T1L17: Principles of the Nervous System 1

Question 1

Axon hillock

Answer 1

Origin of axon

Very excitable

Question 2

Axon/nerve fibre

Answer 2

Transmit action potential

Usually only one

Question 3

Axon terminals

Answer 3

Synapse on other neurons, effector organs or forms specialised ending

Question 4

Afferent

Answer 4

Information TO CNS

Primary sensory neuron

Question 5

Efferent

Answer 5

Information AWAY from CNS

Motor neurons

Question 6

Chemical synapses [4]

Answer 6

Majority
Use neurotransmitters
Depolarisation of presynaptic membrane opens Ca2+ channels
Vesicles fuse +release neurotransmitter

Question 7

Astrocytes [6]

Answer 7

Provide structural support

Supply nutrients

Maintain ionic environment (remove K+)

Neurotransmitter uptake

Repair nervous system

Form barrier around vessels

Question 8

Oligodendrocytes [2]

Answer 8

Production and maintenance of myelin sheath

One oligodendrocyte myelinates multiple axons

Question 9

Microglia [4]

Answer 9

• Immune cells
• Phagocytic (like macrophage)
• Cytotoxic (release H2O2)
Promote repair

Question 10

Neuroglia of PNS [4]

Answer 10

• Schwann cells = neuroglia of PNS 
Myelinate axons (spiral wrapping) 
 Important for regeneration - substrate to grow alongside 
One schwann myelinate one axon cell

Question 11

Forebrain

Answer 11

• Cerebral hemisphere = highly divided
• Outer grey matter = cerebral cortex
○ 10-20 billion neurons / 2.5 mm thick
○ Highly folded to fit into skull
• Process motor and sensory information
80% of cortex function in cognition

Question 12

Frontal lobe

Answer 12

Primary motor cortex

Question 13

Parietal lobe

Answer 13

Primary somatosensory cortex

Question 14

Temporal lobe

Answer 14

Primary auditory cortex & olfaction

Question 15

Occipital lobe

Answer 15

Primary visual cortex

Question 16

Forebrain - thalamus

Answer 16

Relay centre of brain
Paired structure
Centrally located
All sensory NOT smell

Question 17

Forebrain - hypothalamus

Answer 17

Controls ANS and endocrine system

Question 18

Hindbrain

Answer 18

Cerebellum coordinate complex muscular movement

Question 19

Spinal cord

Answer 19

Extend from atlas to 1st lumbar vertebrae
Sit within vertebral canal
PNS to brain (sensory) and back (motor)
Involved in reflexes and segmentally organised

Question 20

Spinal cord anatomy

Answer 20

Inner core of gray matter: neuronal cell bodies

Outer, white matter: myelinated axons and convey info to/from bones

Question 21

Peripheral nervous system

Answer 21

• Connects CNS with periphery
• Nerve supply to muscles, glands, skin, vessels, viscera
• Peripheral nerves convey motor, sensory and autonomic axons
Two components:
1. Somatic (voluntary) component
(skeletal muscles, touch, pain)
2. Autonomic (involuntary) component
(organs, vessels)
But many peripheral nerves contain axons from both components
- Therefore, not always anatomically separate

Question 22

Somatic component - motor

Answer 22

Somatic motor neurons

spinal cord/brainstem cells -> efferent fibres from CNS -> muscle

Question 23

Somatic component - somatosensory neurons

Answer 23

Axons of primary sensory n 
external environment (exteroceptive) and within body (proprioceptive)