Circulatory System Continued - share1

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					CIRCULATORY SYSTEM
    CONTINUED
        Andy Hunt
      Gloria Lonsdale
        J.D. Nixon
PLAN FOR TODAY
• Structure and Functions (6.2.5)
   • Arteries
   • Veins
   • Capillaries
• Stuff that’s in blood (6.2.6)
• Stuff that blood transports (6.2.7)
• Random bonus quiz :)
ARTERIES
•   Structure:
     • Walls of arteries have 3 different layers:
          • Connective tissue (outermost layer) allows for stretching and recoiling of
            the arteries to stabilize blood pressure even when the heart relaxes
            between contractions. It also is thicker to accommodate blood that is being
            pumped rapidly and at high pressure by the heart
          • Smooth muscle (middle layer) also provides some elasticity once again to
            maintain the blood pressure
          • The endothelium (the innermost layer) is a layer of flattened cells that gives
            the artery a smooth surface that therefore minimizes the resistance of blood
            flow
          • Breaks into arterioles that connect to capillaries
ARTERIES CONTINUED
• Functions:
    • Carries blood AWAY from the heart to organs
    • Blood is usually oxygenated with the exceptions of the pulmonary
      arteries and umbilical arteries in the fetus (don’t need to know umbilical,
      just pulmonary).
        • Pulmonary arteries carry deoxygenated blood away from the right
          ventricle, to the lungs, then back to the left atrium after oxygenated
          by lungs through pulmonary veins
    • Therefore, arteries transport oxygen-rich blood to the organs (except
      pulmonary!)
VEINS
• Structure:
    • Just like arteries- connective tissue, smooth muscle, and endothelium
    • Although they have the same layers, the veins have thinner outer walls
      compared to those of the arteries
         • They are thinner because when they pump blood back to the heart, it
           is done at low velocity and pressure. Thick walls are not needed.
    • Blood flows through veins as a result of muscle action. When you move,
      the skeletal muscles squeeze the veins and push blood through
    • In larger veins, flaps of tissue act as valves for the veins. They only allow
      blood to flow toward the heart.
    • Break into venules that connect to capillaries
VEINS CONTINUED
• Functions:
   • Convey blood back to the heart from the organs
   • Usually deoxygenated blood, except in the case of the
     pulmonary veins
       • Pulmonary veins carry oxygen-rich blood back to the
         heart (left atrium) from the lungs
CAPILLARIES
• Structure:
    • Lack the outer layers that arteries and veins have (tissue and muscle)
      and solely consist of basement membrane and the endothelium
    • These two thin layers allow the exchange of substances between blood
      and interstitial fluid that bathes the cells
    • Connection between arterioles and capillaries are called precapillary
      sphincters
    • Connection through capillary bed between arteriole and venule directly is
      called the thoroughfare channel.
CAPILLARIES CONTINUED
•   Functions:
•   Connects arterioles and venules; transports blood
     • Quick fun fact: only about 5-10% of the body’s capillaries have blood flowing through
       them at any given time. But since each tissue has many capillaries, every part of the
       body has blood at all times
           • Brain, heart, liver, and kidneys are usually filled to capacity, but in other places it
             differs depending on what you’re doing
           • For example, after you eat, blood supply to your digestive tract increases. Or
             while exercising, blood diverts itself from the digestive tract to skeletal muscles
             and skin
•   Two mechanisms regulate the blood distribution in the capillaries: the
    contraction/relaxation of the smooth muscle layer in the wall of the arteriole AND the
    precapillary sphincters
CAPILLARIES CONTINUED
•   Two Mechanisms
     • Smooth Muscle Layer
          • Contractions- when the smooth muscle layer in the wall of an arteriole contracts,
            it constricts the vessel, therefore reducing its diameter and decreasing blood
            flow through the capillary bed
          • Relaxations- when the layer relaxes, the arteriole dialates, allowing blood to
            enter the capillaries
     • Precapillary sphincters- rings of smooth muscle
          • Contractions- when contracted, blood does not flow through capillary beds and
            goes directly through thoroughfare channel
          • Relaxations- blood flows freely throughout the bed
CAPILLARIES CONTINUED
• Functions:
    • Exchanges substances between blood and interstitial fluid that bathes
      cells- occurs across thin endothelial membrane
    • Different ways of exchange:
        • Carried across an endothelial cell in vesicles that form by
          endocytosis on one side of the cell and release by exocytosis on
          other side
        • Diffusion between blood and interstitial fluid (such as oxygen and
          carbon dioxide). These smaller molecule diffuse down concentration
          gradients across endothelial cells
        • Fluid consisting water and small solutes (sugars salts, and urea) are
          diffused through capillary between adjoining capillary cells
CAPILLARIES CONTINUED
•   Once again… Fluid consisting water and small solutes (sugars salts, and urea)
    are diffused through capillary between adjoining capillary cells
     •   Transporting these clefts occurs mainly by bulk flow due to fluid pressure
     •   Blood pressure within the capillary pushes fluid through the clefts
     •   This outward movement of this fluid causes a net loss of fluid from the
         upstream end of the capillary near an arteriole
     •   Blood cells in blood and most proteins in blood are too big to pass through
         endothelium, so they remain in capillaries
     •   These remaining blood proteins create a constant osmotic pressure from
         the arteriole to the venule end of the bed
     •   Blood pressure drops and this huge difference between osmotic and blood
         pressure drives fluid out out of capillaries at arteriole end and into
         capillaries at the venule end
YOUTUBE… YAY!
•   http://www.youtube.com/watch?v=Q530H1WxtOw
•   http://www.youtube.com/watch?v=BeAYjETW-7Y
QUIZ TIME :)
WHAT TYPE OF BLOOD VESSEL IS THIS?
VEIN
WHAT CONNECTS
 AN ARTERIOLE
 AND A VENULE
  DIRECTLY?
THOROUGHFARE
   CHANNEL
 WHAT ARE THE TWO
 MECHANISMS THAT
REGULATE THE BLOOD
   FLOW INTO THE
    CAPILLARIES?
SMOOTH MUSCLE
   LAYER IN
ARTERIOLES AND
 PRECAPILLARY
  SPHINCTERS
NOW MORE FUN IB STUFF… HERE ARE TWO
STATEMENTS THEY TELL ME TO TEACH YOU
•   Statement #1: blood is composed of plasma, erythrocytes, leucocytes (phagocytes and
    lymphocytes) and platelets
     • Plasma- a liquid matrix that suspends the cells that are in blood; 90% water, but also
       composed of blood electrolytes that form ions that, when combined, it’s important in
       mantaining the osmotic balance of blood. Plasma proteins act as pH buffers, osmotic
       balance sustainers, and contribute to the thickness of the blood
     • Erythrocytes- red blood cells; transport oxygen by rapidly diffusing across their
       plasma membranes. Also transport carbon dioxide.
     • Leucocytes- white blood cells; for defense and immunity to fight off infections.
       Normally outside the circulatory system in the interstitial fluid and the lymphatic
       system
     • Platelets- fragments of cells; clot blood
CONTINUED REQUIRED STUFF
• Statement #2: the following are transported by
  the blood: nutrients, oxygen, carbon dioxide,
  hormones, antibodies, urea, and heat
• Not really a need for explanation.. Just write it
  down and remember. Please :)
 REAL QUIZ
TIME… GOOD
   LUCK!

				
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posted:4/17/2013
language:Latin
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