In this problem, a person has a cardiac output of 5 L/min…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In this problem, a person has a cardiac output of 5 L/min. The resistance of the blood vessels is 18 mm Hg for each L/min. The blood pressure is the output times the resistance. ANF dilates the vessels and lowers the resistance by , or .
- What is the pressure after a fall of in the resistance?
- What is the pressure after a fall of ?
- What is the pressure after a fall of ?
Need a reminder? The key ideaShow
The atrial wall makes ANF, which dilates the blood vessels and lowers the blood pressure. The kidney makes erythropoietin, which stimulates the making of red blood cells. Gastrin acts on the gastric glands (HCl and pepsinogen), secretin on the exocrine pancreas (water and bicarbonate), CCK on the pancreas and gall bladder (enzymes and bile), and GIP inhibits the stomach. Blood pressure is the cardiac output times the resistance.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Output: L/min. Resistance: mm Hg for each L/min. The falls are assumed values.
Plan. New resistance, then pressure output resistance.
Step 1. . Resistance: . Pressure: mm Hg.
Step 2. . Resistance: . Pressure: mm Hg.
Step 3. . Resistance: . Pressure: mm Hg.
Answer: mm Hg; mm Hg; mm Hg.
Check. Without ANF the pressure is mm Hg, and every answer is lower.
Watch out. This is a simple model of the idea that wider vessels mean a lower pressure. A real person has many other controls.
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