Ch. 20 - Cardiovascular System: Blood Vessels and Circulation Study
Guide
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DIRECTIONS: Answer the following questions, definitions, labels, etc. READ AND ANSWER
EVERYTHING SO YOU DON’T MISS POINTS.
Chapter 20
20.1. Structure and Function of Blood Vessels
I. Background
1. Arteries carry blood ___away__ __from____ the heart
2. Capillaries are where nutrients and wastes are ___exchanged___.
3. Veins _return___ blood to the heart.
4. Blood is transported in two circuits, the _pulmonary__ circuit and the
__systemic___ circuit.
II. Shared Structures
1. Due to the higher pressure in arteries do they have thicker or thinner
walls than veins? Yes.
2. The hollow passageway that blood flows through in arteries, capillaries,
and veins is the _lumen__.
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3. Valves contain __venous___ that provide unidirectional flow of blood
back to the heart.
4. Large arteries and veins need a blood supply separate from what passes
through their lumen, and this blood supply the “vessels of the vessel” is
the _vasa___ __vasorum____.
5. What are the three layers, or tunics, of arteries and veins from the lumen
out?
a) Tunica __Intima_____
b) Tunica __Media____
c) Tunica __Externa____
A. Tunica Intima
1. What composes the tunica intima? Epithelial and connective tissue
layers.
2. What type of arteries have a thick internal elastic membrane? Muscular
arteries.
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a) What purpose do the elastic fibers serve? Provide the vessel with
additional flexibility.
B. Tunica Media
1. What kind of muscle is found in the tunica media? Smooth muscle.
2. Vasoconstriction has what effect on blood flow? Decreases blood flow.
3. The _Vasomotor___ __nerves__, or “nerves of the vessel” help to
regulate vasoconstriction and vasodilation in the vessels.
4. The external elastic membrane separates the tunica media from what?
Tunica externa.
C. Tunica Externa
1. Why is it important for the tunica externa to hold the vessel in place? It
holds the vessel in place so it doesn’t shift, twist, or collapse, helping
maintain proper blood flow and support.
III. Arteries
1. Compared to veins, are arteries exposed to higher or lower pressures?
Higher pressures.
2. The aorta, the largest artery in the body is an __electric__ __artery_.
3. Beyond elastic arteries are ___muscular___ __arteries__ which have a
thick tunica media. These are also known as distributing arteries.
IV. Arterioles
1. Arterioles lead to __capillaries____.
2. Arterioles are both the primary site for __resistance__ and regulation of
__blood___ __pressure___.
V. Capillaries
1. What is perfusion? Blood flow through tissues.
2. What do capillaries exchange with the tissue? Gases, nutrients, wastes,
hormones, and fluids.
3. _Microcirculation____ is used to describe flow through the capillaries.
A. Continuous Capillaries
1. How common are continuous capillaries in the body? The most common
type.
2. What type of junctions are found between the endothelial cells of
continuous capillaries? Tight junctions.
a) Do the junctions here mean these capillaries do not participate in
exchange? they still participate in exchange.
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