Cardiovascular System (cvs): Cardiovascular System (cvs)



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Cardiovascular System (CVS):

  • Cardiovascular System (CVS):

    • Heart
    • Blood vessels
  • Lymphatic System:



Cardiac

  • Cardiac

  • (heart)



1. Transportation:

  • 1. Transportation:

  •  O2 & CO2.

  •  digestion products.

  •  wastes.

  •  distribution of body fluids.

  • 2. Regulation:

  •  Hormonal.

  •  Immune.

  •  Protection.

  •  Temperature.



■ Walls composed of 3 “tunicas:”

  • ■ Walls composed of 3 “tunicas:”

    • Tunica externa:
      • Outer layer of connective tissue.
    • Tunica media:
      • Middle layer of smooth muscle.
    • Tunica interna:
      • Innermost simple squamous endothelium.
      • Layer of elastin.




1. Aorta … (elastic recoil)

  • 1. Aorta … (elastic recoil)

  • ■ Numerous layers of elastin fibers b/w smooth ms.

      • Expand when the pressure of the bl rises.
        • Act as recoil system when ventricles relax.
  • 2. Arteries … (muscular, low resistance vessels)

    • Less elastic & have a thicker layer of smooth ms.
    • Diameter changes slightly as BP raises & falls.
  • 3. Arterioles … (high resistance vessels)

    • Contain highest % smooth muscle.
      • Expand less under pressure (less compliance).
        • Called resistance vessels (greatest resistance to flow).


Capillaries … (exchange vessels)

  • Capillaries … (exchange vessels)

    • Smallest blood vessels.
      • 1 endothelial cell thick.
        • Provide direct access to cells.
          • Permits exchange of nutrients & wastes.
  • Venules

      • Formed when capillaries unite.
        • Very porous.


6. Veins … (capacitance vessels)

  • 6. Veins … (capacitance vessels)

  • ■ Contain little smooth muscle or elastin.

        • Capacitance vessels (blood reservoirs).
      • Contain 1-way valves that ensure blood flow to the heart.
  • ■  2/3 of total blood volume is located in veins ( 70%).





Mean arterial pressure:

  • Mean arterial pressure:

    • = 90 – 100 mmHg.
  • Mean venous pressure:

    • Is only 2 mmHg (low).
      • Due to:
      • 1. Pressure drop b/w arteries & capillaries.
      • 2. High venous compliance.
    • N.B. Venous pressure is highest in venules (10 mmHg), & lowest at junction of venae cavae w Rt atrium (0 mmHg).














■ Distribution of ECF between plasma and interstitial compartments is in state of dynamic equilibrium.

  • ■ Distribution of ECF between plasma and interstitial compartments is in state of dynamic equilibrium.

    • Balance between tissue fluid and blood plasma.
  • ■ Hydrostatic pressure:

    • Exerted against the inner capillary wall.
    • Promotes formation of tissue fluid.
    • Net filtration pressure.
  • ■ Colloid osmotic pressure:

    • Exerted by plasma proteins.
    • Promotes fluid reabsorption into circulatory system.


■ Hydrostatic pressure of blood capillaries minus the hydrostatic pressure in the interstitial fluid.

  • ■ Hydrostatic pressure of blood capillaries minus the hydrostatic pressure in the interstitial fluid.

    • Blood hydrostatic pressure (arteriolar pressure) = 37 mm Hg.
    • Blood hydrostatic pressure (venular end) = 17 mm Hg.
    • Interstitial hydrostatic pressure = 1 mm Hg.


■ Pressure exerted by plasma proteins or interstitial proteins.

  • ■ Pressure exerted by plasma proteins or interstitial proteins.

  • ■ Difference between plasma osmotic pressure and interstitial osmotic pressure is called oncotic pressure.

    • Plasma osmotic pressure = 25 mm Hg.
    • Interstitial osmotic pressure = 0 mm Hg.




■ Lymphatic vessels present b/w capillaries.

  • ■ Lymphatic vessels present b/w capillaries.

  • 3 basic functions:

    • Drain excess interstitial (tissue) fluid back to the bl, in order to maintain original bl volume.
    • Transports absorbed fat from small intestine to the bl.
    • Helps provide immunological defenses against pathogens.


■ Lymphatic capillaries:

  • ■ Lymphatic capillaries:

    • Closed-end tubules that form vast networks in intercellular spaces.
  • ■ Lymph:





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