control of blood flow test 2 Flashcards
explain the vasodilator theory of acute control
increase metabolism leads to decreased oxygen availability which leads to the formation of vasodilators
explain the oxygen (nutrient) lack theory of acute control
decreased oxygen concentration leads to blood vessel relaxation which leads to vasodilation
what leads to the long-term control of local blood flow
increase in sizes/numbers of vessels
define vasomotion
cyclical opening and closing of pre capillary sphincters
what is the active reaction to hyperemia
when tissue becomes active, rate of blood flow increases
what does rapid increase in arterial pressure do to blood flow
increases blood flow
explain the metabolic theory of blood flow autoregulation
increase in blood flow leads to too much oxygen or nutrients which washes out vasodilators
explain the myogenic theory of blood flow autoregulation
stretching of vessels lead to reactive vasculature constriction
what neurotransmitters are involved in vasoconstriction
norepinephrine, epinephrine, angiotensin II, vasopressin
what is the major function of vasopressin/ADH
to control body fluid volume
what is the function of angiotensin II
normally acts to increase total peripheral resistance
what neurotransmitters are involved in vasodilation
bradykinins and histamines
what does bradykinins do
causes both vasodilation and increased capillary permeability
what is histamine derived from
mast cells and basophils
what vessels does the sympathetic system not innervate
capillaries
what is the primary result of sympathetic regulation in blood flow
vasoconstriction
what is the vasoconstrictor area of the brain
anterolateral portions of upper medulla
what is the definition of vasomotor tone
partial state of contraction of blood vessels in the vasoconstrictor area of the brain
what is the vasodilator area of the brain
bilateral in the anterolateral portions of lower medulla
what is the sensory area of the vasomotor center
bilateral in tractus solitarius in posterolateral portion of medulla
what does the sensory area of the vasomotor center in the brian receive signals from
vagus and glossopharyngeal nerves
what are the higher nervous centers of the vasomotor center in the brain
reticular substance (RAS)
hypothalamus
cerebral cortex
what does the adrenal medulla secrete
epinephrine and norepinephrine
where are baroreceptors located
carotid sinuses and aortic sinus
what pressure are carotid sinuses stimulated at
greater than 60 mm Hg
what pressure are aortic sinuses stimulated at
greater than 30 mm Hg
what signals come from baroreceptors
inhibit vasoconstrictor center
excite vasodilator center
signals cause either increase or decrease in arterial pressure
primary function is to reduce the minute-by-minute variation in arterial pressure
where are chemoreceptors located
in carotid bodies in bifurcation of the common carotids and in aortic bodies
what are chemosensitive cells sensitive to
lack of oxygen, carbon dioxide excess, and hydrogen ion excess
what doe the signals from chemoreceptors pass through
Herring’s nerves and vagus nerves
what do chemoreceptors play an important role in
respiratory control
what does an increase in atrial stretch result in
reflex dilation of kidney afferent arterioles increase in heart rate signals to hypothalamus ANP decrease sodium reabsorption
define arterial pressure
cardiac output X total peripheral resistance
what are common characteristics of primary hypertension
increased cardiac output, sympathetic nerve activity, angiotensin II and aldosterone levels
impairment of renal-pressure natriuresis mechanism
inadequate secretion of salt and water
what are major factors of primary hypertension
weight gain and sedentary life style
what are renal causes of hypertension
chronic renal disease renal artery stenosis renin-producing tumors acute glomerulonephritis polycystic disease renal vasculitis
what are the endocrine causes of hypertension
cushing syndrome exogenous hormones pheochromocytoma acromegaly hypothyroidism hyperthyroidism pregnancy induced
what are the cardiovascular causes of hypertension
coarctation of the aorta polyarteritis nodosa increased intravascular volume rigidity of the aorta increased cardiac output
what are the neurologic causes of hypertension
psychogenic
increased intracranial pressure
sleep apnea
acute stress
what factors result in decreased peripheral resistance (vessel dilation) leading to decreased blood pressure
increased production of nitric oxide
increased release of prostacyclin and kinins
increase in ANP
decreased neural factors
what factors result in decreased cardiac output leading to decreased blood pressure
decreased blood volume, heart rate, contractility
what factors result in increased cardiac output leading to increased blood pressure
increased heart rate, contraction, and blood volume (aldosterone)
what factors result in increased peripheral resistance leading to increased blood pressure
increased angiotensin II, catecholamines, thromboxane, neural factors
what are the humoral vasoconstrictors
angiotensin II, catecholamines, endothelin
what are humoral vasodilators
kinins, prostaglandins, nitric oxide
what are the lethal effects of chronic hypertension
early heart failure and coronary artery disease
cerebral infarct
kidney failure
what is the major characteristic of artherosclerosis
presence of lesions within the intima of the vessel wall that protrude into the vessel lumen
what is C-reactive protein
CRP: major marker for inflammation (synthesized by liver, plays important role in opsonizing bacteria and activating complement)
what are characteristics of metabolic syndrome
obesity, insulin resistance, fasting hyperglycemia, increased lipid triglycerides, decreased HDL levels, hypertension
where do lipoproteins accumulate
intima
how are lipoproteins oxidized
by oxygen free radicals generated by macrophages or endothelial cells
what ingests oxidized LDL
macrophages which become foam cells
what does oxidized LDL stimulate the release of
growth factors, cytokines, and chemokines
what is oxidized LDL toxic to
endothelial cells and smooth muscle cells
what controls the short term control of arterial pressure
via sympathetic nervous system effects on total peripheral vascular resistance and capacitance; cardiac pumping ability)
what controls the long term control of arterial pressure
via multiple nervous and hormonal controls
via local controls in kidney that regulate: salt and water excretion
what are the primary determinants of the long-term arterial pressure level
degree of pressure shift of the renal output curve for water/salt
level of water/salt intake
define chronic hypertension
one;s mean arterial pressure is greater than the upper range of the accepted normal measure
what are the lethal effects of chronic hypertension
early heart failure coronary heart disease heart attack cerebral infarct destruction of areas of kidneys, leading to kidney failure, leading to uremia and eventually death
when does one kidney goldblatt hypertension occur
when one kidney is removed and remaining renal artery is constricted
