Neurones Lecture 31

Question 1

What are the two original theories of the composition of the nervous system?

Answer 1

Reticular theory

Cell theory

Question 2

What is the reticular theory?

Answer 2

The nervous system was made up of a series of continuous tubes which conducted messages around the body

Question 3

What is cell theory?

Answer 3

The theory that the body is made up of cells

Question 4

What did Camillo Golgi discover?

Answer 4

That the brain is made up of lots of different cells which was discovered by leaving it in silver nitrate ( a stain now called the Golgi stain)

Question 5

What did Ramon y Cajal do?

Answer 5

Used Golgi’s stain on CNS PNS tissues to draw & classify the different cell types & the contacts between them

Question 6

What did Golgi and Cajal’s work show?

Answer 6

Golgi’s and Cajal’s work showed that the nervous system was made of millions of individual cells called neurons

Question 7

What is the reflex arc?

Answer 7

Stimulus->Receptor->Sensory Neurone/Afferent neurone->CNS->Motor neurones/Efferent neurones -> Effector (Muscle or gland).

Question 8

What is transduction?

Answer 8

Converting stimulus into electrical signal.

Question 9

What is the cause of any change in one’s body or behaviour?

Answer 9

Stimulus- change in environment

Question 10

What is the CNS?

Answer 10

The central nervous system which is made up of the brain and spinal cord

Question 11

What is the PNS?

Answer 11

Peripheral nervous system - this is made up of everything excluding the central nervous system i.e. the receptor, sensory neurone, motor neurone , effector.

Question 12

How many pairs of nerves connect the CNS to the rest of the body

Answer 12

43 pairs

Question 13

How many pairs of cranial nerves are there in the body

Answer 13

12 pairs exiting the brain and 31 pairs exiting at various levels of the spinal cord

Question 14

What is the sensory system called

Answer 14

Afferent system

Question 15

Where does the afferent system take the impulse

Answer 15

To the CNS

Question 16

What is the motor system in the body called?

Answer 16

Efferent system

Question 17

The efferent system consists of two types of responses, what are they?

Answer 17

Somatic (innervates skeletal muscle) and autonomic (innervates smooth & cardiac muscle and glands

Question 18

The autonomic response system can be broken down into?

Answer 18

Sympathetic (flight, or fight response) or parasympathetic (resting and digesting)

Question 19

What are the two types of cells of the nervous system and their roles

Answer 19

Neurones or nerve cells, which generate and transmit electrical signals and supporting cells (neuroglia) which have supporting roles in nerve cell functions

Question 20

What do dendrites do and how are they specialised

Answer 20

Dendrites receive incoming electrical information, they have branches and spines to increase surface area

Question 21

What does the cell body consist of

Answer 21

Prominent nucleus and nucleolus and RER

Question 22

What do axons do and how are they specialised

Answer 22

Axons take electrical signals away from the cell body and are covered in myelin sheath.

Axoplasm is surrounded by a ‘normal’ phospholipid bilayer membrane embedded with proteins (which act as ion channels).

Axons are attached to the cell body by a ‘axon hillock’.

Axons contain microfilaments (actin), microtubules & intermediate filaments which move
substances via ‘axonal
transport’ and ‘axoplasmic
flow’

Question 23

What are the two types of transport of substances within an axon

Answer 23

Axoplasmic flow - anterograde transport from cell body to synapse, involves intermediate filaments and is slow

Axonal transport - anterograde and retrograde, mediated via microtubules and neurofilaments at much faster rates

Question 24

How do axons terminate

Answer 24

In a series of synapses, where electrical signals are transferred to other neurones and muscles through neurotransmitters

Question 25

What are the neural supporting cells in the CNS

Answer 25

Oligodendrocytes, microglia, ependymal cell and astrocytes

Question 26

What are the neural supporting cells in the PNS

Answer 26

Schwann and satellite cells

Question 27

Function of Schwann cells

Answer 27

Produce myelin in the PNS and wrap its cell membrane repeatedly around an axon

Question 28

Function of nodes of Ranvier

Answer 28

This is where the electrical signal is regenerated

Question 29

Function of oligodendrocytes

Answer 29

Produce myelin in the CNS, a single oligodendrocyte provides myelin for only several neurones

Question 30

Functions of astrocytes

Answer 30

They are ‘star-shaped’ and are important for blood, damage repair and they store nutrients such as glucose. They also isolate synapses (mopping up neurotransmitters).

Question 31

Functions of Ependymal cells

Answer 31

Line ventricles of brain and central canal of spinal cord and is involved in secretion of CSF

Question 32

Functions of microglia

Answer 32

Normally dormant but involved in CNS injury/inflammation, where they phagocytose debris and pathogens and release cytokines to attract other immune cells

Question 33

What are 4 morhphological types of nerve cells

Answer 33

1) Anaxonic - no axon (rare) - e.g retinal amacrine cell
2) Unipolar - only one neurone emanating from the cell body - e.g some sensory neurones
3) Bipolar - one dendritic process and one axon leave the cell body - e.g retina
4) Multipolar - many neurites emanating from the cell body - e.g most CNS neurones

Question 34

What is a nerve

Answer 34

A nerve is a collection of neurons. It can contain both afferent and efferent fibres
Individual neurons are separated by a connective tissue sheath –endoneurium
The epineurium forms an outer coat around each fascicle splitting the nerve