Circulatory Systems and Fluid Systems in the Body
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Questions and Answers

What is the primary function of the Blood Vascular System in the body?

  • To maintain blood pressure
  • To facilitate the movement of cerebrospinal fluid
  • To regulate body temperature
  • To transport oxygen and nutrients to cells and remove waste products (correct)

    • Which of the following fluid systems is responsible for the transportation of materials to cells and the removal of waste products?

  • Lymphatic System
  • Cerebrospinal Fluid
  • Blood Vascular System (correct)
  • Interstitial Fluid

    • What is the characteristic of closed circulatory systems?

  • Blood is circulated through a system of capillaries
  • Blood flows through a network of open arteries
  • Blood is pumped to the tissues in closed arteries without a venous return
  • Blood never leaves the vessels (correct)

    • Which of the following is an example of an open circulatory system?

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

    What is the main function of capillaries in the circulatory system?

    <p>To facilitate the exchange of fluids and nutrients</p> Signup and view all the answers

    How do the blood vessels in mammals grade into each other?

    <p>Smoothly and gradually</p> Signup and view all the answers

    What is the main function of the vasa vasorum?

    <p>To supply the connective tissue of the large vessel</p> Signup and view all the answers

    What is the characteristic of the Intima layer in veins?

    <p>Layer of endothelium and few layers of smooth muscle</p> Signup and view all the answers

    What is the number of fluid systems in the body?

    <p>5</p> Signup and view all the answers

    Which of the following is NOT a function of the blood system?

    <p>Regulation of body temperature</p> Signup and view all the answers

    What is the approximate thickness of capillaries?

    <p>8-10μm</p> Signup and view all the answers

    What is the estimated number of capillaries in the human body?

    <p>10 billion</p> Signup and view all the answers

    What is the purpose of precapillary sphincters?

    <p>To close off the circulation to the capillary bed</p> Signup and view all the answers

    What is the percentage of blood volume that is in the capillaries at any time?

    <p>5%</p> Signup and view all the answers

    What is the term for direct connections between the arterial and venous sides?

    <p>Arterio-venous anastomoses</p> Signup and view all the answers

    What is the characteristic of blood flow through the capillary beds?

    <p>Intermittent flow</p> Signup and view all the answers

    What is the primary function of vasomotion in the capillary beds?

    <p>To autoregulate oxygen levels in local tissues</p> Signup and view all the answers

    What is the approximate percentage of solids in plasma?

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

    What is the main difference between the blood volume of males and females?

    <p>The difference in blood volume is related to body weight</p> Signup and view all the answers

    What is the function of the precapillary sphincters in the capillary beds?

    <p>To control the flow of blood into the capillaries</p> Signup and view all the answers

    What is the percentage of protein in plasma?

    <p>7%</p> Signup and view all the answers

    What is the term for the fluid that surrounds the cells of a given tissue?

    <p>Interstitial fluid</p> Signup and view all the answers

    What is the result of decreased oxygen levels in local tissues on the smooth muscle?

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

    What is the term for the rhythmic contraction and relaxation of the precapillary sphincters?

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

    What is the net filtration pressure at the arterial end of a capillary?

    <p>8.3 mmHg</p> Signup and view all the answers

    What percentage of plasma passing through the capillaries is lost as a result of net filtration?

    <p>2%</p> Signup and view all the answers

    What is the direction of fluid movement when the pressure sign is positive?

    <p>Fluid leaves the location</p> Signup and view all the answers

    What is the estimated diffusion rate for the entire body capillary network?

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

    What is the net loss of fluid as a percentage of total volume that passes into the Lymphatic system?

    <p>10%</p> Signup and view all the answers

    What is the purpose of the negative interstitial fluid pressure?

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

    What is the primary process for trans-capillary exchange of solutes and solvents?

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

    What is the direction of fluid movement in the lymphatic system?

    <p>From tissue to lymphatic system</p> Signup and view all the answers

    What is the primary reason why most proteins cannot escape the capillary?

    <p>Because of the size of the pores in the capillary wall</p> Signup and view all the answers

    What is the net effect of the interstitial fluid pressure and interstitial fluid colloid osmotic pressure on fluid exchange?

    <p>They suck fluid out of the capillary</p> Signup and view all the answers

    What is the primary mechanism by which some proteins leave the capillary?

    <p>Through the process of pinocytosis</p> Signup and view all the answers

    What is the direction of fluid movement due to the capillary hydrostatic pressure?

    <p>Out of the capillary</p> Signup and view all the answers

    What is the primary force that pulls fluid back into the capillary?

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

    What is the term for the filtration and absorption of fluid across the capillary wall?

    <p>Fluid exchange</p> Signup and view all the answers

    Study Notes

    Circulatory Systems

    • There are two types of circulatory systems: open and closed systems
    • Open systems: the heart pumps blood to the tissues in closed arteries, without a venous return (e.g., in Arthropods)
    • Closed systems: blood never leaves the vessels (e.g., in humans)

    Fluid Systems in the Body

    • There are five fluid systems in the body:
      • Blood Vascular System
      • Lymphatic System
      • Cerebrospinal Fluid
      • Coelomic/Peritoneal Fluid
      • Interstitial Fluid

    Blood Vascular System

    • The main functions of the blood system are:
      • Transportation of materials necessary for cell metabolism and synthesis
      • Transportation of waste products of cell activity
    • Oxygen and nutrients must be supplied to the cells, and carbon dioxide and nitrogenous wastes removed

    Blood Vessels

    • Blood vessels are divided into arteries, capillaries, and veins
    • Arteries, veins, and capillaries grade smoothly into each other
    • Vasa vasorum: small blood vessels in the wall of a large vessel that supply the connective tissue and then drain back into the main vessel

    Veins

    • Histology:
      • Intima: endothelium and a few layers of smooth muscle
      • Media: a few layers of smooth muscle
      • Adventitia: the largest layer with longitudinally arranged thick collagen fibers
    • Both large arteries and veins have their own blood supply called the vasa vasorum

    Capillary Networks

    • Capillaries are the smallest vessels, formed of a single layer of endothelial cells, 8-10μm thick, without smooth muscle
    • Estimated 10 billion capillaries in the body, rare for any cell to be more than 20-30μm from a capillary
    • Capillaries tend to be arranged in capillary beds, with only about 5% of blood volume in the capillaries at any time
    • Blood leaves the metarteriole and enters the capillary bed via precapillary sphincters, which can close off the circulation to the capillary bed

    Capillary Dynamics

    • Blood does not flow continuously through the capillary beds; in most organs, only a small number of capillaries are filled
    • Direct connections called preferential channels or arterio-venous anastomoses shunt blood rapidly from the arterial to venous side
    • Vasomotion: rhythmic myogenic activity of contraction and relaxation of the precapillary sphincters, affecting the entrance to the capillaries

    Physiology - Capillary Dynamics

    • Few cells are in direct contact with the capillaries; most cells obtain their nutrient and oxygen requirements via the interstitial fluid
    • The blood volume is about 8% body weight, with a difference in blood volume between males and females related to body weight
    • Red blood cells in a capillary

    Physiology - Fluid Exchange

    • Fluid exchange in the capillary bed involves four pressures:
      • Capillary hydrostatic pressure (25 mmHg)
      • Plasma colloid osmotic pressure (28 mmHg)
      • Interstitial fluid pressure (-6.3 mmHg)
      • Interstitial fluid colloid osmotic pressure (5 mmHg)
    • Net filtration pressure (tendency for plasma to leave the blood at the arterial end of a capillary) = 8.3 mmHg
    • Net body filtration rate = 1.7-3.5 ml/min or 2.5-5.0 liters/day
    • Diffusion occurs in both directions and is estimated for the entire body capillary network at 240 liters/minute

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    Description

    Learn about the types of circulatory systems, including open and closed systems, and explore the five fluid systems in the human body.

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