Question

how did you save clark?
the following list is not in the correct order. the first two events are given to you as a starting point. drag and drop the remaining events to identify the sequence of events showing how hypertonic saline restored equilibrium and stopped the seizures in clarks brain.

1. seizures
2. administer hypertonic saline
3. drop here
4. drop here
5. drop here
6. drop here
7. drop here

net movement of free water into vessel
seizures stopped
decrease in neuron firing rate
decrease in matrix pressure
increase in blood sodium concentration

Explanation:

Step1: Hypertonic saline effect

When hypertonic saline is administered, it causes an increase in blood sodium concentration. This is because hypertonic solutions have a higher solute (in this case, sodium - related solutes in saline) concentration compared to the surrounding body fluids.
$$\text{Administer hypertonic saline}\to\text{Increase in blood sodium concentration}$$

Step2: Water movement

The increase in blood sodium concentration creates an osmotic gradient. Free water will move from an area of lower solute concentration (the brain tissue matrix, which had a relatively lower sodium - like solute concentration compared to the now - hypertonic blood) to an area of higher solute concentration (the blood vessels). So, there is a net movement of free water into the vessel.
$$\text{Increase in blood sodium concentration}\to\text{Net movement of free water into vessel}$$

Step3: Matrix pressure change

As water leaves the brain tissue matrix (due to the movement into the vessels), the matrix pressure (the pressure within the brain tissue matrix) decreases.
$$\text{Net movement of free water into vessel}\to\text{Decrease in matrix pressure}$$

Step4: Neuron firing rate

A decrease in matrix pressure affects the neurons. Neurons are sensitive to their micro - environment. A change in the physical environment (decrease in matrix pressure) leads to a decrease in neuron firing rate. Neurons fire (send electrical signals) based on various physical and chemical cues in their surroundings.
$$\text{Decrease in matrix pressure}\to\text{Decrease in neuron firing rate}$$

Step5: Seizure stop

Seizures are often associated with abnormal and excessive neuron firing. When the neuron firing rate decreases to a normal level (from the previous abnormal, excessive firing that was causing seizures), the seizures stop.
$$\text{Decrease in neuron firing rate}\to\text{Seizures stopped}$$

Answer:

1. Increase in blood sodium concentration
2. Net movement of free water into vessel
3. Decrease in matrix pressure
4. Decrease in neuron firing rate
5. Seizures stopped