Question

q1.6 how much does the brain swell? the volume of a human brain is normally about 1,200 cm^3. the osmolarity of solutes in the cerebrospinal fluid surrounding the brain is normally about 300 mm. what happens when the cerebrospinal fluid osmolarity drops to 280 mm? fill in as much of the diagram as you can. you may assume that the cerebrospinal fluid is continually replenished such that its solute concentration does not change over time.

Answer 1

A decrease in the osmolarity of CSF from 300 mm to 280 mm leads to brain swelling due to osmotic water flow into brain tissue, potentially resulting in cerebral edema and neurological symptoms. The brain's floatation in CSF is crucial for protection, and any imbalances can be detrimental.

Step-by-step explanation:

When the osmolarity of the cerebrospinal fluid (CSF) surrounding the brain decreases, water tends to enter the brain tissue to reach an osmotic balance. A drop in CSF osmolarity from 300 mm to 280 mm can result in the influx of water into the brain cells due to osmosis, causing the brain to swell. This swelling could potentially lead to an increase in intracranial pressure and can result in a dangerous condition known as cerebral edema.

Normally, the CSF provides flotation to the brain, almost equivalent to the weight of the brain, ensuring that the brain is adequately suspended and protected within the skull. If the brain swells, this balance is disrupted, which can lead to an array of neurological symptoms including headaches, seizures, cognitive problems, and in severe cases, death.

It is important to note that the brain is particularly sensitive to osmotic changes given that it is made up of 80% water. The regulation of water flow between brain cells is critical, controlled by aquaporin channels. Adjustments in water content must be finely controlled to prevent neurological damage.