Lecture 20. Neurons and Nervous Systems

Question 1

What does the nervous system do?

Answer 1

1. Receive and interpret information about the internal and external environments of the body (sensory system)
2. To make decisions about this information (integrating system)
3. To organise and carry out action (motor system)

Question 2

What does the sensory system include?

Answer 2

Sense organs, sensory nerves, central sensory areas

Question 3

What is the integrating system used for?

Answer 3

Making decisions from sensory input and stored record of previous experience (memories)

Question 4

What does the motor system include?

Answer 4

Motor neurones, central motor areas, all muscles and ducted glands of the body

Question 5

What is the motor system used for?

Answer 5

Control of movement - conscious and unconscious

Question 6

What are the units of the brain?

Answer 6

Neurons

Question 7

What is a neuron made up of?

Answer 7

Dendrites
Axon
Myelin
Node of Ranvier
Terminals

Question 8

What do dendrites do?

Answer 8

Increase surface area receive inputs

Question 9

What do axons do?

Answer 9

Carry information over distances

Question 10

What does myelin do?

Answer 10

Coats axon improves conduction

Question 11

What are Nodes of Ranvier do?

Answer 11

Breaks in myelin sheath

Question 12

What are terminals?

Answer 12

Output region transmitter release synapse with other neurones

Question 13

What is anterograde transport (WGA-HRP)?

Answer 13

From soma, down axon to terminals
Two kinds: rapid: 300-400 mm/day (up to 1 μm/s) and slow: 5-10 mm/day

Question 14

What is retrograde transport (HRP)?

Answer 14

From terminals to soma
Worn out mitochondria, SER
Rapid: 150 - 200 mm/day

Question 15

What is required for axonal transport?

Answer 15

Hydrolysis of ATP
Microtubules

Question 16

What do microglial cells do?

Answer 16

Act as scavengers
Clean up cellular debris
Launch immune response

Question 17

What do oligodendrocytes do?

Answer 17

Form myelin sheath in Central NS

Question 18

What do astrocytes do?

Answer 18

Supporting role
Mop up transmitters
Correct ionic environment
Release gliotransmitters (ATP, glutamate, D-serine)
Provide metabolic fuel for neurones

Question 19

How do nervous systems form?

Answer 19

Nerve nets → Nerve ring → Ganglia → Fusion of ganglia

Question 20

What occurs after the fusion of the ganglia?

Answer 20

Fusion of ganglia → Brain and Nerve cord → Vertebrates encephalisation

Question 21

What makes up the central nervous system (CNS)?

Answer 21

Brain and Spinal Cord

Question 22

What makes up the peripheral nervous system (PNS)?

Answer 22

Automatic (involuntary) Nervous System and Somatic (voluntary) Nervous System

Question 23

What are the segments of the spinal cord?

Answer 23

Cervical
Thoracic
Lumbar
Sacral

Question 24

How are brain structures defined?

Answer 24

By embryology

Question 25

What parts of the brain develop after 4 weeks?

Answer 25

Prosencephalon (Forebrain) Mesencephalon (Midbrain) Rhombencephalon (Hindbrain)

Question 26

What parts of the brain develop after 6 weeks?

Answer 26

Prosencephalon (Diencephalon and Telencephalon)

Question 27

What does the diencephalon contain?

Answer 27

Thalamus and Hypothalamus

Question 28

What does the telencephalon contain?

Answer 28

Cerebrum Basal ganglia Hippocampus

Question 29

What does the midbrain mesencephalon?

Answer 29

Inf. Colliculus Sup. Colliculus Ret Formation

Question 30

What does the hindbrain rhombencephalon contain?

Answer 30

Medulla Cerebellum Pons

Question 31

What are the meninges?

Answer 31

Surround the CNS Brain suspended in jacket of cerebrospinal fluid 3 layers 1) Tough outer layer Dura mater 2) Arachnoid mater 3) Pia mater

Question 32

What is the ventricular system?

Answer 32

Principle source of CSF: choroid plexuses in ventricles About 150 ml CSF Renewed ~ 4-5 times in 24 hrs Removes waste products Supplies brain & sp cord with nutrients Buffers changes in blood pressure and protects brain Supplies brain with fluid during dehydration Allows the brain to remain buoyant

Question 33

What links the two hemispheres of the brain?

Answer 33

Corpus callosum

Question 34

What are the functions of the midbrain?

Answer 34

Visual, auditory information, motor control, sensation

Question 35

What is the function of the pons and where are they located?

Answer 35

Links with cerebellum, modifies medulla output

Question 36

What are the functions of the medulla?

Answer 36

Respiration and cardiovascular function

Question 37

What are the functions of the cerebellum?

Answer 37

Balance, gait, fine movement, posture

Question 38

What is the function of the hypothalamus?

Answer 38

Integrates sensory information (LGN vision, MGN hearing)

Question 39

What is the function of the hypothalamus?

Answer 39

Autonomic control, appetitive drives reproductive behaviour, homeostasis, endocrine control