Lecture 5 2/11/25 Flashcards
(49 cards)
What are the two main determinants of blood pressure?
-peripheral resistance
-cardiac output
Which factors help to regulate blood pressure?
-baroreceptor reflex
-renin-angiotensin system
-aldosterone
What are the characteristics of the baroreceptor reflex?
-rapid responder
-deals with minute-to-minute changes in BP
-responds to pressure or stretch
Where are the most important baroreceptors located?
-aortic arch
-carotid sinus
What are the characteristics of the renin-angiotensin-aldosterone system (RAAS)?
-long-term regulation
-can have systemic and local effects
When is RAAS activated as a compensatory measure?
in response to a reduction in blood pressure
What can lead to chronic activation of RAAS?
-endothelial dysfunction
-tissue fibrosis
-cellular remodeling
-proteinuria
What are the steps of RAAS?
-hypovolemia triggers the kidneys to produce renin
-renin converts angiotensinogen produced by the liver into angiotensin 1
-angiotensin 1 is converted into angiotensin 2 via ACE-converting enzyme
-angiotensin 2 triggers the adrenal glands to produce aldosterone
-angiotensin 2 also acts as a potent vasoconstrictor at the arteries
-the effects of angiotensin 2 at these sites improves blood volume and pressure
How does angiotensin 2 increase GFR?
angiotensin 2 leads to constriction of the efferent arteriole, which increases glomerular capillary pressure and increases GFR
What is the function of ACE-inhibitors?
to inhibit ACE-converting enzyme and prevent angiotensin 1 converting to angiotensin 2
What is the function of angiotensin receptor blockers?
to inhibit the action of angiotensin 2 on the adrenal glands and the arteries
What are the characteristics of aldosterone?
-mineralocorticoid produced in the zona glomerulosa of the adrenal gland
-stimulated for release by angiotensin 2 and hyperkalemia
What are the effects of aldosterone on the kidneys?
-act on the principal cells
-potassium excretion
-sodium retention
What are the characteristics of hypoadrenocorticism?
-deficiency in glucocorticoid and mineralocorticoid/aldosterone
-leads to increased K+
-leads to decreased Na+
How does hyperaldosteronism impact electrolytes?
-increased Na+
-decreased K+
What considerations must be kept in mind when measuring BP?
-breed
-temperament
-method
-operator skill
-interpatient variability
-conscious vs. anesthetized
-standardized protocol
What is the best setting for a blood pressure reading?
-acclimated to a quiet room
-with the owner
-no sedation
-comfortable restraint
What are the characteristics of BP cuff size?
-want the cuff width to be 30-40% of the circumference of the cuff site
-too narrow/loose overestimates BP
-too wide/tight underestimates BP
Which sites are commonly used when placing a BP cuff?
-limb
-tail base
Where should the cuff be in relation to the heart?
level with the heart base
What are the steps to follow when taking a BP measurement?
-ensure a calm, motionless patient
-discard first reading
-take 5 to 7 measurements and average the readings
What should be included in the record regarding BP measurement?
-cuff size and site
-animal position
-values obtained
-rationale for excluding any values
-final/average result
-interpretation
-person who completed measurements
What is the gold standard for BP measurement?
arterial catheterization, direct method
What are the indirect/non-invasive methods of BP measurement?
-doppler ultrasonic flow detector
-oscillometry