Brainscape's Knowledge GenomeTM

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


See full index

Biology > 5.1.3 - NEURONAL COMMUNICATION > Flashcards

5.1.3 - NEURONAL COMMUNICATION Flashcards

1
Q

What are the THREE main types of neurones?

A
  • Sensory
  • Motor
  • Relay (Intermediate)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a transducer?

A

Something that converts one form of energy into another

E.g. pacinian corpuscle converts pressure into electrical impulses

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

What common features do the three neurones have?

A
  • Cell body
  • Dendrons
  • Axons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are dendrons?

A

Carry the action potentials to surrounding cells

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

What are axons?

A

Conductive, long fibres that carry the nervous impulse along the motor neurone

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

What is the myelin sheath?

A
  • A lipid wrapped around the axon made from Schwann cells
  • Insulated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the gaps between the myelin sheath called?

A

Nodes of Ranvier

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

What is saltatory conduction>

A
  • Action potential jumps from node to node
    ^— means action potential travels along the axon faster as it doesn’t have to generate an action potential along the entire length
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the role of the sensory neurone

A

Carry electrical impulses from the sensory receptor cell to the relay neurone

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

Describe the structure of the sensory neurone

A
  • Has a long dendron which carries the impulse from teh sensory receptor cell to the cell body of the neuron
  • An axon to carry the impulse from the cell body to the next neurone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the role of the relay neurone

A
  • Carries impulses between the sensory + motor neurones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the structure of the relay neurone

A
  • Multiple short axons + dendrons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the role of the motor neurone

A
  • Carries the impulse from a relay or sensory neurones to the effector (muscle of gland)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the structure of the motor neurone

A
  • One long axons
  • Multiple short dendrites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

List the three types of sensory receptor

A
  • Photoreceptors (light)
  • Thermoreceptors (skin)
  • Mechanoreceptors (pressure)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give an example of a photoreceptor

A
  • Rods
  • Cone cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Give an example of a thermoreceptor

A

Skin

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

Give an example of a mechanoreceptor

A

Pacinian corpuscle

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

What is the pacinian corpuscle?

A

Pressure receptor located deep in skin, mainly fingers + feet

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

What happens to the pacinian corpuscle when pressure is applied?

A
  • Stretch-mediated sodium channels in the membranes open and allow sodium to enter the sensory neurones only when they are stretched + deformed
    ^— when this occurs, it deforms the neurone plasma membrane, stretches and widens the sodium channels so sodium diffuses in which leads the establishment of a generator potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a resting potential?

A
  • Has a value of around -65mV to -70mV
22
Q

Describe how a resting potential is produced

A
  • In either side of the members are sodium ions move + potassium ions
  • Sodium-potassium pump actively transports sodium ions OUT of the axon and potassium ions INTO the axon
    ^— higher conc. of potassium ions inside than outside membrane
    ^— higher conc. of sodium ions outside than inside membrane
  • For every 3 sodium ions transported out, only 2 potassium ions are transported in
    ^—therefore, number of positive ions outside the membrane is greater than inside - establishes membrane potential
  • Here is an electrochemical gradient
  • Ion channels in the membrane switch between open and closed (SODIUM MAINLY CLOSED - low diffusion rate of sodium into axon | POTASSIUM MAINLY OPEN - high diffusion rate of potassium out of axon)
    ^— therefore inside of membrane more negative than outside

MORE POSITIVELY CHARGED IONS OUTSIDE THAN INSIDE AXON - PRODUCING MEMBRANE POTENTIAL

23
Q

What is a generator potential?

A

The nervous impulse the pacinian corpuscle produces in response to pressure

24
Q

Describe the structure of the pacinian corpuscle

A
  • In the centre, the end of the sensory neurone
    ^— surrounded by many layers of connective tissue with a layer of gel between each
25
Q

What does it mean if the membrane of a neurone is polarised?

A

The inside of the membrane is negative with respect to the outside
(RESTING POTENTIAL)

26
Q

Explain how the pacinian corpuscle generates a nerve impulse in response to pressure

A
  • Sodium channels in the corpuscle membrane are stretch-mediates sodium channels (normally too narrow for sodium ions to diffuse through)
  • When pressure is applied, shape of the corpuscle changes, causing the membrane to stretch
    ^— causes the stretch-mediated sodium channels to widen
  • Sodium ions diffuse through the channels into the neurone
    ^— INTERIOR BECOMES POSITIVELY CHARGED (DEPOLARISED)
    ^— the effect of this is called the generator potential —> causes a wave of depolarisation to pass down the sensory neurone to the CNS (ACTION POTENTIAL)
27
Q

What is the action potential?

A

How a nerve impulse is transmitted

28
Q

What are voltage-gated ion channels?

A

Only open when the membrane potential reaches a certain value

29
Q

What are the stages a membrane enters as an action potential travels?

A
  • Resting potential
  • Depolarisation
  • Repolarisation
  • Hyperpolarisation
  • Resting potential
30
Q

Describe what happens during detection of a stimulus (neurones)

A
  • Receptor detects a stimulus
  • Energy of the stimulus triggers voltage-gated sodium channels to open
    ^— sodium ions rapidly diffuse into the axon down their electrochemical gradient
  • Inside of axon becomes less negative
31
Q

Describe what happens during depolarisation of an axon

A
  • Inside of axon is less negative
  • Change in voltage bow triggers more voltage-gated sodium channels to open
    ^— allows more sodium ions to diffuse into the axon (POSITIVE FEEDBACK)
  • Potential of +40mV
  • Voltage-gated sodium channels close + voltage-gated potassium ion channels open
  • Sodium ions stop diffusing into the axon
32
Q

Describe what happens during repolarisation of an axon

A
  • Potassium ions diffuse out of the axon down electrochemical gradient
    ^— meanwhile inside of axon switches from positive to negative
33
Q

Describe what happens during hyperpolarisation of an axon

A
  • Because large amount of potassium ions diffuse out of the axon, the inside become more negative than the resting potential
  • Voltage-gated potassium ion channels close
34
Q

Describe how the resting potential is restored after hyperpolarisation

A
  • Sodium-potassium pump pumps sodium ions out of the axon + potassium ions into the axon
35
Q

What is the all or nothing principle?

A
  • Action potential is only generated if the stimulus is greater than a certain threshold
    ^— If below, no action potential is generated
  • if the stimulus is greater than the threshold, action potential generated
  • Size of the action potential does not depend on the strength of the stimulus (weaker stimulus will generate same potential as a stronger one)
    ^— stronger stimulus produces a greater frequency of action potentials than a weaker stimulus
36
Q

describe how an action potential is transmitted along a non-myelinated axon

A
  • Resting state: more sodium ions outside membrane than inside | higher conc. of potassium ions inside than inside | Inside membrane as a negative charge relative to the outside of the membrane
  • A stimulus causes the beginning of the membrane to depolarise, causing voltage-gated sodium ion channels to open + allow sodium channels inside axon down electrochemical gradient
  • Sodium ions move sideways to next region, attracted to negative charge (LOCALISED ELECTRICAL CIRCUIT)
    ^— causes voltage-gated sodium ion channels to open in second region —> sodium ions diffuse in (depolarises)
  • In first region, voltage-gated sodium ion channels close + voltage-gated potassium ion channels open
  • Potassium ions diffuse out of axon in first region (A) - beginning to REPOLARISE
  • Localised electrical circuits form between region B and C
    ^— action potential continues to propagate down the axon
  • Meanwhile, region A is negative inside + positive outside | sodium ions actively transported out of axon in region A by S-P pump (now back to RESTING POTENTIAL)
  • Wave of depolarisation down axon, + previously depolarised areas have to repolarise
37
Q

What is the refractory period?

A

Once a region of the membrane has transmitted an action potential, there is a short period where it cannot transmit another action potential

38
Q

Why is there a refractory period?

A
  1. After a wave of depolarisation, the membrane has to repolarise (reestablish the electrochemical gradient for sodium + potassium ions)
  2. Once voltage-gated sodium ion channels have closed, they cannot open again for a short period of time
39
Q

Give 3 reasons why the refractory period is important

A
  • Because the axon membrane enters the refractory period once it transmits an action potential —> ensures that the potential can only travel in one direction
  • this period means that a. potentials are clearly separated from each other and cannot overlap
  • Time delay between a. potentials limits the number of them that can be transmitted during a time period (creates a maximum frequency of action potentials in all-or-nothing principle - max stimulus strength)
40
Q

Describe the process of saltatory conduction

A
  • e.g. stimulus triggers depolarisation of left part of axon
    ^— voltage-gated sodium ions actively channels open in the membrane at the first node (of Ranvier)
  • Sodium ions diffuse into axon down electrochemical gradient at first node, depolarisation axon at node a and making it positive
    ^— positive sodium ions attracted sideways towards negative charges at second node (LOCALISED ELECTRICAL CIRCUIT between 1st & 2nd node)
    ^— triggers voltage-gated sodium ion channels at 2nd node to open + sodium ions diffuse into axon (DEPOLARISATION)
  • LOCALISED ELECTRICAL CIRCUIT forms between 2nd & 3rd node (3rd node depolarises)
41
Q

Give two advantages of saltatory conduction

A
  • Transmission is much faster
  • Because depolarisation only takes place @ Nodes of Ranvier, only these regions need to be repolarised (less ATP required to repolarise a myelinated axon at voltage-gated sodium ion channels)
42
Q

Describe the structure of the synapse

A
  • In synaptic knob, contains large number of vesicles contains neurotransmitters
  • Synaptic cleft (space between presynaptic and postsynaptic neurone)
  • Synaptic knob (end of action potential) - contains mitochondria + endoplasmic reticulum to produce neurotransmitter
43
Q

What is a cholinergic synapse?

A
  • An excitatory synapse - transport of neurotransmitter acetylcholine
44
Q

What is an excitatory synapse?

A
  • Triggers an action potential in the postsynaptic neurone
45
Q

What is an inhibitory synapse?

A
  • Prevents an action potential in the postsynaptic neurone
46
Q

Describe what happens during synaptic transmission

A
  • Action potential arrives at the presynaptic neurone - triggers voltage-gated calcium ions actively channels channels to open
  • Calcium ions diffuse into synaptic knob, triggers vesicles to fuse with the presynaptic membrane
    ^— acetylcholine released into synaptic cleft + diffuse across cleft, binding with sodium ions actively channels channels on postsynaptic membrane
    ^— triggers sodium ion channels to open
  • Sodium ions diffuse into postsynaptic neurone, triggering action potentials in postsynaptic neurone
  • if acetylcholine remains attached to channels, could trigger multiple action potentials
  • Enzyme acetylcholinesterase hydrolyses acetylcholine to choline + ethanoic acid
    ^— choline + ethanoic acid reenter presynaptic neurone where energy from ATP turns them to acetylcholine
47
Q

Describe the functions of synapses

A
  • Synapses ensure that transmission takes place in one direction only
    ^— neurotransmitter can only be released from PRESYNAPTIC membrane + neurotransmitter receptors are only found on POSTSYNAPTIC neurone (UNIDIRECTIONAL)
  • One neurone can form synapses with a large number of other neurones
    ^— likewise, several different neurones can form synapses with one neurone
48
Q

Describe temporal summation

A
  • Action potential arrives at neurone A and triggers the release of a neurotransmitter, but insufficient neurotransmitter was released for neurone B to reach the threshold to trigger an action potential
    ^— neurotransmitter is now broken down + recycled back in presynaptic neurone
  • Another action potential arrives at neurone A and the neurotransmitter is released, however another a. potential arrives and more neurotransmitter is released
    ^— conc. in synaptic cleft is enough to trigger an action potential in neurone B
  • Effects of multiple action potentials acting over time can add together
  • only works if incoming a. potentials are close together in time
49
Q

Describe spatial summation

A
  • Action potentials arrive at two presynaptic neurones that have synapses with one postsynaptic neurone
    ^— individually, neither releases a bough neurotransmitter to trigger an action potential on the postsynaptic neurone
  • Here, the effects of the two neurones add together
    ^— combined effect of the neurotransmitter released from both separate neurones reach the threshold in the shared neurone and trigger an action potential
50
Q

Describe the synaptic transmission of inhibitory synapses

A
  • E.g. GABA (in the brain) is released into the synaptic cleft
    ^— diffuses across the synaptic cleft + binds with chloride ion channels on the postsynaptic membrane
    ^— causes chloride ion channels to open + chloride ions diffuse into postsynaptic neurone
  • Potassium ion channels also triggered to open and diffuse OUT of postsynaptic neurone
    ^— hyperpolarisation interior of postsynaptic neurone (MORE NEGATIVE THAN RESTING POTENTIAL) - -80mV
    LESS LIKELY ACTION POTENTIAL IS GENERATED

Biology (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions