Blood Vessels and Circulation
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Blood Vessels
 ________________________________________________________________________
________________________________________________________________________
 Delivery system of dynamic structures that begins and ends at the heart
▪ Arteries: ______________________________________________; oxygenated
except for pulmonary circulation and umbilical vessels of a fetus
▪ Capillaries: ________________________________________________________
▪ The vital functions of the cardiovascular system occur at the capillary
level: ______________________________________________________
___________________________________________________________
▪ Veins: ____________________________________________________________
Structure of Blood Vessel Walls
 Arteries and veins have 3 layers:
▪ _______________________ – innermost layer
▪ _______________________ – middle layer containing smooth muscle for
contraction (vasoconstriction) and relaxation (vasodilation)
▪ _______________________ – outermost layer, anchors vessel
Arteries
 When traveling from the heart to capillaries blood goes through elastic arteries,
muscular arteries, and arterioles:
▪ ___________________________
▪ Large thick-walled arteries with elastin in all three tunics
▪ Aorta and pulmonary trunk and their major branches
▪ Act as pressure reservoirs—expand and recoil during the cardiac cycle
▪ ___________________________
▪ Deliver blood to body organs and skeletal muscle
▪ ___________________________
▪ Smallest arteries
▪ Lead to capillary beds
▪ Alter blood pressure and rate of flow through dependent tissues
Capillaries
 ________________________________________________________________________
________________________________________________________________________
 Capillaries do not function as individual units but as part of an interconnected network
called a capillary bed
 The entrance to each capillary is guarded by a precapillary sphincter (a band of smooth
muscle)
▪ _________________________________________________________________
Veins
 ________________________________________________________________________
 From capillaries blood flows through the venules to the medium-sized veins to the large
veins and then enters the heart
▪ Large veins includes the 2 vena cavae
Blood Flow
 Factors affecting blood flow:
▪ _________________________
▪ ___________________________________________________________
▪ Largest pressure gradient found in the systemic circuit between the
aorta and entrance to the right atrium (called the circulatory pressure)
▪ Circulatory pressure has 3 components: __________________________
___________________________________________________________
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▪ ___________________________________________________________
▪ Sources of peripheral resistance:
 _____________________ – resistance of blood vessels to blood
flow. The most important factor in vascular resistance is friction
between blood &vessel walls
 _____________________ – the resistance to flow resulting
from interactions among molecules and suspended materials in
a liquid
 _____________________ – high flow rates, irregular surfaces,
or sudden changes in diameter can upset smooth blood flow,
this is turbulance. It slows flow and increases resistance
Blood Pressure
 The pressure in arteries fluctuates, rising during ventricular systole and falling during
ventricular diastole
▪ Systolic pressure – __________________________________________________
▪ Diastolic pressure – _________________________________________________
▪ The difference between the 2 pressures is the pulse pressure
 ____________________________________________________
Capillary Pressure
 ________________________________________________________________________
▪ Contributes to capillary exchange
▪ Capillary exchange has 4 important functions:
1. ____________________________________________________
____________________________________________________
2. ____________________________________________________
____________________________________________________
3. ____________________________________________________
____________________________________________________
4. ____________________________________________________
____________________________________________________
Venous Pressure
 Venous system requires less pressure than the atrial system
 When standing, venous blood below the heart must overcome gravity. 2 factors help:
▪ Muscular compression – _____________________________________________
▪ The respiratory pump – ______________________________________________
_________________________________________________________________
Cardiovascular Regulation
 3 mechanisms:
▪ _______________________________
▪ Automatic adjustment of blood flow to each tissue
▪ _______________________________
▪ Respond to changes in arterial pressure or blood gas levels at specific
sites
 Baroreceptor reflexes respond to changes in blood pressure,
and chemoreceptor reflexes respond to changes in chemical
composition
▪ _______________________________
▪ The endocrine system releases hormones that enhance short-term
adjustments and direct long-term changes in cardiovascular
performance
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Exercise and the Cardiovascular System
 During exercise, cardiac output and blood distribution change markedly
 As exercise begins 3 main changes take place:
▪ Extensive vasodilation – _____________________________________________
▪ Venous return increases – ____________________________________________
▪ Cardiac output rises – _______________________________________________
 Other changes: cardiac output increases, blood pressure increases, and blood flow is
restricted
Cardiovascular Response to Hemorrhage
 If blood clotting fails (severe injuries, disorders, etc.) the entire system begins making
adjustments
▪ The short-term elevation of blood pressure
▪ ___________________________________________________________
___________________________________________________________
▪ The long-term restoration of blood volume
▪ ___________________________________________________________
___________________________________________________________
___________________________________________________________
Pulmonary and Systemic Circuit Patterns
 They exhibit 3 general patterns:
▪ _________________________________________________________________
_________________________________________________________________
▪ _________________________________________________________________
_________________________________________________________________
▪ _________________________________________________________________
_________________________________________________________________
Systemic Arteries
 ______________________________ – begins at the aortic semilunar valve of the left
ventricle and ends at the aortic arch
 ______________________________ – contains 3 elastic arteries: the brachiocephalic,
the left common carotid, and the left subclavian
 ______________________________ – continuous with the aortic arch and ends at the
diaphragm
Systemic Veins
 ______________________________ – receives blood from the head, neck, upper limbs,
shoulder, and chest
 ______________________________ – collects most of the venous blood from organs
inferior to the diaphragm
 ______________________________ – delivers blood containing __________________
________________________________ to the liver, where the liver cells absorb them
for storage, metabolic conversion, or excretion