Free medical quiz
Hypertension and Heart Failure Quiz
Focused SBA-style practice, followed by the answer and explanation for every question.
- Free now
- 5 questions
- Full bank
- 14 questions
- Answers
- Explained
Free question
Try one with the answer
A question from this quiz. Answer it to see the explanation students get.
When central venous pressure is small enough to ignore, which equation approximately relates mean arterial pressure, cardiac output and total peripheral resistance?
- A Mean arterial pressure equals cardiac output multiplied by total peripheral resistance You picked ✓
- B Mean arterial pressure equals total peripheral resistance divided by cardiac output You picked ✕
- C Mean arterial pressure equals stroke volume multiplied by total peripheral resistance You picked ✕
- D Mean arterial pressure equals heart rate multiplied by stroke volume You picked ✕
- E Mean arterial pressure equals cardiac output plus total peripheral resistance You picked ✕
Correct!
Incorrect
The answer is A: Mean arterial pressure equals cardiac output multiplied by total peripheral resistance
Explanation
Why A is correct
See Blood Pressure Physiology. Option A is correct because arterial pressure is the product of flow and resistance, just as voltage equals current multiplied by resistance in Ohm's law. In the circulation, flow is the cardiac output (the volume of blood the heart pumps per minute) and resistance is the total peripheral resistance (the combined resistance of the systemic blood vessels, set mainly by the width of the small arteries called arterioles). The MSD Manual states that blood pressure equals cardiac output multiplied by total peripheral vascular resistance. Strictly, the pressure drop across the systemic circulation is mean arterial pressure minus central venous pressure, and the venous pressure is only a few mmHg, so it can be ignored for most purposes, which is why the question says approximately. Cardiac output itself equals heart rate multiplied by stroke volume (the volume of blood ejected per beat). This is why drugs and conditions that change heart rate, stroke volume or arteriolar width all alter blood pressure, and why hypertension can be driven by a high output, a high resistance or both. A memory aid: pressure is flow times resistance, and flow is rate times beat volume.
- Formula: blood pressure equals cardiac output multiplied by total peripheral resistance.
- Cardiac output: heart rate multiplied by stroke volume.
- Resistance: set mainly by the width of the arterioles.
Why the other options are incorrect
- B. Mean arterial pressure equals total peripheral resistance divided by cardiac output: Dividing resistance by flow reverses the relationship. Pressure rises when flow or resistance rises, so it must be their product and not a quotient. Your answer
- C. Mean arterial pressure equals stroke volume multiplied by total peripheral resistance: Stroke volume is the volume ejected in one beat, so it ignores heart rate. Only heart rate multiplied by stroke volume gives cardiac output, which is the flow term in the relationship. Your answer
- D. Mean arterial pressure equals heart rate multiplied by stroke volume: Heart rate multiplied by stroke volume gives cardiac output, the flow term. It does not include resistance, so it cannot give blood pressure by itself. Your answer
- E. Mean arterial pressure equals cardiac output plus total peripheral resistance: Adding flow and resistance is not meaningful because the two have different units. Pressure comes from flow multiplied by resistance, not from their sum. Your answer
With Premium, questions you miss become Revision Coach flashcards, scheduled for review.
Question preview
What you will practise
More questions from this set. Start the quiz to answer them and see each explanation.
-
1
A clinic blood pressure reading is the first step in assessing a person for hypertension. Which of the following clinic readings falls in the NICE range for stage 2 hypertension, before confirmation with ambulatory or home monitoring?
-
2
A 52-year-old woman is started on chlortalidone for newly diagnosed essential hypertension. Which of the following best describes the main site and mechanism of action of this drug?
Need wider coverage?
Explore every Pharmacology topic set, or build a tailored mixed session.
Browse subject quizzes