Blood pressure and its regulation
What blood pressure measures, what makes it vary (output and resistance), how the body regulates it within seconds (baroreflex) and within hours (kidney, renin-angiotensin-aldosterone system), and what happens when it rises or collapses.
- 43 cards
- 5 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- On the diagram
- The steps
- Scenarios
- Understand
A few cards from the deck
Systolic and diastolic pressure: what is it?
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The highest pressure in the arteries, during ejection, and the lowest, while the heart fills.
They are written 120/80 mmHg; hypertension starts at 140/90 in the clinic.
The renin-angiotensin-aldosterone system: which step comes after "Fall in kidney perfusion"?
- The kidney releases renin
- Angiotensinogen turned into angiotensin I
- Conversion to angiotensin II by the converting enzyme
- Vasoconstriction and aldosterone release
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The kidney releases renin
The kidney, sensing the fall in pressure, triggers a cascade that tightens vessels and increases blood volume.
Mean arterial pressure: what is it?
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The average pressure that perfuses the organs, roughly diastolic plus a third of the gap between systolic and diastolic.
It is closer to diastolic because diastole lasts longer.
An older person feels dizzy every time they stand up quickly. What is looked for?
- Hypertension
- Ventricular fibrillation
- Orthostatic hypotension
- Hyperkalaemia
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Orthostatic hypotension
Pressure is measured lying, then standing, at one and three minutes.