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THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 15
Blood Flow and the Control
of Blood Pressure
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
About this Chapter
• How various blood vessels are constructed and
role in circulation
• Components of "blood pressure", role and
measurement
• Product exchange at the capillary beds
• Lymph vessels, distribution and role in circulation
• How blood pressure and circulation are regulated
• Key components of cardiovascular disease
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
The Blood Vessels and the Cardiovascular System
• Arteries: blood from heart
• Strong & Elastic
• Conduct blood to capillaries
• Sphincters
• Capillaries: exchange with cells
• Veins
• Return blood to heart
• Valves
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The Blood Vessels and the Cardiovascular System
Figure 15-1: Functional model of the cardiovascular system
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Make Up of Blood Vessels: Arteries and Arterioles
• Endothelium
• Elastic tissues
• Rebounds
• Evens flow
• Smooth muscles
• Fibrous tissue
• Tough
• Resists stretch
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Figure 15-2: Blood vessels
Make Up of Blood Vessels: Capillaries
• Endothelium: one cell thick
• Continuous
• Fenestrated
• Basement membrane
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Make Up of Blood Vessels: Capillaries
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Figure 15-16: Types of capillaries
Make Up of Blood Vessels:
Veins and Venules (Contrasted to Arteries)
• Thinner walls
• Larger diameter
• Closer to skin
• Less muscle
• Less elastic
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Figure 15-3: Metarterioles
Angiogenesis: Growth of New Blood Vessels
• Normal body maturation and growth
• Endometrium
• Endurance training
• Abnormal growth to service cancerous tissue
• Wound repair and consequences
• Failure to regrow in heart tissues after heart
attack
• Failure to regrow in brain after stroke
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Blood Pressure:
Generated by Ventricular Contraction
• Pulsatile: surges in arteries
• Elastic rebound evens & maintains pressure
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Blood Pressure:
Generated by Ventricular Contraction
Figure 15-4: Elastic recoil in the arteries
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Blood Pressure (BP): Measurements
• "Blood pressure"
• Systolic over diastolic
• About 120/80 mmHg
• Sphygmomanometer
• "Estimate of pressure"
• Korotkoff sounds
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Blood Pressure (BP): Measurements
Figure 15-7: Measurement of arterial blood pressure
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More Blood Pressures:
Pulse and Mean Arterial Pressures
• Pulse pressure = Systolic–Diastolic
• Mean arterial pressure (MAP) = Diastolic +
1/3 pulse pressure
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More Blood Pressures:
Pulse and Mean Arterial Pressures
Figure 15-5: Pressure throughout the systemic circulation
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Factors Controlling MAP :
The Driving Pressure for Blood Flow
• Blood volume
• Cardiac output
• Resistance
• Distribution
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Factors Controlling MAP :
The Driving Pressure for Blood Flow
Figure 15-10: Factors that influence mean arterial pressure
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Antihypertensive Drug Classes: Action Sites
Blood
Pressure
=
Cardiac
Output

Antihypertensive
Drug Classes
-Blockers
Total Peripheral
Resistance
-Blockers
ACE Inhibitors
AT1 Blockers
Direct renin
inhibitors
1-Blockers
Non-DHP
CCBs
2-Agonists
Diuretics
Diuretics
All CCBs
Sympatholytics
Vasodilators
ACE = angiotensin-converting enzyme; AT1 = angiotensin type 1;
CCBs = calcium channel blockers; DHP = dihydropyridine
Slide Source
Hypertension Online
www.hypertensiononline.org
Classes of Antihypertensive Drugs
• Aldosterone receptor
antagonists (blockers)
• Angiotensin II antagonists
• Angiotensin-converting
enzyme inhibitors
• -Blockers
– 1-Selective
– Nonselective
• -Blockers
– -1/-2
– -1 predominant
– /
– Intrinsic
sympathomimetic activity
• Calcium channel antagonists
– Nondihydropyridine
– Dihydropyridine
• Central 2 agonists
• Direct renin inhibitors
• Direct vasodilators
• Diuretics
– Thiazide-type
– Loop-type
– Potassium-sparing
• Ganglionic blockers
Slide Source
Hypertension Online
www.hypertensiononline.org
Arteriole Resistance: Control of Local Blood Flow
• Myogenic auto regulation
• Paracrines:
• Hyperemia
• Sympathetic nerves – CNS
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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Distribution of Blood in the Body Organs
• Responds to metabolic need
• Precapillary sphincters
• Local & CNS regulators
• Huge variations (example: skeletal m 20-85%)
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Distribution of Blood in the Body Organs
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Figure 15-13: Distribution of blood in the body at rest
Capillary Blood Flow:
Greatest Total Cross Sectional Area
• Lowest Velocity
• Hydrostatic
pressure drops
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Figure 15-17: The velocity of flow depends on the total crosssectional area
Capillary Exchange:
Colloidal Osmotic Pressure is Constant
• Proteins stay in capillary
• Water, oxygen, glucose – move out
• CO2, N wastes, water – move in
• Bulk flow out on arterial side, in on venous side
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Capillary Exchange: Hydrostatic Pressure Declines
• High on arterial side – bulk flow out
• Low on venous side – bulk flow in
• Fenestrations &/or leaky joints speed exchange
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Figure 15-18a: Fluid exchange at the capillary
Net Out Flow Into ECF
• Net filtration – net absorption = net out flow
• About 2 L/day collected by lymph vessels
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Figure 15-18b: Fluid exchange at the capillary
Lymphatic System: Structure and Roles (overview)
• Lymphatic structures
• Capillaries with valves
• Lymph vessels
• Lymph nodes & organs
• Immune defense: lymphocytes
• Transport of fats
• Collects excess ECF
• Returns to plasma
• Edema
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Lymphatic System: Structure and Roles (overview)
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Figure 15-19: The lymphatic system
Lymphatic System: Overview
• Consists of two semi-independent parts
• A meandering network of lymphatic vessels
• Lymphoid tissues and organs scattered
throughout the body
• Returns interstitial fluid and leaked plasma
proteins back to the blood
• Lymph – interstitial fluid once it has entered
lymphatic vessels
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Figure 20.2a
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Lymphatic System: Overview
Figure 20.1a
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Lymphatic Vessels
• A one-way system in which lymph flows toward
the heart
• Lymph vessels include:
• Microscopic, permeable, blind-ended
capillaries
• Lymphatic collecting vessels
• Trunks and ducts
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Lymphatic Capillaries
• Similar to blood capillaries, with modifications
• Remarkably permeable
• Loosely joined endothelial minivalves
• Withstand interstitial pressure and remain
open
• The minivalves function as one-way gates that:
• Allow interstitial fluid to enter lymph
capillaries
• Do not allow lymph to escape from the
capillaries
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Lymphatic Capillaries
• During inflammation, lymph capillaries can
absorb:
• Cell debris
• Pathogens
• Cancer cells
• Cells in the lymph nodes:
• Cleanse and “examine” this debris
• Lacteals – specialized lymph capillaries present in
intestinal mucosa
• Absorb digested fat and deliver chyle to the
blood
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Lymphatic Trunks
• Lymph is delivered into one of two large trunks
• Right lymphatic duct – drains the right upper
arm and the right side of the head and thorax
• Thoracic duct – arises from the cisterna chyli
and drains the rest of the body
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Lymph Transport
• The lymphatic system lacks an organ that acts as a
pump
• Vessels are low-pressure conduits
• Uses the same methods as veins to propel lymph
• Pulsations of nearby arteries
• Contractions of smooth muscle in the walls of
the lymphatics
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Regulation of Blood Pressure and Heart Rate
• Medullary cardiac control center (Brainstem)
• Cardioacceleratory Center
• Cardioinhibitory Center
• Baroreceptor reflex
• Carotid
• Aortic
• Kidney: blood volume
• Hypothalamus & Cortex: stress, blushing, etc.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Regulation of Blood Pressure
Figure 15-22: The baroreceptor reflex: the response to increased blood pressure
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Cardiovascular Diseases: #1 killer
• Risk Factors:
• Smoking
• Obesity
• Diabetes
• Genes
• Diseases:
• Hypertension
• Stroke
• "Heart Attack"
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Mechanism of Atherosclerosis
• LDL build up
• Plaque
•  Flow
• Rupture
• Clot
• Blocked flow
• Tissue death
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How Atherosclerosis Develops
We now understand that atherosclerosis is a chronic inflammation of arteries, which
develops over decades in response to the biologic effects of risk factors.
Atherogenesis begins as a qualitative change to intact endothelial cells; when subjected to
oxidative, hemodynamic, or biochemical stimuli (from smoking, hypertension, or
dyslipidemia) and inflammatory factors, they change their permeability to promote the
entry and retention of blood-borne monocytes and cholesterol-containing LDL particles.
Inflammation and biochemical modifications ensue, causing endothelial and smooth-muscle
cells to proliferate, produce extracellular matrix molecules, and form a fibrous cap over the
developing atheromatous plaque.
Plaques lead to clinical symptoms by producing flow-limiting stenoses (causing stable
angina) or by provoking thrombi that interrupt blood flow on either a temporary basis
(causing unstable angina) or a permanent one (causing myocardial infarction).
Physical disruption (rupture) of the plaque exposes procoagulant material within the core
of the plaque to coagulation proteins and platelets, triggering clotting.
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Mechanism of Atherosclerosis
Figure 15-24: The development of atherosclerotic plaques
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Mechanism of Atherosclerosis
Figure 15-24: The development of atherosclerotic plaques
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Summary
• Blood vessels, anatomy & role in circulation
• Measuring blood pressures, MAP & pulse
pressure
• Role of resistance in BP and distribution of blood
• Autoregulation, baroreceptros, medullary cardiac
control center and CNS regulation of blood
pressure & distribution
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Summary
• Hydrostatic & colloidal osmotic pressures direct
bulk flow in capillary exchange by diffusion,
fenestrations & leaky joints
• Role of lymphatic system to return excess ECF to
plasma
• Atherosclerosis common to several
cardiovascular diseases
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings