Blood Vessels I Flashcards
carry blood away from the heart.
Arteries
carry blood toward the heart
Veins
are the smallest blood vessels, through the walls of which gases and nutrients are
exchanged with tissues
Capillaries
are the walls of blood vessels, while _____ is the central space through which
blood flows.
Tunics; the lumen
The innermost wall of the blood vessels is called the _____ or _____.
tunica interna; tunica intima
The tunica intima consists of _____, which is surrounded, in larger
vessels, by a thin layer of connective tissue
simple squamous epithelium
OR endothelium
is the middle tunic of blood vessels, and primarily consists of a mixture of _____
and _____
Tunica media; smooth muscle;
elastin
The _____ (also called _____) refers to the outermost layer of the blood vessel wall.
tunica externa; tunica adventitia
Larger blood vessels are anchored to the surrounding tissue by their outermost layer,
which is composed mostly of _____
loosely woven collagen fibers
In larger vessels, the outermost layer is too far from the blood it carries to exchange gases
or chemicals, and so they have their own blood supply: the _____
vasa vasorum
Nerve fibers, lymphatic vessels, and in large veins, elastin fibers are found in the _____ of
the blood vessels.
tunica externa OR tunica
adventitia
Arteries are classified into three types: _____, _____ and _____
elastic artery; muscular artery;
arteriole
. Veins are classified into two types: _____ and _____.
venule; vein
connect arterioles to venules.
Capillaries
arteries are the thick-walled arteries nearest the heart, and function as shockabsorbers to minimize the difference between _____ and _____ blood pressure.
Elastic; systolic; diastolic
Elastic arteries are sometimes referred to as _____
conducting arteries
Muscular arteries have more _____ and less _____ than elastic arteries
smooth muscle; elastic tissue
The purpose of muscular arteries is to _____.
distribute blood
Another name for muscular arteries is ____
distributing arteries
_____, also called _____, are the smallest arteries.
Arterioles; resistance vessels
_____ refers to the narrowing of the lumen of blood vessels due to contraction of smooth
muscles in the blood vessel walls, while _____ refers to the widening of the lumen due to
their relaxation.
Vasoconstriction; vasodilation
Capillaries are so small that in some cases a(n) _____ spans the entire circumference of
the capillary wall, and RBCs must _____ to travel through.
single cell; deform slightly
In general, nutrient and waste exchange and gas exchange occurs by _____, but there
are exceptions
diffusion across capillary walls
(True or False) Cartilage and epithelia receive their nutrients from an extensive capillary
bed
FALSE: cartilage and epithelia
have no capillaries
The avascular cornea and lens of the eye receive nutrients and exchange gases with the
_____.
aqueous humor
. _____ capillaries are abundant in the skin and muscle.
Continuous
. _____ capillaries are the most common
Continuous
Endothelial cells in _____ capillaries are joined together by tight junctions, and are
separated only by rare gaps called _____ which allow fluid and very small solutes to pass.
continuous; intercellular clefts
Continuous capillaries in the brain are unique in that they lack _____. As a result, even
fluids and very small solutes _____
intercellular clefts; cannot cross
the capillary wall
Capillaries which contain oval pores called _____ through which fluids and solutes pass
with ease are called _____
fenestrations; fenestrated
capillaries
_____ capillaries are found in the small intestine and are needed to absorb ____
Fenestrated; nutrients from
digested foods
_____ capillaries are present in the kidneys to allow filtration of blood plasma
Fenestrated
_____ are extremely leaky capillaries through which even blood cells may sometimes
pass. (They are often simply referred to as _____.)
Sinusoidal capillaries; sinusoids
In the liver, some capillaries have walls which are partially formed by large macrophages
called _____. These capillaries are a type of _____.
Kupffer cells; sinusoid
The blood vessel that is structurally intermediate to an arteriole and a capillary is called
a(n) ____
metarteriole
The blood vessel that is structurally intermediate to an arteriole and a capillary is called
a(n) ____
metarteriole
From the point at which a capillary branches off from a metarteriole until it reaches the
venule, the blood vessel conducting blood from the arteriole to the venule even when the
capillary bed is not in use is called a(n) _____
thoroughfare channel
From the point at which a capillary branches off from a metarteriole until it reaches the
venule, the blood vessel conducting blood from the arteriole to the venule even when the
capillary bed is not in use is called a(n) _____
thoroughfare channel
Whether or not blood can leave a thoroughfare channel and enter the capillaries which
make up the _____ depends on whether or not the _____ are open
capillary bed; precapillary
sphincters
Whether or not blood can leave a thoroughfare channel and enter the capillaries which
make up the _____ depends on whether or not the _____ are open
capillary bed; precapillary
sphincters
Precapillary sphincters are made of _____.
smooth muscle
Precapillary sphincters are made of _____.
smooth muscle
Veins, especially those of the limbs, include _____ to prevent blood from flowing
backwards.
valves
Much of the structural integrity of veins is maintained by _____, which is why the valves of
surface veins are more often damaged than those of deep veins.
surrounding tissue
_____ are low pressure channels which are not, structurally, typical veins, into which
venous blood drains prior to entering true veins.
Venous sinuses
_____ are interconnections between blood vessels which allow blood to have multiple
paths of flow
Anastomoses
_____ anastomoses are more common than _____ ones.
Venous; arterial
_____ is the volume of blood flowing through a region in any given minute
Blood flow (F)
Combining the effects of viscosity, radius, pressure, vessel length, and resistance on
blood flow gives a relationship known as _____.
Poiseuille’s Law
_____ is measured by determining the amount of pressure that must be applied in order
to prevent blood flow
Blood pressure (P)
Blood leaving the heart causes the nearby arteries to _____. As the heart enters diastole,
the nearby arteries _____ due to their _____.
stretch; recoil; elasticity
The reason blood keeps flowing even during ventricular diastole is that _____.
the distended arteries recoil,
forcing blood forward
The three sources of resistance are _____, _____ and _____.
blood viscosity; vessel length;
vessel diamete
The thicker a liquid is, the more _____ it is: for example, honey is more _____ than water.
When moving through a tube, thick liquids generate more _____
viscous; viscous; friction or
resistance
Since the resistance to blood flow is a function of _____, gaining weight increases
resistance
the distance that the blood
must travel
Changes in blood pressure due to environmental shifts are controlled by altering the
_____.
blood vessel diameter
The relationship between vessel diameter and resistance to blood flow varies as a function of \_\_\_\_\_.
1/ r4 where r is the radius
Blood flow, pressure, and resistance are related by the formula: _____.
F = (change in pressure)/R
The change in pressure between two points in the circulatory system is determined simply
by _____
subtracting the lower pressure
from the higher one
The relationship between cardiac output, blood flow through the entire body, pressure,
and resistance is given by the formula: _____.
CO = F = (change in pressure)/
R
The blood pressure during the contraction of the ventricles is the _____ pressure, and is
normally _____ in a healthy adult
systolic; 120 mm Hg
The blood pressure during the relaxation of the ventricles is the _____ pressure, and is
normally _____ in a healthy adult
diastolic; 70 - 80 mm Hg
The _____ pressure is the difference between systolic and diastolic pressures
pulse
_____ is chronically increased by arteriosclerosis because the arteries do not distend
during ventricular systole, and thus store no energy to propel the blood during _____.
Pulse pressure; ventricular
diastole
The _____ is the average pressure that propels the blood through the tissue
mean arterial pressure; MAP
The relationship between systolic, diastolic, and mean arterial pressures is _____.
MAP = diastolic pressure +
pulse pressure/3
Blood pressure in capillaries is _____, because although each capillary is small, the cross
sectional area through all capillaries as a group is _____
low; large
Two factors besides the blood pressure generated by the heart promote return of the
blood to the heart: _____ and _____. Both of these _____, pushing blood through the
one-way valves and moving it toward the heart.
respiration; muscular
contraction; squeeze the veins
The effects of respiration and muscular contraction on the heart are referred to as the
_____ and _____, respectively.
respiratory pump; muscular
pump
If the blood volume were 0, the blood pressure would be _____. As blood volume
increases, _____
zero; so does blood pressure
Short-term, rapid compensation is mediated ___
neurally
Neural controls of peripheral blood flow have two major effects: by altering _____, they
control (1) the ultimate _____ of the blood, and (2) the _____ at which it is delivered
vessel diameter; destination;
rate and pressure
The central control of blood pressure and flow is the _____ in the ___
cardiovascular center; medulla
oblongata
The cardiovascular center has three centers: the _____, which controls blood vessel
diameter, the _____, which accelerates the heart and increases contractility, and the
_____, which decelerates the heart.
vasomotor center;
cardioacceleratory center;
cardioinhibitory center
Stimulation by the vasomotor center causes vasoconstriction of both _____ and ____
arteries; veins
. Arterioles are almost always somewhat constricted. This condition is called _____
vasomotor tone
Control of artery and arteriole diameter is transmitted from the vasomotor center to the
arteries and arterioles by _____ fibers which exit the CNS in the _____ and _____
regions.
vasomotor; thoracic; upper
lumbar
The vasomotor system is part of the _____ nervous system, and thus its neurotransmitter
is primarily _____ and the response is _____.
sympathetic; norepinephrine;
vasoconstriction
The cardiovascular center receives input from three sources: _____, which sense blood
pressure; _____, which sense oxygen, carbon dioxide, and pH; and _____, which conveys
information regarding stress, temperature, and other indirect factors
baroreceptors;
chemoreceptors; higher brain
regions
One group of _____, which sense blood pressure, are located in the _____, which are
slightly wider regions of the internal carotid arteries.
baroreceptors; carotid sinuses
The cluster of baroreceptors near the heart is located in the __
aortic arch
Signals from the baroreceptors indicating that blood pressure is high result in three
events: the _____ and _____ centers become less active, and the _____ center becomes
more active.
vasomotor; cardioacceleratory;
cardioinhibitory
Signals from the baroreceptors indicating that blood pressure is low result in three events:
the _____ and _____ centers become more active, and the _____ center becomes less
active
vasomotor; cardioacceleratory;
cardioinhibitory
The baroreceptors in the carotid sinus participate in the _____ reflex, and function to
protect the ____
carotid sinus; blood supply to
the brain
The baroreceptors in the aortic arch participate in the _____ reflex, and function to
maintain _____
aortic arch; blood pressure in
the systemic circuit
When blood pH decreases, carbon dioxide exhalation must be _____ to help return the
pH to its normal value. This requires that heart rate, blood pressure and breathing rate
_____.
increased; increase
When blood pH increases, carbon dioxide exhalation must be _____ to help return the pH
to its normal value. This requires that heart rate, blood pressure and breathing rate ____
decreased; decrease
Changes in blood pH are sensed by _____ in the _____, _____, and ___
chemoreceptors; medulla
oblongata; carotid arteries;
aorta
When blood carbon dioxide increases beyond acceptable levels, carbon dioxide
exhalation must be _____. This requires that heart rate, blood pressure and breathing rate
_____.
increased; increase
Changes in blood carbon dioxide levels are sensed by _____ in the _____, _____, and
_____.
chemoreceptors; medulla
oblongata; carotid arteries;
aorta
When blood oxygen falls to dangerous levels, oxygen inhalation must be _____. This
requires that heart rate, blood pressure and breathing rate ____
increased; increase
Changes in blood oxygen levels are sensed by _____ in the _____ and ___
chemoreceptors; carotid arteries;
aorta
Blood pressure and heart rate are modified due to information from chemoreceptors in
response to _____ changes in blood chemistry, and so are generally unused except in
emergencies
dramatic
_____ is released by the medulla of the adrenal glands in response to exercise or stress.
This hormone mimics the effects of _____, and _____ blood pressure and heart rate.
Epinephrine (or adrenaline);
norepinephrine; increases
Arterioles and veins have two types of _____ receptors which bind epinephrine. This
allows one chemical to have two effects depending on its concentration and location.
adrenergic
Long-lasting, slow compensation to adjust blood pressure is primarily controlled by the
_____.
kidneys
The direct renal mechanism alters _____.
blood volume
The indirect renal mechanism, also known as the _____ mechanism, triggers a series of
reactions that produce the potent vasoconstrictor _____.
renin-angiotensin-aldosterone;
angiotensin II
When blood pressure in the kidneys is insufficient, they release _____. This in turn leads
to the production of _____, and this in turn stimulates _____ and also production of
_____.
renin; angiotensin II;
vasoconstriction; aldosterone
Aldosterone, released by the cortex of the _____, _____ blood pressure by causing
_____ and thus _____
adrenal glands; increases; salt
retention; water retention
ADH (_____; it is also known as _____) is released by the _____ in response to
decreased blood pressure and increased blood osmolality.
antidiuretic hormone;
vasopressin; pituitary
_____ are low pressure channels which are not, structurally, typical veins, into which
venous blood drains prior to entering true veins.
Venous sinuses
. Varicose veins are veins which distend due to damage to their ____
valves
_____ are interconnections between blood vessels which allow blood to have multiple
paths of flow
Anastomoses
The smallest venules are the _____ venules
post-capillary
Veins, especially those of the limbs, include _____ to prevent blood from flowing
backwards.
valves
Much of the structural integrity of veins is maintained by _____, which is why the valves of
surface veins are more often damaged than those of deep veins.
surrounding tissue
