Exam Review Week 2 Flashcards
What is normal BP?
systolic: under 120; diastolic: under 80
What is prehypertension?
systolic: 120-139; diastolic: 80-89
What is Stage 1 hypertension?
systolic: 140-159; diastolic: 90-99
What is Stage 2 hypertension?
systolic: 160+; diastolic: 100+
What is the % of patients with hypertension? Pre-hypertension?
30% prehypertension, 30% hypertension
What can hypertension lead to?
increased afterload, leading to heart failure, MI and myocardial ischemia; arterial damage and atherosclerosis, leading to aortic aneurysm and dissection, stroke, retinopathy, and nephrosclerosis and renal failure
How do you calculate BP?
BP = CO x TPR
What factors regulate CO?
filling pressure, heart rate, force of contraction
How does sodium retention affect CO?
retaining sodium means retaining fluid - volume goes u,p, causing filling pressure to go up and CO to increase
How does the sympathetic system affect CO?
increases HR, increases force of contraction
How does the parasympathetic system affect CO?
decreases HR
What increases vasoconstriction?
norepinephrine, angiotensin; these both increase vascular resistance
What decreases vasoconstriction?
nitric oxide - this decreases vascular resistance
What are the 2 major systems that regulate blood pressure?
- autonomic nervous system; 2. Renin-Angiotensin-Aldosterone System
How does the autonomic nervous system affect blood pressure?
Regulated through the brain, sympathetic nerves, and adrenal glands; Increases cardiac output and peripheral resistance; Increases renin release from the kidneys; Feedback loop by baroreceptors
How does the Renin-Angiotensin-Aldosterone System affect blood pressure?
Regulated through the kidney, blood stream, and adrenal glands; Increases sodium (and water) retention and peripheral resistance (increases BP); Feedback loop in kidney
How do the carotid and aortic arch baroreceptors work?
responsive to stretch - BP goes up, vessel stretches, baroreceptors notice (activation increases); if BP goes down, then there is less activation up the nerves pretty easy to palpate can be manipulated by MD b/c it’s a mechanical receptor
What is the reflex to acute bleeding?
Response of the baroreceptor reflex to acute hemorrhage. The reflex is initiated by a decrease in mean arterial pressure (Pa). The compensatory responses attempt to increase Pa back to normal. These responses include decreased stretch on baroreceptors, decreased firing rate of carotid sinus, decreased parasympathetic activity to the heart (and increased HR), and increased sympathetic activity to the heart and blood vessels.
How does standing affect BP?
Standing leads to pooling of blood in veins, decrease in arterial pressure, baroreceptor reflex, increase in sympathetic outflow, and therefore increase in arterial pressure toward normal
What are the steps of the Renin-Angiotensin-Aldosterone System?
Prorenin is in the Juxtaglomerular cells, renin is formed, released into plasma, Angiotensinogen, Angiotensin I, and then Angiotensin-converting Enzyme (from lungs, kidney) causes production of Angiotensin II
What is Angiotensin II?
Stimulates the synthesis/secretion of aldosterone in the adrenal cortex, and Aldosterone acts on renal distal tubule and collecting duct – increases Na+ reabsorption (increases ECF volume and blood volume, increases CO); leads to vasoconstriction in arterioles (increases TPR); directly stimulates Na+ - H+ exchange in renal proximal tubule and increases reabsorption of Na+ and HCO3- (increases CO); Increases thirst and water intake; stimulates antidiuretic hormone (increases water reabsorption in collecting ducts - increases CO; vasoconstriction – increases TPR)
What stimulates renin secretion?
Renin secretion is stimulated by decreased renal perfusion (sensed by mechanoreceptors), decreased Na+, also sympathetic activation
What is the difference in timing between the major systems that regulate pressure?
autonomic nervous system reacts in seconds to minutes, while renin-angiotensin-aldosterone system takes hours to days (even weeks!)
What other mechanisms (beside the major systems) can regulate BP?
- Chemoreceptors in Carotid and Aortic Bodies
- Central chemoreceptors
- Antidiuretic hormone
- Cardiopulmonary (Low-Pressure) Baroreceptors