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Mind, Brain & Behaviour > Neurons, Neurotransmission & the Nervous System > Flashcards

Neurons, Neurotransmission & the Nervous System Flashcards

1
Q

What are neurons?

A

Nerve cells
The basic building blocks of the nervous system

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2
Q

What are the three main parts of a neuron?

A

Soma/cell body
Axon
Dendrites

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3
Q

What is the soma responsible for?

A

Keeping the cell alive
Contains the nucleus and therefore genetic material

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4
Q

What is the axon responsible for?

A

Conducts electrical impulses away from the soma to other neurons, muscles, or glands

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5
Q

What are the dendrites responsible for?

A

Collects messages from neighbouring neurons and sends them to the soma

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6
Q

What are the two things that neurons do?

A

Generate electricity that creates nerve impulses
Release chemicals to communicate with other neurons, muscles and glands

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7
Q

What are the three stages of electrical activity in neurons?

A

Resting potential
Action potential
Return to resting potential

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8
Q

Describe resting potential

A

Substances are able to pass through the cell membrane of the neuron via ion channels
The ions that remain within the axon of the neuron are more negatively charged than those that pass to the outside of the cell
This results in a net negative charge (polarisation)

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9
Q

Describe action potential

A

The electrical shift that occurs when a neuron is stimulated
Positive sodium ions enter the neuron
This causes a brief depolarisation, which begins at one end of the axon and moves down along it

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10
Q

Describe what happens after an action potential

A

There is a recovery period (the absolute refractory period) where the membrane is not excitable and cannot discharge another impulse

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11
Q

What are the two benefits of the absolute refractory period?

A

It stops the charge from moving backwards along the axon
It limits how often a neuron can fire

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12
Q

What is an “all or none event” ?

A

The idea that action potentials occur either at a uniform and maximum intensity, or not at all

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13
Q

What is a graded potential?

A

A change in the negative resting potential that does not reach the action potential threshold

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14
Q

What is special about graded potentials?

A

Multiple graded potentials may combine to trigger an action potential in certain circumstances

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15
Q

What is the myelin sheath?

A

A layer of fatty insulation that surrounds the axon
It allows electrical conduction to take place at a higher speed (due to the nodes of Ranvier)

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16
Q

Give an effect of damage to myelin sheath

A

Multiple sclerosis

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17
Q

How do neurons communicate with each other?

A

Via synapses

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18
Q

What is a synapse?

A

The conjunction of the axon terminal of one neuron and the membrane of another neuron

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19
Q

What is the synaptic space?

A

The tiny gap between the axon terminal of one neuron and the next neuron

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20
Q

What is a pre-synaptic neuron?

A

A neuron that sends messages

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21
Q

What is a post-synaptic neuron?

A

A neuron that receives messages

22
Q

What are neurotransmitters?

A

Chemical substances that carry messages across the synaptic space

23
Q

What are the five steps of chemical communication?

A

Synthesis
Storage
Release
Binding
Deactivation

24
Q

Describe synthesis

A

The neurotransmitter molecules are formed

25
Q

Describe storage

A

The neurotransmitter molecules are stored in synaptic vesicles in the axon terminal

26
Q

Describe release

A

The action potential causes the neurotransmitter molecules to move out of the vesicles and across the synaptic space

27
Q

Describe binding

A

The neurotransmitter molecules bind themselves to receptor sites that are embedded in the post-synaptic neuron’s cell membrane
Neurotransmitters fit like a key in a lock and each is specifically complementary to its binding site

28
Q

Describe deactivation

A

The neurotransmitter molecules are broken down by other chemicals or undergo reuptake - where they are taken back into the pre-synaptic neuron’s axon terminal

29
Q

What is an excitatory neurotransmitter?

A

A neurotransmitter that increases the likelihood of an action potential firing

30
Q

What is an inhibitory neurotransmitter?

A

A neurotransmitter that decreases the likelihood of an action potential firing

31
Q

What is summation?

A

The idea that the rate at which an axon fires is determined by the activity of the synapses - if the excitatory neurotransmitters are more active than the inhibitory ones, then an action potential will be caused and vice versa

32
Q

What is acetylcholine?

A

A neurotransmitter involved in muscle activity and memory

33
Q

What happens when acetylcholine is underproduced?

A

It can weaken the neural circuit that stores memories, leading to Alzheimer’s

34
Q

What happens when acetylcholine is blocked by drugs?

A

When blocked by botulism paralysis can be caused, potentially even leading to death if the respiratory muscles are paralysed
When blocked by botox wrinkles are removed by paralysing the muscles causing these wrinkles

35
Q

What happens when acetylcholine is overproduced?

A

Violent muscle contractions and convulsions can be caused, e.g. with black widow spider bites

36
Q

What are neuromodulators?

A

Chemicals that modulate the sensitivity of neurons to their specific neurotransmitters

37
Q

Give an example of a neuromodulator and what it does

A

Endorphins - they travel through the brain inhibiting pain transmission and enhancing pleasurable feelings

38
Q

What are the three types of neuron?

A

Sensory neurons
Motor neurons
Inter neurons

39
Q

What do sensory neurons do?

A

Carry input messages from the sense organs to the spinal cord and brain

40
Q

What do motor neurons do?

A

Transmit output impulses from the brain and spinal cord to the body’s muscles and organs

41
Q

What do inter neurons do?

A

Perform connective or associative functions within the nervous system

42
Q

What are the two branches of the nervous system?

A

Central Nervous System
Peripheral Nervous System

43
Q

What does the central nervous system consist of?

A

Brain
Spinal Cord

44
Q

What is the spinal cord?

A

A densely packed bundle of nerve fibres that run along the spine and transmit messages from sensory and motor neurons

45
Q

What are the two branches of the peripheral nervous system?

A

Somatic Nervous System
Autonomic Nervous System

46
Q

What is the somatic nervous system?

A

A system of sensory and motor neurons that allows us to sense and respond to our environment

47
Q

What is the autonomic nervous system?

A

A system that senses the body’s internal functions and controls many glands and muscles - it is largely concerned with involuntary functions

48
Q

What are the two branches of the autonomic nervous system?

A

Sympathetic Nervous System
Parasympathetic Nervous System

49
Q

What is the sympathetic nervous system?

A

Responsible for the activation or arousal function that occurs when facing stress (fight or flight)

50
Q

What is the parasympathetic nervous system?

A

Responsible for the slowing down of the body (one or two organs at a time)

51
Q

What is homeostasis and how does it relate to the sympathetic and parasympathetic nervous systems?

A

A delicately balanced and steady internal state
These two systems work with each other to maintain this state, and they may also need to coordinate in order for certain functions to be performed, e.g. sex

52
Q

Describe a withdrawal reflex

A

A noxious stimulus (e.g. hot plate of food) produces a burst of action potentials in the sensory neurons
The axons fire
The neurotransmitter substance is released
This causes the inter neurons to fire
The inter neurons excite the motor neurons
The motor neurons cause the muscles to release (e.g. withdraw the hand and drop the plate)
But, a neuron in the brain excites an inhibitory inter neuron which decreases the rate of firing of the motor neuron (e.g. allowing you to put the plate down safely before dropping it)

Mind, Brain & Behaviour (17 decks)

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