Question

Suppose you suffer from hemorrhage and you lose 0.6 L of blood. Answer questions regarding the physiological systems that are affected and respond after the hemorrhage.

(a) Calculate the final osmolarity of extracellular fluid (ECF) and intracellular fluid (ICF). Information that you may need to answer this question is below. Show all your work. (worth 5 marks)

ECF volume = 15 L

ICF volume = 25 L

Initial osmolarity of ECF = 290 mOsM

Initial osmolarity of ICF = 290 mOsmM

Molecular weight of NaCl = 60 g/mol

(b) Provide a detailed description of how your cardiovascular and renal systems will respond when trying to achieve homeostasis after the hemorrhage. (worth 15 marks)

Answer 1

Haemorrhage is defined as external or internal loss of blood from tissues or organs due to any chronic pathology or trauma.

The physiological changes occuring in body during Haemorrhage are:

1. Cardiovascular Compensation and Hypovolumic state is attained. The hematocrit and the concentration of electrolytes will not get altered. Vasopressin release is triggered by baroreceptors sensing a loss of blood pressure resulting in drop of arterial and venous pressure. The heart rate increases and cardiac output remains in state of equilibrium even on decreased preload.

2. Transcapillary refill and Isovolemic Anaemia : The sympathetic response to haemorrhage results in a decrease in the diameter of the arterioles, and therefore a reduced pressure at the capillaries.

3. The interstitial fluid deficit is replaced by activation of the renin-angiotensin-aldosterone system. It results in sodium retention, and sodium is distributed into extracellular fluid. The concentration of extracellular sodium does not change very much with haemorrhage, and hence there is little osmotic pressure for water to move out of cells. There will be a sudden haemopoietic response to haemorrhage and the bone marrow replenish the lost erythrocytes by increasing the production and releasing immature reticulocyte into the circulation. The replacement of erythrocyte takes 60 to 120 days.