-
The walls of all blood vessels except the smallest consist of three layers
- Tunica interna
- Tunica media
- Tunica externa
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The ____________ reduces friction between the vessel walls and blood
tunica interna
-
The __________ controls vasoconstriction and vvasodilation of the vessel
tunica media
-
THe __________ protects, reinforces, and anchors the vessel to surrounding structures
tunica externa
-
Elastic, or ________, arteries contain large amounts of elastin which enables these vessels to withstand and smooth out pressure fluctuations due to heart action
conducting
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Muscular, or __________, arteries deliver blood to specific body organs, and have the greatest proportion of tunica media of all vessels, making them more active in vasoconstriction
-
____________ are the smallest arteries and regulate blood flow into capillary beds through vasoconstriction and vasodilation
Arterioles
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___________ are the smallest vessels and allow for exchange between the blood and interstitial fluid
capillaries
-
_____________ capillaries are most common and allow passage of fluids and small solutes
Continuous
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___________ capillaries are leaky capillaries that allow large molecules to pass between the blood and surrounding tissues
sinusoidal
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________________ capillaries are more permeable to fluids and solutes than continuous capillaries
Fenestrated
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___________ are microcirculatory networks consisting of a vascular shunt and true capillaries, which function as the exchange vessels
capillary beds
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A cuff of smooth muscles, called a _________________, surrounds each capillary at the ____________ and acts as a valve to regulate blood flow into the capillary
- precapillary sphincter
- metarteriole
-
__________ are formed where capillaries converge and allow fluid and white blood cells to move easily between the blood and tissues
venules
-
Venules join to form
veins
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_____________ are relatively thin-walled vessels with large lumens containing about 65% of the total blood volume
veins
-
______________ form where vascular channels unite, allowing blood to be supplied to and drained from an area even in one channel is blocked
vascular anastomoses
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___________ is the volume of blood flowing through a vessel, organ, or the entire circulation in a given period, and may be expressed as ml/min
blood flow
-
___________ is the force per unit area exerted by the blood against a vessel wall, and is expressed in millimeters of mercury (mm Hg).
Blood pressure
-
____________ is a measure of the friction between blood and the vessel wall, and arises from three sources:
Resistance
- Blood viscosity
- Blood vessel length
- Blood vessel diameter
-
If blood pressure increases, blood flow _________; if peripheral resistance increases, blood flow ________
-
Peripheral resistance is the most important factor influencing local blood flow, because...
Vasoconstriction or vasodilation can dramatically alter local blood flow, while systemic blood pressure remains unchanged
-
pressure results when blood flow is
opposed by resistance
-
Systemic blood pressure is highest in the ______, and declines throughout the pathway until it reaches 0 mmHg in the _______
aorta
right atrium
-
___________ reflects how much the arteries close to the heart can be stretched (compliance, or distensibility), and the volume forced into them at a given time
Arterial blood pressure
-
When the __________ contracts, blood if forced into the aorta, producing a peak in pressure called _____________ (120 mm Hg)
left ventricle
systolic pressure
-
___________ occurs when blood is prevented from flowing back into the ventricles by the closed semilunar valve, and the aorta recoils (70-80 mm Hg)
Diastolic pressure
-
THe difference between diastolic and systolic pressure is called the
pulse pressure
-
The mean atrial pressure (MAP) represents the
pressure that propels blood to the tissues
-
Capillary blood pressure is low, ranging from _______ mm Hg, which protest the capillaries from rupture, but is still adequate to ensure exchange between blood and tissues
40-20
-
Venous blood pressure changes very little during the _________, and is low, reflection cumulative effects of peripheral resistance
cardiac cycle
-
Blood pressure varies directly with changes in blood volume and cardiac output, which are dertmined primarily by
venous return and neural and hormonal controls
-
__________________________ alter blood distribution to meet specific tissue demands, and maintain adequate MAP by altering blood vessels diameter
short-term neural controls of peripheral resistance
-
___________________ is a cluster of sympathetic neurons in the medulla that controls changes in the diameter of blood vessels
the vasomotor center
-
____________ detect stretch and send impulse to the vasomotor center, inhibiting its activity and promoting vasodilation of arterioles and veins
baroreceptors
-
______________ detect a rise in carbon dioxide levels of the body, and stimulate the cardioacceletory and vasomotor centers, which increase cardiac output and vasoconstriction
Chemoreceptors
-
The _______ and __________ can modify arterial pressure by signaling the medullary centers
-
Chemical controls influence blood pressure by
acting on vascular smooth muscle or the vasomotor center
-
___________ and ___________ promote an increase in cardiac output and generalized vasoconstriction
Norepinephrine and epinephrine
-
________________ acts as a vasodilator and an antagonist to aldosterone, resulting in a drop in blood volume
Atrial natriuretic peptide
-
______________ promotes vasoconstriction and water conservation by the kidneys, resulting in an increase in blood volume
Antidiuretic hormone
-
_____________ acts as a vasoconstrictor, as well as promoting the release of aldosterone and antidiuretic hormone
Angiotensin II
-
_______________ promote vasoconstrictions, and are released in response to low blood flow
Endothelium-derived factors
-
_____________________ counteracts an increase in blood pressure by altering blood volume, which increase the rate of kidney filtration
The direct renal mechanism
-
The __________________ is the renin-angiotensin mechanism, which counteracts a decline in arterial blood pressure by causing systemic vasoconstriction
indirect renal mechanism
-
Monitoring circulatory efficiency is accomplished by measuring _______________; these values together with respiratory rate and body temperature are called
pulse and blood pressure
vital signs
-
A ________ is generated by the alternating stretch and recoil of elastic arteries during each cardiac cycle
pulse
-
Systemic blood pressure is measured indirectly using the ____________ method, which relies on the uses of a blood pressure cuff to alternately stop and reopen blood flow into the brachial artery of the arm
ascultatory method
-
________ = low bp
_________ = high bp
hypotension
transient or persistent hypertension
-
___________ is the slow intermittent flow of blood throughout he capillaries. It reflects the action of the ______________ in response to local _______________
- Vasomotion
- precapillary sphincters
- autoregulatory controles
-
Capillary exchange of nutrients, gases, and metabolic wastes occurs between the blood and interstitial space through ________
diffusion
-
________________ is the force of a fluid against a membrane
hydrostatic pressure (HP)
-
________________, the force opposing hydrostatic pressure, is created by the presence of large, nondiffusible molecules that are prevented from moving through the capillary membrane
Colloid osmotic pressure (OP)
-
Fluids will ________ the capillaries if net HP exceeds net OP, but fluids will ____________ the capillaries if net OP exceeds net HP
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