hypertension Flashcards
what is hypertension?
persistently elevated blood pressure (>140/90)
BP=
cardiac output (CO) x peripheral resistance (PR)
at rest, cardiac output is
STABLE but PR fluctuates for varying reasons
changes in PR occur from vasoconstriction and vasodilation
changes in cardiac output affect the body
systemically
systole=
PUMPING phase (around 120 mmHg)
diastole=
RESTING phase (around 80 mmHg)
4 control mechanisms of BP?
baroreceptors
vascular autoregulation
renin angiotensin-aldosterone system (RAAS)
fluid volume regulation
baroreceptors?
located centerly in aorta and carotid arteries
- detect changes in PRESSURE
- feed info to NS
- HOMEOSTATIC mechanisms engage to return pressure to original state
- located in TUNICA EXTERNA/ADVENTITA
- SENSORY NEURON excited by stretch of vessel—> AP—> CNS—> stimulation of vascular smooth muscle—> constrict or dilate—> alter PR—>alter BP
what is vascular autoregulation?
blood vessels constrict and dilate in response to many changes in the body (like pH, pO2)
what is the renin-angiotensin-alodsterone system (RAAS)
homeostatic mechanism triggered by DECREASED BP
it INCREASES THE BP to NORMAL RANGE
point form explain RAAS
-juxtaglomerular cells (kidneys) release RENIN, liver releases -
angiotensinogen —> angiotensin
-angiotensin I circulates until ACE is made by pulmonary capillaries
-ACE converts angiotensin I- II
-angiotensin II: stimulates thirst,constricts efferent arteriole to increase pressure, stimulates release of: aldosterone (from adrenal cortex), antidiuretic hormone (from posterior pituitary gland) BOTH promote H20 and Na retention—> INCREASE BP
what is fluid volume regulation?
kidney: excretes and retains fluid to maintain BV and BP
- OPERATES together with RAAS
- RAAS only occurs when there is DECREASED BP
when is BP highest?
in the morning! BP varies on circadian rhythm
when is BP lowest?
between 2 and 5am
mild htn?
140-159/ 90-99
moderate htn?
160-179/100-109
severe htn?
> 180/>110
what is primary hypertension?
> 140/90, idiopathic (unknown cause)
- 1 or 4 control mechanisms is defective
- may be multifactoral
- most cases
what is systolic hypertension?
systolic >140, diastolic remains normal, less than 90
occurs mostly after age 50
peripheral resistance in vessels increases d/t some degree of atherosclerostic change, change in elasticity of vessels
white coat hypertension?
CLINICAL setting hypertension
malignant hypertension?
ACUTE EMERG, diastolic exceeds 120
gestational hypertension?
during pregnancy
most women return to normal after
what is secondary hypertension?
not second phase of primary, develops because of underlying problem
-etiology is identifiable, usually due to renal disease
kidneys receive blood to filter and perfuse renal tissue
-significant part of CO goes to kidney, if excretion/reabsorption not balanced, BP affected
-decreased renal perfusion—> RAAS activated
what is renovascular hypertension?
a FORM of secondary
-increased BP caused by kidneys responding to narrowed/blocked arteries supplying kidneys
