Question

you have chosen isotonic saline. predict the effects of your treatment on the following: blood sodium concentration initial value 114 (low) decrease no change increase brain matrix pressure 27 (high) neuron firing rate 4.5 (high) net free water movement initial value out of vessel into vessel in equilibrium out of vessel

Explanation:

Step1: Understand isotonic saline

Isotonic saline has the same osmolarity as blood plasma.

Step2: Analyze blood sodium concentration

Since isotonic saline doesn't change the overall sodium - water balance in a way that would directly affect sodium concentration, and the initial sodium is low due to other factors not related to the isotonic saline's osmotic effect, there will be no change.

Step3: Analyze brain matrix pressure

Isotonic saline does not cause a significant shift in fluid between compartments that would affect brain matrix pressure. High brain matrix pressure is likely due to other pathologies not related to the osmotic action of isotonic saline, so there is no change.

Step4: Analyze neuron firing rate

The isotonic nature of the saline does not directly alter the ion gradients or fluid environment in a way that would change the neuron firing rate. High firing rate is likely due to other neurological factors, so there is no change.

Step5: Analyze net free water movement

Isotonic saline does not create an osmotic gradient for net water movement between the vessel and the surrounding tissues. Since the initial net free water movement is out of the vessel due to other factors, isotonic saline will bring it to equilibrium.

Answer:

Blood Sodium Concentration: No Change
Brain Matrix Pressure: No Change
Neuron Firing Rate: No Change
Net Free Water Movement: In Equilibrium