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this means by which blood flow is altered and distributed and by which blood pressure is regulated

tunica interna, tunica media, tunica externa

what are the three layers in a generalized blood vessel

tunica interna

this layer of the blood vessel is closest to the lumen, has direct contact with the blood and is continuous with the endocardium

inner endothelium, basement membrane

the tunica interna consists of two things

tunica media

this blood vessel layer consists of smooth muscle and elastic fibers that provide for changes in lumen diameter

tunica externa

this blood vessel layer consists of elastic and collagen fibers - it forms a protective layer


this is the formation of new blood vessels - it is stimulated by some cancers and a potential form of treatment is to inhibit it


these carry blood away from the heart to the tissues

tunica interna, tunica media, tunica externa

what are the layers of artery walls

elasticity, contractility

what are the functional properties of arteries


the tunica interna and media have this - it allows the arteries to accept blood under great pressure from the contraction of the ventricles and to send it on through the system


this is due to the smooth muscle in the tunica media - it allows arteries to increase or decrease lumen size and to limit bleeding from wounds.

elastic arteries

large arteries with more elastic fibers and less smooth muscle are called - they are able to receive blood under pressure and propel it onward

conducting arteries

this is another name for elastic arteries - they conduct bllod from the heart to medium sized muscular arteries

muscular arteries

these have a large amount of smooth muscle in their walls and distribute blood to various parts of the body


these are very small, almost microscopic, arteries that regulate the flow of blood to capillaries


a decrease in the size of the lumen of a blood vessel


a increase in the size of the lumen of a blood vessel


these assume a key role in regulating blood flow from arteries into capillaries and in altering arterial blood pressure


these are microscopic vessels that usually connect arterioles and venules


the flow of blood through the capillaries is called


these are found near almost every cell in the body, but their distribution varies with the metabolic activity of the tissue

blood, tissue cells

the primary function of capillaries is to permit the exchange of nutrients and waste between ___________ and _________ ________ through interstitial fluid


capillary walls are composed of only a single layer of ______________ cells and a basement membrane

surface area

capillaries branch to form an extensive capillary network throughout the tissue - this network increases the ___________ _______ allowing a rapid exchange of large quantities of materials


the flow of blood through capillaries is regulated by _________ with smooth muscle in their walls

precapillary sphincters

rings of smooth muscle fibers called _____ _______ regulates blood flow through true capillaries

continuous, fenestrated, sinusoids

there are three types of capillaries - what are they


these are small vessels that are formed from the union of several capillaries - they merge to form veins


these drain blood from capillaries into veins


these consist of the same three tunics as arteries but have a thinner tunica interna and media and a thicker tunica externa - they have less elastic tissue and smooth muscle and are therefore thinner walled


these are in veins to prevent backflow of blood

vascular sinuses

these are veins with very thin walls with no smooth muscle to alter their diameters - examples are the brain's superior sagittal sinus and the coronary sinus of the heart

varicose veins

weak valves in veins can lead to


this is the union of the branches of two or more arteries supplying the same region - they provide alternate routes for blood to reach a tissue or organ

collateral circulation

this is the alternate flow of blood to a body part through an anastomoses

end arteries, necrosis

arteries that do not anastomose are known as ________ - the occlusion of it interrupts the blood supply to a whole segment of an organ, producing __________ of that segment

blood reservoirs

at rest, the largest portion of the blood is in systemic veins and venules - collectively called ________ _________

venous vasoconstriction

blood sits in reservoirs and through _______ ______________ can move blood to other parts of the body if the need arises


in cases of _____________ when blood pressure and volume decrease, vasoconstriction of veins in venous reservoirs helps to compensate for the blood loss

liver, spleen, skin

the principal blood reservoirs of the veins are the

diffusion, transcytosis, bulk flow

this is how substances enter and leave capillaries


the most important method of capillary exchange is simple _________ - substances such as O2, CO2, glucose, amino acids, hormones diffuse down their concentration


all ________ solutes, except larger proteins, pass freely across most capillary walls

blood brain barrier

the prime exception of diffusion of water soluble materials across capillary walls is in the brain where the _________ _______ _________ exists


this is the enclosing of substances within tiny vesicles that enter cells by endocytosis - how some materials cross the capillary membrane

bulk flow

whereas diffusion is more important for solute exchange between plasma and interstitial fluid _______ __________ is more important for regulation of the relative volumes of blood and interstitial fluid

starlings law

the near equilibrium at ther arterial and venous ends of a capillary by which fluids exit and enter is called _________ _______ of the capillaries


occasionally, the balance of filtration and reabsorption between interstitial fluid and plasma is disrupted, allowing an abnormal increase in interstitial fluid called

blood pressure

this is the pressure exerted on the walls of a blood vessel - in clinical use it refers to the pressure in arteries

cardiac output (co)

thie equals mean aortic blood pressure (mabp) divided by total resistance (r)

cardiac output, blood volume, viscosity, resistance, elasticity

what are the five factors that affect blood pressure

systemic circulation

as blood leaves the aorta and flows through _________ ____________ , its pressure progressively falls to 0mm Hg by the time it reaches the right atrium


this refers to the opposition to blood flow as a result of friction between blood and the walls of the blood vessels


_________ resistance depends on the diameter of the blood vessel, blood viscosity, and total blood vessel length

systemic vascular resistance

this refers to all of the vascular resistances offered by systemic blood vessels - most resistance is in arterioles, capillaries, and venules due to their small diameters

venous return

this occurs because of the pressure gradient between the venules and the right atrium

veins, breathing

blood return to the heart is maintained by several factors, including skeletal muscular contractions, valves in _________ (extremities) and pressure changes associated with ________

blood flow

the volume of blood that flows through any tissue in a given period of time is


_________ of blood flow is inversely related to the cross-sectional area of blood vessels - blood flows most slowly where cross sectional area is greatest

decreases, increases

blood flow _________ from the aorta to arteries to capillaries and _________ as it returns to the heart


________or fainting, refers to a sudden, temp loss of consciousness followed by spontaneous recovery - it is most commonly due to cerebral ischemia but it may occur for several other reasons

cardiovascular center (cv)

this is a group of neurons in the medulla that regulates heart rate, contractility, and blood vessel diameter - it receives input from higher brain regions and sensory receptors


____________ impulses along cardioaccelerator nerves increase heart rate and contractility


____________ impulses along vagus nerves decrease heart rate

vasomotor nerves

the sympathetic division continually sends impulses to smooth muscle in blood vessel walls via

vasomotor tone

this is a moderate state of tonic contraction or vasoconstriction of the blood vessel walls


these are important pressure sensitive sensory neurons that monitor stretching of the walls of blood vessels and the atria

cardiac sinus reflex

this is concerned with maintaining normal blood pressure in the brain and is initiated by baroreceptors in the wall of the carotid sinus

aortic reflex

this is concerned with general systemic blood pressure and is initiated by baroreceptors in the wall of the arch of the aorta or attached to the arch

fall in bp

what will result in the baroreceptor reflexes accelerating heart rate, an increased force of contraction, and promote vasoconstriction

carotid sinus massage

this can slow heart rate in paroxysmal superventricular tachycardia


this receptor is sensitive to chemicals - they are located close to the baroreceptors of the carotid sinus and arch of the aorta - they monitor blood levels of O2, CO2, and hydrogen ion concentration

cardiac output, systemic vascular resistance, total blood volume

hormones such as angiotensin II, epinephrine, norepinephrine, antidiuretic, and atrial natriuretic peptide affect blood pressure and blood flow by altering (3)


the ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for supply of O2 and nutrients and removal of waste is

physical, chemical

what are the two general types of stimuli that cause autoregulatory changes in blood flow


this is the alternate expansion and elastic recoil of an artery wall with each heartbeat - it may be felt in any artery that lies near the surface

70, 80 (bpm)

a normal resting pulse heart rate is between


this is a rapid resting pulse rate - greater than 100 beats/min


this is a slow resting pulse rate - less than 60 beats/minute

blood pressure

this is the pressure exerted by blood on the wall of an artery when the left ventricle undergoes systole and then diastole - it is measured by the use of a sphygmomanometer - usually in one fo the brachial arteries

systolic blood pressure

this is the force of blood recorded during ventricular contraction

diastolic blood pressure

this is the force of blood recorded during ventricular relaxation


the various sounds that are heard while taking blood pressure called the ________sounds


normal blood pressure of a young adult make is ________ mm

pulse pressure

this is the difference between systolic and diastolic pressure - it is normally about 40mm and provides information about the condition of the arteries

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