Circulatory System Quiz
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Questions and Answers

What characteristic of sinusoids and sinus capillaries allows for blood cell traffic?

  • Lack of smooth muscle
  • High permeability (correct)
  • Low pressure
  • Narrow diameter

    • Where do most cells receive their oxygen and nutrients from?

  • Through the vascular channels
  • Directly from the capillaries
  • From the plasma
  • From the interstitial fluid (correct)

    • What is the primary cause of intermittent blood flow within the capillary bed?

  • Plasma content fluctuation
  • Vasomotion (correct)
  • Arteriole innervation
  • Constant sphincter contraction

    • What is the typical percentage of solids in blood plasma?

    <p>8% (C)</p> Signup and view all the answers

    What happens to blood flow if there is a decrease in local tissue oxygen levels?

    <p>Smooth muscles relax, precapillary sphincters open, more flow to capillaries. (A)</p> Signup and view all the answers

    Which of the following best describes the tunica media of elastic arteries?

    <p>Predominantly elastic tissue with less smooth muscle. (A)</p> Signup and view all the answers

    In an open circulatory system, how does blood return to the heart after circulating through the body?

    <p>It does not return directly to the heart through a venous system; it bathes tissues directly. (B)</p> Signup and view all the answers

    What is the primary function of the vasa vasorum?

    <p>To supply blood to the connective tissues of large vessel walls. (B)</p> Signup and view all the answers

    Which of the following accurately describes the primary function of the blood vascular system?

    <p>To transport necessary materials to cells and remove their waste products. (A)</p> Signup and view all the answers

    How are the walls of capillaries generally structured?

    <p>A single layer of endothelial cells without any smooth muscle. (B)</p> Signup and view all the answers

    What best describes the transition from arteries to veins in the circulatory pathway?

    <p>The vessels grade smoothly into each other, with no sharp distinction between them. (C)</p> Signup and view all the answers

    What is the role of precapillary sphincters in a capillary bed?

    <p>To regulate blood flow into the capillary bed by closing off capillary circulation. (D)</p> Signup and view all the answers

    Which sequence correctly represents the flow of blood from the aorta back to the vena cava?

    <p>Aorta → arteries → arterioles → metarterioles → arterial capillaries → venous capillaries → venules → veins → vena cava (D)</p> Signup and view all the answers

    What is the relative amount of smooth muscle and elastic tissue in muscular arteries?

    <p>More smooth muscle than elastic tissue. (D)</p> Signup and view all the answers

    What makes blood vessels distinct from just being metallic pipes?

    <p>They are a living and growing system, constantly adapting to tissue needs. (C)</p> Signup and view all the answers

    Which of the following is closest to the typical diameter of a capillary?

    <p>3-12 μm (D)</p> Signup and view all the answers

    Among the given options, which best describes the role of metarterioles within the vascular system?

    <p>Serves as the immediate extensions of arterioles that feed into capillary networks. (A)</p> Signup and view all the answers

    What type of nerve supply modulates the blood flow in an artery?

    <p>Sympathetic nervous system. (B)</p> Signup and view all the answers

    In the circulatory system, where do metarterioles directly lead?

    <p>Arterial capillaries. (A)</p> Signup and view all the answers

    Aside from the blood vascular system, how many other major fluid systems are identified in the human body?

    <p>Four (C)</p> Signup and view all the answers

    What are the structures responsible for carrying out all transport in the blood system?

    <p>Arteries, capillaries, and veins (B)</p> Signup and view all the answers

    What is the total percentage of solids in blood plasma as described in the text?

    <p>8.3% (C)</p> Signup and view all the answers

    Which of the following does NOT contribute to the total protein content of blood plasma?

    <p>Amino acids (C)</p> Signup and view all the answers

    Why does fluid exit arterial capillaries, according to the text?

    <p>Due to the pressure of fluid inside the capillary (C)</p> Signup and view all the answers

    What is the main reason that most of the fluid that leaves the capillaries is reabsorbed?

    <p>The osmotic pressure of proteins in the plasma (C)</p> Signup and view all the answers

    Which pressure has the primary effect of drawing fluid back into the capillary?

    <p>Plasma colloid osmotic pressure (D)</p> Signup and view all the answers

    What does the term 'fluid exchange' refer to?

    <p>The movement of fluid into and out of the capillaries (B)</p> Signup and view all the answers

    What is the approximate value of plasma colloid osmotic pressure, as mentioned in the text?

    <p>28 mmHg (D)</p> Signup and view all the answers

    Which pressure is described as a negative value?

    <p>Interstitial fluid pressure (B)</p> Signup and view all the answers

    What is the primary function of lymphatic capillaries in relation to interstitial fluid?

    <p>To collect excess fluid from the interstitial tissue and return it to circulation. (B)</p> Signup and view all the answers

    Why is monitoring the fluid returning to the blood through the lymphatic system considered important?

    <p>To detect and manage any inflammation processes or foreign particles in the tissues. (D)</p> Signup and view all the answers

    What is the specific anatomical feature of lymphatic capillaries that allows them to collect interstitial fluid?

    <p>They feature blind-ended beginnings. (A)</p> Signup and view all the answers

    What is the immediate destination of the interstitial fluid that enters the lymphatic capillaries?

    <p>Lymphatic nodes for filtration. (A)</p> Signup and view all the answers

    What would happen if the lymphatic system failed to return fluid to the circulation?

    <p>A decrease in blood pressure due to fluid accumulation in the tissues. (A)</p> Signup and view all the answers

    What is the primary determinant of fluid movement across capillary walls?

    <p>The interaction of hydrostatic and colloid osmotic pressures. (C)</p> Signup and view all the answers

    What is the net fluid pressure in the arterial end of the capillary?

    <p>8.3 mmHg, driving fluid out of the capillary. (A)</p> Signup and view all the answers

    Why is interstitial fluid pressure typically negative?

    <p>To create a force for fluid to enter the tissue. (D)</p> Signup and view all the answers

    Which of the following net fluid exchange events is NOT directly reabsorbed by venous capillaries?

    <p>The 10% total volume not returned through the venous capillaries. (D)</p> Signup and view all the answers

    How does the colloid osmotic pressure influence fluid dynamics at the capillary level?

    <p>It draws fluid into the capillary due to protein concentration. (A)</p> Signup and view all the answers

    What is the estimated total body capillary network diffusion rate?

    <p>240 litres/minute (D)</p> Signup and view all the answers

    In a capillary network, what is the primary role of the lymphatic system regarding fluid?

    <p>To manage the 10% fluid volume not reabsorbed by the venous side. (C)</p> Signup and view all the answers

    What is the net pressure for fluid movement at the venous end of a capillary?

    <p>6.7 mmHg, moving fluid into the capillary. (D)</p> Signup and view all the answers

    Study Notes

    Cardiovascular System, Biological Fluids, Renal Function

    • CFR.2 The systematic circulation, blood vessels, capillary networks are covered.
    • Different types of circulatory systems (open and closed) are discussed.
    • Function and histology of blood vessels (arteries, veins, and capillaries) are described.
    • Physiology and dynamics of fluid exchange in capillary beds are explained.

    Circulatory Systems

    • Open systems pump blood to tissues in closed arteries without a venous return (e.g., arthropods).
    • Closed systems (e.g., vertebrates) keep blood within vessels; blood is one of several fluid systems in the body.

    Fluid Systems in the Body

    • Blood vascular system
    • Lymphatic system
    • Cerebrospinal fluid
    • Coelomic/Peritoneal fluid
    • Interstitial fluid

    Blood Vascular System

    • The blood system transports materials for metabolism/synthesis and waste products.
    • Oxygen and nutrients are supplied to cells; carbon dioxide and other wastes are removed.
    • Blood vessels (arteries, capillaries, and veins) carry out transport; distinctions are not sharp.
    • No sharp boundaries between blood cells, vessel walls, and other tissues
    • Blood vessels transition from aorta to arteries to arterioles to capillaries to venules to veins to vena cava.

    Blood Vessels - Histology

    • Blood vessels are living, growing structures adapting to tissue needs.
    • Arteries and veins have three layers: tunica intima, tunica media, and tunica adventitia/externa.
    • Different layers vary in composition and thickness depending on the vessel type (arteries vs veins) and size.

    Arteries - Histology

    • Large arteries (e.g., aorta) have a thick tunica media mostly composed of elastic tissue.
    • Medium-sized arteries (muscular arteries) have less elastic tissue and more smooth muscle.

    Veins - Valves

    • Veins have valves to prevent blood backflow.

    Vasa Vasorum

    • Small blood vessels within larger vessel walls supply the connective tissue.

    Capillary Networks

    • Capillaries are the smallest vessels, formed by a single layer of endothelial cells, usually 8-12 μm, but can be as small as 3 μm.
    • They are arranged in beds, are not continuous, and only about 5% of blood volume is in them at any given time.
    • Blood flows through capillaries via sphincters.

    Capillary Beds

    • Estimated to be 10 billion capillaries in the body.
    • Most cells are within 20-30 μm of a capillary.
    • Blood flow is not continuous in all capillary beds of organs.
    • There are preferential channels from arterial to venous sides.

    Capillaries

    • Non-fenestrated capillaries have low permeability; fenestrated have small pores; and discontinuous have large gaps.
    • They vary depending on their need to exchange substances.

    Physiology - Capillary Dynamics

    • Few cells are in direct contact with capillaries.
    • Most cells obtain nutrients and oxygen through the interstitial fluid.
    • Blood volume is about 8% of body weight (5-6 L in males, 4-5 L in females).

    Physiology - Vasomotion

    • Metarterioles and precapillary sphincters are not innervated, causing blood flow to be intermittent in capillary beds.
    • Vasomotion is regulated by auto-regulation of oxygen levels in local tissues; tissues with high oxygen levels will have constricted capillaries and the opposite will occur with low oxygen.

    Blood

    • Blood consists of plasma and blood cells.
    • Plasma is a watery fluid containing 8% solids (mostly proteins) and 92% water.
    • Blood can be separated into plasma and cellular components by centrifugation.

    Physiology – Blood, Plasma, and Capillary Dynamics

    • Plasma proteins include albumin, globulins, and fibrinogen (with their amounts specified).

    Physiology - Capillary Dynamics

    • Major blood vessels are water-tight; fluid does not leak out easily.
    • However, fluid leaves arterial capillaries due to blood pressure (hydrostatic pressure).
    • Most filtered fluid returns to capillaries due to osmotic pressure of proteins.
    • Fluid exchange across capillary walls is filtration and absorption.

    Physiology - Fluid Exchange

    • Four pressures regulate fluid exchange: capillary hydrostatic pressure, plasma colloid osmotic pressure, interstitial fluid pressure, and interstitial fluid colloid osmotic pressure.
    • Capillary hydrostatic pressure forces fluid out of capillaries; plasma colloid osmotic pressure draws fluid back in.

    Fluid Exchange

    • Net body filtration rate is 1.7-3.5 ml/min or 2.5-5.0 L/day.
    • Diffusion occurs in both directions.
    • 10% of filtered fluid (about 240L/min) is not reabsorbed into venous capillaries and is passed to the lymphatic system.

    Overview of the Systemic Blood Circulation and the Lymphatic System

    • Fluid left over in interstitial tissue after exchange processes must return to the circulation.
    • This return is collected via blind-starting lymphatic capillaries; this must be monitored as inflammation can occur in tissues.

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    Description

    Test your knowledge on the human circulatory system with this quiz. You'll explore the characteristics of blood vessels, the flow of blood through the body, and the functions of different components. Perfect for biology students and enthusiasts!

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