Lecture 34 - CSF

Question 1

CSF produced at?

Answer 1

choroid plexus, network of fenestrated capillaries surrounded in epithelium w microvilli in ventricles - part of BBB, seperaed by tight junctions

Question 2

CSF numbers?

Answer 2

usually 150ml, increases w increaing age, 25ml in ventricles rest in subarachnoid space, constant turn over 3-4x daily

Question 3

Routes of CSF absorption?

Answer 3

arachnoid villi, arachnoid granulations - unidirectional non-regulated bulk flow, proportional to pressure

Question 4

Diagnosing meningitis?

Answer 4

increased WBC and proteins, potential glucose decrease

Question 5

Diagnosing subarachnoid haemmorhage

Answer 5

increased RBC, xanthachromia (yellow)

Question 6

normal CSF numbers?

Answer 6

<5mill WBC, no RBC, <0.45g/l proteins, >2.5mmol/l

Question 7

Functions of CSF?

Answer 7

homeostasis, mechanical protection, counter sudden increase in intracranial pressure

Question 8

Normal intracranial pressure?

Answer 8

65-195mm or 5-15mmHg

Question 9

Measuring ICP?

Answer 9

lumbar puncture (dangerous), intracranial pressure monitoring device

Question 10

Compensatory mechanisms?

Answer 10

CSF movement to spinal subarachnoid space, collapse of cerebral veins, increased CSf absorption, distensible lumbosacral dura

Question 11

Cushing’s syndrome and triad?

Answer 11

arterial hypertension, slow HR, slow RR; decreased blood flow to medulla

Question 12

Arterial blood pressure affecting intracranial pressure?

Answer 12

Usually doesn’t in physiological ranges due to cerebrovascular autoregulation keeping cerebral perfusion pressure constant - CPP = MAP - ICP

Question 13

Other factors affecting ICP?

Answer 13

venous prssure, thoracic pressure, posture, arterial pressure of gases, temperature

Question 14

Functions of BBB?

Answer 14

regulation of ionic balance of brain, transport essential substrates, barrier from harmful molecules

Question 15

Nervous endothelial cells vs rest of body?

Answer 15

tight junctions not fenestrated, more mitochondria w thicker basement membranes, astrocytic foot places

Question 16

Factors affecting BBB transport?

Answer 16

molecular weight, lipid solubility, ionisation, protein binding (-), transport systems

Question 17

Disorders of BBB?

Answer 17

disruption of tight junctions, proteolysis of basement membrane, glial cell interacion failure, transporter alterations, new vessels (tumors)