Topic 6 - The brain

Question 1

What are the steps and key stages in the development of the nervous system?

(how does ANS develop)

Answer 1

neural plate at 17 days old ( ectoderm = skin and neural plate = nervous system)

1) NEURALATION - 22 yrs old - neural plate -> neural groover and folds –> neural tube (CNS) and neural crest (PNS)
2) DIFFERENTIATION - primary and secondary brain vesicles

Question 2

Why have folic acid during pregnancy?

Answer 2

• Neural tube fails to close - folic acid helps neural tube form
• Environment influences sequences of gene expression
• Folic acid = 90% reduction = influences DNA synthesis

Question 3

What are the primary brain vesicles?

And what are the secondary brain vesicles of the forebrain?

Answer 3

3 PRIMARY BRAIN VESICLES:
- Forebrain, midbrain, hindbrain

SECONDARY BRAIN VESICLES OF THE FOREBRAIN:

• Telencephalic vesicles
• Diencephalon
• Optic vesicles

Question 4

What is the role of the midbrain?

Answer 4

• for sensory processing and voluntary movement.

Question 5

What are the 3 types of cerebral cortex?

Answer 5

1. Olfactory cortex – sensory information
2. Neocortex
3. Hippocampus

Question 6

Describe the structure of the neocortex.

Answer 6

• Has 6 layers which differ in structure

- Mapping the neocortex – Brodmann’s cytoarchitectural map / using lesions or direct stimulation

Question 7

How can the cortex be mapped using non-invasive functional imaging?

Answer 7

• PET – position emission tomography
• fMRI – Functional magnetic resonance imaging
• Electroencephalography (EEG)

Question 8

What 3 types of fibres does white matter have?

Answer 8

CPA

• Commissural fibres – connect between hemispheres
• Projection fibres – link to non-cortical areas
• Association fibres – link areas within a hemisphere

Question 9

In the hypothalmaus, what is Aden-hypophysis and neuro-hypophysis?

Answer 9

ADENOHYPOPHYSIS = troph cells stimulated by releasing hormones from parvocellular neurons of the hypothalamus

NEUROHYPOPHYSIS = Release hormones from the magnocellular neurons directly into systematic circulation.

Question 10

What is the organisation of the ANS?

Answer 10

Preganglionic neurons –> postganglionic neurons –> effector cells
Brainstem & spinal cord –> ganglia –> effector cells.