CVS physiology 4 Flashcards
Where are baroreceptors located?
Carotid sinus and aortic arch
Where does information from baroreceptors travel to?
Medullary cardiovascular centres
What nerves carry information from baroreceptors in carotid sinus to the brain?
Glossopharyngeal nerve
What is the valsalva manoeuvre?
Forced expiration against a closed glottis
What are the 5 stages of the valsalva manoeuvre?
- Increased thoracic pressure is transmitted through to aorta
- Increased thoracic pressure reduces the filling from veins
- Reduced MAP is detected by baroreceptors
- At the end of the manoeuvre, decreased in thoracic pressure is transmitted through to aorta
- Venous return is restored which increases SV
What effect does an increase in thoracic pressure have on mean arterial pressure, and why?
Increase in thoracic pressure causes decreased venous return, which decreases mean arterial pressure.
How is blood pressure regulated long term?
Controlling plasma volume via the kidneys
What 3 hormone systems are used to control plasma volume?
- Renin-angiotensin-aldosterone system
- Antidiuretic factor (ADH, vasopressin)
- Atrial natriuretic peptide and brain natriuretic peptide
Where is renin produced?
Juxtaglomerular cells of the kidney
What triggers renin production?
Activation of sympathetic nerves to the juxtaglomerular apparatus
What is the role of renin?
Converts angiotensinogen to angiotensin I, which then is converted by angiotensin converting enzyme to form angiotensin II
What is the role of angiotensin II?
- Stimulates release of aldosterone from the adrenal complex
- Increases release of ADH from pituitary
- Causes vasoconstriction
Where is antidiuretic hormone produced?
Synthesised in the hypothalamus and released for the posterior pituitary gland
Which triggers the release of antidiuretic hormone?
- Decrease in blood volume
- Increase in osmolarity of interstitial fluid
- Circulating angiotensin II
What is the role of antidiuretic hormone?
Increases the permeability of the collecting duct to water, therefore reduces diuresis and increases plasma volume.
Also causes vasoconstriction
What impact does antidiuretic hormone have on mean arterial pressure?
Causes increased MAP
Where is atrial natriuretic peptide (ANP) produced?
Myocardial cells in the atria
What is brain natriuretic peptide (BNP) produced?
Myocardial cells in the ventricle
What triggers the release of ANP and BNP?
Increased distension of atria and ventricles
What is the role of ANP and BNP?
- Increased Na+ excretion (natriuresis)
- Inhibits release of renin
- Acts on medullary CV centres to reduce MAP
What effect do ANP and BNP have on mean arterial pressure?
Causes decrease MAP
