Physiology of the Brain Flashcards

What is the normal intracranial pressure (ICP) range for a resting adult?

Answer: 5–15 mmHg

Normal adult ICP is roughly 5–15 mmHg, and sustained values above 20–22 mmHg are treated.

How is cerebral perfusion pressure (CPP) calculated?

Answer: MAP − ICP

CPP equals mean arterial pressure minus intracranial pressure.

Which combination makes up Cushing's triad, a sign of severely raised ICP?

Answer: Hypertension, bradycardia, irregular respirations

Cushing's triad is hypertension, bradycardia and irregular respirations from brainstem compression.

Cerebral autoregulation normally keeps cerebral blood flow constant across approximately which MAP range?

Answer: 50–150 mmHg

Autoregulation maintains steady flow at MAP of about 50–150 mmHg, and this is often impaired after TBI.

How does an elevated PaCO2 (hypercapnia) affect the cerebral vessels?

Answer: Vasodilation increasing cerebral blood volume and ICP

CO2 is a potent vasodilator, so hypercapnia increases cerebral blood volume and ICP.

The Monro-Kellie doctrine states that the cranial vault contains which fixed-volume components?

Answer: Brain, blood and CSF

The rigid skull holds brain tissue, blood and CSF, so an increase in one must be offset by a decrease in another.

Where is most cerebrospinal fluid (CSF) produced?

Answer: Choroid plexus of the ventricles

The choroid plexus in the ventricles produces about 500 mL of CSF per day.