Exam 3: Lecture 11 Flashcards
Describe long-term control of localized tissue regulation
Increases in sizes/numbers of vessels
Occurs over a period of days, weeks, or months
Describe acute control of localized tissue regulation
Rapid changes in local vasodilation/constriction
Occurs in seconds to minutes
What is vasomotion
Cyclical opening and closing of precapillary sphincters
What is autoregulation
Tissues control how much blood they get/need
Blood flow returns to normal within minutes even with elevated pressure
Ranges from 75-175 mmHg
What is the “Metabolic Theory of Autoregulation?”
Increase in blood flow->too much oxygen/nutrients->washes out vasodilators
What is they “Myogenic Theory of Autoregulation?”
Stretching of vessels->reactive vasculature constriction
What is the role of NO in vasodilation/vasoconstriction?
Damaged cells block production of NO which inhibits vasodilation, creating vasoconstriction
What is humoral circulation control?
What’s in the blood that can control circulation
What components of circulation control vasoconstriction?
Norepinephrine
Epinephrine
Angiotensin II
Vasopressin
What components of circulation control vasodilation?
Bradykinins
Histamine
T/F: The sympathetic nervous system innervates all vessels except capillaries which primarily results in vasodilation.
False, it primarily results in vasoconstriction
What part of the brain is the “Vasoconstriction area of the brain?”
Anterolateral portions of upper medulla
What are vasoconstrictor tones?
Continual firing of vasoconstriction area of brain
What are vasomotor tones?
Partial state of contraction of blood vessels due to vasoconstriction area of brain
Where in the brain is the “Vasodilation area of the brain?”
Bilateral in the anterolateral portions of lower medulla
How does the vasodilation area of the brain function?
It causes vasodilation by inhibiting vasoconstriction at vasoconstriction are of brain in upper medulla
What does the adrenal medulla secrete?
Epinephrine
Norepinephrine
Neural rapid control of arterial pressure is simultaneously caused by…
Constriction of most systemic arteries (increases peripheral resistance)
Constriction of veins
Increased HR
T/F: The simultaneous changes that control neural rapid arterial pressure all increase blood pressure.
True
What do baroreceptors do?
Sense pressure changes
Stimulated by low arterial pressure
Carotid sinus stimulated by pressure <30 mmHg
What are the 4 main functions of baroreceptors?
1) Inhibit vasoconstriction center
2) Excited vasodilator center
3) Cause either increase or decrease in arterial pressure
4) Reduce minute-by-minute variation in arterial pressure
What is the effective range of baroreceptors?
~60-110 mmHg
Describe chemoreceptors
Located in bifurcation of common carotids/aortic bodies
Sensitive to lack of O2, CO2, & H+ ion excess
Plays important role in respiratory control
What are atrial reflexes?
Low pressure receptors located in atria and pulmonary arteries that play important role in minimizing arterial pressure changes in response to changes in blood volume
An increase in atrial stretch reflex results in…
Reflex dilation of kidney afferent arterioles
Increase in HR
Signal hypothalamus to decrease ADH
Atrial natriuretic peptide (ANP)->Kidneys->GFR or Na+ reabsorption
What is the equation for atrial pressure?
Atrial pressure = Cardiac output x total peripheral resistance
What are the 4 major causes of hypertension?
Renal causes
Endocrine causes
Cardiovascular causes
Neurologic causes
What is atherosclerosis?
Type of arterioslcerosis
Characterized by lesions within tunica intima that protrude into lumen
What are non-modifiable risk factors associated with atherosclerosis?
Age
Gender
Genetics
What are modifiable risk factors associated with atherosclerosis?
Hyperlipidemia (esp. hypercholesterolemia)
Hypertension
Cigarette smoking
Diabetes
Name 6 other factors contributing to atherosclerosis.
Inflammation Hyperhomocystinemia Metabolic syndrome Lipoprotein (a) Factors affecting hemostasis Life style
What are the stages of atherosclerosis formation due to accumulation of lipoproteins?
1) Accumulation in intima & oxidized by O2 free radicals
2) Oxidized LDL ingested by macrophages which become foam cells
3) Oxidized LDL stimulate release of growth factors, cytokines, & chemokines
4) Oxidized LDL is toxic to endothelial & smooth muscle cells
What are the stages of atherosclerosis formation due to monocyte adhesion to endothelium?
1) Monocytes & T-cells bind to endothelium via VCAM-1
2) Monocytes become macrophages and engulf lipoproteins
3) T-cells stimulate chronic inflammatory response
4) Activated leukocytes & endothelial cells release growth factors that promote smooth muscle cell proliferation
What is a “mature atheroma?”
Cap of smooth muscle cells, macrophages, foam cells, & other extracellular components overlying a necrotic center composed of cell debris, cholesterol, foam cells, & Ca++
What is the process of atherosclerosis development?
Earliest lesions are fatty streaks Plaques impinge on lumen of artery (appear white/yellow) Plaques progressively enlarge Plaques often undergo calcification Plaques may rupture, ulcerate, or erode
What are the most common arterial sites for atherosclerosis?
Lower abdominal aorta Coronary arteries Popliteal arteries Internal carotid arteries Circle of Willis
How is short-term arterial pressure controlled?
Via SNS on total peripheral vascular resistance and capacitance (cardiac pumping ability)
How is long-term arterial pressure controlled?
Via multiple nervous & hormonal controls
Via local control in kidneys that regulate salt/water excretion
What are the primary determinants of long-term arterial pressure level?
Degree of pressure shift of renal output curve for water/salt
Level of water/salt intake
Define chronic hypertension
One’s mean arterial pressure is grater than upper range of accepted normal measure
What is the normal measure of BP?
90 mmHg
Ranging from 70-110
What is the hypertensive measure of BP?
110 mmHg
Ranging from 90-135
What is considered severe hypertensive measure of BP?
150-170 mmHg
Ranging from 130-220
What are 5 causes of lethal effects of chronic hypertension?
1) Early heart failure
2) Coronary heart disease
3) Heart attack
4) Cerebral infarct
5) Destruction of areas of kidneys
List 5 characteristics of primary hypertension
1) Increased cardiac output
2) Increased SNS activity
3) Increase in angiotensin II & aldosterone levels
4) Impairment of renal-pressure natriuresis mechanism
5) Inadequate secretion of salt/water
T/F: Primary hypertension accounts for 90-95% of hypertension and has no known origin.
True
What is secondary hypertension?
Hypertension caused by something else
EX: Renal artery constriction, Preeclampsia, Neurogenic hypertension, Genetic causes
