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75 Cards in this Set
- Front
- Back
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What are the delivery system of dynamic structures that begins and ends at the heart? |
Arteries; Capillaries; Veins |
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________ carry blood away from heart; mostly oxygenated except for __________ and _________ |
Arteries; pulmonary circulation and umbilical vessels of fetus |
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contact tissue cells; directly serve cellular needs |
Capillaries |
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________ carry blood towards the heart |
Vein |
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Defined as Central blood-containing space |
Lumen |
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Three wall layers in arteries andveins |
Tunica intima, tunica media, and tunica externa |
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What is the structure of the capillaries? |
–Endothelium with sparse basal lamina |
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Outer layer of connective tissue Collagen fibers |
Tunica externa (adventitia) |
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Middle layer of smooth muscle |
Tunica media |
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Innermost simple squamous endothelium Layerof elastin lumen |
Tunica interna |
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3 Types of Arteries |
Elastic Arteries Muscular (distributing) arteries Arterioles |
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•Largest type of artery •Closest to heart •Stretch during systole •Recoil during diastole •Aorta and its major branches |
Elastic Arteries |
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•deliver blood to body organs •Have thick tunica media •Active in vasoconstriction |
Muscular (Distributing) arteries |
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•Smallest arteries •Lead to capillary beds |
Arterioles |
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Where exchange between blood and cells takes place |
Capillaries |
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•Microscopic blood vessels •Walls of thin tunica intima, one cell thick •Size allows only a single RBC to pass at a time |
Capillaries |
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What part of the body does not have capillaries? |
cartilage, epithelia, cornea and lens of eye |
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What are the functions of capillaries? |
Exchange of gases, nutrients, wastes, hormones, etc., between blood and interstitial fluid |
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What are the 3 types of capillaries? |
1.Continuous capillaries 2.Fenestrated capillaries 3.Sinusoid capillaries (sinusoids) |
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Least permeable and most common capillary (e.g., skin, muscle). |
Continuous capillaries |
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Large pores increase permeability. Occurs in areas of active absorption or filtration (e.g., kidney, small intestine). |
Fenestrated Capillaries |
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Most permeable capillary Occurs in special locations(e.g., liver, bone marrow, spleen). Macrophages in lining to destroy bacteria |
Sinusoid capillaries |
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Interwoven arterioles and venules |
Capillary beds |
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metarteriole–thoroughfare channel connecting an arteriole directly with a postcapillary venule |
Vascular shunts |
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10 to 100 exchange vessels per capillary bed |
True Capillaries |
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_____________ regulate blood flow into true capillaries |
Precapillary sphincters |
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___________ is where exchange occurs |
Microcirculation |
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Fill in the Blank __________ to feed the capillaries __________ exchange with the tissues __________ to receive capillary blood |
Arterioles to feed the capillaries Capillaries exchange with the tissues Venules to receive capillary blood |
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Exchange in Capillaries due to: 3 things |
Diffusion Filtration Reabsorption |
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Water, ions, small molecules Large water soluble compounds Lipids Plasma proteins-sinusoids of the liver |
Diffusion |
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Removal of solutes due to hydrostatic pressure in vessels; in most capillaries, large solutes and proteins remains in the blood vessel |
Filtration |
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Result of osmosis -diffusion of water across a membrane toward solution with higher osmotic pressure (amount of solutes) |
Reabsorption |
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Exerted against the inner capillary wall. Promotes formation of tissue fluid. Net filtration pressure. |
hydrostatic pressure |
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Exerted by plasma proteins. Promotes fluid reabsorption into circulatory system. |
Colloid osmotic pressure
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Distribution of ECF (extracellular fluid) between plasma and interstitial compartments is in state of ____________. Balance between tissue fluid and blood plasma. |
dynamic equilibrium |
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Are formed when capillary beds unite Allow fluids and WBCs to pass from the bloodstream to tissues |
Venules |
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Formed when venules converge Blood pressure is lower than in arteries Called capacitance vessels (blood reservoirs); contain up to 65% of the blood supply |
veins |
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Veins are also called _____ contain up to _____% of the blood supply |
capacitance vessels (blood reservoirs); 65% |
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Veins have ____ blood pressure and _____ than arteries |
much lower; thinner walls |
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_______ offer little resistance |
Large-diameter lumens |
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__________ prevent backflow of blood Most abundant in veins of limbs |
Venous valves |
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__________: flattened veins with extremely thin walls (e.g., coronary sinus of the heart and dural sinuses of the brain) |
Venous sinuse |
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Defined as volume of blood flowing through vessel, organ, or entire circulation in given period |
Blood flow |
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Blood Flow: Fill in the blank Measured as ______ __________ for entire vascular system Relatively _______ when at rest _______ widely through individual organs, ______ |
Measured as ml/min Equivalent to cardiac output (CO) for entire vascular system Relatively constant when at rest Varies widely through individual organs, based on needs |
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Force per unit area exerted on wall of blood vessel by blood |
Blood Pressure |
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______________ provides driving force that keeps blood moving from higher to lower pressure areas |
Pressure gradient |
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Opposition to flow ( wall of blood vessels) Measure of the amount of friction blood encounters |
Resistance |
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Three important sources of resistance |
1. Blood viscosity The “stickiness” of the blood 2. Blood vessel length The longer the vessel, the greater the resistance encountered 3. Blood vessel diameter Varies inversely with the fourth power of vessel radius E.g., if the radius is doubled, the resistance is 1/16 or decreased |
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__________ are the major determinants of peripheral resistance |
Small-diameter arterioles |
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Pumping action of heart generates blood flow Pressure results when flow is opposed by resistance Steepest drop occurs in arterioles |
Systemic Blood Pressure |
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Systemic pressure: Fill in the blank Highest in ________ _______ throughout pathway 0 mm Hg in _______ |
Highest in aorta Declines throughout pathway 0 mm Hg in right atrium |
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What does the Arterial Blood Pressure reflect? |
Two Factors: 1. Elasticity (compliance or distensibility) 2. Volume of blood forced into them at any time |
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Pressure exerted in aorta during ventricular contraction Averages 120 mm Hg in normal adult |
Systolic Pressure |
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Lowest level of aortic pressure |
Diastolic |
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Different between systolic and diastolic pressure |
Pulse Pressure |
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pressure that propels blood to tissues |
Mean Arterial Pressure |
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MAP (Mean Arterial Pressure) = |
MAP = [(2xdiastolic pressure) + systolic pressure]/3 |
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Pulse pressure and MAP both _____ with increasing distance from heart |
decline |
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Capillary Blood Pressure: Fill in the Blank Ranges from ______ mm Hg _________ is desirable ____________, thin-walled capillaries _________ so low pressure forces filtrate into interstitial spaces |
Ranges from 17 to 35 mm Hg Low capillary pressure is desirable High BP would rupture fragile, thin-walled capillaries Most very permeable, so low pressure forces filtrate into interstitial spaces |
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Venous Blood Pressure: Fill in the Blank Changes _______ during cardiac cycle ______ pressure gradient; about _____ mm Hg Low pressure due to _______ |
Changes little during cardiac cycle Small pressure gradient; about 15 mm Hg Low pressure due to cumulative effects of peripheral resistance |
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contraction of skeletal muscles "milks" blood toward heart; valves prevent backflow |
Muscular pump |
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pressure changes during breathing move blood toward heart by squeezing abdominal veins as thoracic veins expand |
Respiratory pump |
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under sympathetic control pushes blood toward heart |
Venoconstriction |
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What does maintaining blood pressure require? 2 things |
Cooperation of heart, blood vessels, and kidneys Supervision by brain |
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What are the 3 main factors influencing blood pressure? |
Cardiac output (CO) Peripheral resistance (PR) Blood volume |
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Blood Pressure = |
Blood pressure = CO × PR (and CO depends on blood volume) |
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Cardiac Output = |
CO = SV × HR normal = 5.0-5.5 L/min |
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What counteracts fluctuations in blood pressure by altering peripheral resistance and CO? |
Short-term neural and hormonal controls |
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What counteracts fluctuations in blood pressure by altering blood volume |
Long-term renal regulation |
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Neural controls operate via reflex arcs that involve: |
Baroreceptors
Cardiovascular center of medulla Vasomotor fibers to heart and vascular smooth muscle Sometimes input from chemoreceptors and higher brain centers |
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Baroreceptors located in: 3 places |
Carotid sinuses Aortic arch Walls of large arteries of neck and thorax |
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Decrease in blood pressure due to what 3 things? |
Arteriolar vasodilation Ventilation Decreased cardiac output |
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Fill in the blank: Short term regulation via changes in ________ Long term regulation via changes in ________ |
Short term regulation via changes in peripheral resistance Long term regulation via changes in blood volume |
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Alters blood volume independently of hormones |
Direct Renal Mechanism |
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Fill in the Blank: Increased BP or blood volume causes ___________ Decreased BP or blood volume causes __________ |
Increased BP or blood volume causes elimination of more urine, thus reducing BP Decreased BP or blood volume causes kidneys to conserve water, and BP rises |
