Blood Pressure Control and Hypertension Flashcards Preview

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Flashcards in Blood Pressure Control and Hypertension Deck (9)
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1
Q

How is BP controlled in the short-term?

A

relatively neural and usually due to the baroreflex

2
Q

What is the baroreflex?

A

The baroreflex is associated with BP homeostasis and is a form of negative feedback. It takes place in the arterial baroreceptors and the brainstem autonomic centres.

3
Q

What are the baroreceptors? Where are they situated?

A

They are situated in the carotid sinus (which is thin walled and highly innervated within the internal carotid artery) as well as the aortic arch. With a greater degree of stretch comes greater firing which responds very quickly. (within one cardiac cycle)

4
Q

What is the Brainstem Cardiovascular Control Centre?

A

This is situated in the medulla and has both pressor and depressor centres, operating via sympathetic and parasympathetic nerves.

5
Q

What is the baroreflex buffer and how is the baroreflex reset?

A

The baroreflex ‘buffer’ refers to the baroreflex’s ability to stabilise pressure and smooth out variations that can occur due to posture, eating, defecation and noise.

Resetting the baroreflex requires 1-2 days for the threshold for baroreflex firing to adjust/reset to new pressure levels.

6
Q

What are chemoreceptors?

A

These receptors respond to very low oxygen levels. They are situated in carotid and aortic bodies outside of the arteries and are stimulated at very low MAP (low flow; low oxygen; high carbon dioxide, low pH)

7
Q

Explain Correlating factors with respect to BP.

A

Sex & BP: Men have higher BP than Women (males: mean = 94; females: mean = 89)
Age & BP: blood pressure rises with age
Body size & BP: bigger body mass leads to a higher BP
Diurnal Variation: lower BP at night (20mmHg); less variability at night; less sympathetic activity at night
Seasonal Variation: Summer pressures are about 2mmHg lower than winter

8
Q

What is hypertension?

A

Hypertension is simply the upper end of the distribution (high BP). It is defined by an arbitrary and falling cut-off.

9
Q

Explain the population paradox surrounding High BP.

A

A population paradox can be seen in that in a population, more deaths occur in the larger number of people at moderate risk than in the small number of people at the highest risk.