Chapter 21: The Cardiovascular
System: Blood Vessels
 Heart  arteries  arterioles 
capillaries  venules  veins  heart
Blood Vessel Anatomy
 Arterial Blood System
______________ vessels- “air,” “to
carry”
 Types:
 Elastic = conducting
 muscular = distributing
 Venous Blood System _________________ vessels
 Capillaries - ______________ vessels
Arteries- 3 tunics figure 21.1
 ____________________- lining of simple
squamous epithelium = 1. ____________,
closest to the lumen
 2. Basement membrane
 3. Internal elastic lamina
 ________________- middle coat, usually
thickest, elastic & circular smooth muscle
 __________________- stretch without tearing
 Innervated by sym NS for constriction/dilation
 _____________________- outer, elastic &
collagen
Vaso vasorum
 “_______________________”
 Larger blood vessels require oxygen
and nutrients, to do so they are
served by these types of blood
vessels
Types of arteries
 ________________–largest diameter
 __________________ in tunica media
 Walls ___________ compared to
diameter
 Help ______ blood while ventricles relax
 Walls stretch to store ______________
 Conduct blood to more muscular arteries
 Aorta, brachoiocephalic, common coratid,
subclavian, vertebral, pulmonary,
common iliac
Types of arteries (2)
 _____________________- distribute
to various parts of the body
 Media- more smooth muscle, less elastic
 Capable of > vasoconstriction/dilation
 Examples: brachial artery, radial artery
Arterioles
Small artery
10-100 μm in diameter
________________________
Similar to arteries but usually just a ring of
endothelial cells surrounded by scattered
smooth muscle fibers
 ______________ – opposition to blood flow
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 Mainly friction between blood an inner walls
 Arterioles can be dilated or constricted  called
resistance vessels
 _________________ can affect bp
Capillaries = microcirculation
 Microscopic vessels, 4-10μm
 connect arterioles to venules
 Near almost every cell in the body
 # vary w/metabolic activity of the tissue
 _______________ – exchange of nutrients
and waste between blood and tissue cells
thru interstitial fluid
 Walls= single cell layer thick & b.m.
 ________________– emerges from
arteriole & supplies 10-100 capillaries
(capillary bed)
Capillaries (2)
 __________________ – ring of
smooth muscle at the junction of the
arteriole with metarteriole
 Control flow to capillary bed
 __________________- bypasses the
capillary bed
Types of capillaries, fig. 21.4
 _______________ – endothelial cells form
continuous tube only interrupted by
intercellular clefts (gaps)
 Skeletal & smooth muscle, CT, lungs
 __________ – “window,” have small pores
 Kidneys, villi, choroid plexuses, endocrine glands
 ____________ – wider than other cap,
may have unusually large fenestrations
 Incomplete or absent basement membrane
 Liver, red bone marrow, spleen, some endocrine
Venule
 ______________________ forming
these small veins
 Walls very porous
 Many phagocytic WBC migrate from here
 Few scattered smooth muscle cells
 Larger venules more ____________
_______________________
Veins
 3 layers, interna & media much thinner
than artery (less smooth muscle & elastic)
 thickest layer - tunica externa = collagen &
elastic fibers, lack external & internal
elastic lamina
 __________ to handle volume & pressure
Δ yet not capable to withstand  pressure
 have abundant __________ (esp. in limbs)
 thin folds in the tunica interna form flaplike
cusps projecting into the lumen towards the 
 _________________________
Capillary exchange, fig 21.7
 7% blood in systemic cap at any one time
 Diffusion
 _______________- plasma in vesicles are
endocytosed by endothelial cells &
exocytosed out other side
 Insulin, Ab from mother to fetus
 ________________- passive process, large
# of ions, molecules particles move in same
direction at rates > than w/diffusion
 Filtration & resorption
Pressure driven movements
 ________– fluid & solutes  interstitial fluid
 ___________– FROM interstitial fluid 
blood capillaries
 2 pressures accountable for filtration:
 Blood hydrostatic pressure (BHP)- generated by
pump action of heart
 Interstitial fluid osmotic pressure
 Main pressure accountable for reabsorption:
 Blood colloid osmotic pressure (BCOP)
 _____________________ (NFP) = balance
of all of these pressures
Pressure driven movements (2)
 __________________ – pressure due to
water in plasma exerted against bv
 Interstitial fluid hydrostatic pressure pushes
fluid back into capillaries
 Is close to zero
 Difference in ________________ across
due to plasma proteins too large to pass
pores or fenestrations
 BCOP force of these large proteins to pull IF into
capillaries (remember- diffusion from  to )
Edema
 __________________________________
 Interstitial fluid 30% > than normal
 Causes of excess filtration:
  capillary blood pressure
  permeability of capillaries
 Chemicals, bacterial, thermal, mechanical
 Cause of inadequate reabsorption:
  concentration of plasma proteins
 Liver disease, burns, malnutrition, kidney
disease
Blood pressure
 Hydrostatic pressure exerted by blood on
walls of blood vessel
 __________________________________
 __________________________________
 @ 110mmHg during systole drops
to70mmHg during diastole
 Systolic- highest pressure in arteries during
systole
 Diastolic- lowest arterial pressure during diastole
 Pressure falls progressively as distant from L.V.
Mean arterial pressure
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MAP = average bp in arteries
@1/3 between systolic & diastolic
MAP = diastolic bp +1/3(systolic-dia)
 CO   MAP
 blood volume   MAP
 *Don’t forget, just as in the ventricles,
blood flows from areas of high to low
pressure
Resistance = opposition to flow
 BF = DP/R
 BP = CO x TPR (TPR=total peripheral
resistance= all the vascular R offered by
systemic bv)
 Viscosity- thickness,  viscosity   resistance, flow
 vessel length- longer vessel,  resistance
 vessel diameter (1/ r4)-  lumen   resistance
 Blood volume-  volume   pressure
 CO = SV x HR
 If CO, P as long as R is same
Systemic Vascular Resistance
(SVR) and venous return
 Arterioles control SVR  bp & blood flow to
particular areas by Δ diameter
 Controlled by brainstem
 ____________________:
 Besides heart 2 mechanisms to pump blood:
 _________________: valves open, muscle
contraction pushes blood thru proximal valve
and closes distal, muscle relax & close proximal
 _________________:  pressure in thoracic 
 pressure in abdominal   volume from
abdomen to Rt Atrium
Regulation of Blood pressure
 CV center – input from higher brain regions
& sensory receptors
 Figure 21.12
 Neural
 Baroreceptors – Δ pressure
 Carotid sinus- for pressure in the brain
 Aortic- regulate systemic pressure
 Chemoreceptors – Δ O2, CO2, H +
 acidosis   symp hormones, vasoconstriction
 Hormonal control
 Renal regulation, symp hormones, ANP,
Angiotensin II
Hormonal regulation of bp
 _______________________ (RAA)- blood
volume falls or kidney blood flow, renin 
angiontensin II   bp
 Vasoconstriction
 Stimulates release of aldosterone
 ______________-  CO by  HR and force,
also cause vasoconstriction
 _______- released due to  blood volume
  urine output,  vasoconstriction
 __________________________- released
by ,  bp by vasodilation
Circulatory shock
 Failure to deliver O2 and nutrients to meet
metabolic need
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Hypovolemic – low blood volume
Cardiogenic – poor heart function
Vascular – inappropriate vasodilation
Obstructive- obstruction to blood flow
 See figure 21.16 – responses
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Activation of RAA
ADH
Sympathetic hormones
Local vasodilators: K+, H+, lactic acid, NO
Shock: signs and symptoms
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Systolic bp  90
Resting HR  due to symp
Pulse weak and rapid, CO &  HR
Skin is cool, pale, clammy
Mental state altered
 urine production
 thirst
 pH due to acidosis
Nausea - impaired blood flow to GI tract
Disorders
 _________________- a group of diseases
characterized by thickening of artery walls
and loss of elasticity
 _____________- thin weakened section of
the wall of artery or vein, bulges out
 Graft or replace
 _______- inflammation of vein, often in leg
 CVA= cerebrovascular accident- destruction
of brain tissue (infarction) resulting of
obstruction or rupture of bv supplying brain
Atherosclerosis, LDL, and HDL
 Atherosclerosis - a stage of arteriosclerosis
involving fatty deposits or plaques
(atheromas) inside the arterial walls, thus
narrowing the arteries
 Plaques develop from due to excessive LDL
(containing much cholesterol) accumulate
in the inner layer of the artery wall
 HDLs decrease amount of excessive
cholesterol, transport it to liver for
elimination
Hypertension
 Silent killer- damage to bv, heart, brain, kidney before
any noticable pain or symptoms
 Major risk factor for both#1 cause of death = heart
disease, & #3 = stroke
 Lifestyle changes: lose weight, exercise, reduce salt
intake, maintain proper electrolyte intake, don’t
smoke, manage stress
 Drug treatment ACE (angiotensin converting enzyme) inhibitors
 beta blockers- inhibit renin
 Vasodilators
 Ca 2+ channel blockers- decrease heart rate
Fetal circulation
 O2 & nutrients- diffusion from maternal
blood (& eliminates its CO2 & wastes)
 exchange occurs ______________-inside uterus
 Normally, no direct mixing of maternal &
fetal blood; all exchanges by diffusion thru
capillaries
 Deoxy blood from fetus to placenta via 2
umbilical arteries -____________________
 ___________________________________
Fetal circulation (2)
 Umbilical vein ascends to liver, forms 2
branches:
 some thru the branch that joins the
hepatic portal vein
 most flows into ____________  IVC
 Deoxygenated blood  IVC mingles
w/blood from ductus venosus
 Deoxy blood from upper body  SVC,
this blood mixes in the right atrium
Fetal circulation (3)
 Most blood does not pass to rt
ventricle & lungs but thru _________opening between right & left atria,
bypassing pulmonary circuit
 Blood reaches rt ventricle, but little
reaches nonfunctioning lungs
 Instead, most blood sent thru another
bypass _____________-vessel
connecting pulmonary trunk & aorta
(becomes ____________________)