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Ch 21 Blood Vessels
Lecture Exam 2
43
Anatomy
Undergraduate 1
01/28/2020

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Term
Capillaries
Definition
the smallest blood vessels
Location of exchange between blood and interstitial fluid
Term
Tunica intima
Definition
(inner layer)
Includes endothelium and surrounding CT
Term
Tunica media
Definition
(middle layer)
Smooth muscle in a framework of loose CT
Muscle activity influences vessel diameter and blood flow
Term
Tunica externa
Definition
(outer layer)
Connective tissue sheath, fibers typically blend into nearby tissues to anchor the blood vessel
Term
Vasoconstriction
Definition
occurs as smooth muscle contracts
Term
Vasodilation
Definition
occurs as smooth muscle relaxes
Term
Aneurysm
Definition
A bulge in an arterial wall
Is caused by weak spot in elastic fibers
Pressure may rupture vessel
Term
Elastic Arteries
Definition
Large vessels such as pulmonary trunk and aorta
Tunica media has many elastic fibers and few muscle cells
Elasticity evens out pulse force
Term
Muscular Arteries
Definition
Are medium sized (most arteries)
Many muscle cells in tunica media
Term
Arterioles
Definition
Are small with little/no tunica externa and thin/incomplete tunica media
Term
Capillaries
Definition
Are the only vessels that permit exchange between blood and interstitial fluid
Term
Continuous Capillaries
Definition
Permit diffusion of water, small solutes, and lipid-soluble materials
Have very restricted permeability (tight junctions)
For example, the blood–brain barrier
Term
Fenestrated Capillaries
Definition
Have pores in endothelial lining
Permit rapid exchange of water and larger solutes between plasma and interstitial fluid
Are found in choroid plexus, endocrine organs, kidneys, intestinal tract
Term
Sinusoids (Sinusoidal Capillaries)
Definition
Have gaps between adjacent endothelial cells that permit free exchange of water and large plasma proteins
Found in liver, spleen, bone marrow, and some endocrine organs
Term
precapillary sphincter
Definition
a band of smooth muscle that regulates flow into the capillary
Term
arterial anastomosis
Definition
a joining of blood vessels
Term
Vasomotion
Definition
The cycling of contraction and relaxation of capillary sphincters
Causes blood flow in capillary beds to constantly change routes
Term
Venous Valves
Definition
Folds of tunica intima
Prevent backward flow
Term
Heart, arteries, and capillaries contain
Definition
30–35% of blood volume
Term
Venous system contains
Definition
60–65% of blood volume
Term
Capillary blood flow is determined by
Definition
pressure and resistance
Term
Flow (F) is directly proportional to
Definition
pressure (P)
Term
Flow (F) is inversely proportional to resistance (R)
Definition
resistance (R)
Term
Blood pressure (BP)
Definition
Arterial pressure in the systemic circuit
Term
Viscosity is the
Definition
resistance to flow caused by interactions among molecules and suspended materials in a liquid
Term
Whole blood viscosity is about _____ times greater than water
Definition
five
Term
Turbulence is
Definition
swirling action that disturbs the smooth flow of a liquid
Term
As blood flows from the aorta to the capillaries, the cross-sectional area _____ and blood velocity _____
Definition
Increases, Dcreases
Term
Systolic pressure
Definition
Peak arterial pressure during ventricular systole
Term
Diastolic pressure
Definition
Minimum arterial pressure during diastole
Term
Pulse pressure
Definition
Difference between systolic pressure and diastolic pressure
Term
Normal BP =
Definition
120/80
Term
Hypertension is abnormally high BP
Greater than
Definition
130/90
Term
Hypotension is abnormally low BP
Less than
Definition
90/60
Term
Elastic Rebound
Definition
Arterial walls stretch during systole and rebound (recoil to original shape) during diastole
Keeps blood moving during diastole
Term
the 3 most important processes driving capillary exchange
Definition
Diffusion, filtration, and reabsorption
Term
Diffusion
Definition
movement of ions or molecules from areas of higher concentration to areas of lower concentration
Term
Filtration
Definition
is the movement of a fluid across a membrane whose pores restrict certain solutes based on their size
Driven by hydrostatic pressure
Term
Reabsorption
Definition
is the return of fluids into the bloodstream
Term
Net capillary hydrostatic pressure tends to
Definition
push water and solutes out of capillaries and into the interstitial fluid
Term
Net capillary colloid osmotic pressure (plasma proteins) tends to
Definition
pull water and solutes into a capillary from the interstitial fluid
Term
Net filtration pressure =
Definition
hydrostatic pressure – osmotic pressure
Term
Tissue perfusion is affected by (3 things):
Definition
Cardiac output
Peripheral resistance
Blood pressure
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