11.1 The Nervous System

Question 1

What can a pituitary stalk tumour have an affect on?

Answer 1

Can press on optic nerves affecting peripheral vision

Question 2

What is the cauda equina and its function?

Answer 2

Within the lumbar cistern, part of the PNS

Motor innervation of pelvic organs and lower limbs
Sensory innervation of perineum (area between scrotum/vulva and anus) and bladder

Question 3

What is a schwannoma?

Answer 3

Tumour of the myelin sheath

It could cause compression on other nerves causing pain and progressive deterioration of neurological function

Question 4

What is a lumbar puncture and why is it done between L3 an L4 region?

Answer 4

Sample of cerebrospinalfluid taken to see if infection in CNS region.

Least risky place to do it as cauda equina is here and we’d rather hit a PNS nerve than CNS

Question 5

What is a deep tendon reflex and its physiological role?

Answer 5

blow to the tendon causing quadriceps femoris muscle contraction, and hamstring to relax

If knee gives way, it is an automatic unconscious movement to regain balance

Question 6

What is a glioblastoma?

Answer 6

Cancer of glial cells in brain

Question 7

If tumour in cranial region, what happens to the intracranial pressure?

Answer 7

It is normally 7-15mmHg
Tumour increases this although pressure increase in one constituent is responded to by a decrease in another.
But once this compensatory reserve is exceed, pressure for a given increase in volume rises dramatically.

Question 8

What is a craniotomy?

Answer 8

Surgical removal and replacement of part of bone from skull

Question 9

What does the CNS and PNS consist of?

Answer 9

CNS - The spinal cord and the brain

PNS - Somatic nervous system and Autonomic Nervous system (Sympathetic and parasympathetic)

Question 10

Function of the CNS and PNS?

Answer 10

CNS - in charge, make sensible motor responses based on sensory input.

PNS - converys sensory input to CNS and sends motor output to the muscles

I.e. Receiving info and Dissemination info to diff parts of body

Question 11

What is the function of the brain?

Answer 11

Cerebral cortex - responsible for higher functions

Question 12

What is the function of the brain stem?

Answer 12

Consists of medulla oblongata, pons, mid brain
Controls flow of messages between brain and body
Regulation of cardiovascular function, breathing, sleep, wakefulness

Question 13

What is the cerebellum and its function?

Answer 13

Highly folded so lots of neurones can fit here

In charge of fine aspects of motor control

Question 14

What does the spinal cord do?

Answer 14

Carries sensory and motor information to and from the CNS

Question 15

What are ganglia and nuclei?

Answer 15

Collection of neuronal cell bodies within the PNS

Collection of neuronal cell bodies within the CNS

Question 16

What are nerves called in the CNS?

Answer 16

Tracts

Question 17

What is the central canal?

Answer 17

Spinal cord is a hollow tube in the middle, this is called the central canal

Question 18

What is the difference between white and grey matter?

Answer 18

Grey matter- composed of neurones, information processing computer
White matter - composed of axons, disseminate info to where it needs to go - like cables

Question 19

Describe a transverse section through the spinal cord.

Answer 19

Central canal surrounded by grey matter surrounded by white matter. Dorsal and ventral roots coming out of spinal cord which connect forming a spinal nerve. The dorsal root has a function called the dorsal root ganglia.

Question 20

What is the dorsal horn and root, and its function?

Answer 20

Sensory information travels from receptor through the spinal nerve, to the dorsal root ganglion, through dorsal root, to the grey matter lobe (dorsal horn).

Question 21

What is the ventral horn/root and its function?

Answer 21

Motor information travels from grey matter (ventral horn) through ventral root to spinal nerve where it goes and effects the relevant tissue/muscle

Question 22

What is an interneurone?

Answer 22

Neurone connecting sensory and motor neurons
Located within grey matter
Where complex processing occurs

Question 23

Describe the structure of a nerve.

Answer 23

Axon covered by myelin sheath
Axons held together by endoneurium forming fascicles
Fascicles held together by perineurium forming spinal nerve
Spinal nerve wrapped in epineurium
Goes on to form dorsal and ventral rootlets
Which connect to the spinal cord

Question 24

What is the glia?

Answer 24

Connective tissue of the nervous system made up of lots of different cells

Question 25

What is a schwann cell,the two types and their functions?

Answer 25

1) produces myelin which is made of lipid
2) myelinating
- insulates axon
- one cell to one axon
3) non-myelinating
- supporting (not really insulation)

Question 26

What is an oligodendrocyte and its function?

Answer 26

1) produces myelin made of lipid
2) in the CNS
3) one cell insulates MANY axons

Question 27

What is an astrocyte?

Answer 27

1) cellular vacuum
- vacuums excess NT diffusing away from synapses so cant go an activate elsewhere
2) blood brain barrier
- end feet of astrocyte cover blood vessels preventing certain molecules from getting through to brain and spinal cord

Question 28

What is a microglial cell?

Answer 28

Fine branched processes on cell constantly moving and protecting CNS
Turns into a macrophage if it comes across anything foreign