4. Insufficient cardiac output (relative to the body’s needs) is known as circul

Question

4. Insufficient cardiac output (relative to the body’s needs) is known as circulatory shock (usually, just “shock”). For example, a loss of blood can result in decreased stroke volume and cardiac output. You have learned numerous ways that the body might compensate for such a situation. However, if severe enough, shock can become an example of positive feedback in which the body responds to the low cardiac output (and therefore low BP) in a way that ends up making the problem worse.

(a) Explain how the response to shock could become a downward spiral. Although there are many aspects to this, focus on regulation of local blood flow patterns. (5 points)

(b) Describe the expected pH status of a person in shock, and explain your reasoning. Assuming the person is conscious, how would they compensate for this change in pH? (5 points)

Explanation / Answer

A) shock- circulation shock is a downward spiral - in circulatory failure the most common cause is cardiogenic shock in which myocardial ischemia is most common.

Due to cardiogenic shock their is fall in both systolic and diastolic function of heart due to ischemic necrosis of wall of the heart.

Due to systolic failure- decrease in cardiac outpout as well fall in stroke volume lead to Decrease in systemic perfusion and hypotension lead to decrease cornary artery perfusion.

Due to low systemic perfusion their is activation o the RENIN-ALDOSTERONE-ANGIOTENSIN SYSTEM. Which causes compensatory vasoconstriction and fluid retention lea to increased preload and afterload over ischemic heart. Due to angiotensin 2 and aldo sterone further rise in peripheral resistance and fluid accumulation in bodybody, lead to high venous return as - peeload and high TPR lead to high afterload will furthur increased myocardial o2demand and more ischemia develops.

Diastolic failure- lead to high LVEDP with pulmonary congestion which cause hypoxemia these conditions furthur aggravated ischemia.

Both these conditions cause further myocardial ischemia lead to progressive myocardial dysfunction and death.

B) due to tissue hypoxia their is production of lactic acidosis cause metabolic acidosis state in body, so ph of body get lowered., it can be compensated by respiratory alkalosis mainly as well by bicarbonate retention in the kidney tubule and more H+ ions excretion, due to respiratory alkalosis increased ventilation and co2is washout result in increased blood ph and that's maintained ph.

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