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125 Cards in this Set
- Front
- Back
3 major types of blood vessels |
1) Arteries 2) Veins 3) Capillaries |
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Define blood vessels |
Delivery system of dynamic structures that begins and ends at the heart |
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Arteries carry blood ____ the heart |
away from |
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Arteries carry ____ blood is the systemic system and _____ blood in the pulmonary system and umbilical vessels of fetus |
1) oxygenated 2) Oxygen poor |
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Veins carry blood ____ the heart |
towards |
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Only ____ have intimate contact with tissue cells and directly serve cellular needs |
capillaries |
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Exchange between blood and tissue cells occurs through ___ |
gossamer-thin capillary walls |
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Three layers of blood vessels walls |
1) Tunica intima 2) Tunica media 3) Tunica externa |
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Define lumen |
central blood-containing space |
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The ____ has intimate contact with the blood lumen |
Tunica Intima |
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Tunica intima contains ___ that lines the ___ of all vessels |
1) endothelium 2) lumen |
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Purpose of the endothelium of tunica intima |
Creates a slick surface that minimizes friction as blood moves through lumen |
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Tunica Media is mostly ___ and ___ |
1) Smooth muscle 2) sheets of elastin |
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The activity of smooth muscle cell in ___ is regulated by ____ of the autonomic nervous system. This controls _____ and _____ of vessels. |
1) tunica media 2) vasomotor nerve fibers 3) Vasconstriction 4) Vasodilation |
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Tunica externa is also called ___ |
tunica adventitia |
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Tunica externa is composed largely of ___ that ___ and ___ the vessel. |
1) collagen fibers 2) protect 3) anchor |
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In larger vessels, the tunica externa contains ____ which _____ |
1) Vasa vasorum 2) nourish the more external tissues of the blood vessel wall |
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3 types of arteries |
1) Elastic 2) Muscular 3) Arterioles |
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Define elastic arteries |
Large, thick-walled arteries with elastin in all three tunics |
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Arteries that are elastic arteries |
aorta and its major branches |
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___ arteries are the largest in diameter |
Elastic |
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Large ___ of elastic arteries offers ___ |
1) Lumen 2) low resistance |
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____ act as pressure reservoirs that ____ and ___ as the heart ejects blood |
1) Elastic arteries 2) expand 3) recoil |
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_____ are relatively inactive in vasoconstriction |
Elastic arteries |
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Elastic arteries allow blood to |
flow fairly continuously rather than starting and stopping with the pulse of the heartbeat |
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Elastic arteries are also called |
conducting arteries |
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Muscular arteries are also called |
distributing arteries |
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Define muscular arteries |
Distal to the elastic arteries and deliver blood to body organs |
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____ arteries account for most of the named arteries |
Muscular |
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___ have the thickest tunica media which contains more ____ and less ____ |
1) Muscular 2) smooth muscle 3) elastin |
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____ arteries are more active in vasoconstriction/vasodilation |
Muscular |
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Define arterioles |
Smallest arteries |
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Large arterioles have _____ |
all three tunics |
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Small arterioles lead _____ and are little more than ____ |
1) into capillary beds 2) a single layer of smooth muscle around endothelial lining |
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Arterioles controls flow into ____ via ____ and ___ |
1) capillary beds 2) vasoconstriction 3) vasodilation |
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Define capillaries |
Smallest blood vessels in the body |
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Walls of capillaries consist of |
just a thin tunica intima |
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The size of the capillary allow |
RBCs to pass one at a time |
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Capillaries exist in all tissues except |
1) Cartilage 2) Epithelia 3) Cornea and lens of eye |
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Function of capillaries |
Exchange of materials such as gases, nutrients, hormones, and wastes |
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Three structural types of capillaries |
1) Continous 2) Fenestrated 3) Sinusoidal (sinusoids) |
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____ capillaries are most common and exist in the skin and muscles |
Continous |
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_____ are connected by tight junctions to create uninterrupted lining in continuous capillaries |
Endothelial cells |
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Define Intercellular clefts |
Gaps of unjoined membrane in tight junctions of continuous capillaries that allow passage of fluid and solutes. |
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Brain capillary tight junctions are ___ and create the ___ |
1) complete 2) blood brain barrier |
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Fenestrated capillaries contain ___ in their endothelial cells |
fenestrations (oval pores) |
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____ capillaries are more permeable to fluids and solutes |
Fenestrated |
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Function of fenestrated capillaries and are found in ___ |
1)Function in absorption or filtrate formation 2) Kidneys, endocrine organs, and small intestines |
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Define Sinusoids |
Highly modified, leaky capillaries found in the liver, adrenal medulla, bone marrow, and spleen. |
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_____ have large, irregular lumens and are usually ___ |
1) Sinusoids 2) fenestrated |
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Endothelial cells of ___ have fewer ____, larger ___ and larger ____ |
1) Sinusoids 2) tight junctions 3) lumens 4) intercellular clefts |
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Sinusoids allow ___ |
large molecules and blood cels to pass between blood and surrounding tissue |
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Define capillary beds |
Interwoven networks of capillaries form the microcirculation between arterioles and venules |
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Veins are called ____ and ___ because they can hold up to ____ of the body's blood supply at any time |
1) Capacitance vessels 2) blood reservoirs 3) 65% |
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Define blood pressure |
Force per unit area exerted on the wall of a blod vessel by the blood |
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Blood pressure is expressed in |
mmHg |
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The ___ provides the driving force that keeps ____ |
1) pressure gradient 2) blood moving from higher to lower pressure areas |
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Define resistance in terms of blood pressure |
Opposition to flow and is a measure of the amount of friction blood encounters as it passes through vessels |
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Resistance is called ____ because ____ |
1) peripheral resistance 2) most friction is encountered in the systemic (peripheral) circulation |
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Three sources of resistance |
1) Blood viscosity (remains relatively constant) 2) Total blood vessel length (remains relatively constant) 3) Blood vessel diameter |
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Define blood viscosity |
The stickiness of blood due to formed elements and plasma proteins |
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Relationship between blood vessel length and resistance |
The longer the vessel the more resistance |
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Resistance varies inversely with the ___ |
fourth power of vessel radius |
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If the radius of a vessel doubles the resistance drops to ___ of its original value |
1/16th |
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____ are the major determinants of peripheral resistance |
Small-diameter arterioles |
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____ is directly proportional to the blood pressure gradient |
Blood flow |
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If blood pressure increases, blood flow ___ |
speeds up |
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Blood flow is inversely proportional to ____ |
peripheral resistance |
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If peripheral resistance increases, blood flow ___ |
decreases |
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Peripheral resistance is more important in ____ because it is _____ |
1) influencing blood flow 2) because it is easily changed by altering blood vessel diameter |
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As ___ decreases, velocity increases |
cross sectional area |
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____ of blood flow is fastest in the ____ and slowest in ___ |
1) Velocity 2) large arteries 3) capillaries |
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Systemic pressure if highest in the ____ and declines throughout the pathway to finally reach ___ |
1) aorta 2) 0 mm hg in the right atrium |
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The steepest drop in systemic pressure occurs in the ___ which offer the ___ |
1) arterioles 2) greatest resistance to blood flow |
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Arterial blood pressure reflects two factors ___ and ____ |
1) How much the elastic arteries close to the heart can stretch (compliance or distensibility) 2) Volume of blood forced into them at any time |
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Blood pressure is ____ near the heart |
Pulsatile - it rises and falls |
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Defie Systolic pressure |
pressure exerted during the ventricular contraction |
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Define Diastolic pressure |
lowest level of arterial pressure |
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Define Pulse pressure |
The difference between systolic and diastolic pressure |
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Capillary blood pressure ranges from ___ to ___ |
15 to 35 |
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Venous Blood Pressure has a ___ pressure gradient |
small, about 15 mm Hg |
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The low pressure of the venous system reflects the ____ |
cumulative effects of peripheral resistance |
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Three factors important for venous return |
1) Muscular pump 2) Respiratory Pump 3) Sympathetic venoconstriction |
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Define Respiratory pump |
The pressure changes created during breathing that move blood toward the heart by squeezing abdominal veins as thoracic veins expand |
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Define muscular pump |
Contraction of skeletal muscles "milk" blood toward the heart and valves prevent backflow |
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Define Sympathetic venoconstriction |
As the layer of smoother muscle around the veins contricts under sympathetic control, venous volume is reduced and blood is pushed toward the heart |
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Maintaining blood pressure requires |
1) Cooperation of the heart, blood vessels, and kidneys 2) Supervision by the brain |
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Main factors influencing blood pressure |
1) Cardiac Output 2) Peripheral resistance 3) Blood volume |
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____ controls alter both CO and PR |
Neural controls |
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Blood pressure is maintained in the short-term by ____ which counteract fluctuations by ____ |
1) neural and hormone controls 2) altering peripheral resistance |
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Blood pressure is maintained in the long-term by ____ which counteract fluctuations by ____ |
1) renal regulation 2) altering blood volume |
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Neural controls of peripheral resistance are directed at two main goals: |
1) Maintain MAP by altering the blood vessel diameter 2) Alter blood distribution in response to specific demands |
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Neural controls operate via reflex arcs that involve |
Baroreceptors Vasomotor centers and fibers Vascular smooth muscle |
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Define vasomotor center |
A cluster of sympathetic neurons in the medulla that oversee changes in the blood vessel diameter |
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Baroreceptors are located in (3) |
1) Carotid sinuses to protect the brain 2) Aortic arch 3) Walls of large arteries of the neck and thorax |
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Norepinephrine and epinephrine cause |
generalized vasocontriction and increase cardiac output |
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_____, generated by kidney release of renin, causes vasocontriction |
Angiotensin |
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_____ causes blood volume and blood pressure to decline, which causes __ |
1) Atrial Natriurectic peptide 2) generalized vasodilation |
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___ causes intense vasocontriction in cases of extremely low BP |
ADH |
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____ quickly adapt to chronic high or low BP |
Baroreceptors |
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Long-term mechanisms step in to control BP by altering ___ |
blood volume |
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Kidneys act directly and indirectly to regulate ___ |
arterial blood pressure |
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How direct renal mechanism works |
alters blood volume independently of hormones |
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Increased BP or blood volume causes the kidneys to ___, thus reducing BP |
eliminate more urine |
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Decreased BP causes the kidneys to ____, thus BP rises |
conserve more water |
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Kidneys regulate blood pressure indirectly through the ____ |
renin-angiotensin-aldosterone mechanism |
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When ___ declines, certain cells in the kidneys release the enzyme ___ in the blood. This produces ___ which causes ____. This causes renal absorption of ____ which ___ urine formation. |
1) arterial blood pressure 2) renin 3) Angotensin II 4) aldosterone secretion 5) Na 6) decreases |
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Hormones that can affect BP |
1) Renin 2) ANP 3) Angiotensin 4) Nitric oxide 5) Aldosterone |
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____ capillaries in the small intestine receive nutrients from digested food. |
Fenestrated |
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____ capillaries in the endocrine organs allow hormones rapid entry into the blood |
Fenestrated |
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_____ capillaries with perpetually open pores occur in the kidneys where rapid filtration of blood plasma is essential. |
Fenestrated |
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Blood flows sluggishly through the _____, allowing time for it to be _____ |
1) Sinusoids 2) modified in various ways. |
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Define microcirculation |
The flow of blood from an arteriole to a venule |
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Capillary bed consists of two types of vessels |
1) Vascular shunt 2) True capillaries |
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Define vascular shunt |
A short vessel that directly connects the arteriole and venule at opposite ends of the bed |
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Define True capillaries |
the exchange vessels |
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Factors that affect blood flow to capillary |
1) Local chemical conditions 2) Arteriolar vasomotor nerve fibers |
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___ carry blood from capillary beds toward the heart |
Veins |
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Define Venules |
Capillaries unite to form these |
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____ join to form veins |
Venules |
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____ usually have three distinct tunics, but their walls are always ____ and their lumens are ___ than corresponding arteries. |
1) Veins 2) thinner 3) larger |
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Tunica media of ____ is poorly developed and tends to be thin even in larger ones. |
Veins |
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Because of their ____ and ____ veins can accommodate a fairly large blood volume |
1) large lumens 2) thin walls |
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The walls of veins can be much thinner than arterial walls without the danger of bursting because ____ |
the blood pressure is low |
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Two adaptions of veins that ensure veins return blood to the heart at the same rate it is pumped into circulation. |
1) Large lumens that offer little resistance to blood flow 2) valves that prevent blood from flowing backward |