Control of arterial blood pressure Flashcards
Define blood pressure
The outward pressure exerted by the blood on the blood vessel walls
Define systolic arterial blood pressure
Pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contacts
Define diastolic arterial blood pressure
Pressure exerted by the blood on the walls of the aorta and systmic arteries when the heart relaxes
What are the ranges for clinical hypertension?
Blood pressure that exceeds 140/90mmHg
Equation to calculated MAP
- 3 equations
MAP= [(2xdiastolic) + systolic] / 3
MAP = diastolic + 1/3 pulse pressure
MAP = CO X SVR
What are baroreceptors?
Sensitive to changes in blood pressure
Where are the baroreceptors located
- aortic arch
- carotid sinus
What happens to the firing rate of baroreceptors if MAP decreases?
Rate of firing also decreases
______ is responsible for activting a high MAP
a) parasympathetic
b) sympathetic
b) sympathetic
What is postural hypotension?
Results from failure of baroreceptor response to gravitational shifts in blood, when moving from horizontal to vertical position
Natural way to control MAP
- altering the volumes of extracellular fluids
What 3 hormones are responsible for extracellular fluids?
- Renin- Angiotensin- Aldosterone - System (RAAS)
- Naturetic Peptides (NPs)
- Antidiuretic Hormones (ADH)
Explain the process and effect of Renin- Angiotensin - Aldosterone - System
- Renin formed by kidneys
- formation of angiotensin 1
- converted into angiotensin 2
- stimulates release of aldosterone
- causes vasoconstriction
- increases SVR
- increases thirst
Explain the process and effect of natriutetic peptides
- synthesised by the heart
- released in response to cardiac distension
- excretion of salt and water
- decreases blood pressure
- causes vasodilation
Explain the process and effect of antidiuretic hormone
- synthesised in the hypothalamus
- stimulated by reduction in extracellular fluid
- increases reabsorption of water
- increases blood pressure
Define pulse pressure?
- the difference between systolic and diastolic values
What is the normal range for pulse pressure?
- 30-50mmHg
What is the 1st korotkoff sound?
- systolic BP
What korotkoff sound represents diastolic BP?
- 5th korotkoff sound
Explain the Renin Angiotensin Aldestorne system in terms of regulating blood pressure
- Renin released from the kidneys
- combines with angiotensionogen
- forms angiotensin 1
- angiotesin 1 convereted by ACE to angiotensin 2
- angiotensin 2 causes vasoconstriction, increased thirst and increased ADH, and production of aldeosterone
- aldosterone causes water and salt retention
What does the Naturitc peptides do?
- decreases MAP
- Excretion of water and salts
What does Antidiuretic Hormone do?
- increases MAP
- Increases absorption of water and salts
What are the 3 hormones that influence extracellular fluid and thus the blood pressure?
- ADH
- RAAS
- NPs
What regulates systemic vasular resistance?
- arterial smooth muscle
