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Vascular System

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Distribution of blood within the circulatory system at rest: ... Promotes fluid reabsorption into circulatory system. Net Filtration Pressure ... – PowerPoint PPT presentation

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Title: Vascular System


1
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2
Cardiovascular Physiology
  • Vascular System

3
Components of Circulatory System
  • Cardiovascular System (CVS)
  • Heart
  • Blood vessels
  • Lymphatic System

4
Cardiovascular System (CVS)
  • Cardiac
  • (heart)

Vascular
  • Arteries
  • Arterioles
  • Capillaries
  • Venules
  • Veins
  • Right sided
  • (volume pump)
  • Left sided
  • (Pressure pump)

5
Major function of Systemic Circulation
? To direct the flow of blood from the heart to
capillaries, back to the heart.
  • 1. Transportation
  • ? O2 CO2.
  • ? digestion products.
  • ? wastes.
  • ? distribution of body fluids.
  • 2. Regulation
  • ? Hormonal.
  • ? Immune.
  • ? Protection.
  • ? Temperature.

6
Blood Vessels
  • 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.

7
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8
Classification of the vascular system
  • 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).

9
Classification of the vascular system (continued)
  • 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.

10
Classification of the vascular system (continued)
  • 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).

11
Distribution of blood within the circulatory
system at rest
12
Mean Arterial and Venous pressure (continued)
  • 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).

13
Arteries
14
Structure of an arteriole
15
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16
Exchange of Fluid between Capillaries and Tissues
17
Capillaries
18
Fluid Movement (continued)
19
Exchange of Fluid between Capillaries and Tissues
  • 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.

20
Net Filtration Pressure
  • 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.

21
Colloid Osmotic Pressure
  • 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.

22
Arterioles, Capillaries, Venules
Capillary
23
Lymphatic System
  • 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.

24
Lymphatic System (continued)
  • Lymphatic capillaries
  • Closed-end tubules that form vast networks in
    intercellular spaces.
  • Lymph
  • Fluid that enters the lymphatic capillaries.
  • Lymph carried from lymph capillaries, to lymph
    ducts, and then to lymph nodes.
  • Lymph nodes filter the lymph before returning it
    to the veins.

25
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