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Blood vessels

QuestionAnswer
arteries carry blood away from heart; high pressure
veins carry blood back to heart; low pressure
capillaries connect smallest arteries to veins; intermediate pressure
tunica interna endothelium= simple squamous epithelium over a BASEMENT MEMBRANE & loose connective tissue, secretes VASODILATORS & VASO CONSTRICTORS, produce cell-adhesion molecules (for leukocytes)
tunica media smooth muscle, collagen, and elastic tissue; provides strength; VASOMOTION= smooth muscle changes blood vessel DIAMETER and affecting PRESSURE
tunica externa loose connective tissue that BINDS vessel to adjacent structures & anchors nerves, small vessels; VASA VASORUM= blood supply to large vessels!
elastic (conducting) arteries have internal and external ELASTIC LAMINA; recoil during diastole which lessens fluctuations in blood pressure, absorb PRESSURE DIFFERENCES
muscular (distributing) arteries distributes blood to SPECIFIC ORGANS, smooth muscle is THICK
arterioles control AMOUNT of blood to various organs, smooth muscle is THICK, minimal tunica externa
aneurysm a weak point in an artery or the heart wall; forms bulging sac that may burst; causes= atherosclerosis and hypertension
arterial sense organs= carotid sinuses, carotid bodies/ aortic bodies
baroreceoptors carotid sinuses; in walls of internal carotid artery; INCREASE blood pressure --> DECREASE heart rate & vasodilation
chemoreceptors carotid bodies/ aortic bodies; adjust respiratory rate to stabilize pH, CO2, O2; adjust heart rate to deliver blood to lungs
capillary layers only have the TUNICA INTIMA: (endothelium & basement membrane)
continuous capillaries Most common, Very NARROW intercellular clefts allow substances to diffuse in/out of capillary, Pericytes act as stem cells and may regulate diameter
fenestrated capillaries small holes pass through plasma membrane; important in organs engaging in absorption/ filtration
sinusoids LARGE GAPS between cells, Large fenestrae, Proteins and cells can pass through, Found in liver, bone marrow, lymphatic tissue
capillary beds network of capillaries, supplied by single metarteriole
profusion filling of capillary beds w/ blood
veins properties Great capacity for blood; thinner walls, flaccid, less muscular and elastic tissue ; collapse when empty, expand easily ; subjected to relatively low blood pressure (~10 mm Hg)
movement of blood in veins via.... skeletal muscle pump, respiratory pump, vasomotion, gravity
skeletal muscle pump localized pressure moves blood; one-way valves (ensure movement toward heart)
respiratory pump negative pressure in thoracic cavity when inhaling draws blood into heart
vasomotion smooth muscle contracts to increase VENOUS PRESSURE
veins: postcapillary venules porous & allow white blood cells to pass through; no smooth muscle
muscular venules receive blood from postcapillary venules; some muscle present
medium veins Travel with muscular arteries and drain individual muscles and organs
large veins Veins that lead into heart; Smooth muscle in all 3 tunics
most common circulatory route heart --> arteries --> arterioles --> capillaries --> venules --> veins
portal system blood flow through TWO consecutive capillary networks before returning to heart
anastomosis merging of 2 blood vessels
blood flow depends on.... depends on pressure gradients (PRESSURE DIFFERENCE) and is diminished by resistance (F=P/R)
blood pressure= the force that blood exerts against a vessel wall
pulse pressure difference between systolic and diastolic pressure; important measure of stress exerted on arteries
mean arterial pressure (MAP): average blood pressure that most influences risk level for edema, aneurysm, etc.
diastolic pressure minimum arterial BP taken during ventricular relaxation (diastole) between heart beats
systolic pressure peak arterial BP taken during ventricular contraction (ventricular systole)
hypertension high blood pressure; resting BP > 140/90. consequences= can weaken small arteries and cause aneurysms
hypotension chronic low resting BP; caused by blood loss, dehydration, anemia
3 factors influencing blood pressure cardiac output, peripheral resistance, blood volume
factors of peripheral output blood viscosity (albumin, RBC count, dehydration), vessel length & vessel radius (friction w/ blood vessel walls) longer vessels= more friction, smaller radius= more friction
vasomotion powerful way of altering blood pressure & flow; 1. local control 2. neural control 3.hormonal control
local control (3 factors) autoregulation, vasoactive chemicals, angiogenesis
autoregulation =ability of tissue to adjust its own blood supply via vasomotion or angiogenesis; “metabolic theory of autoregulation” describes that the accumulation of WASTES stimulates VASODILATION; ↓wastes → vasoconstriction
vasoactive chemicals substances SECRETED by platelets, endothelial cells, and perivascular tissue stimulate VASOMOTION
angiogenesis= growth of new blood vessels
neural control of blood flow Medullary ischemic reflex, chemoreceptors, baroreceptors
medullary ischemic reflex Medulla monitors its own O2 levels; When low, peripheral VASOCONSTRICTION and heart rate are INCREASED
chemoreceptors for blood pH, CO2; Coordinated effects with respiratory system ↑CO2 (hypercapnia)/↓pH (acidosis) stimulate vasoconstriction except in lungs
baroreceptors provide info on blood pressure; DECREASE blood pressure= VASOCONSTRICTION; INCREASE= VASODILATION
vasoactive hormones ANGIOTENSIN II= kidneys detect low BP; NE, E: baroreceptors (carotid sinus) respond to changes in BP via VESSEL RADIUS
hormones regulating water balance ANP: heart detects high pressure/volume; Aldosterone: adrenal cortex detects ↓Na +; ADH: hypothalamus detects ↑Na+; RESPOND VIA BLOOD VOLUME CHANGE
what moves across capillaries? water nutrients (O2, glucose, amino acids, lipids), wastes (CO2, creatin, urea, ammonia), ions/minerals, antibodies, hormones
fluid filtered out of ________ and reabsorbed at ___________ filtered out of ARTERIAL end of capillary & reabsorbed @ VENOUS end
net filtration pressure= NET HYDROSTATIC PRESSURE (drives fluid out of capillary) + NET OSMOTIC PRESSURE (drives fluid into capillary)
capillaries reabsorb _______% of fluid they filter 85%
remaining 15% reabsorbed by.... LYMPHATIC SYSTEM and returned to the blood
edema occurs when fluid filters into a tissue faster than it is absorbed; causes=increased capillary filtration, reduced capillary reabsorption, obstructed lymphatic drainage
circulatory shock 1. cardiogenic 2. Low Venous Return (LVR) Shock
low venous return shock Hypovolemic Low volume Obstructed venous return, Tumors, clots, etc., Venous pooling, Failure of blood to leave limbs
excess of CO2 in blood= hypercapnia
Created by: kpan