A question from Kaplan's MCAT Biology Review asks:
In bacterial sepsis (overwhelming bloodstream infection), a number of capillary beds throughout the body open simultaneously. What effect would this have on the blood pressure? Besides the risk of infection, why might sepsis be dangerous for the heart?
The answer is:
Opening up more capillary beds (which are in parallel) will decrease the overall resistance of the circuit. The cardiac output will therefore increase in an attempt to maintain constant blood pressure. This is a risk to the heart because the increased demand on the heart can eventually tire it, leading to a heart attack or a precipitous drop in blood pressure.
I had always viewed blood pressure as a means to achieve appropriate blood flow, and a system with lower resistance would simply operate with lower pressure (via Ohm's Law). However, the answer implies that maintaining normal blood pressure is a goal in itself, such that the body would naturally raise cardiac output to dangerous levels in order to maintain it.
Can someone help explain:
Does blood pressure play a role in blood circulation that makes it more important than just a means towards appropriate cardiac output?
What are health consequences of abnormal blood pressure unrelated to cardiac output from a biochemical perspective? If I search for "abnormal blood pressure" I'll get broad symptoms like "dizziness" that don't explain its effect on different tissues that cause the symptoms.