ANAPHY FINALS BLOOD VESSELS Flashcards
Blood moves through the body by ___ through blood vessels
bulk flow
Flow is proportional to a ____ that must overcome resistance
pressure gradient
carry blood away from the heart and
branch to form other vessels
Arteries
Capillary exchange with tissues occurs primarily via ___
diffusion
___ carries blood throughout body to supply oxygen and nutrients to tissues
Systemic circuit
____ carries blood to the lung for gas exchange
Pulmonary circuit
Arteries branch to form—
arterioles
are the sites of exchange
Capillaries
(Circulation pathways) this carries blood back toward heart
Venules and veins
Blood vessels share same general characteristics with—
They vary in structure
Arteries and veins
hollow space blood flows through
Lumen
Why do Arteries and arterioles have smaller lumen and thicker walls
To withstand higher pressures
have thinner walls and larger lumen
Venules and veins
__ travels throughout body in blood vessels
Blood
Travels from areas of higher to lower pressure
Blood
Blood vessel walls are made of layers called tunics. Name the three.
- Tunica intima
- Tunica media
- Tunica externa
innermost layer
• Composed of endothelium and basement membrane
• Larger arteries contain internal elastic membrane (lamina)
• Additional layer of elastic fibers
• Provides additional elasticity to larger arteries
• Not found in veins
Tunica Intima (interna)
Damage to endothelium exposes collagen fibers, leading to
Clot formation
Endothelial cells release ___ to regulate vasoconstriction
Endothelins
middle layer • Mainly smooth muscle
▪ Nervi vasorum regulates contraction and relaxation of muscle
• Leads to vasoconstriction and vasodilation
• Primarily sympathetic innervation except for external genitalia
• Thicker tunica media in arteries than veins
• Larger arteries contain external elastic membrane (lamina)
• Provides additional elasticity in arteries • Not seen in smaller arteries or veins
Tunica media
outermost tunic
• Composed mainly of collagen and elastic fibers
• Maintains shape and structure of vessel
• Thicker in arteries than in veins
• Larger arteries and veins are supplied by vasa vasorum
• Vessels that exchange nutrients and wastes for the wall
Tunica externa
higher percentage of elastic fibers
• Help propel blood during ventricular diastole
Elastic arteries
higher percentage of smooth
muscle
• Aid in controlling distribution of blood
Muscular arteries
Microscopic arteries that lead to capillaries
• All three tunics are very thin
• Smooth muscle slightly contracted to maintain vascular tone
• Site of greatest resistance to blood flow
• Able to regulate blood pressure and distribution of blood flow
Arterioles
Used for exchange of substances between blood and
tissues
Thin walled vessels
Three types of capillaries
A. Continuous capillaries
B. Fenestrated capillaries
C. Sinusoid(al) capillaries
most common type
• Complete endothelial lining
• Allows exchange of water, gases, and small molecules
Continuous capillaries
contain pores in endothelial lining
• Found in small intestine and kidneys
• Allow greater exchange of fluid and larger molecules
Fenestrated capillaries
least common
• Large gaps in endothelium and basement membrane
• Found in liver, spleen, and red bone marrow
• Allow exchange of plasma proteins and cells
Sinusoid(al) capillaries
____ regulate flow of blood into capillary beds using precapillary sphincters
• Located at openings of capillary beds from metarteriole
Metarterioles
contract to limit blood flow through capillary
Sphincters
Extremely small veins
• Merge to form veins
Venules
Blood vessels that carry blood toward the heart • Thinner walls than arteries
• Larger lumens
• Low pressure vessels
• Contain valves to prevent backflow
• Function as blood reservoirs due to larger lumen
• Venoconstriction speeds up venous return to heart
Veins
Typical pattern of blood flow is:
Artery, arteriole, capillary bed, venule, then vein
Variations to blood flow pathways
Arterial anastomosis
Venous anastomosis
Portal system
multiple arteries supply a common capillary bed
▪ Provides alternate routes for arterial blood to reach tissue
Arterial anastomosis
venules split and contribute to multiple veins
Venous anastomosis
links two capillary beds between the artery and vein
▪ Artery, arteriole, capillary bed, connecting vessel, capillary bed, venule, vein
Portal system
the movement of blood through the body
Blood flow
Flow rate is influenced by
pressure gradient
The greater the ____ , the higher the blood pressure must be to maintain flow
▪ The greater the _____ , the greater the flow rate
Resistance ; pressure gradient
Flow rate is opposed by
resistance
Arterial Blood Pressure (APR) Measured using a _____ at the brachial artery
sphygmomanometer
Which is systolic and diastolic? 120/80 mm Hg
The top—120 is the systolic
The bottom—80 is the diastolic
difference between systolic and diastolic pressures
Pulse pressure (PP)
“average” pressure arteries experience
Mean arterial pressure (MAP)
Homeostatic range for MAP is
70 – 110 mm Hg
Low MAP can lead to ____ due to poor blood flow
ischemia
may lead to hypoxia and tissue death
Ischemia
The expansion and recoil of arteries as blood flows through them
Pulse
Common pulse points are the: (3)
radial artery (wrist),
common carotid artery (neck),
and dorsalis pedis artery (foot)
Factors that influence pressure or resistance will affect flow
• Cardiac output
• Blood volume
• Vessel compliance
• Viscosity of blood
amount of blood ejected from each ventricle per minute
Cardiac output (CO)
amount of blood within vascular system
Blood volume
This equation relates resistance to blood flow
Poiseuille’s equation
