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Human Biology > Chapter 3 - Nerves and Neurons > Flashcards

Chapter 3 - Nerves and Neurons Flashcards

- Nerve Cells - Nerve Impulses - Receptors and Reflexes - Comparison of Hormonal and Nervous Coordination

1
Q

What are neurons?

A

The basic structural and functional units of the whole nervous system. They are also highly specialised cells.

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2
Q

What are the three basic functions of the nervous system?

A
  1. Sensation
  2. Integration
  3. Reaction/Response
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3
Q

What is meant by ‘sensation’ as one of the functions of the nervous system?

A

The nervous system monitors changes/events occuring in and outside the body. Such changes are known as stimuli and the cells that monitor them are receptors

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4
Q

What is meant by ‘integration’ as one of the functions of the nervous system?

A

The nervous system processes and interprets sensory information to determine the appropriate response

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5
Q

What is meant by ‘reaction/response’ as one of the functions of the nervous system?

A

The nervous systems motor output: The activation of muscles or glands to carry put a response

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6
Q

What are neurons designed for?

A

Rapid communication of messages in the body

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7
Q

How do neurons communicate messages around the body?

A

They reciece stimuli and transmit information (electrochemically)

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8
Q

What is the basic organisation of a neuron?

A
  1. Cell body
  2. Dendrites: Input
  3. Axon: Output
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9
Q

What is the purpose of neuroglia cells?

A

To support and protect neurons

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10
Q

Are all neurons the same size and shape?

A

No, they vary in size and shape but they all consist of a cell body and two different types of extension from the cell – the dendrites and the axon.

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11
Q

What is the cell body?

A

Cytoplasm mass that contains the nucleus of a neuron

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12
Q

What does the cell body contain?

A

The nucleus (DNA), cytoplasm and the organelles; mitochondria, endoplasmic reticulum, ribosomes and golgi apparatus.

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13
Q

What is the cell body responsible for?

A

Controlling the functioning of the cell

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14
Q

Describe the appearance and location of the cell body

A

Round, centrally located structure

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15
Q

What is the function of the cell body?

A

Direct Metabolism

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16
Q

Does the cell body play a role in neural signaling?

A

Nope

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17
Q

What are dendrites?

A

Fairly short extensions of the cytoplasm of the cell body that are often highly branched that carry impulses towards the cell body.

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18
Q

What is the function of dendrites?

A

Carry messages, or nerve impulses, into the cell body
INFORMATION COLLECTOR

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19
Q

What is an axon?

A

Often a single, long extension of the cytoplasm that carries impulses away from the cell body

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20
Q

What is the function of an axon?

A

Usually carries nerve impulses away from the cell body

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21
Q

What are the two distinct parts of an axon?

A
  1. Tube-like structures (axis cylinder)
  2. Axon terminal branches at the end that connect to dendrites of other cells
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22
Q

Does the length of axons vary?

A

Yes, those in the brain may only be a few mm long, while the axons that run from the spinal cord to the foot may be a metre in length or so. They are usually longer than dendrites.

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23
Q

What happens at the end of axons?

A

At the end the axon divided into many small branches. Each branch terminates at the axon terminal.

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24
Q

What is a nerve fibre?

A

The term ‘nerve fiber’ is used for any long extension of a cell, usually referring to the axon

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25
What is a myelin sheath?
A layer of fatty material that covers most axons
26
What does a myelin sheath act as?
An electrical conductor
27
When a myelin sheath is present, what does it do?
Increases the speed of neural signals down the axon
28
What are axons with a myelin sheath called?
Myelinated fibres
29
What are axons without a myelin sheath called?
Unmyelinated fibres
30
What happens if a myelin sheath isn't present?
Slower transmissions
31
What is the myelin sheath produced by outside of the brain and spinal cord?
Special cells called Schwann cells
32
Where are Schwann cells located?
They are wrapped around the axon
33
Are myelinated sheaths continous?
No, there are gaps called Nodes of Ranvier
34
What are Nodes of Ranvier?
Gaps in the myelin sheath at intervals along the axon
35
What do Nodes of Ranvier do?
Speed up nerve transmissions
36
What are the three important functions of the myelin sheath?
1. Act as an insulator 2. Protect the axon from damage 3. Speed up the movement of nerve impulses along the axon
37
What is the neurilemma?
A membrane that covers the myelin sheath and axons of neurons
38
What is the purpose of a neurilemma?
Assists in the repair of neurons
39
What is the myelin sheath produced by in the brain and spinal cord?
Oligodendrocytes
40
What is white matter?
Areas containing myelinated fibres due to the fatty nature of the myelin appear white
41
What is grey matter?
The areas made up of body cells and unmyelinated fibres due to their grey colour
42
What is a synaptic knob?
The end of axon terminals that are enlarged to form a synapse
43
What occurs at synaptic knobs?
The electrical signal is converted into a chemical signal to pass to the dendritre of another neuron or to a muscle/gland
44
What are synapses?
The junction where the axon terminal one neuron joins with a dendrite or the cell body of another, the neurons do not physically touch, there is a small gap.
45
How are messages carried across the synapse?
By the movement of chemicals called neurotransmitters.
46
What are two types of neuroglia in the PNS?
1. Schwaan cells 2. Satelite cells
47
What do satelite cells do?
Surround neuron cell bodies in ganglia, provide support and nutrients
48
What is a neuromuscular junction?
A tiny gap that is similar to a synapse where an axon meets a skeletal muscle cells
49
What are the three functional types of neurons?
Sensory, Motor and Interneurons
50
What are sensory neurons also known as?
Afferent or receptor neurons 
51
What is the function of sensory neurons?
Carry messages from receptors in the sense organs or in the skin to the central nervous system, the brain and spinal cord (CNS)
52
What are motor neurons also known as?
Efferent or effector neurons
53
What is the function of motor neurons?
Carry messages from the CNS to the effectors, the muscles and glands
54
What are interneurons also known as?
Association neurons, connector neurons or relay neuron
55
What is the function of interneurons?
They are the link between the sensory and motor neurons.
56
Where are interneurons located?
In the central nervous system
57
What are the four structural types of neurons?
Multipolar, bipolar, unipolar and pseudounipolar neurons
58
What are the structural types of neurons based on?
The number of extensions from the cell body of the neuron
59
How many axons and dendrites do multipolar neurons have?
One AXON Multiple DENDRITES
60
How many axons and dendrites do bipolar neurons have?
One AXON One DENDRITES
61
How many axons and dendrites do unipolar neurons have?
One AXON No DENDRITES
62
How many axons and dendrites do pseudounipolar neurons have?
One AXON that divides into two No DENDRITES
63
What is an example of a multipolar neuron?
Motor neurons and Interneurons
64
What is an example of a bipolar neuron?
Neurons in the eyes, ears and nose
65
What is an example of a unipolar neuron?
NOT found in the human body
66
What is an example of a pseudounipolar neuron?
Sensory Neurons
67
What are nerve fibres?
The axons and dendrites of nerve cells
68
What is a nerve?
Bundles of nerve fibres held together by connective tissue
69
Compare and contrast a synapse and a neuromuscular junction.
Compare: Both the synapse and the neuromuscular junction are gaps that require a neurotransmitter to diffuse across in order to transmit a nervous impulse. Contrast: A synapse is found between the axon and dendrite of two adjacent neurons. The neuromuscular junction is found at the end of an axon and a skeletal muscle cell.
70
Why are interneurons multipolar in their structure?
Because it allows multiple dendrites for sensory neurons to connect and one axon to deliver the impulse on to a motor neuron.

Human Biology (14 decks)

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