Cerebrospinal fluid
A. Is an ultrafiltrate of plasma.
B. Is the main source of the brain’s nutrition.
C. Has the same pH as arterial blood.
D. Has a higher glucose concentration than has plasma.
E. Has a higher calcium concentration than has plasma.
The correct answer is: A. Is an ultrafiltrate of plasma.
Cerebrospinal fluid (CSF) is a clear, colorless fluid that surrounds the brain and spinal cord. It is indeed an ultrafiltrate of plasma, meaning it is formed by the filtration of plasma through the blood-brain barrier.
The other options are not correct:
– B. CSF is not the main source of the brain’s nutrition. The brain receives most of its nutrients and oxygen from the bloodstream.
– C. CSF has a slightly higher pH than arterial blood, ranging from 7.32 to 7.35.
– D. CSF has a lower glucose concentration than plasma, typically around 50-80 mg/dL compared to plasma’s 100 mg/dL.
– E. CSF has a lower calcium concentration than plasma, typically around 1.1-1.3 mmol/L compared to plasma’s 2.2-2.6 mmol/L.