physiology

Question 1

what is cerebrospinal fluid?

Answer 1

-a clear, colourless liquid composed mostly of water

Question 2

what produces cerebrospinal fluid?

Answer 2

-secretory epithelium of the choroid plexus

Question 3

what ate the major functions of cerebrospinal fluid?

Answer 3

• mechanical protection: shock- absorbing medium that protects brain tissue. Brain ‘floats’ inside the cranial cavity
• Homeostatic function: pH of CSF affects pulmonary ventilation and cerebral blood flow. Transports hormones
• Circulation: medium for minor exchange of nutrients and waste products between blood and brain tissue

Question 4

where is CSF obtained for clinical analysis?

Answer 4

-obtained via a lumbar puncture

Question 5

what dies clinical CSF analysis allow the diagnosis of?

Answer 5

-problems in the brain, meninges and spinal cord

Question 6

Describe normal CSF

Answer 6

• clear and colourless
• contains little protein (15-45mg/dl)
• contains little immunoglobulins
• contains only 1 to 5 cells/ ml

Question 7

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

Answer 7

-a tube (neural canal)

Question 8

what is the choroid plexus?

Answer 8

-networks of capillaries in walls of ventricles

Question 9

CSF secretion involves the transport of mainly what ions across the epithelium from blood to CSF?

Answer 9

• sodium (na+)
• chloride (Cl-)
• bicarbonate (HCO3-)

Question 10

what is the basolateral side?

Answer 10

-the blood side

Question 11

what is the apical side?

Answer 11

epithelium side

Question 12

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

Answer 12

-the active Na+ transport across the cells into the CSF

Question 13

how does CSF return to venous blood?

Answer 13

-through arachnoid granulations into the superior sagittal sinus (SSS)

Question 14

what restricts the blood supply to the majority of the brain?

Answer 14

-the blood brain barrier (BBB)

Question 15

what is hydrocephalus?

Answer 15

• the accumulation of CSF in the ventricular system or around the brain (either due to obstruction or overproduction)
• subsequent enlargement of one or more ventricles and increase in CSF pressure

Question 16

what are symptoms of idiopathic intracranial hypertension?

Answer 16

-headache and visual disturbances due to papilloaedema