Physiology

Question 1

what is CSF mostly composed of?

Answer 1

water

Question 2

what produces CSF?

Answer 2

secretory epithelium of the choroid plexus

Question 3

how many times a day is CSF replaced?

Answer 3

3-4 times

Question 4

what does the CSF supply?

Answer 4

water, amino acids and ions

Question 5

what does CSF remove?

Answer 5

metabolites

Question 6

what are the 3 major functions of CSF?

Answer 6

mechanical protection, homeostatic function, circulation function

Question 7

how does CSF provide mechanical protection?

Answer 7

shock-absorbing medium that protects brain tissue

Question 8

what is the homeostatic function of CSF?

Answer 8

pH of CSF affects pulmonary ventilation and cerebral blood flow. transports hormones.

Question 9

embrylogically, at 3 weeks what does the developing nervous system consist of?

Answer 9

a tube - neural canal

Question 10

what does the cavity of the neural canal give rise to in the adult brain?

Answer 10

the brains ventricles and the spinal cord’s central canal

Question 11

what does the choroid plexus develop from?

Answer 11

cells in walls of the ventricles

Question 12

what forms the choroid fissure?

Answer 12

developing arteries invaginate the roof of the ventricle

Question 13

what does the secretion of fluid by the choroid plexus depend on?

Answer 13

on the active sodium transport across the cells into the CSF

Question 14

what is the difference in ion, glucose and protein concentrations from blood plasma and CSF?

Answer 14

CSF has lower potassium, glucose and much lower protein than blood plasma, has higher concentrations of sodium and chloride than blood plasma

Question 15

is the production of CSF in the choroid plexuses directly dependent on the arterial BP?

Answer 15

no it is an active secretory process

Question 16

what connects the lateral ventricle to the third ventricle?

Answer 16

intraventricular foramina (of Monroe)

Question 17

what connects the 3rd ventricle to the 4th?

Answer 17

cerebral aqueduct (of Sylvius)

Question 18

what connects the 4th ventricle to subarachnoid space?

Answer 18

foramen of Magendie: Median aperture

Question 19

what does the lateral aperture of Foramina of Luschka connect?

Answer 19

4th ventricle to subarachnoid space

Question 20

where is the site of the blood-brain-barrier (BBB)?

Answer 20

endothelial cells in brain capillaries

Question 21

what does the BBB consist of?

Answer 21

of the capillary endothelium, its basal membrane and perivascular astrocyes

Question 22

what parts of the brain do not have the BBB?

Answer 22

circumventricular organs or pineal gland

Question 23

what does the BBB protect the brain from?

Answer 23

many common bacterial infections and toxins, drug delivery

Question 24

where is a colloid cyst of the brain often found?

Answer 24

at the interventricular foramen

Question 25

what does a ependymonas arrise from?

Answer 25

arrising from ependymal cells lining the ventricles

Question 26

what kind of hematoma is it if it is arterial blood between the skull and dura?

Answer 26

epidural hematoma

Question 27

what kind of blood and where is the blood in a subdural hematoma?

Answer 27

venous blood between the dura and the arachnoid

Question 28

what is hydrocephalus?

Answer 28

accumulation of CSF in the ventricular system or around the brain

Question 29

what can cause hydrophalus?

Answer 29

either obstruction of over-production of CSF

Question 30

what are the 2 layers of epithelium in the ciliary body and posterior surface of iris?

Answer 30

-a forward continuation of the pigmented epithelium of the retina overlain by an inner nonpigmented epithelial layer

Question 31

what are the 4 main regions of a photoreceptor?

Answer 31

- outer segement - inner segement - cell body - synaptic terminal

Question 32

what are the types of photoreceptors?

Answer 32

rods and cones

Question 33

what do photoreceptors do?

Answer 33

converts electromagnetic radiation to neural signals

Question 34

what happens the Vm of photoreceptors on light exposure?

Answer 34

it hyperpolarizes

Question 35

what is a positive Vm of photoreceptors due to?

Answer 35

the 'dark current'

Question 36

what type of channel in the photoreceptors opens in the dark and closes in the light?

Answer 36

cGMP-gated sodium channel

Question 37

this change in sodium with light in the photoreceptors enables what?

Answer 37

the brain to perceive objects in the visual field

Question 38

what are the visual pigment molecules called?

Answer 38

Rhodopsin

Question 39

where are Rhodopsin present?

Answer 39

in membrane folds called discs in the outer segment

Question 40

what does light convert 11-cis-Retinal to?

Answer 40

to all-trans-Retinal

Question 41

when is the dark current channel open?

Answer 41

in the dark

Question 42

what is visual acuity?

Answer 42

ability to distinguish 2 nearby points

Question 43

what is visual acuity largely determined by?

Answer 43

photoreceptor spacing and refractive power

Question 44

what photoreceptors are used more in daylight?

Answer 44

cones