Circulatory System

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Circulatory System
2012-02-05 12:10:19
Circulatory System

Circulatory System
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  1. All circulatory systems have three major parts
    • A pump, the heart, that keeps the blood circulating
    • A liquid, blood, that serves as a medium of transport
    • A system of tubes, blood vessels, that conduct the blood throughout the body

  2. The vertebrate circulatory system has diverse functions
    • Transport of O2 andCO2
    • Distribution of nutrients from the digestive system to all body cells
    • Transport of waste products and toxic substances to the liver/ kidneys
    • Distribution of hormones from glands/organs to tissues
    • Regulation of body temperature
    • Wound healing and blood clotting
    • Protection against disease by circulating white blood cells and antibodies

  3. The heart consists of muscular chambers
    • atria collect blood and contractions send blood into
    • ventricles, chambers whose contractions circulate blood through the lungs and to the rest of the body

  4. Valves maintain the direction of blood flow
    • When the ventricles contract, blood must be prevented from flowing back into the atria
    • The directionality of blood flow is maintained by one-way valves:
    • atrioventricular
    • semilunar

  5. The heart beats in a coordinated fashion
    • 1) Both atria contract and pump blood into the ventricles
    • 2) Both ventricles contract and pump blood into the arteries that exit the heart
    • 3) All chambers relax briefly before the cycle repeats

  6. Blood has two major components
    • plasma: primarily water in which proteins, salts, nutrients, and wastes are dissolved
    • about 90% water with 100 different types of molecules, (hormones, nutrients, cellular wastes, ions)
    • Proteins are the most abundant and include:
    • Albumin: to maintain the bloods osmotic strength
    • Globulins: antibodies
    • Fibrinogen: important in blood clotting
    • cell-based portion: rbc, wbc, and platelets
    • All three cell components originate from blood stem cells that reside in the bone marrow

  7. Red blood cells carry oxygen from the lungs to the tissues
    • called erythrocytes
    • red color caused by the protein hemoglobin, which transports oxygen in the blood
    • Each hemoglobin can bind four oxygen molecules, (one on each of four iron-containing heme groups)
  8. Macrophages
    (white blood cells) in the spleen and liver engulf and break down the dead red blood cells

  9. There are five types of white blood cells, also called leukocytes
    • Neutrophils
    • Eosinophils
    • Basophils
    • Lymphocytes
    • Monocytes

  10. Platelets, cell fragments that aid in blood clotting
    cell fragments that aid in blood clotting

  11. Blood clotting plugs damaged blood vessels
    • exposed collagen fibers attract platelets
    • release chemicals, initiate a series of reactions:
    • producing the enzyme thrombin
    • Thrombin catalyzes the conversion of the soluble plasma protein fibrinogen into insoluble strands of a protein called fibrin
    • Fibrin threads adhere to one another, increasing the density of the clot
    • this dense clot is called a scab

  12. Capillaries allow exchange of nutrients and wastes
    • Capillaries allow individual body cells to exchange nutrients and wastes with the blood by diffusion
    • Capillaries are so narrow that red blood cells pass through them single file
    • The relatively high blood pressure within the capillaries causes fluid to leak into the space surrounding the capillaries (extracellular fluid). This fluid provides body cells with nutrients and accepts their wastes
    • most of the extracellular fluid is restored to the blood through the capillary walls on the venous side of the capillary network

  13. Veins and venules carry blood back to the heart
    • After picking up carbon dioxide and other wastes from cells, capillary blood drains into larger vessels, called venules, which empty into still larger veins
    • Walls of veins are thinner, less muscular, and more expandable than those of arteries
    • When veins are compressed, one-way valves keep blood flowing toward the heart
  14. lymphatic system organs functions
    • Return excess extracellular fluid to the bloodstream
    • Transport fats from the small intestine to the bloodstream
    • Filter aged blood cells and other debris from the blood
    • Defend the body by exposing bacteria and viruses to white blood cells
    • The lymphatic system transports fats from the small intestine to the blood

  15. lymphatic organs
    • tonsils
    • thymus
    • spleen
    • hundreds of lymph nodes located along lymphatic vessels—all are important in the immune response
  16. Spleen
    • : a fist-sized organ between the stomach and diaphragm, filters the blood
    • lined with white blood cells, (macrophages), which engulf aged red blood cells and platelets, fragments of dead cells, and foreign matter, removing them from the blood