Question

The stomach flu has been going around, and you have been infected. Your digestive tract is a mess. You are vomiting and have diarrhea.

1. Using the mass balance equation, explain how these conditions would lead to dehydration.
2. Using the concept of osmolarity and tonicity, explain how these conditions would affect water balance between your ICF and ECF.
3. Explain how and why the dehydration would affect blood volume and blood pressure.
4. Describe the hormonal regulatory mechanisms that would be implemented by the body to correct for the problems that have arisen due to the dehydration. Include all hormones that would be involved, the trigger for their release, their effectors, and the effector responses. Include how the effector responses would help to resolve the problem.
5. Despite your body’s best efforts, your dehydration has become severe and you end up in the emergency room at your local hospital. What would the medical staff do to address your severe dehydration as your body continues to work to rid itself of the flu virus?

Answer 1

Due to vomiting and diarrhea ; there is loss of water and electrolytes.This leads to dehydration.

The water loss from ICF in the form of diarrhea and vomiting leads to increased tonicity of ICF.So water flows from ECF to ICF so that their tonicities equalize.

Due to dehydration ; blood volume decreases.So venous return and hence cardiac output decrease.Since blood pressure is a product of cardiac output and total peripheral resistance ; blood pressure decreases.

The hormones secreted are--

1) ADH(Antidiuretic hormone)-- Increased blood osmolarity and decreased blood volume are the triggers.It acts on collecting tubules of kidney and increases water reabsorption.So blood volume increases.

2)Renin-angiotensin-aldosterone system-Decreased blood volume is the trigger.Aldosterone increases reabsorption of both sodium and water from the collecting duct.