Transcript Blood

CHAPTER 23
Circulation and Respiration
PowerPoint® Lectures for
Essential Biology, Third Edition
– Neil Campbell, Jane Reece, and Eric Simon
Essential Biology with Physiology, Second Edition
– Neil Campbell, Jane Reece, and Eric Simon
Lectures by Chris C. Romero
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Biology and Society:
Doped Up
• The 1998 Tour de France
– Was marred by alleged use of performanceenhancing drugs by some teams.
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Figure 23.1
• The drug at the center of the controversy was
erythropoietin (EPO),
– A natural hormone that boosts the production of
red blood cells and that can be harmful if used as
a supplement.
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Unifying Concepts of Animal Circulation
• Every organism must exchange materials with its
environment.
– The purpose of the circulatory system is to
facilitate this exchange.
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Open and Closed Circulatory Systems
• All but the simplest animals have circulatory
systems with three main components:
– A central pump
– A vascular system
– The circulating fluid
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• Open circulatory system
– The heart pumps blood into large open-ended
vessels.
– Fluid circulates freely among cells.
– Many invertebrates, such as molluscs and
arthropods have open circulatory systems.
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Figure 23.2a
• Closed circulatory system
– Blood is confined to vessels and is distinct from
the interstitial fluid.
– Earthworms, octopuses, and vertebrates have
closed circulatory systems.
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Figure 23.2b
• The closed circulatory system in vertebrates is
called a cardiovascular system.
– This system includes the heart and blood vessels.
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The Human Cardiovascular System
• In the human cardiovascular system,
– The central pump is the heart.
– The vascular system is the blood vessels.
– The circulating fluid is the blood.
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The Path of Blood
• In humans and other vertebrates, the three
components of the cardiovascular system are
organized into a double circulation system.
– There are two distinct circuits of blood flow.
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• The pulmonary circuit carries blood between the
heart and the lungs.
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Figure 23.3a
• The systemic circuit carries blood between the
heart and the rest of the body.
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Figure 23.3b
• A trip through the human cardiovascular system
Path of Blood Flow in Mammals
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Figure 23.4
How the Heart Works
• The human heart is a muscular organ about the size
of a fist.
– It is located under the breastbone.
– It has four chambers.
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• The path of blood flow through the human heart
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Figure 23.5
The Cardiac Cycle
• The heart relaxes and contracts regularly:
– Diastole is the relaxation phase of the heart cycle.
– Systole is the contraction phase.
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Figure 23.6
The Pacemaker and the Control of Heart Rate
• The pacemaker, or SA (sinoatrial) node, sets the
tempo of the heartbeat.
• The pacemaker is composed of specialized muscle
tissue in the wall of the right atrium.
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Figure 23.7a
• The impulses sent by the pacemaker produce
electrical currents that can be detected by
electrodes placed on the skin.
– These are recorded in an electrocardiogram (ECG
or EKG).
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• In certain kinds of heart disease, the heart’s
electrical control fails to maintain a normal rhythm.
– The remedy is an artificial pacemaker.
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Figure 23.7b
Blood Vessels
• If the heart is the body’s “pump,” then the
“plumbing” is the system of arteries, veins, and
capillaries.
– Arteries carry blood away from the heart.
– Veins carry blood toward the heart.
– Capillaries allow for exchange between the
bloodstream and tissue cells.
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• All blood vessels are lined by a thin layer of tightly
packed epithelial cells.
– Structural differences in the walls of the different
kinds of blood vessels correlate with their
different functions.
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Figure 23.8
Blood Flow Through Arteries
• The force that blood exerts against the walls of
your blood vessels is called blood pressure.
– Blood pressure is the main force driving the blood
from the heart to the capillary beds.
– A pulse is the rhythmic stretching of the arteries
caused by the pressure of blood forced into the
arteries during systole.
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• Optimal blood pressure for adults is below 120
systolic and below 80 diastolic.
• High blood pressure is persistent systolic blood
pressure higher than 140 and/or diastolic blood
pressure higher than 90.
– It is also called hypertension.
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Blood Flow Through Capillary Beds
• At any given time, about 5–10% of your capillaries
have a steady flow of blood running through them.
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Figure 23.9a
• The walls of capillaries are thin and leaky.
– As blood enters a capillary at the arterial end,
blood pressure pushes fluid rich in oxygen,
nutrients, and other substances into the interstitial
fluid.
– At the venous end of the capillary, CO2 and other
wastes diffuse from tissue cells and into the
capillary bloodstream.
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Figure 23.9b
Blood Return Through Veins
• After chemicals are exchanged between the blood
and body cells, blood returns to the heart via the
veins.
– By the time blood exits the capillaries and enters
the veins, the pressure originating from the heart
has dropped to near zero.
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– Blood still moves through the veins against the
force of gravity.
– As skeletal muscles contract, they help squeeze
the blood along.
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Figure 23.10
Blood
• The circulatory system of an adult human has about
5 L (11 pints) of blood.
– Just over half of this volume is plasma.
– Suspended within the plasma are several types of
cellular elements.
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Figure 23.11
Red Blood Cells and Oxygen Transport
• Red blood cells are by far the most numerous type
of blood cell.
– They are also called erythrocytes.
– Carbohydrate-containing molecules on the surface
determine the blood type.
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Figure 23.12a
• Each red blood cell contains large amounts of the
protein hemoglobin.
– Hemoglobin contains iron and transports oxygen
throughout the body.
– Anemia is an abnormally low amount of
hemoglobin or a low amount of red blood cells.
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White Blood Cells and Defense
• White blood cells fight infections and cancer.
– They are also called leukocytes.
– There are about 700 times fewer white blood cells
than red blood cells.
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Figure 23.12b
Platelets and Blood Clotting
• Blood contains two components that aid in clotting:
– Platelets (thrombocytes) are bits of cytoplasm
pinched off from larger cells in the bone marrow.
– Fibrinogen is a membrane-wrapped protein found
in plasma.
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• Platelets release molecules that convert fibrinogen
into fibrin.
– Fibrin is a threadlike protein.
– Fibrin forms a dense network to create a patch.
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Figure 23.12c
Stem Cells and the Treatment of Leukemia
• New blood cells are continually formed from
unspecialized stem cells found in red bone marrow.
– Stem cells differentiate into red and white blood
cells and the cells that produce platelets.
– Bone marrow cells show great promise for the
treatment of disease.
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• Leukemia is cancer of the white blood cells.
– A person with leukemia has an abnormally high
number of white blood cells, most of which are
defective.
– Leukemia is usually fatal unless treated.
– Not all cases respond to treatment.
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The Role of the Cardiovascular System in
Homeostasis
• The cardiovascular system performs several
homeostatic functions:
– Controlling chemical balance
– Controlling the composition of the blood
– Regulating body temperature
– Distributing hormones
– Defending against foreign invaders
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Cardiovascular Disease
• Cardiovascular disease accounts for 40% of all
deaths in the United States.
– The leading cause of death in the United States is
heart attack.
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• When blood exits the heart, several coronary
arteries immediately branch off to supply the heart
muscle.
– If one or more of these arteries is blocked, the
heart muscle cells will quickly die.
– This is called a heart attack.
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Figure 23.13
• Atherosclerosis is a chronic cardiovascular disease.
– The blood vessels become impaired gradually.
– Vessels are narrowed by plaques of cholesterol
and other substances that form in the inner walls
of arteries.
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Figure 23.14
• How can you avoid becoming a heart disease
victim?
– Don’t smoke.
– Exercise.
– Eat a heart-healthy diet.
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