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Questions and Answers
What is the main function of the circulatory system?
What are the two main parts of the circulatory system?
What is the function of arterioles?
What is the function of venules?
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What is the innermost layer of the blood vessel wall?
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What is the function of the tunica media?
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What is the external elastic lamina?
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What separates the tunica media from the tunica externa?
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What is the primary function of vein valves?
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What is a characteristic of large veins?
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What is true about muscular venules?
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What is a key difference between arteries and veins?
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What is the function of postcapillary venules?
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What is the main component of the tunica externa?
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What is a characteristic of medium-sized veins?
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What is the function of the vasa vasorum?
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What is true about venules?
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What is a characteristic of vein structure?
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What is a characteristic of capillaries?
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What type of capillary has pores in the endothelial lining?
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What is a characteristic of sinusoids?
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What is the function of arteriovenous anastomoses?
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What is a characteristic of elastic arteries?
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What is a characteristic of arterioles?
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What is the main function of veins?
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What are the three categories of veins based on size?
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Study Notes
The Circulatory System
- The circulatory system is a transport system that carries blood and lymph to and from the tissues of the body.
Cardiovascular System
- The cardiovascular system includes the heart and vessels.
- There are 5 classes of blood vessels:
- Arteries: carry blood away from the heart
- Arterioles: smallest branches of arteries
- Capillaries: smallest blood vessels, location of exchange between blood and interstitial fluid
- Venules: collect blood from capillaries
- Veins: return blood to heart
Common Structure of Blood Vessels
- The wall of blood vessels is composed of three layers: tunica intima, tunica media, and tunica externa
- Tunica intima: innermost layer, includes endothelial lining and connective tissue layer (subendothelial)
- Tunica media: middle layer, contains concentric sheets of smooth muscle in loose connective tissue
- Tunica externa: outer layer, contains connective tissue sheath principally of collagen (type I) and elastic fibers
Capillaries
- The smallest blood vessels
- Have small diameter and thin walls
- Diameter is similar to red blood cell
- Chemicals and gases diffuse across walls
- No tunica media and externa
- Endothelial cell inside thin basal lamina and pericytes
- Types of capillaries:
- Continuous
- Fenestrated (with diaphragm and without diaphragm)
- Discontinuous (sinusoids)
Arteriovenous Anastomoses & Glomus
- Direct connections between arterioles and venules
- Bypass the capillary bed
- Endothelium lies directly upon a specialized tunica media comprising a sphincter
- Are in skeletal muscle and skin of hands and feet and tissue that metabolic activity is intermittent
Artery Characteristics
- From heart to capillaries, arteries change:
- From elastic arteries (large artery) to muscular arteries (medium-sized artery) to arterioles (small artery)
Elastic Arteries
- Large vessels (e.g., pulmonary trunk and aorta)
- Tunica media has many elastic fibers and few muscle cells
Muscular Arteries
- Also called distribution arteries
- Are medium-sized (most arteries)
- Tunica media has many muscle cells (40 layer)
Arterioles
- Are small
- Have little or no tunica externa
- Have thin or incomplete tunica media (2-5 layer)
Veins
- Collect blood from capillaries in tissues and organs
- Return blood to heart
- 3 categories based on size:
- Small veins or venules: very small veins, collect blood from capillaries, exchange vessels
- Medium-sized veins (≤10 mm): tunica intima, thin tunica media, tunica externa with longitudinal bundles of elastic fibers, have vein valves
- Large veins (≥10 mm): have all 3 tunica layers, thin tunica media, thick tunica externa and longitudinal bundles of smooth muscle
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Description
This quiz covers the circulatory system, including the cardiovascular system and lymphatic system, including the heart and vessels.
