Physiology Hypertension Flashcards
What does AMA recommend diagnosis of hypertienion is systolic or diastolic pressures were meausred to greater than….
140/90
How many Americans are hypertensive?
50 million
What is the optimal/NOrmal BP according to JNC 7
What is BP that is considered to be hypertenstive
140/90
What is Secondary Hypertension
Patents in whom a cause can be determined
What is primary hypertension
When a cause cannot be determined
we can essentially have no idea what’s causing it
What are some examples of secondary Hypertension (5)
Pheochromocytoma
Renal artery Constirction
Primary hyperaldosteronism (Conn’s syndrome)
Aortic Coarctation
Pehochromocytoma- what is it?
Tx?
Non-malignant tumor of chromaffin tissue which produces and releases catechoalmines
Tx: cut it out when possible
Renal artery constriction
Diagnosed by renal arteriogram
Reduces renal artery pressure and increases renin relase
Tx: Resect or dialte the constrction
Pirmary hyperalodsteronisn (Conn’s Syndrome)
excess productino f the mineralcorticoid causes retention of salt and water
Aortic Coarctation
produces upper body hypertension with lower body being normotenxive
Rx: Surgical Correction
What are risk factors for Essential Hypertension (95-99% of people)
(6)
- GEnetic
- Race
- Aging
- Salt Intake
- Obesity
- Psychological Stress
Race as a factor for hypertentions
African Americans vs whites
Chinese peple vs Chinese Americans
African Americans have 2-3x greater risk
Yet, not tentire
Chinese peopel have low insidence of hypertension, while Chinese Americans suffer the same high incidence as teh American national average
Aging. Wha tis risk of having hypertension if 55-65 year olds live up to be 80
90%
How does increasein BP with age affect systolic and diastolic presures
Systolic pressures continously increase with age
Diastolic pressure rises with age until late 50s then actually declines!
This means Pulse Pressure increases with age
What diseases does Hypertensino put you at risk for? (4)
Coronary disease
Stroke
Peripheral Artery Disease
Cardiac Failure
What is the minimum daily intake of sodium of “average American”
10-15
while minimum dialy intake of sodium is about 0.5 gm/day
Equation for CHange in Pressure
Change in Pressure = Flow x Resistance
Arterial P could be increased by either incrase in CO or TPR
How does CO elevate? What becomes more sensitive
Increase in cardiac puping secondary to increased beta adrenoreceptor sensitivity
no evidence that cardiac sensitiivyt is increased in chronic hypertensino, but increased beta 1 adrenoceptor numbers can be seen durign onset of hypertension
How else could CO be incrased
by increased Venous return via a preload effect
How does positive fluid balance affect CO
Positive fluid balance (input-output > 0) could produce retention of fluid, overinflation of vascular system and increased venous return
What does positive fluid balance imply
there must be inappropriate renal functioning to retain fluid in spite of elevated arterial pressure
ECF and plasma volumes of chronic hypertensive patients
generally within the nomral range
however, proponesents argue that hypertension could be intitaitoed by sustaned increase in BV of as alittle as 5% change that is too small to be meausred
what are two ways of periphearl resistance changing
Intrinsic arteriolar changes (arteriol narrowing)
Extrinsic
Intrinsic arteriolar changes
Arteriole media is thickened in hypertensive patients and
encroaches on the lumen,
tehreby reducing its diamter and increaseing its resistance
This ia SEONCDARY of high pressure and not the cause of hypertension, but may aid in progression and maintenance of the probelm
Vascular sooth uscles of muslce of hypertenisve peopel
hypersenstive to wide variety of agonsists
these changes occur before hypertensino, and perist in vacular beds of hypertenisve indicual which hve een protected agaisnt high pressure
Hypersensitivey is NOT a seconary effect, and may result in increased resistance to flow
Extrinsic influences on arteries
Even if peripheral vascuularture is normal in sturcture and funciton it may be abnormally constricted by increased levels of stimulation, eitehr neural or humoral
A tthis point we have moved teh intiating event away from teh vasculature to other areas
What is nerual influence of arteries and resistance
presence f elevated sympathetic nerve activity in hypertenstive rat have been well esatlbished
BaroR may laterd in hpertenives
What CNS areas are improtant for CV regulation (3)
- Nucleus solitarius- major synapse point for BaroR input
- Hypothalamus- has major effect on thurs, ADH, fluid balnace, temp regulation
- Cerebral cortex- has multiple connectiosn with the hypothalamus and thus NTS
What is teh CNS transmitter that is related to BP control
NE
Alternation in NE levels, alpha 1 adrenoceptor number and NE turnover are all seen in vairous CNS areas of expereimentally hypertenstive animals
What aother HUMORAL influences have been nomianted a role in hypertension
Renin-angiotesin sstem- most popular humoral system
- Ang II has a direct constirctor effect on vascular SM
- Angi II and Ang III situalte relaese of aldosterone –> increase BV by its renal effects
- Ang II has effects in hypothalamus and other CNS areas that affect thirs, ADH and symp nerve activity
How mnay hyeprtensive pateints have elevated renin
only 1/3 hypertensive patients
1/3 are normal
1/3 have nomral renin levels
What are other humor agents in hypertension
Bardykinin
PG
Natriuretic homrone
Antihypertensive nueutral renal lipid
What is the ajor treatmetn probem
patient complieance!
What are CO changes
Sympathetic stimulation
Beta 1 hypersensitivity
Increased vascular volume, Preload
What are periphearl resistance changes
Arteriole changes: hypersensitivity, wall thickening
Elevated sympathetic stimualtion SH Rat
Humoral stimulation
Renin-angio
Mosaic theory
Hypertenstive Treatmetn
Lifestyle Modification
Drugs
What kind of dugs
Diurectics Beta blockers Ace inhibitors A2 inhibitors Ca ch blockers alpha 1 blockers central alpah 2 blockers direct vasodilators
