BIO AND COG WEEK 3

Question 1

NEURODEVELOPMENT

Answer 1

• adult brain=80 billion neurons
• early embryonic life= neurons added at a rate of 250,000 neurons
• 2 years after birth- 80% of adult size
• single neuron interacts with an average of 15 000 other cells

Question 2

Describe the process of the embryonic life for the first 2 weeks

Answer 2

zygote - cleavage - gastrulation- ECTODERM= central nervous system, peripheral nervous system,epidermis- MESODERM- Skeletal system , muscles,vascular region- ENDODERM= gut,lungs,liver

Question 3

briefly explain the formation of neural tube = 2-4 weeks ?

Answer 3

2 weeks= neural plate
3 weeks= neural crest
4 weeks= neural tube

Question 4

what are the stages of neuro development?

Answer 4

1- neurogenesis 
2- neural migration 
3- neural differentiation 
4- synaptogenesis
5- apoptosis
6- synapse reorganisation

Question 5

what is neurogensis?

Answer 5

The progenitor - stem cells are divided in the neural tube by mitosis
as in early development they divide symmetrically to increase the number of progenitor cells
which they later split asymmetrically into one progenitor cell and one immature neuron

= 8-16 weeks after conception

Question 6

what is neural migration?

Answer 6

This is when newly-formed neurons in the ventricular zone are guided into position by radial glia cells

• As each successive wave of neurons passes neurons that migrated earlier so the most recently formed neurons occupy layers closer to the cortical surface

Question 7

what takes place in the neural differentiation process?

Answer 7

• When the immature neurons are in position they differentiate into different types of specialised neurons

…….. resulting in the laminar structure of cortex

Question 8

what happens in the synaptogenesis process?

Answer 8

Here there is an over production of synapses, redundancy which begins from about 17 weeks after conception but its mostly postnatal

Question 9

what happens in the Apoptosis ( cell death) process?

Answer 9

Here it clears and kills of neurons who’s axons don’t find their targets which is activated by genetic processes inside a cell different from necrosis

= early as 16 weeks after conception until after birth

Question 10

what happens at synaptic reorganisation?

Question 11

what is myelination?

Answer 11

produced by oligodendrocytes a type of glial cell
- which gradual increase in the myelin sheath surrounding the axons
- starts=visual system before birth then progresses other sensory systems
- sensory neurons are myelinated before motor ones;
= all white matter fibre tracts have myelination before 2 years

Question 12

HORMONES

Question 13

what does the autonomic nervous system have?

Answer 13

parasympathetic= slows heartbeat , stimulates secretion. stimulates bile release
= acetylcholine

sympathetic= dilutes pupil, inhibits salivation,accelerates heartbeat, stimulates glucose production and release
= NORADRENALINE

Question 14

what is a hormone?

Answer 14

• it is a chemical messenger that travels in the bloodstream which targets other organs

Question 15

Name me a few examples of hormones?

Answer 15

Ghrelin- ''the hunger hormone''
insulin- involved in glucose metabolism 
testosterone and oestrogen
human growth hormone 
Adrenaline and Cortisol ( stress)

Question 16

what happens in the adrenal gland?

Answer 16

Adrenaline- secreted from the adrenal medulla under sympathetic control
- it sustains the fight or flight response which continues to raise heart rate, increase breathing etc

Question 17

what is cortisol?

Answer 17

• ## a human when one is under stress, known to affect the immune system

Question 18

what are small world networks?

Answer 18

it is characterised by dense local connectivity and a smaller number of long range connections efficient kind of network and can be seen in other kinds of network as well as the brain