Download Structure and Function of Blood Vessels

CHAPTER
23
Circulation
Chapter Objectives
Opening Essay
Describe the adaptations of giraffes and humans to circulate blood against the pull of gravity.
Circulatory Systems
23.1
23.1
23.2
Describe the general functions of a circulatory system.
Compare the structures and functions of gastrovascular cavities, open
circulatory systems, and closed circulatory systems.
Compare the cardiovascular systems of a fish, an amphibian, a reptile, a bird,
and a mammal.
The Human Cardiovascular System and Heart
23.3
23.4
23.5
23.6
Describe the pathway of blood through the mammalian cardiovascular system.
Note the names of all blood vessels and heart chambers identified in
Figure 23.3A, B.
Distinguish between diastole and systole. Explain why blood moves in one
direction through the heart.
Explain how heartbeats are controlled.
Define a heart attack and cardiovascular disease. Explain what causes them and
what can be done to reduce the chances of developing cardiovascular disease.
Structure and Function of Blood Vessels
23.7
23.8
Relate the structure of blood vessels to their function.
Explain how and why blood pressure changes as blood moves away from the
heart. Explain how blood is moved back to the heart.
23.9 Explain how blood pressure is measured. Give examples of normal and high
blood pressure readings. Describe lifestyle changes that can help to reduce high
blood pressure.
23.10 Explain how blood flow through capillaries is regulated.
23.11 Explain how the structure of a capillary relates to its functions.
Structure and Function of Blood
23.12 Describe the components of blood and their functions.
23.13 Describe the structure, function, and production of red blood cells. Explain why
exercising at high altitudes, injecting synthetic EPO, and blood doping increase
red blood cell concentrations.
23.14 Describe the process of blood clotting.
23.15 Define leukemia and describe the most common forms of treatment.
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Lecture Outline
I. Introduction
A. In many animals, the pull of gravity influences the flow of blood through the body.
B. To regulate the pressure of blood in the head, the circulatory system of a giraffe uses
1. special valves,
2. saclike sinuses, and
3. other mechanisms.
C. In humans, special one-way valves in veins prevent blood from flowing back down the
legs.
II. Circulatory Systems
A. 23.1 Circulatory systems facilitate exchange with all body tissues
1. All cells must
a. receive nutrients,
b. exchange gases, and
c. remove wastes.
2. Diffusion alone is inadequate for large and complex bodies.
3. In most animals, circulatory systems facilitate these exchanges.
4. An internal transport system assists diffusion by moving materials between
a. surfaces of the body and
b. internal tissues.
5. A gastrovascular cavity in cnidarians and flatworms
a. promotes digestion and
b. distributes substances.
6. Most animals use a true circulatory system that consists of a
a. circulatory fluid (blood),
b. muscular pump (heart), and
c. set of tubes (blood vessels) to carry the fluid.
7. Open circulatory systems are found in arthropods and many molluscs and consist of
a. a heart,
b. open-ended vessels, and
c. blood that directly bathes the cells and functions as the interstitial fluid.
8. Closed circulatory systems are found in vertebrates, earthworms, squids, and
octopuses and consist of
a. a heart and
b. vessels that confine blood, keeping it distinct from interstitial fluid.
9. The vertebrate circulatory system is often called a cardiovascular system, including
three types of vessels.
a. Arteries carry blood away from the heart.
b. Veins return blood to the heart.
c. Capillaries convey blood between arteries and veins.
10. The cardiovascular system of a fish includes a heart with two main chambers:
a. The atrium receives blood from veins.
b. The ventricle pumps blood to gills via large arteries. These large arteries branch
into
i. arterioles that give rise to
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ii. capillaries, the smallest blood vessels that branch into networks called
capillary beds.
iii. Capillaries converge into venules, which in turn converge into larger veins.
B. 23.2 EVOLUTION CONNECTION: Vertebrate cardiovascular systems reflect evolution
1. A two-chambered heart
a. is characteristic of fish and
b. pumps blood in a single circulation in which blood moves
i. from gill capillaries,
ii. to systemic capillaries, and
iii. back to the heart.
2. Land vertebrates have a double circulation consisting of a separate
a. pulmonary circuit and
b. systemic circuit.
3. Three-chambered hearts
a. are found in amphibians, turtles, snakes, and lizards and
b. consist of
i. two atria and
ii. one undivided ventricle.
c. This arrangement generally separates oxygen-poor and oxygen-rich blood.
4. Four-chambered hearts
a. are found in crocodilians, birds, and mammals and
b. consist of
i. two atria and
ii. two ventricles.
c. These two circuits do not mix
i. oxygen-rich and
ii. oxygen-poor blood.
III. The Human Cardiovascular System and Heart
A. 23.3 The human cardiovascular system illustrates the double circulation of mammals
1. Blood flow through the double circulatory system of humans
a. drains from the superior vena cava (from the head and arms) or inferior vena
cava (from the lower trunk and legs) into the right atrium,
b. moves out to the lungs via the pulmonary artery,
c. returns to the left atrium through the pulmonary vein, and
d. leaves the heart through the aorta.
IV. Structure and Function of Blood Vessels
A. 23.7 The structure of blood vessels fits their functions
1. Capillaries
a. have thin walls consisting of a single layer of epithelial cells,
b. are narrow, about as wide as one red blood cell, and
c. increase surface area for gas and fluid exchange with the interstitial fluid.
2. Arteries and veins
a. are lined by a single layer of epithelial cells and
b. have elastic fibers in an outer connective tissue layer that allows these vessels to
recoil after stretching.
c. Arteries contain a thick layer of smooth muscle in their walls that can constrict and
reduce blood flow.
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d. Veins have one-way valves that restrict backward flow of blood.
B. 23.8 Blood pressure and velocity reflect the structure and arrangement of blood vessels
1. Blood pressure
a. is the force blood exerts on vessel walls,
b. depends on cardiac output and resistance of vessels to expansion, and
c. decreases as blood moves away from the heart.
2. Blood pressure is
a. highest in arteries and
b. lowest in veins.
3. Blood pressure is measured as
a. systolic pressure—caused by ventricular contraction and
b. diastolic pressure—low pressure between contractions.
4. How does blood travel against gravity, up legs?
a. Veins are squeezed by pressure from muscle contractions between
i. two muscles or
ii. muscles and bone or skin.
b. One-way valves limit blood flow to one direction, toward the heart.
V. Structure and Function of Blood
A. 23.12 Blood consists of red and white blood cells suspended in plasma
1. Blood consists of several types of cells suspended in a liquid called plasma, which
a. is about 90% water and
b. contains many different substances.
2. Two classes of cells are suspended in blood plasma.
a. Red blood cells or erythrocytes transport O2 bound to hemoglobin.
b. White blood cells, or leukocytes,
i. function inside and outside the circulatory system and
ii. fight infections and cancer.
iii. Monocytes and neutrophils are white blood cells called phagocytes, which
engulf and digest bacteria and debris from our own dead cells.
Key Terms
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aorta
artery
atrium (plural, atria)
blood
blood pressure
capillary
closed circulatory system
double circulation
erythrocyte
heart
inferior vena cava
leukocyte
open circulatory system
plasma
platelet
pulmonary circuit
pulse
single circulation
superior vena cava
systemic circuit
vein
ventricle
Word Roots
atrio- = a vestibule (atrium [plural, atria]: a heart chamber that receives blood from the veins);
-ventriculo = ventricle (atrioventricular node: a region of specialized heart muscle tissue between the left
and right atria)
capill- = hairlike [here, in the sense of a tube with a very small diameter] (capillary: microscopic blood
vessel that conveys blood between an arteriole and a venule)
cardi- = heart; -vascula = a little vessel (cardiovascular disease: any disease of the heart or blood
vessels; cardiovascular system: a closed circulatory system with a heart and branching network of
arteries, capillaries, and veins)
erythro- = red; -cyto = cell (erythrocyte: a red blood cell); -poiet = produce (erythropoietin: a hormone
that stimulates the production of erythrocytes; secreted by the kidney when tissues of the body do not
receive enough oxygen)
fibrino- = a fiber (fibrin: the activated form of the blood-clotting protein fibrinogen, which aggregates
into threads that form the fabric of a blood clot); -gen = produce (fibrinogen: the plasma protein that is
activated to form a clot when a blood vessel is injured)
hyper- = high (hypertension: abnormally high blood pressure, or a persistent blood pressure above
140/90)
leuko- = white (leukemia: a cancer of the blood or bone marrow characterized by the production of an
abnormally high number of leukocytes); -cyto = cell (leukocyte: a white blood cell)
phago- = eat; -cyto- = cell (phagocyte: a white blood cell that engulfs bacteria, foreign proteins, and the
remains of dead body cells)
pulmo- = a lung (pulmonary artery: an artery that transports blood from the heart to the lungs; pulmonary
circuit: one of the two main blood circuits in terrestrial vertebrates; responsible for conveying blood
between the heart and the lungs; pulmonary vein: a vein that transports blood from the lungs to the heart)
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