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86 terms

Ch 21 Blood Vessels

Morris
STUDY
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hemodynamics
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
angioigenisis
this is the formation of new blood vessels - it is stimulated by some cancers and a potential form of treatment is to inhibit it
arteries
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
elasticity
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
contractility
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
arterioles
these are very small, almost microscopic, arteries that regulate the flow of blood to capillaries
vasoconstriction
a decrease in the size of the lumen of a blood vessel
vasodialation
a increase in the size of the lumen of a blood vessel
arterioles
these assume a key role in regulating blood flow from arteries into capillaries and in altering arterial blood pressure
capillaries
these are microscopic vessels that usually connect arterioles and venules
microcirculation
the flow of blood through the capillaries is called
capillaries
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
endothelium
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
vessels
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
venules
these are small vessels that are formed from the union of several capillaries - they merge to form veins
venules
these drain blood from capillaries into veins
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
valves
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
anastomoses
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
hemorrhage
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
diffusion
the most important method of capillary exchange is simple _________ - substances such as O2, CO2, glucose, amino acids, hormones diffuse down their concentration
plasma
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
transcytosis
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
edema
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
resistance
this refers to the opposition to blood flow as a result of friction between blood and the walls of the blood vessels
vascular
_________ 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
velocity
_________ 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
syncope
________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
sympathetic
____________ impulses along cardioaccelerator nerves increase heart rate and contractility
parasympathetic
____________ 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
baroreceptors
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
chemoreceptors
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)
autoregulation
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
pulse
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
tachycardia
this is a rapid resting pulse rate - greater than 100 beats/min
bradycardia
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
korotkoff
the various sounds that are heard while taking blood pressure called the ________sounds
120/80
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