Blood Vessels and Circulation

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Chapter 13 Blood Vessels and Circulation
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• Peripheral system
• Systemic
• Pulmonary
• Peripheral circulatory system heart are
  regulated to maintain sufficient flow of blood
  flow to the tissues.
• Functions
• Transport
• Exchange nutrients
• Regulate BP
• Direct blood flow

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Vessels

• Arteries Take blood away from heart
• Originate from ventricles
• Veins bring blood into the heart
• Open into atria
• Capillaries exchange nutrients and wastes

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• Except for Capillaries and venules, all vessels
  have three layers
• Tunica intima
• Tunica medi
• Tunica externa or adventitia
• Composition and amount of tissue in each varies
• Capillaries and venules have only Tunica intima
  help exchange of materials.

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• Elastic arteries More elastic fibers in tunica
  intima. Can recoil and provide no resistance to
  pressure
• Muscular arteries More smooth muscle in tunica
  intima. Called distributing arteries. Can undergo
  vasoconstriction and vasodilation
• Arterioles Has precapillary sphincter, local
  distribution of blood
• Capillaries exchange of materials
• Veins large diameter, valves for one way flow,
  relatively thin walled low pressure

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Fig. 13.1a
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Fig. 13.1b
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Fig. 13.3
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Fig. 13.4
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Fig. 13.5
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Fig. 13.6
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Fig. 13.14
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• Blood Pressure force blood exerts on the walls.
• Ventricles contract Systolic pressure (120 mmHg)
• Ventricles relax Diastolic pressure (80mmHg)
• Listening to Korotkoff sounds
• No blood flow no sound
• When pressure is released each time ventricles
  contract blood turbulence produces sounds
  systolic pressure
• When perrsure is still lowered all vessels are
  open and no turbulence and no sounds diastolic
  pressure

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Fig. 13.21
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• Pressure and resistance
• Elastic arteries high variations in blood
  pressure due to low resistance
• Arterioles resist most and pressure change is
  dampened by reducing the difference between
  systolic and diastolic pressure
• Capillarie 30 mmHg
• Veins slowly reduces to O mmHg
• Blood flow always down the pressure gradient
• Muscular arteries control regional blood flow
• Arterioles and sphincters regulate blood flow
  through local tissues

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Fig. 13.22
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Fig. 13.25
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Capillary Exchange

• Most exchange by diffusion.
• Arterial end High BP move of fluid out of
  capillaries and osmosis movement into capillaries
• Venous end Low BP move into capillaries and
  osmosis movement of the capillaries
• 9/10th of the fluids reenters capillaries and
  1/10th is returned by lymphatic system

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Fig. 13.24
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Nervous Control

• The vasomotor center (sympathetic division)
• Can excite or inhibit the center
• Control blood vessel diameter
• Vasomotor tone
• Maintain BP and routing the flow to all except
  capillaries and precapillary sphincters

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Fig. 13.26
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Regulation of Arterial Pressure

• Baroreceptors located at the carotid and aortic
  arch
• Sensitive to stretch
• Change peripheral resistance, heart rate and
  stroke volume
• Chemoreceptors located at the carotid and aortic
  arch
• Detect CO2, pH and oxygen
• Hormonal
• Epinephrine adrenal medulla
• Renin released from kidney due to low BP,
  production of Angiotensin II which causes
  vasoconstriction and aldosterone reduces urine
  production
• ADH from pituitary gland reduces urine output
• Atrial natriuretic hormone from heart increases BP

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Fig. 13.27
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Fig. 13.28
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Fig. 13.30
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Fig. 13.31
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Fig. 13.32
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Fig. 13.33