Lecture 1 - ORGANISATION OF NERVOUS SYSTEM

Question 1

Sponges, jellyfish

Answer 1

nerve net which gives the ability to react to external stimuli

Question 2

invertebrates cord?

Answer 2

dorsal

Question 3

vertebrates cord?

Answer 3

ventral

Question 4

Brain divisions common to all vertebrates

Answer 4

olfactory bulb, cerebral hemispheres, cerebellum, optic tectum, medulla oblongata

Question 5

Mammals brains

Answer 5

neocortex which is multi-layered, specialised structure not found in the likes of reptiles, shows a development of processing power which changes as you move higher up the animal

Question 6

forebrain

Answer 6

telencephalon

• cortex
• olfactory bulb

Diencephalon

• thalamus
• hypothalamus
• prosencephalon of forebrain
• telencephalic vesicles
• diencephalon
• optic vesicles

Question 7

midbrain

brainstem

Answer 7

mesencephalon

• tectum
• tegmentum

Question 8

hindbrain

brainstem

Answer 8

rhombencephalon

• pons
• medulla

Question 9

spinal cord

Answer 9

spinal cord

Question 10

Neural tube

Answer 10

1. endoderm – linings of organs; viscera
2. mesoderm – bones and muscles
3. ectoderm – nervous system and skin

Question 11

Neural plates

Answer 11

folds and fuses to form the neural tube

• CNA develops walls of the tube
• PNS derives from the neural chest

Question 12

Spina Bifilda

Answer 12

• Failure of the posterior neural tube to close
• Foetus wont develop a brain
• anterior end doesn’t close, then the spinal cord will stick out of the column – anterior makes up the peripheral end and starts to swell
• Supplementing diet with folic acid in early pregnancy can reduce neural tube defect incidence by 90%
• Some anti-epilepsy/ bipolar drugs interfere with folate metabolism and increase risk of SB

Question 13

Development differentiation

Answer 13

• Three swellings at the rostral end of the neural tube becomes primary vesicles
• Three primary vesicles: fore, mid, hind brain

Question 14

Ventricles

Answer 14

• hollow and bathed in CSF
• four fluid filled cavities called ventricles
• Act to cushion brain and have a role maintaining chemical stability and removing waste products
• brain shock absorber

Question 15

The Spinal Cord:

Answer 15

• protected by spinal column, surrounded by meninges (membranes and connective tissues) and CSF
• primary channel for messages from skin joints and muscles to/from the brain
• dorsal roots (closest to the skin at the back) of spinal cord contain sensory, afferent neurons
• ventral roots contain motor, efferent neurons (signals to the rest of the body)
• grey matter = neuron cell bodies
• white matter = myelinated axons

Question 16

root route

Answer 16

dorsal root —-> sensory —-> spinal cord —-> motor —->ventral root

Question 17

The Brainstem

Answer 17

• oldest part of the brain
  1. midbrain – movement, sensory, input eyes and ears
  2. pons – switchboard connects the cerebellum to the cerebral cortex which swells out from the ventral surface of the brain stem and is important relay between cortex and cerebellum (controls blood pressure and if damaged can result in major life threatening problems)
  3. medulla – autonomic functions and is important in control of blood pressure and respiration
  4. cerebellum

Question 18

Brain stem damage

Answer 18

• hydrocephalus (the accumulation of fluid) or haemorrhage

- severe cases can lead to coning which is damage to the medulla causes respiratory arrest

Question 19

Cerebellum

Answer 19

• movement control centre
• extensive connections to cerebrum and spinal cord
• You can live without a cerebellum

Question 20

Diencephalon and Mesencephalon

Answer 20

• Midbrain: linkages between components of motor systems (e.g. substantia nigra) and eye movements
  Diencephalon: thalamus (relay and gating roles) and hypothalamus (homeostasis and reproduction

Question 21

Cerebral Cortex

mammals have 6-layer neocortex

Answer 21

• 2 halves along a sagittal fissure
• Controls:
  1. Voluntary actions
  2. Cognition
  3. Perception/ awareness

Question 22

Cortical folding

Answer 22

• Increase intelligence to increase processing power
• Cortical neurons represent processing power which increase number of cortical neurons
• keeps skull volume and mass to minimum
• big hards are harder to protect

Question 23

Homunculus

Answer 23

• shows how much neocortex is linked to a function
• proportional to neuronal composition
• important for finger and jaw movement

Question 24

SUMMARY

Answer 24

1. there are major similarities and differences exist between the major brain regions in animals
2. development and function of all the major regions of the spine and human brain all derive from the neural tube