Circulatory System
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Questions and Answers

What is the main function of the circulatory system?

  • To regulate body temperature
  • To remove waste products from the body's tissues
  • To carry blood and lymph to and from the body's tissues (correct)
  • To transport oxygen to the body's tissues

    • What are the two main parts of the circulatory system?

  • Cardiovascular and lymphatic systems (correct)
  • Cardiovascular and respiratory systems
  • Cardiovascular and nervous systems
  • Lymphatic and endocrine systems

    • What is the function of arterioles?

  • To collect blood from capillaries
  • To carry blood away from the heart
  • To regulate blood pressure (correct)
  • To exchange substances with interstitial fluid

    • What is the function of venules?

    <p>To collect blood from capillaries</p> Signup and view all the answers

    What is the innermost layer of the blood vessel wall?

    <p>Tunica intima</p> Signup and view all the answers

    What is the function of the tunica media?

    <p>To regulate blood pressure</p> Signup and view all the answers

    What is the external elastic lamina?

    <p>A layer of elastic fibers in the tunica intima</p> Signup and view all the answers

    What separates the tunica media from the tunica externa?

    <p>External elastic lamina</p> Signup and view all the answers

    What is the primary function of vein valves?

    <p>To prevent blood from flowing backward</p> Signup and view all the answers

    What is a characteristic of large veins?

    <p>All 3 tunica layers with thin tunica media</p> Signup and view all the answers

    What is true about muscular venules?

    <p>They have a diameter of ≤1 mm</p> Signup and view all the answers

    What is a key difference between arteries and veins?

    <p>Arteries have thicker walls and higher blood pressure</p> Signup and view all the answers

    What is the function of postcapillary venules?

    <p>To collect blood from capillaries</p> Signup and view all the answers

    What is the main component of the tunica externa?

    <p>Collagen fibers</p> Signup and view all the answers

    What is a characteristic of medium-sized veins?

    <p>Thin tunica media and few smooth muscle cells</p> Signup and view all the answers

    What is the function of the vasa vasorum?

    <p>To supply blood to the vascular walls themselves</p> Signup and view all the answers

    What is true about venules?

    <p>They are very small veins that collect blood from capillaries</p> Signup and view all the answers

    What is a characteristic of vein structure?

    <p>Many collagen fibers and a large lumen</p> Signup and view all the answers

    What is a characteristic of capillaries?

    <p>Thin walls and small diameter</p> Signup and view all the answers

    What type of capillary has pores in the endothelial lining?

    <p>Fenestrated</p> Signup and view all the answers

    What is a characteristic of sinusoids?

    <p>Enlarged diameter and thin walls</p> Signup and view all the answers

    What is the function of arteriovenous anastomoses?

    <p>To bypass the capillary bed</p> Signup and view all the answers

    What is a characteristic of elastic arteries?

    <p>Few muscle cells and many elastic fibers</p> Signup and view all the answers

    What is a characteristic of arterioles?

    <p>Small diameter and thin walls</p> Signup and view all the answers

    What is the main function of veins?

    <p>To collect blood from capillaries</p> Signup and view all the answers

    What are the three categories of veins based on size?

    <p>Small, medium, and large</p> Signup and view all the answers

    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.

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