord is white

A

Full mostly of axons
Axons contain Shwann cells and since these make the axon myelinated, this is a fatty substance so the area appears white

86
Q

Word for Shwann cells contained myelin

A

Myelinated

87
Q

Explain what the spinal cord is

A

A flattened cylinder of nervous tissue

88
Q

Where does the spinal cord run from and to?

A

Form the base of the brain to the lumbar region

89
Q

What is the spinal cord protected by?

A

Vertebrae

90
Q

Describe the central canal of the spinal cord

A

Runs all the way through
Is filled with cerebrospinal fluid, which also surrounds the spinal cord

91
Q

Where is cerebrospinal fluid found?

A

Fills the central canal of the spinal cord
Surrounds the spinal cord

92
Q

What is cerebrospinal fluid responsible for?

A

Carrying nutrients
Absorbing shocks to avoid damage to the spinal cord

93
Q

What is responsible for absorbing shocks to avoid damage to the spinal cord?

A

Cerebrospinal fluid

94
Q

Number of effectors in simple invertebrate organisms + explanation

A

Small
Respond to a limited number of stimuli

95
Q

What type of organisms only respond to a limited number of stimuli?

A

Simple invertebrate organisms

96
Q

Example of a simple invertebrate organism

A

Hydra

97
Q

What do simple invertebrate organisms such as Hydra have as opposed to a nervous system?

A

Nerve net

98
Q

What does a nerve net not have that a nervous system does?

A

No brain
No spinal cord
No central nervous system
No myelinated axons

99
Q

Briefly explain what a nerve net is

A

Simple nerve cells with short extensions joined to each other and branching in a number of different directions

100
Q

What can a simple nerve net only respond to?

A

A limited number of stimuli

101
Q

What does a simple nerve net have as a result of only being able to respond to a limited number of stimuli?

A

A small number of effectors

102
Q

Compare the nerve net in hydra to the nervous system of mammals

A

(First is hydra, second is mammals)
Nerves branch in all directions, nerves branch in one direction (along the axon)
Impulses travel slowly, impulses travel at high velocity
Only one type of nerve cell, three types of neurone: sensory, relay and motor
Short branches, axons can be very long e.g - from the spinal cord to the tips of fingers in humans

103
Q

Can we detect the source of a stimulus in nerve nets? Why?

A

No, since the nerves branch in all directions

104
Q

What is maintained across the axon membrane when no nerve impulse is being transported along the axon?

A

A resting potential

105
Q

Describe the axon membrane at the resting potential

A

Charged (outside positive, inside negative)

106
Q

Potential difference across the axon membrane during a resting potential

A

-70mV

107
Q

What does the axon have to do to set up the resting potential and how is this one?

A

Has to separate charges across the membrane
Uses active transport proteins; sodium-potassium pumps in the axon membrane

108
Q

What type of active transport proteins are used in order to set up the resting potential of the axon?

A

Sodium-potassium pumps

109
Q

Explain in detail how the resting potential is set up in the axon membrane?

A

1.) sodium-potassium pump actively transports sodium ions out of the axon into tissue fluid and pumps potassium ions into the axon
2.) even though both of these ions are positively charges, there is a potential difference formed since the sodium-potassium pump pumps 3 Na+ out of the axoplasm and only 2 K+ in
3.) now there is an unequal distribution of sodium and potassium across the membrane, with more positive charges outside of the axon, so the membrane is polarised
4.) also, since there is now a concentration gradient and the axon membrane is highly permeable to K+, they leak out by facilitated diffusion through open channels, which contributes to the charge distribution

110
Q

What is required to maintain the resting potential of the axon and why?

A

Energy in the form of ATP
Active transport is occurring

111
Q

How is ATP provided for setting up the resting potential of the axon?

A

Produced by the numerous mitochondria present in the axoplasm of the axon

112
Q

What does the use of ATP to maintain the resting potential of the axon prove?

A

We require ATP even when resting

113
Q

What happens when a nerve impulse is generated in the axon?

A

The action potential

114
Q

What are nerve impulses caused by?

A

A rapid change in the permeability of the neurone membrane to K+ and Na+

115
Q

Describe the action potential in an axon in detail

A
  1. The membrane of the axon also has specific channels for Na+ and K+
  2. Since these channels are voltage-gated channels, they can close to prevent them from allowing ions through
  3. When an impulse arrives, the sodium ion cancels on the membrane open first
  4. Na+ flood into the axon down their concentration gradient
  5. Potential across the membrane changes from -70mV (resting potential) to +40mV (action potential) —> the membrane is said to be depolarised
  6. About a millisecond after the sodium ion channels close, the potassium ion channels are open
  7. K+ diffuse out of the axon down their concentration gradient
  8. Polarity is restored —> repolarises the membrane
  9. An excess of K+ leave the son before the Na+/K+ pump restored the resting potential. This is known as the refractory period during which no further action potentials can occur
116
Q

Which ion channels open first when a nerve impulse arrives in the axon?

A

Sodium

117
Q

Potential of the membrane at the action potential

A

+40mV

118
Q

What is the membrane said to be when at +40mV?

A

Depolarised

119
Q

What happens dung the refractory period of the action potential?

A

An excess of K+ leave the axon before the Na+/K+ pump restored the resting potential
No further action potentials can occur

120
Q

When during the action potential can no further action potentials occur?

A

The refractory period

121
Q

How is the polarity restored in the axon during a nerve impulse?

A

When K+ diffuse out of the axon down their concentration gradient

122
Q

List the stages of the action potential of a nerve impulse

A

Resting potential
Threshold potential
Depolarisation
Action potential
Repolarisation
Hyperpolarisation - refractory period

123
Q

What type of response is action potential?

A

All or nothing

124
Q

What do we mean when saying that action potential is an “all or nothing” response?

A

Same size of polarisation and depolarisation each time

125
Q

Explain when action potential would be an “all” and when it would be a “nothing” response

A

If the stimulus isn’t strong enough for enough sodium ions to cross the membrane and we don’t reach the threshold, the impulse drops to the resting potential
If enough sodium ions diffuse into the axon and we pass the threshold, we get the whole action potential

126
Q

Under which circumstance would the whole action potential not occur? What would happen instead?

A

If the stimulus isn’t strong enough for enough sodium ions to cross the membrane and we don’t reach the threshold, the impulse drops to the resting potential

127
Q

When do we get the whole action potential?

A

If enough sodium ions diffuse into the axon and we pass the threshold we get the whole action potential

128
Q

Explain what is happening when the line shoots up on the oscilloscope graph of action potential

A

This is where the membrane is depolarised
Sodium ions are diffusing rapidly into the membrane (channels are open)

129
Q

what causes the axon to depolarise?

A

Sodium ions diffusing in

130
Q

How do we generate an action potential graph?

A

Using an oscilloscope to measure the potential difference

131
Q

What causes repolarisation of the membrane of the axon?

A

Potassium diffusing out of the axon out of their channels down a concentration gradient

132
Q

What is the hyper polarisation of the membrane of the axon?

A

When the line falls below the resting potential when repolarised

133
Q

What do we need for the refractory period of the axon potential?

A

Hyperpolrisation of the membrane

134
Q

What happens during the refractory period of the action potential?

A

The sodium-potassium pumps restore the resting potential by pumping the ions back
A new action potential can’t be formed until the resting potential has been restored

135
Q

During which point can’t a new action potential by formed?

A

The refractory period

136
Q

What does the refractory period ensure?

A

The separation between action potentials, no matter how strong the stimulus

137
Q

What would happen if the refractory period didn’t occur?

A

One big action potential would form and the central nervous system wouldn’t be able to tell the different between strong and weak stimuli

138
Q

How does the central nervous system know the difference between strong and weak stimuli?

A

It’s due to the frequency of the impulse in the axon

139
Q

Example of a situation where the central nervous system would need to differentiate between a strong and weak stimulus

A

Reaping to a warm v.s boiling surface

140
Q

Describe the frequency of a strong stimulus

A

High frequency of action potentials

141
Q

Describe the frequency of a weak stimulus

A

Low frequency of action potentials (less impulses produces per second)

142
Q

With the nerve impulse process described, what kind of axon was this occurring on?

A

Non-myelinated

143
Q

What type of axons are in our cells?

A

Myelinated

144
Q

What do the Schwann cells do and what does this act as?

A

Wrap around the axon and secrete a fatty myelin sheath which is an electrical insulator

145
Q

Where in a myelinated axon can depolarisation not occur and why?

A

Wherever Schwann cells are
Schwann cells secrete a fatty myelin sheath which is an electrical insulator

146
Q

What cannot occur on the axon where a Shwann cell is present?

A

Depolarisation of the axon

147
Q

What are the only parts of a myelinated axon that can become depolarised?

A

The nodes of Ranvier

148
Q

What do the nodes of Ranvier contain in a myelinated axon to allow them to become depolarised?

A

Voltage gated Na+ channels

149
Q

What happens in a myelinated axon in terms of the cation potential?

A

Cation potential of the nerve impulse jumps from one node to the next, which speeds up the rate of transmission

150
Q

What type of axons do nerve impulses travel fastest along?

A

Myelinated

151
Q

Name for depolarisation only occuring in the nodes of ranvier of a myelinated axon

A

Saltatory conduction

152
Q

Saltatory conduction

A

Depolarisation only occuring in the nodes of ranvier in a myelinated axon

153
Q

What increases the rate of transmission in a myelinated axon?

A

Greater distance between the nodes

154
Q

What type of species are the only ones to have myelinated axons?

A

Vertebrates

155
Q

Symptoms of someone with demyelinated neurones

A

Feel tired
Slower reaction times
Paralysis

156
Q

Advantages of having myelinated axons

A

Increased rate of conduction
Less ATP required (to restore resting potential) = aerobic respiration can occur at a lower rate

157
Q

What type of respiration can occur at a lower rate with myelinated axons?

A

Aerobic

158
Q

Another way of speeding up the impulse along the axon that isn’t myelination

A

Have a bigger axon

159
Q

Effect of having a bigger axon on the speed of the impulse along the axon +explanation

A

The greater the diameter of the axon, the lower the resistance to the movement of ions

160
Q

Correlation between the axon diameter and conduction velocity?

A

Positive

161
Q

Example of creatures with giant axons

A

Cephalopod molluscs (e.g - squids)

162
Q

Why do squids need giant axons?

A

Have unmyelinateed axons
Are very active and move very fast and so they need a very efficient nervous system

163
Q

Size of squid axons + importance of this

A

1mm in diameter
Important in our understanding of the nervous system
Allow them to react quickly in low temperatures = conduct nerve impulse quickly

164
Q

Synapse

A

The junction between 1 neurone and a cell
Could be an effector cell (e.g - muscle or gland) or another neurone

165
Q

Functions of the synapse

A

Transmit information from neurone to neurone
Pass impulses in one direction
Act as junctions
Prevents overstimulation
Filter out low level stimuli

166
Q

In which direction does synaptic transmission occur?

A

In 1 direction only

167
Q

Example of a neurotransmitter substance involved in synaptic transmission

A

Acetylcholine

168
Q

What is acetylcholine?

A

A neurotransmitter substance

169
Q

Do neurotransmitters vary?

A

Yes - there are different neurotransmitters in different parts of these nervous system

170
Q

3 examples of neurotransmitters

A

Oxytocin
Serotonin
Acetylcholine

171
Q

Explain synaptic transmission in detail

A

1.) when a nerve impulse (actionpotential) arrives at a synaptic end bulb, it causes voltage-dependent calcium channels in the membrane to open
2.) calcium ions diffuse rapidly into the pre-synaptic end bulb down their concentration gradient
3.) in the pre-synaptic neurone end bulb, there are vesicles that contain a neurotransmitter ( a chemical produced by the cell) substance. Ca2+ stimulates here synaptic vesicles that contain neurotransmitters (e.g - acetylcholine) to move towards and fuse with the pre-synaptic membrane
4.) the contents of the vesicles are released into the synaptic left by exocytosis
5.) the neurotransmitter diffuses along the synaptic cleft and binds to a receptor (a transmembrane protein) in the post-synaptic membrane
6.) sodium ion channels in the post synaptic membrane open and sodium ions diffuse into the post-synaptic neurone
7.) this causes depolarisation
8.) if the threshold potential is reached, an action potential is initiated in the post synaptic neurone and starts a nerve impulse

172
Q

What do neurotransmitters do?

A

Start a response in the effector cell

173
Q

Why can’t neurotransmitters stay in the synaptic cleft?

A

Would keep stimulating the post synaptic cell

174
Q

Enzyme that removes neurotransmitters in the synaptic cleft

A

Acetylcholine esterase

175
Q

Acetylcholine esterase function

A

Removes neurotransmitters from the synaptic cleft

176
Q

What happens when acetylcholine esterase is present in the synaptic cleft?

A

Without the neurotransmitter, there’s no longer an impulse set up in the post synaptic nerve
The products are absorbed back into the pre-synaptic cell to be reused

177
Q

How are the products of the reaction between acetylcholine esterase and neurotransmitters in the synaptic cleft absorbed back into the post-synaptic cell to be reused?

A

Because of reuptake pumps - proteins in the membrane of the pre synaptic nerve that actively transport neurotransmitters back in

178
Q

2 main types of drugs

A

Inhibitory drugs (antagonists)
Excitatory drugs (agonists)

179
Q

Types of inhibitory drugs

A

Mimic inhibitory neurotransmitters
Block excitatory neurotransmitter receptors

180
Q

Example of a mimic inhibitory neurotransmitter drug + how it works

A

Alcohol
Fewer action potentials set up
Slows down the nervous response

181
Q

Example and explanation of how they work - block excitatory neurotransmitter receptors

A

Opiates (painkillers)
-prevent propagation of action potentials
-enter the synaptic cleft + block the receptors on the post synaptic membrane —> prevents neurotransmitters from attaching to receptors and opening the channels

182
Q

3 examples of excitatory drugs

A

1.) block the re uptake pumps for neurotransmitters
2.) mimic excitatory neurotransmitters
3.) block inhibitory neurotransmitters

183
Q

Example of an excitatory drugs that blocks the reuptake pumps for neurotransmitters + the neurotransmitter blocked

A

Cocaine blocks the reuptake of the neurotransmitter dopamine

184
Q

Example of a mimic excitatory neurotransmitters drug + explanation

A

Cause increase in action potential formation in the post synaptic membrane
E.g - nicotine

185
Q

Example of block inhibitory neurotransmitters + explanation

A

Prevent inhibition of action potentials in post synaptic neurone
e.g - caffeine (works in the opposite way to alcohol - but it doesn’t sober you up, just reverses the symptoms since alcohol is still in the body)

186
Q

What’s the problem with organophosphate?

A

Destroyed the myelin sheath and effects the synapse

187
Q

What is organophosphate commonly used in?

A

Farming as an insecticide

188
Q

Explain how organophosphate poisoning occurs

A

Organophosphate acts as an inhibitor of the acetylcholine-esterase enzyme
Attaches to the enzymes’ active sites and inhibits them from breaking down the acetylcholine in the synaptic cleft
As a result, more of the neurotransmitters remain in the synaptic cleft
This will keep firing off the post-synaptic neurone, leading to cramps, spasms or even paralysis

189
Q

Which enzyme does organophosphate inhibit?

A

Acetylcholine esterase

190
Q

What inhibits acetylcholine esterase?

A

Organophosphate

191
Q

Symptoms of organophosphate poisoning + explanation

A

Cramps, spasms, paralysis
Neurotransmitters remain in the synaptic cleft so they keep firing off the post-synaptic neurone

192
Q

The impulse along which neurone is not occurring if no pain is felt by an individual?

A

The impulse along the sensory neurone to the brain isn’t occurring

193
Q

which part of the brain produces nerve impulses?

A

hypothalamus

194
Q

Word that has to be used when describing synaptic transmission

A

The fact that calcium ions diffuse rapidly into the pre-synaptic end bulb down their concentration gradient

195
Q

what do we use to measure the potential difference across a membrane?

A

oscilloscope

196
Q

what can happen is the distance between nodes on an axon is too far and why?

A

the impulse can actually slow down since it takes too long for ions to diffuse

197
Q

how do we differentiate between a pre synaptic and a post synaptic neurone on a photomicrograph?

A

the pre synaptic neurone will have more synaptic vesicles

198
Q

what does acetylcholine esterase do to neurotransmitters?

A

hydrolyses and breaks them down

199
Q

what type of inhibitor is organophosphate to acetylcholine esterase enzymes?

A

competitive

200
Q

Where is the action potential not sent with anaesthetics?

A

Along the sensory neurone towards the brain

A level Biology (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions