Principles of Neuroscience Lecture 3 Structure of the Nervous system

Question 0

Where does the cerebrospinal fluid sit?

Answer 0

The CSF resides in the subarachnoid space

Between the arachnoid and pia maters

Question 1

What is the name for the protective layers on the brain?

Describe the layers

Answer 1

These are collectively called the Meninges
Pia: close
Arachnoid: spidery
Dura: hard (has its own vascularisation, fused with skull)

Question 2

What are arachnoid granulations?

Answer 2

These are projections that release CSF back into the super sagital space for venous return

Question 3

Where and what is the super sagital space?

Answer 3

It is within the dura mater. It contains blood for venous return

Question 4

Where is CSF made?

Answer 4

It is made in the ventricles in the brain

Question 5

How many ventricles are there?

Answer 5

2 lateral
3rd ventricle
4th ventricle

Question 6

What is the name of the blood vessels delivering nutrients into the ventricles for the CSF?

Answer 6

Choroid plexus

Question 7

How much cerebrospinal fluid is made per day?

Answer 7

Around half a litre

Question 8

What is the difference between white matter and grey matter?

Answer 8

White matter has much more extensive myelination

The fat gives it the white colour

Question 9

Describe how CSF moves from the ventricles to the subarachnoid space

Answer 9

Moves down into the 3rd and fourth ventricles, then into the subarachnoid space

Question 10

Is the vasculature in the brain dense or no?

Is vasculature in the white or grey matter more dense?

Answer 10

The vasculature is very dense due to the hi energy demands of the brain
Vasculature is more dense in the grey matter

Question 11

Which arteries delivery blood to the brain?

Answer 11

Internal carotid arteries

Vertebral arteries

Question 12

Which arteries circulate blood through the brain?

What are the subdivisions?

Answer 12

The cerebral arteries

Posterior, Middle and Anterior.
The middle is most important

Question 13

What is important about the blood supply to the four sections of the brain?

Answer 13

The blood supply to the four sections is discrete. This means that if there is a problem with blood flow to one area, that section is deprived of blood

Question 14

What is another name for a stroke?

Answer 14

Cerebrovascular accident

Question 15

What is responsible for most of the problems that occur in the brain?

Answer 15

Issues with vascularisation (CVAs)

Question 16

What are the two types of cerebrovascular accidents?

Answer 16

Occlusive

Haemorrhagic

Question 17

What is an occlusive CVA?

Give an example

Answer 17

Occlusive CVAs involve narrowing and blockage of the vascularisation of the brain.
Eg. Atherosclerosis, thrombosis

Question 18

What is an haemorrhaging CVA?

Give an example

Answer 18

Haemorrhaging is bleeding, due to the rupture of vessels

Eg. Aneurysm, trauma, elevated blood pressure

Question 19

What do CVAs lead to?

Answer 19

Tissue ischemia (lack of oxygen), leading to atrophy of the area

Question 20

Is vascularisation different among individuals?

What does this mean in terms of characteristic loss of function?

Answer 20

Vascularisation is consistent between individuals (in such a way that function organisation of the brain is)

This means that CVAs in a particular region will lead to a characteristic loss of function

Question 21

What is herniation?

Answer 21

Herniation is when an organ is displaced, protruding through the wall of the cavity containing it

Question 22

Why is raised intra-cranial pressure dangerous?

Answer 22

The skull resists expansion, so there is a build up of pressure, leading to herniation

Question 23

What are the four ways that intra-cranial pressure can increase

Answer 23

1. Haemorrhage
2. Vasogenic oedema : increased permeability, increased volume of CSF
3. Cytotoxic oedema: swelling of cells
4. Hydrocephalus : over secretion of CSF

Question 24

What is haemorrhage?

Answer 24

Bleeding

Question 25

What is cytotoxic oedema?

Answer 25

When cells swell, reducing the volume of ECF

Question 26

What is hydrocephalus?

Answer 26

This is when there is over secretion of ECF

Question 27

What is vasogenic oedema?

Answer 27

This is when there is increased permeability leading to increased volume of ECF

Question 28

What is the role of the blood brain barrier?

Answer 28

To closely control what can get into the blood supply to the brain

Question 29

What is the main requirement for molecules in order for them to be able to cross the blood brain barrier?

Answer 29

The must be small and lipid soluble

Receptor on the epithelium that can transport the molecule in

Question 30

What structural feature means that the blood brain barrier is very selective?

Answer 30

The tighht junctions between the epithelial cells of the capillaries in the vasculature of the brain means that molecules cannot get through

Question 31

What are the two ways that molecules can cross the BBB?

Answer 31

Be small and lipid soluble

Have a transporter protein

Question 32

Why is the BBB problematic for drug designers?

Answer 32

It is hard to make the drug acceptable to the brain

Even if it gets into the brain, it may be expelled back out again

Question 33

What are astroglia?

Answer 33

Astroglia regulate the ionic composition of the ECF and recycle neurotransmitters

Question 34

What are micro glia?

Answer 34

Micro glia are like macrophages

They clean up detritus and dead cells

Question 35

What are the two phases of micro glia?

Answer 35

Ameboid (active)

Ramified (resting)

Question 36

What is the role of atrocytes?

Answer 36

They maintain the tight junctions in the capillaries of the brain