Control of blood pressure Flashcards
Why is the mean arterial pressure so important?
The driving force pushing blood through circulation
What could an MAP that is too low lead to?
Syncope (fainting)
What are the 2 sets of the baroreceptors called?
Aortic arch
Carotid sinus
What nerve do the carotid sinus baroreceptors use?
Glossopharyngeal nerve
What nerve do the aortic arch baroreceptors use?
Vagus nerve
Where do both sets of baroreceptors lead to?
The medullary cardiovascular centres
What do the medullary cardiovascular centres interpret?
Whether the baroreceptors are firing too low or too high
What do the parasympathetic fibres do the heart when controlled by the cardiovascular medullary centres?
Decrease HR
What do the sympathetic fibres do to the heart?
Activate beta-1 receptors
Increase heart rate
Increase contractility
Constrict smooth muscle in vessels
What are the other inputs to the cardiovascular medullary centres other than the baroreceptors?
Cardiopulmonary baroreceptors
Central chemoreceptors
Muscle chemoreceptors
Joint receptors
When is the baroreflex used the most?
During posture
What happens during standing posture?
Hydrostatic pressure increases
Decreased baroreceptor firing rate
Engages sympathetic nerves
What 3 hormone systems mediate the long term control of BP?
Renin-angiotensin-aldosterone system
Antidiuretic factor
Atrial natriuretic peptide
If collecting duct permeability increases, what happens to water reabsorption rate?
It increases
Where is renin produced?`
Juxtaglomerular of the kidney
Which types of nerve activate the production of renin?
Sympathetic nerves
What are the 3 main causes of renin release?
Reduced delivery of sodium and chloride ions
Decreased distension
Sympathetic innervation
What is renin used to do?
Convert angiotensin (inactive) into angiotensin I
What does angiotensin II stimulate?
The release of aldosterone from the adrenal cortex
What does aldosterone do?
Increases Na+ reabsorption
What is ADH release triggered by?
Decreased blood volume
Increase in osmolarity of ISF
Circulating angiotensin II
How does ADH work?
Increases permeability of collecting duct, increases plasma volume
Causes vasoconstriction
Where is ANP produced?
Myocardial cells of the atria
What is ANP triggered by?
Increased distension of atrium
How does ANP work?
Increases Na+ excretion
Inhibits release of renin
Acts on medullary CV centres to decrease MAP
