CNS 2

Question 1

the brain is protected from injury by…

Answer 1

• the skull
• the meninges
• the blood brain barrier
• the cerebrospinal fluid

Question 2

the 3 layers of membranous connective tissue, the meninges provide what?

Answer 2

support + protection

Question 3

what are the 3 layers the meninges is composed of?

Answer 3

• dura mater
• arachnoid layer
• pia mater

Question 4

what are the main functions of the meninges?

Answer 4

• protecting brain + spinal cord from mechanical injury
• providing blood supply to skull + to hemispheres
• providing space for flow of cerebrospinal fluid

Question 5

what is the blood brain barrier (BBB)?

Answer 5

highly selective semi-permeable membrane barrier that separates circulating blood from brain and extracellular fluid in CNS

Question 6

what does the BBB tightly regulate?

Answer 6

movement of molecules, ions + cells between blood and CNS

Question 7

what does the BBB prevent?

Answer 7

large molecules, immune cells, + disease-causing organisms e.g. bacteria + viruses from passing from blood stream into CNS

Question 8

the BBB is a tightly packed layer of cells that…

Answer 8

line blood vessels in brain + spinal cord

Question 9

the BBB is composed of 3 cellular elements of the brain microvasculature

what are they?

Answer 9

• endothelial cells
• astrocytes (astroglia)
• pericytes

Question 10

endothelial cells

Answer 10

= thin layer of cells that line interior surface of all blood vessels

Question 11

astrocytes (astoglia)

Answer 11

tightly encircle endothelial cells + = critical for induction + maintenance of tight junction barrier (TJs)

Question 12

what do TJs between the cerebral endothelial cells form?

Answer 12

diffusion barrier which selectively excludes most blood-borne substances from entering the brain

Question 13

pericytes

Answer 13

= mural cells of microcirculation that wrap round endothelial cells that line capillaries

pericytes help endothelial cells to differentiate, multiply, form vascular branches + survive apoptotic signals

Question 14

neurological disorders linked to BBB

extrinsic factors?

Answer 14

• multiple sclerosis: autoimmune, infectious, traumatic initiation
• meningitis: bacterial + viral
• encephalitis: herpes, HIV

Question 15

neurological disorders linked to BBB

intrinsic factors - acute?

Answer 15

• ischemia/hypoxia

- traumatic brain injury

Question 16

neurological disorders linked to BBB

intrinsic factors - chronic?

Answer 16

• small vessel disease

- amyloid angiopathy (disease of blood vessels)

Question 17

what is the ventricular system?

Answer 17

set of structures containing cerebrospinal fluid in brain

is continuous with central canal of spinal cord

Question 18

what is the CSF produced by?

Answer 18

modified ependymal cells of choroid plexus

Question 19

the CSF has 4 main purposes

what are they?

Answer 19

• buoyancy - supports brain against gravity
• protection - protects brain from striking cranium when head jalted
• chemical stability
• waste removal - removes waste in absence of lymphatic system

Question 20

the brain and CSF are similar density

what does this make the brain do?

Answer 20

float in neutral buoyancy suspended in CSF

Question 21

without oxygen and important nutrients, what would happen to brain cells?

Answer 21

damaged/ die in few mins

Question 22

the brain relies on 2 sets of major arteries for its blood supply

what are they?

Answer 22

• internal carotid arteries (supply anterior brain)

- vertebral arteries (supply brainstem + posterior brain)

Question 23

what does cerebrovascular refer to?

Answer 23

blood flow in brain

Question 24

what do cerebrovascular diseases include (CVDs)?

Answer 24

all disorders in which area of brain = temporarily / permanently affected by ischemia/ bleeding

Question 25

what are the 4 most common CVDs?

Answer 25

• stroke - part of brain damaged by lack of blood supply/bleeding into brain from burst blood vessel
• transient ischemic attack - temp fall in blood supply to one part of brain
• subarachnoid hemorrhage - type of stroke where blood leaks out brains vessels onto surface of brain
• vascular dementia - persistent impairment in mental ability resulting from stroke / other prob with blood circulation to brain