Anatomy and Physiology by Rod R Seeley 6th edition chapter 21 power-point

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Anatomy and Physiology, Sixth Edition
Rod R. SeeleyIdaho State University Trent D.
StephensIdaho State University Philip
TatePhoenix College
Chapter 21 Lecture Outline
See PowerPoint Image Slides for all figures and
tables pre-inserted into PowerPoint without notes.
Copyright The McGraw-Hill Companies, Inc.
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Chapter 21

• Peripheral Circulation and Regulation

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Peripheral Circulatory System

• Systemic vessels
• Transport blood through most all body parts from
  left ventricle and back to right atrium
• Pulmonary vessels
• Transport blood from right ventricle through
  lungs and back to left atrium
• Blood vessels and heart regulated to ensure blood
  pressure is high enough for blood flow to meet
  metabolic needs of tissues

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Blood Vessel Structure

• Arteries
• Elastic, muscular, arterioles
• Capillaries
• Blood flows from arterioles to capillaries
• Most of exchange between blood and interstitial
  spaces occurs across the walls
• Blood flows from capillaries to venous system
• Veins
• Venules, small veins, medium or large veins

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Capillaries

• Capillary wall consists mostly of endothelial
  cells
• Types classified by diameter/permeability
• Continuous
• Do not have fenestrae
• Fenestrated
• Have pores
• Sinusoidal
• Large diameter with large fenestrae

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Capillary Network

• Blood flows from arterioles through
  metarterioles, then through capillary network
• Venules drain network
• Smooth muscle in arterioles, metarterioles,
  precapillary sphincters regulates blood flow

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Structure of Arteries and Veins

• Three layers except for capillaries and venules
• Tunica intima
• Endothelium
• Tunica media
• Vasoconstriction
• Vasodilation
• Tunica adventitia
• Merges with connective tissue surrounding blood
  vessels

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Structure of Arteries

• Elastic or conducting arteries
• Largest diameters, pressure high and fluctuates
• Muscular or medium arteries
• Smooth muscle allows vessels to regulate blood
  supply by constricting or dilating
• Arterioles
• Transport blood from small arteries to capillaries

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Structure of Veins

• Venules and small veins
• Tubes of endothelium on delicate basement
  membrane
• Medium and large veins
• Valves
• Allow blood to flow toward heart but not in
  opposite direction
• Atriovenous anastomoses
• Allow blood to flow from arterioles to small
  veins without passing through capillaries

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Blood Vessel Comparison
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Aging of the Arteries

• Arteriosclerosis
• General term for degeneration changes in arteries
  making them less elastic
• Atherosclerosis
• Deposition of plaque on walls

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Pulmonary Circulation

• Moves blood to and from the lungs
• Pulmonary trunk
• Arises from right ventricle
• Pulmonary arteries
• Branches of pulmonary trunk which project to
  lungs
• Pulmonary veins
• Exit each lung and enter left atrium

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Systemic Circulation Arteries

• Aorta
• From which all arteries are derived either
  directly or indirectly
• Parts
• Ascending, descending, thoracic, abdominal
• Coronary arteries
• Supply the heart

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Branches of the Aorta
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Major Arteries
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Head and Neck Arteries
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Arteries of the Brain
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Head and Thorax Major Arteries
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Arteries of Upper Limb and Shoulder
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Arteries of Abdomen and Pelvis
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Arteries of Pelvis and Lower Limb
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Arteries of Lower Limb
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Systemic Circulation Veins

• Return blood from body to right atrium
• Major veins
• Coronary sinus (heart)
• Superior vena cava (head, neck, thorax, upper
  limbs)
• Inferior vena cava (abdomen, pelvis, lower limbs)
• Types of veins
• Superficial, deep, sinuses

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Major Veins
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Veins of Head and Neck
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Head and Thorax Veins
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Veins of Shoulder and Upper Limb
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Veins of Thorax
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Hepatic Portal System
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Veins of Abdomen and Pelvis
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Veins of Pelvis and Lower Limb
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Veins of Lower Limb
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Dynamics of Blood Circulation

• Interrelationships between
• Pressure
• Flow
• Resistance
• Control mechanisms that regulate blood pressure
• Blood flow through vessels

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Laminar and Turbulent Flow

• Laminar flow
• Streamlined
• Outermost layer moving slowest and center moving
  fastest
• Turbulent flow
• Interrupted
• Rate of flow exceeds critical velocity
• Fluid passes a constriction, sharp turn, rough
  surface

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Blood Pressure

• Measure of force exerted by blood against the
  wall
• Blood moves through vessels because of blood
  pressure
• Measured by listening for Korotkoff sounds
  produced by turbulent flow in arteries as
  pressure released from blood pressure cuff

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Blood Pressure Measurement
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Blood Flow, Poiseuilles Lawand Viscosity

• Poiseuilles Law
• Flow decreases when resistance increases
• Flow resistance decreases when vessel diameter
  increases
• Viscosity
• Measure of resistance of liquid to flow
• As viscosity increases, pressure required to flow
  increases

• Blood flow
• Amount of blood moving through a vessel in a
  given time period
• Directly proportional to pressure differences,
  inversely proportional to resistance

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Critical Closing Pressure, Laplaces Law and
Compliance

• Vascular compliance
• Tendency for blood vessel volume to increase as
  blood pressure increases
• More easily the vessel wall stretches, the
  greater its compliance
• Venous system has a large compliance and acts as
  a blood reservoir

• Critical closing pressure
• Pressure at which a blood vessel collapses and
  blood flow stops
• Laplaces Law
• Force acting on blood vessel wall is proportional
  to diameter of the vessel times blood pressure

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Physiology of Systemic Circulation

• Determined by
• Anatomy of circulatory system
• Dynamics of blood flow
• Regulatory mechanisms that control heart and
  blood vessels
• Blood volume
• Most in the veins
• Smaller volumes in arteries and capillaries

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Cross-Sectional Area

• As diameter of vessels decreases, the total
  cross-sectional area increases and velocity of
  blood flow decreases
• Much like a stream that flows rapidly through a
  narrow gorge but flows slowly through a broad
  plane

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Pressure and Resistance

• Blood pressure averages 100 mm Hg in aorta and
  drops to 0 mm Hg in the right atrium
• Greatest drop in pressure occurs in arterioles
  which regulate blood flow through tissues
• No large fluctuations in capillaries and veins

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Pulse Pressure

• Difference between systolic and diastolic
  pressures
• Increases when stroke volume increases or
  vascular compliance decreases
• Pulse pressure can be used to take a pulse to
  determine heart rate and rhythmicity

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Capillary Exchange andInterstitial Fluid Volume
Regulation

• Blood pressure, capillary permeability, and
  osmosis affect movement of fluid from capillaries
• A net movement of fluid occurs from blood into
  tissues. Fluid gained by tissues is removed by
  lymphatic system.

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Fluid Exchange Across Capillary Walls
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Vein Characteristics andEffect of Gravity on
Blood Pressure

• Vein Characteristics
• Venous return to heart increases due to increase
  in blood volume, venous tone, and arteriole
  dilation

• Effect of Gravity
• In a standing position, hydrostatic pressure
  caused by gravity increases blood pressure below
  the heart and decreases pressure above the heart

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Control of Blood Flow by Tissues

• Local control
• In most tissues, blood flow is proportional to
  metabolic needs of tissues
• Nervous System
• Responsible for routing blood flow and
  maintaining blood pressure
• Hormonal Control
• Sympathetic action potentials stimulate
  epinephrine and norepinephrine

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Local Control of Blood Flow by Tissues

• Blood flow can increase 7-8 times as a result of
  vasodilation of metarterioles and precapillary
  sphincters in response to increased rate of
  metabolism
• Vasodilator substances produced as metabolism
  increases
• Vasomotion is periodic contraction and relaxation
  of precapillary sphincters

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Nervous Regulation of Blood Vessels
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Short-Term Regulation ofBlood Pressure

• Baroreceptor reflexes
• Change peripheral resistance, heart rate, and
  stroke volume in response to changes in blood
  pressure
• Chemoreceptor reflexes
• Sensory receptors sensitive to oxygen, carbon
  dioxide, and pH levels of blood
• Central nervous system ischemic response
• Results from high carbon dioxide or low pH levels
  in medulla and increases peripheral resistance

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Baroreceptor Reflex Control
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Baroreceptor Effects
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Chemoreceptor Reflex Control
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Effects of pH and Gases
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Long-Term Regulation of Blood Pressure

• Renin-angiotensin-aldosterone mechanism
• Vasopressin (ADH) mechanism
• Atrial natriuretic mechanism
• Fluid shift mechanism
• Stress-relaxation response

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Renin-Angiotensin-AldosteroneMechanism
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Vasopressin (ADH) Mechanism
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Long Term Mechanisms

• Fluid shift
• Movement of fluid from interstitial spaces into
  capillaries in response to decrease in blood
  pressure to maintain blood volume
• Stress-relaxation
• Adjustment of blood vessel smooth muscle to
  respond to change in blood volume

• Atrial natriuretic
• Hormone released from cardiac muscle cells when
  atrial blood pressure increases, simulating an
  increase in urinary production, causing a
  decrease in blood volume and blood pressure

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Shock

• Inadequate blood flow throughout body
• Three stages
• Compensated Blood pressure decreases only a
  moderate amount and mechanisms able to
  reestablish normal blood pressure and flow
• Progressive Compensatory mechanisms inadequate
  and positive feedback cycle develops cycle
  proceeds to next stage or medical treatment
  reestablishes adequate blood flow to tissues
• Irreversible Leads to death, regardless of
  medical treatment