Nervous System

Question 1

What are the 2 major cell types of the nervous system and what proportion are each of them of the total?

Answer 1

glia (90%) and neurones (10%)

Question 2

What are the 2 types of glia?

Answer 2

macroglia and microglia

Question 3

What shape are glia?

Answer 3

stellate (star shaped)

Question 4

What are the macroglia within the CNS?

Answer 4

astrocytes, oligodendrocytes, ependyma

Question 5

What makes up the largest count of macroglia in the CNS?

Answer 5

astrocytes

Question 6

What are the functions of astrocytes?

Answer 6

assist transfer of nutrients and waste between neurones and blood, constitute blood brain barrier, phagocytic functions and physical support for neurones

Question 7

What is the function of oligodendrocytes?

Answer 7

myelination in the CNS

Question 8

How many axons can a oligodendrocyte myelinate at once?

Answer 8

up to 250

Question 9

What is the function of ependyma?

Answer 9

line the ventricles and central canal of spinal cord for the circulation of cerebrospinal fluid

Question 10

What are microglia used for?

Answer 10

immunity and inflammation

Question 11

What are the macroglia of the PNS?

Answer 11

Schwann cells and sattelite cells

Question 12

What is the function of schwann cells?

Answer 12

myelination of peripheral nerve axons

Question 13

How many axons can a Schwann cell myelinate at once?

Answer 13

1 Schwann cell can myelinate 100microns of 1 axon

Question 14

What is the role of satellite cells?

Answer 14

physical support of neurones

Question 15

What are dendrites for?

Answer 15

increase the surface area of a cell body so that it can maintain contact with many cells

Question 16

What are the features of cell bodies?

Answer 16

single, central nucleus, vary in shape, contain Nissl substance for protein synthesis and Golgi apparatus for packaging

Question 17

What is grey matter?

Answer 17

Collections of cell bodies

Question 18

Along a myelinated axon, where are the K+ and Na+ channels?

Answer 18

K+ channels = myelin sheath

Na+ channels = nodes of Ranvier

Question 19

What is an axon hillock?

Answer 19

A kink in the axon, appears as an elevation of the membrane. there is a high density of Na+ channels for initiation of action potentials.

Question 20

In which direction is the main transmission?

Answer 20

From the cell body towards the axon terminal

Question 21

What does conduction velocity equal?

Answer 21

6 x fibre diameter

Question 22

How many times can a Schwann cell wrap itself around the axon?

Answer 22

100 times

Question 23

Name 3 diseases that can demyelinate axons

Answer 23

multiple sclerosis, guillain barre and diabetes

Question 24

What is the relationship between diameter and conduction?

Answer 24

Larger diameter = faster conduction

Question 25

What is the conduction along a myelinated neurone called?

Answer 25

Saltatory conduction

Question 26

What makes up white matter?

Answer 26

Axons

Question 27

What ensheaths a single axon?

Answer 27

Endoneurium

Question 28

What ensheaths a nerve fascicle?

Answer 28

Perineurium

Question 29

What ensheaths an entire nerve?

Answer 29

epineurium

Question 30

What do we call the membrane envelopes of the brain?

Answer 30

Meninges

Question 31

What are the layers of the meninges cells from outer to inner?

Answer 31

dura mater, arachnoid mater, pia mater

Question 32

What happens when an axon is severed?

Answer 32

The proximal segment of axon seals to prevent leakage and a nerve stump formed. The distal segment is cut off from nutritional support of cell body, distal segment dies and undergoes Wallerian degeneration

Question 33

What happens to reform an axon after severing?

Answer 33

The volume of cell body increases due to lots of protein expression.The nucleus gets pushed from centre. The axon usually regrows - Wallerian regeneration, but often ends up at the wrong target.

Question 34

What is an afferent pathway?

Answer 34

conducting in-coming signals, periphery to CNS, sensory neurones

Question 35

What is an efferent pathway?

Answer 35

conducting out-going signals, CNS to periphery, motoneurone or autonomic neurone

Question 36

What is a ganglion?

Answer 36

A collection of neurone cell bodies in the PNS

Question 37

How many pairs of cranial nerves do we have?

Answer 37

12 pairs

Question 38

How many pairs of spinal nerves do we have?

Answer 38

31 pairs

Question 39

How many autonomic ganglia pairs do we have?

Answer 39

25 pairs

Question 40

How many sensory ganglia pairs do we have?

Answer 40

31 pairs

Question 41

Where is the enteric nervous system?

Answer 41

Within the gut

Question 42

What 2 systems is the autonomic nervous system split into?

Answer 42

parasympathetic and sympathetic

Question 43

What are the features of the somatic nervous system?

Answer 43

voluntary, simplest layout possible, efferent neurone terminates directly on effector organ, affects skeletal muscle, inactive during REM sleep, under-developed at birth so that the environment can influence

Question 44

Which of somatic or autonomic has the simplest layout?

Answer 44

Somatic

Question 45

What are the features of the autonomic nervous system?

Answer 45

involuntary, fundamental for life functions, becomes active along with organogenesis, functions non-stop throughout life

Question 46

Which NS is fight or flight?

Answer 46

Sympathetic

Question 47

Which NS is rest and digest?

Answer 47

Parasympathetic

Question 48

Which NS are sweat glands innervated with only?

Answer 48

sympathetic

Question 49

What happens to the bladder under sympathetic control?

Answer 49

bladder fills, internal sphincter closes (relaxed) and detrusor muscle relaxes

Question 50

What happens to the bladder under parasympathetic control?

Answer 50

bladder empties, internal sphincter opens (contract) and the detrusor muscle contracts

Question 51

What can overactivity of the parasympathetic NS lead to?

Answer 51

dilated blood vessels and reduced substrate to brain causing fainting

Question 52

What can overactivity of the sympathetic NS lead to?

Answer 52

constriction of blood vessels causing necrosis

Question 53

Where does the sympathetic NS flow from and what is this called?

Answer 53

spinal cord only: T1-T12 and L1-L2 thoraco-lumbar division of the ANS

Question 54

Which kind of matter is in the centre of the spinal cord?

Answer 54

Grey matter

Question 55

Which horn connects with the outside of the spinal cord?

Answer 55

Dorsal horn

Question 56

What are the 3 possible modes of termination from the spinal cord?

Answer 56

synapse in chain at same level as origin, synapse in chain at different level to origin or may not synapse in paravertebral chain

Question 57

What are the 2 types of sympathetic effector organ receptors?

Answer 57

Alpha and beta (adrenergic)

Question 58

How many types of alpha receptors are there?

Answer 58

2

Question 59

How many types of beta receptors are there?

Answer 59

3

Question 60

Name 4 cranial nerves

Answer 60

oculomotor, facial, glossopharyngeal and vagus

Question 61

Where does the parasympathetic NS flow from?

Answer 61

brain and spinal cord, cranio-sacral division of ANS, cranial nerves III, XII, IX and X, and S2-S4

Question 62

Which receptors are expressed on parasympathetic effector organs?

Answer 62

muscarinic receptors

Question 63

What are muscarinic receptors blocked by?

Answer 63

Atropine

Question 64

What are the 3 interdependent units of the nervous system?

Answer 64

brain, spinal cord and nerves