Ch 19 Flashcards
Tunica externa
collagen fibers protect and reinforce vessel and anchor, innervated
Tunica media
Smooth muscle and elastic fibers, vasoconstriction and vasodilation
Maintains bp and circulation
Tunica intima
Endothelium, lines lumen of all vessels, slick surface to reduce friction of blood
Vasocontriction
Lumen diameter decr. as smooth muscle contracts
Vasodilation
Lumen diameter incr. as smooth muscle relaxes
Elastic arteries
Near heart, thick walled, largest arteries, low resistance, pressure resevoirs
Muscular arteries
Deliver blood to specific organs, thickest tunica media, active in vasocontriction
Arterioles
smallest artery, control blood flow into capillary club
Capillary bed
microcirculation
Veins
Carry blood towards heart, think walls and large lumens, accommodate large blood volume
Vascular anastomoses
Alternative pathways for blood of usual is blocked.
Blood flow
Volume of blood flowing though a vessel/organ/circulation in a given period, in ml/min
Blood pressure
force per unit area exerted on a vessel by the contained blood in mm Hg
Resistance
Opposition to flow, and a measurement of the friction blood encounters in vessels.
Vasomotor center
Controls diameter of blood vessels
Baroreceptors
Decrease bp via vasodilation and decr. cardiac output
Chemoreceptors
raise bp via vacoconstriction
Hormones that raise bp
Epinephrine & norepinephrine
Angiotensin II
Antidiruetic hormone (ADH)
Aldosterone
hormones that lower bp
Atrial natriuretic peptide (ANP)
Autoregulation
local conditions regulate blood flow intrinsically by modifying diameter of arterioles feeding individual organs
Capillary exchange
Co2 and metabolic waste leave cells and diffuse into the capillary blood
Bulk flow
Fluid is forced out of capillaries through the clefts at te arterial end of the bed.
Important in determining relative fluid volume in bloodstream and interstitial space.
Pulmonary circulation
Heart to lungs to heart. Reoxygenates blood in lungs.
Systemic circulation
Routes blood though all body parts and back to the heart
Hepatic portal system
Carries nutrient rich blood from digestive organs to liver, where it is “treated” before being transported to rest of body.
Hepatocytes process nutrients and toxins
Phagocytes rid the blood of bacteria and foreign matter
