1. The Circulatory System

2. The Nature of Blood Circulation
General Information…
A circulatory system distributes materials throughout the vertebrate body (and some invertebrates)
Uses a transport medium called blood.
A heart is a muscular organ that pumps the transport medium (blood) through vessels.
Blood and interstitial fluid (fluid between cells) make up the body’s internal environment

3. There are 2 Kinds of Circulatory Systems
Open Or
Closed
Well actually 3 if you consider that Poriferans, like sponges, exchange gases directly with the environment.

4. Direct Circulation: Diffussion.

5. Open Circulatory Systems
Open circulatory system (of arthropods or mollusks)
Blood moves through hearts and large vessels, but also mixes with interstitial fluid
pump
aorta
heart
spaces or cavities
in body tissues
A In a grasshopper’s open system, a heart (not like yours) pumps blood through a vessel, a type of aorta. From there, blood moves into tissue spaces, mingles with interstitial fluid, then reenters the heart at openings in the heart wall.
Figure 37.2
Comparison of open and closed circulatory systems.
Fig. 37-2a, p. 638

6. Closed Circulatory Systems
Closed circulatory system (of annelids (worms) and all vertebrates)
Blood remains inside heart and blood vessels
Molecules (CO2 & O2) diffuse between blood and interstitial fluid at capillaries
dorsal blood vessel
pump
large-diameter blood vessels
large-diameter blood vessels
two of five hearts
ventral blood vessels
gut cavity
capillary bed (many small vessels that serve as a diffusion zone)
Figure 37.2
Comparison of open and closed circulatory systems.
B The closed system of an earthworm confines blood inside pairs of muscular hearts near the head end and inside many blood vessels.
Fig. 37-2b, p. 638

7. Evolution of Circulation in Vertebrates
Fishes
Heart with two chambers
Single circuit of circulation
Amphibians
Heart with three chambers
Two partially separated circuits
Birds and mammals
Heart with four chambers
Two fully separate circuits

8. capillary beds of gills
Single Circuit of Circulation
A In fishes, the heart has two chambers: one atrium and one ventricle. Blood flows through one circuit. It picks up oxygen in the capillary beds of the gills, and delivers it to capillary beds in all body tissues. Oxygen-poor blood then returns to the heart.
capillary beds of gills
heart
Figure 37.3
(a–c) Comparison of flow circuits in the closed circulatory systems of fishes, amphibians, birds, and mammals. Red indicates oxygenated blood; blue, oxygen-poor blood. (d) Analogy illustrating why blood flow slows in capillaries.
rest of body
Fig. 37-3a, p. 639

9. Two Partially Separate Circuits of Circulation
lungs
B In amphibians, the heart has three chambers: two atria and one ventricle. Blood flows along two partially separated circuits. The force of one contraction pumps blood from the heart to the lungs and back. The force of a second contraction pumps blood from the heart to all body tissues and back to the heart.
right atrium
left atrium
ventricle
Figure 37.3
(a–c) Comparison of flow circuits in the closed circulatory systems of fishes, amphibians, birds, and mammals. Red indicates oxygenated blood; blue, oxygen-poor blood. (d) Analogy illustrating why blood flow slows in capillaries.
rest of body
Fig. 37-3b, p. 639

10. Circulation in Birds and Mammals
The four-chambered heart has two separate halves, each with an atrium and a ventricle
Each half pumps blood in a separate circuit
Pulmonary circuit: Blood flows from right half of heart, to lungs (gains oxygen), to left half of heart
Systemic circuit: Blood flows from left half of heart, to body (loses oxygen), to right half of heart

11. Two Fully Separate Circuits of Circulation
lungs
C In birds and mammals, the heart has four chambers: two atria and two ventricles. The blood flows through two fully separated circuits. In one circuit, blood flows from the heart to the lungs and back. In the second circuit, blood flows from the heart to all body tissues and back.
right atrium
left atrium
right ventricle
left ventricle
Figure 37.3
(a–c) Comparison of flow circuits in the closed circulatory systems of fishes, amphibians, birds, and mammals. Red indicates oxygenated blood; blue, oxygen-poor blood. (d) Analogy illustrating why blood flow slows in capillaries.
rest of body
Fig. 37-3c, p. 639

12. Analogy of Slowing Blood in Capillaries
D Why flow slows in capillaries. Picture a volume of water in two fast rivers flowing into and out of a lake. The flow rate is constant, with an identical volume moving from points 1 to 3 in the same interval. However, flow velocity decreases in the lake. Why? The volume spreads out through a larger cross-sectional area and flows forward a shorter distance during the specified interval.
This extra time allows for diffusion of gases, like oxygen into cells and carbon dioxide out of cells, as well as nutrients like sugars, fats, and proteins.
lake
river in
river out 1 2 3 1 2 3
Figure 37.3
(a–c) Comparison of flow circuits in the closed circulatory systems of fishes, amphibians, birds, and mammals. Red indicates oxygenated blood; blue, oxygen-poor blood. (d) Analogy illustrating why blood flow slows in capillaries. 1 2 3
Fig. 37-3d, p. 639

13. Overview of Circulatory Systems
Fill in the blank.
Many animals have either an ________ or a ________ circulatory system that transports substances to and from all body tissues.
Some organisms have neither, achieving basic circulation by __________, which is the direct exchange of important biomolecules with the environment.
All vertebrates have a _______ circulatory system, in which blood is _______________________________.

14. Overview of Circulatory Systems
Many animals have either an open or a closed circulatory system that transports substances to and from all body tissues
Some organisms have neither, achieving basic circulation by diffusion, which is the direct exchange of important biomolecules with the environment.
All vertebrates have a closed circulatory system, in which blood is always contained within the heart or blood vessels

15. Characteristics of Blood
Blood, considering it is made of cells, can be called a large interconnect tissue.

16. Blood Cells
Blood consists mainly of plasma, a protein-rich fluid that carries wastes, gases and nutrients.
Blood cells and platelets form in bone marrow and are transported in plasma.
Platelets are fragments of megakaryocytes, active in clotting.
Red blood cells (erythrocytes)
Contain hemoglobin that carries oxygen from lungs to tissues
Quantified in cell count
White blood cells (leukocytes)
Defend the body from pathogens
Neutrophils, basophils, eosinophils, monocytes, and lymphocytes (B and T cells)

17. Components of Human Blood
Amounts
Main Functions
Plasma Portion (50-60% of total blood volume)
Cellular Portion (40-50% of total blood volume; numbers per microliter)
1. Water
91-92% of total
plasma volume
Solvent
2. Plasma proteins (albumins,
globulins, fibrinogen, etc.
7-8%
Defense, clotting, lipid transport, extracellular fluid volume controls
3. Ions, sugars, lipids, amino
acids, hormones, vitamins,
dissolved gases, etc.
1-2%
Nutrition, defense, respiration, extracellular fluid volume controls, cell communication, etc.
1. Red blood cells
Red blood cell
4,600,000-5,400,000
Oxygen, carbon dioxide transport to and from lungs
2. White blood cells:
Neutophils
Lymphoctyes
Monocytes (macrophages)
Eosinophils
Basophils
White blood cell
3,000-6,750
1,000-2,700
25-90
Fast-acting phagocytosis
Immune responses
Phagocytosis
Killing parasitic worms
Anti-inflammatory secretions
Figure 37.4
Typical components of human blood. Numbers for cellular components are all per microliter. The sketch of a test tube shows what happens when you prevent a blood sample from clotting. The sample separates into straw-colored plasma, which floats on a reddish cellular portion. The scanning electron micrograph shows these components.
3. Platelets
platelet
250, ,000
Roles in blood clotting
Stepped Art
Fig. 37-4, p. 640

18. monocytes (immature phagocytes) B lymphocytes (mature in bone marrow)
Cellular Components of Human Blood
stem cell in bone marrow
myeloid stem cell
lymphoid stem cell
red blood cell
granulocyte
monocyte
precursor
precursor
precursor
megakaryocytes
Figure 37.5
Main cellular components of mammalian blood and how they originate.
platelets
red blood cells (erythrocytes)
neutrophils
basophils
monocytes (immature phagocytes)
T lymphocytes
(mature in
thymus)
eosinophils
B lymphocytes (mature in bone marrow)
Fig. 37-5, p. 641

19. Hemostasis Hemostasis = Heme (blood) stasis (balance)
Keeping blood pressure/volume stable.
How do we stop bleeding?
Initiated by a hormone cascade when an injury is sustained and blood vessels are broken.
Hemostasis is a three-phase process that stops blood loss, constructs a framework for repairs
Damaged vessel constricts
Platelets accumulate
Cascading enzyme reactions involving plasma proteins cause clot formation

20. Three-Phase Process of Hemostasis
Stimulus
A blood vessel is damaged.
Phase 1 response
A vascular spasm constricts the vessel.
Phase 2 response
Platelets stick together plugging the site.
Phase 3 response
Clot formation starts:
1. Enzyme cascade results in activation of Factor X.
Figure 37.6
The three-phase process of hemostasis. The micrograph shows the result of the final clotting phase—blood cells and platelets in a fibrin net.
2. Factor X converts prothrombin in plasma to thrombin
3. Thrombin converts fibrinogen, a plasma protein, to fibrin threads.
4. Fibrin forms a net that entangles cells and platelets, forming a clot.
Stepped Art
Fig. 37-6, p. 642

21. Blood Typing Blood type
Genetically determined differences in molecules on the surface of red blood cells

22. Agglutination Agglutination
Clumping of foreign cells by plasma proteins
When blood of incompatible types mixes, the immune system attacks the unfamiliar molecules
Light micrographs showing (a) an absence of agglutination in a mixture of two different yet compatible blood types and (b) agglutination in a mixture of incompatible types.

23. ABO Blood Typing
Blood type O is a universal donor; blood type AB can receive blood from any donor

24. Mixing ABO Blood Types Blood Type of Donor O A B AB O A
Blood Type of Recipient B
Figure 37.8
Results of mixing blood of the same or differing ABO blood types.
Figure It Out: How many incompatible combinations are shown?
Answer: Seven AB
Fig. 37-8, p. 643

25. Rh Blood Typing
An Rh- mother may develop Rh+ antibodies if blood from an Rh+ child enters her bloodstream during childbirth
These antibodies may attack the red blood cells of the next Rh+ fetus

26. Rh Complications of Pregnancy
How Rh differences can complicate pregnancy.

27. Blood Composition and Function
Fill in the blanks.
Vertebrate blood is a fluid connective ________.
It consists of _______, ________, ________, and _________ (the transport medium)
_____ _______ cells function in gas exchange; _____ _______ cells defend tissues, and _________ function in clotting

28. Blood Composition and Function
Vertebrate blood is a fluid connective tissue
It consists of red blood cells, white blood cells, platelets, and plasma (the transport medium)
Red blood cells function in gas exchange; white blood cells defend tissues, and platelets function in clotting

29. Human Cardiovascular System
The term “cardiovascular” comes from the Greek kardia (for heart) and Latin vasculum (vessel)
In a cardiovascular circuit, blood flows from the heart through arteries, arterioles, capillaries, venules, veins, and back to the heart.

30. Two Circuits of the Human Cardiovascular System
Pulmonary circuit
Oxygen-poor blood flows from the heart, through a pair of lungs, then back to the heart
Blood takes up oxygen in the lungs
Systemic circuit
Oxygenated blood flows from the heart (through the aorta) into capillary beds where it gives up O2 and takes up CO2, then flows back to the heart

31. Pulmonary Circuit of the Human Cardiovascular System
right pulmonary artery
left pulmonary artery
capillary bed
of right lung
capillary bed
of left lung
pulmonary trunk
to systemic circuit
Accessing the lungs to rid blood stream of excess CO2 & to replenish O2
from systemic circuit
Figure 37.10
(a, b) Pulmonary and systemic circuits of the human cardiovascular system.
pulmonary veins
heart
Blood vessels carrying oxygenated blood are shown in red. Those that hold oxygen-poor blood are color-coded blue.
Fig a, p. 644

32. Systemic Circuit of the Human Cardiovascular System
capillary beds of head, upper extremities
(pulmonary vessels to and from thoracic
cavity)
to pulmonary circuit
aorta
from pulmonary circuit
Accessing the rest of the body to deliver O2
& to retrieve CO2
heart
capillary beds of other organs in thoracic cavity
(diaphragm, the muscular partition
between thoracic and abdominal cavities)
capillary bed of liver
Pulmonary and systemic circuits of the human cardiovascular system. Blood vessels carrying oxygenated blood are shown in red. Those that hold oxygen-poor blood are color-coded blue.
Figure 37.10
(a, b)
capillary beds of intestines B
Systemic Circuit for Blood Flow
capillary beds of other abdominal organs and lower extremities

33. Deoxygenated blood brought to the lungs to replenish O2
The Pulmonary Circuit
Does?
Deoxygenated blood brought to the lungs to replenish O2
Oxygenated blood sent to heart to distribute O2 throughout body
The Systemic Circuit
Does?
Blue = deoxygenated
Red = oxygenated

34. The Circulatory System and Homeostasis
food, water intake
oxygen intake
The Circulatory System and Homeostasis
elimination of carbon dioxide
Digestive System
Respiratory System
nutrients, water, salts
carbon dioxide
oxygen
Circulatory System
Urinary System
Figure 37.12
water, solutes
Functional links between the circulatory system and other organ systems with major roles in maintaining the internal environment.
elimination of food residues
rapid transport to and from all living cells
elimination of excess water, salts, wastes
Fig , p. 645

35. The Human Heart
A sac of connective tissue (pericardium) surrounds the heart muscle (myocardium)
Endothelium lines heart chambers and blood vessels
Heart valves keep blood moving in one direction
AV valves separate atria and ventricles
Semilunar valves separate ventricles and arteries

36. B The heart is located between the lungs in the thoracic cavity. 1
The Human Heart
right lung
left lung
ribs 1–8
B The heart is located between the lungs in the thoracic cavity. 1 2 3 4 5 6 7
Figure 37.13
The human heart. 8
pericardium
diaphragm
Fig b, p. 646

37. The Human Heart superior vena cava arch of aorta
(flow from head, arms)
arch of aorta
trunk of pulmonary arteries (to lungs)
right semilunar valve (shown closed) to pulmonary trunk
left semilunar valve (closed) to aorta
right pulmonary
veins (from lungs)
left pulmonary veins
(from lungs)
right atrium
left atrium
right AV valve (opened) = TRICUSPID VALVE
left AV valve (opened) = MITRAL VAVLE
right ventricle
left ventricle
Figure 37.13
The human heart.
(muscles that prevent valve
from everting)
endothelium
and underlying
connective tissue
inferior vena cava (from trunk, legs)
myocardium
septum (partition between heart’s two halves)
inner layer
of pericardium
heart’s apex
Fig a, p. 646

38. The Human Heart
C Outer appearance. Pads of fat on the heart’s surface are normal.
Figure 37.13
The human heart.
Fig c, p. 646

39. The Cardiac Cycle
Cardiac cycle: Heart muscle alternates between diastole (relaxation) and systole (contraction)
Blood collects in atria
AV valves open, blood flows into ventricles
Contraction of ventricles drives blood circulation
Ventricles contract with a wringing motion from bottom to top

40. The Cardiac Cycle A Atria fill. Fluid pressure opens
the AV valves, blood flows into
the ventricles.
B Next, atria contract. As fluid pressure rises in the ventricles, AV valves close. C
Ventricles contract. Semilunar valves open. Blood flows into aorta and pulmonary artery.
D Ventricles relax. Semilunar valves close as atria begin filling for the next cardiac cycle.
Figure 37.14
Cardiac cycle. You can hear the cycle through a stethoscope as a “lub-dup” near the chest wall. At each “lub,” the heart’s AV valves are closing as its ventricles are contracting. At each “dup,” the heart’s semilunar valves are closing as its ventricles are relaxing.
Stepped Art
Fig , p. 647

41. Cardiac Muscle
Cardiac muscle cells are striated (divided into sarcomeres) and have many mitochondria
Cells attach end to end at intercalated discs
Neighboring cells communicate through gap junctions that conduct waves of excitation

42. Cardiac Muscle Cells and Gap Junctions
intercalated disk
a branching cardiac muscle cell (part of one cardiac muscle fiber)
Figure 37.15
(a) Cardiac muscle cells. Compare Figure 32.8b. Many adhering junctions in intercalated disks at the ends of cells hold adjacent cells together, despite the mechanical stress caused by the heart’s wringing motions. (b) The sides of cardiac muscle cells are subject to less mechanical stress than the ends. The sides have a profusion of gap junctions across the plasma membrane.
b Part of a gap junction across the plasma membrane of a cardiac muscle cell. The junctions connect cytoplasm of adjoining cells and allow electrical signals that stimulate contraction to spread swiftly between them.
Fig , p. 647

43. How the Heart Beats Cardiac pacemaker (SA node)
A clump of noncontracting cells in the right atrium’s wall spontaneously fires action potentials about 70 times per minute
Cardiac conduction system
Signal spreads from SA node to AV node and junctional fibers in the septum, so heart contracts in a coordinated fashion

44. The Cardiac Conduction System
SA node
(cardiac pacemaker)
AV node
(the only point of electrical contact between atria and ventricles)
junctional fibers
branchings of junctional fibers (carry electrical signals through the ventricles)
Figure 37.16
The cardiac conduction system.
Fig , p. 647

45. The Human Heart and Two Flow Circuits
Fill in the blanks
The ______-chambered human heart pumps blood through _____ separate circuits of blood vessels
One circuit extends through _____________, the other through _______ tissue only.
Both circuits loop back to the __________, which keeps blood flowing through the _______ circuits.

46. The Human Heart and Two Flow Circuits
The four-chambered human heart pumps blood through two separate circuits of blood vessels
One circuit extends through all body regions, the other through lung tissue only.
Both circuits loop back to the heart, which keeps blood flowing through the two circuits.

47. Part II
Pressure, Transport, and Flow Distribution

48. Major Blood Vessels of the Human Cardiovascular System
Carotid Arteries
Jugular Veins
Ascending Aorta
Superior Vena Cava
Pulmonary Arteries
Pulmonary Veins
Coronary Arteries
Hepatic Vein
Brachial Artery
Renal Vein
Renal Artery
Figure 37.11
Major blood vessels of the human cardiovascular system. This art is simplified for clarity. For example, the arteries or veins labeled for one arm occur in both arms.
Inferior Vena Cava
Abdominal Aorta
Iliac Veins
Iliac Arteries
Femoral Artery
Femoral Vein
Fig , p. 645

49. Pressure, Transport, and Flow Distribution
Contracting ventricles put pressure on the blood, forcing it through a series of vessels
Arteries carry blood from ventricles to arterioles
Arterioles control blood distribution to capillaries
Capillaries exchange substances
Venules collect blood from capillaries
Veins deliver blood back to heart

50. Human Blood Vessels outer coat smooth muscle basement membrane
endothelium
Artery
Figure 37.17
Structural comparison of human blood vessels. The drawings are not to the same scale.
elastic tissue
elastic tissue
Fig a, p. 648

51. Human Blood Vessels outer coat smooth muscle rings over elastic tissue
basement membrane
endothelium
Arteriole
Figure 37.17
Structural comparison of human blood vessels. The drawings are not to the same scale.
Fig b, p. 648

52. Human Blood Vessels basement membrane endothelium Capillary
(venules have a similar structure)
Figure 37.17
Structural comparison of human blood vessels. The drawings are not to the same scale.
Fig c, p. 648

53. Human Blood Vessels outer coat smooth muscle, elastic fibers
basement membrane
endothelium
Vein
valve
Figure 37.17
Structural comparison of human blood vessels. The drawings are not to the same scale.
Fig d, p. 648

54. Blood Pressure Blood pressure
The pressure exerted by blood on the walls of blood vessels
Highest in arteries, then declines through circuit
Rate of blood flow depends on the difference in blood pressure between two points, and resistance to flow

55. arteries capillaries veins
Blood Pressure in the Systolic Circuit: Plot of fluid pressure for a volume of blood as it flows through the systemic circuit. Systolic pressure occurs when ventricles contract, diastolic when ventricles are relaxed.
Figure 37.18
arterioles
venules
Fig , p. 648

56. Blood Flow
Thick, elastic arteries smooth out variations in blood pressure during the cardiac cycle
Arterioles respond to signals from the autonomic and nervous systems, and to chemical signals, to direct blood flow to different parts of the body

57. Distribution of Cardiac Output in a Resting Person
100%
lungs
heart’s right half
heart’s left half
Distribution of Cardiac Output in a Resting Person 6%
liver
21%
digestive tract
20%
kidneys
15%
skeletal muscle
13%
brain
Figure It Out: What percentage of the brain’s blood supply arrives from the heart’s right half?
Answer: None
Figure 37.19
Distribution of the heart’s output in a resting person. How much blood flows through a given tissue can be adjusted by selectively narrowing and widening arterioles all along the systemic circuit.
Figure It Out: What percentage of the brain’s blood supply arrives from the heart’s right half?
Answer: None 9%
skin 5%
bone 3%
cardiac muscle 8%
all other regions
Fig , p. 649

58. Controlling Blood Pressure
Blood pressure depends on total blood volume, how much blood the ventricles pump (cardiac output), and whether arterioles are constricted or dilated
Receptors in the aorta and carotid arteries monitor blood pressure and send signals to the medulla, which regulates cardiac output and arteriole diameter

59. Measuring Blood Pressure

60. Diffusion at Capillaries, Then Back to the Heart
Capillary
A cylinder of endothelial cells, one cell thick
Capillary beds are diffusion zones, where blood exchanges substances with interstitial fluid
Hydrostatic pressure moves materials out (ultrafiltration)
Osmotic pressure moves water in (capillary reabsorption)

61. Fluid Movement at a Capillary Bed
blood to venule
high pressure
causes outward flow
inward-directed osmotic movement
cells of tissue
blood from arteriole B
Figure 37.21 A
Fluid movement at a capillary bed. Fluid crosses a capillary wall by way of ultrafiltration and reabsorption. (a) At the capillary’s arteriole end, a difference between blood pressure and interstitial fluid pressure forces out plasma, but few plasma proteins, through clefts between endothelial cells of the capillary wall. Ultrafiltration is the outward flow of fluid across the capillary wall as a result of hydrostatic pressure. (b) Reabsorption is the osmotic movement of some interstitial fluid into the capillary. It happens when the water concentration between interstitial fluid and the plasma differs. Plasma, with its dissolved proteins, has a greater solute concentration and therefore a lower water concentration. Reabsorption near the end of a capillary bed tends to balance ultrafiltration at the start of it. Normally, there is only a small net filtration of fluid, which vessels of the lymphatic system return to blood (Section 37.10).

62. Venous Pressure Venules deliver blood from capillaries to veins
Veins deliver blood to the heart
Large-diameter, blood volume reservoirs
Valves help prevent backflow
Amount of blood in veins varies with activity level

63. Venous Valve Action venous valve
Venous valve action. (a) Valves in medium-sized veins prevent the backflow of blood. Adjacent skeletal muscles helps raise fluid pressure inside a vein. (b) These muscles bulge into a vein as they contract. Pressure inside the vein rises and helps keeps blood flowing forward. (c) When muscles relax, the pressure that they exerted on the vein is lifted. Venous valves shut and cut off backflow.
Figure 37.22
Venous valve action. (a) Valves in medium-sized veins prevent the backflow of blood. Adjacent skeletal muscles helps raise fluid pressure inside a vein. (b) These muscles bulge into a vein as they contract. Pressure inside the vein rises and helps keeps blood flowing forward. (c) When muscles relax, the pressure that they exerted on the vein is lifted. Venous valves shut and cut off backflow.
venous valve
Fig a, p. 651

64. valve closed valve closed blood flow to heart valve open valve closed
Figure 37.22
valve closed
valve closed

65. Key Concepts Blood Vessel Structure and Function
The heart pumps blood rhythmically, on its own
Adjustments at arterioles regulate how blood volume is distributed among tissues
Exchange of gases, wastes, and nutrients between the blood and tissues takes place at capillaries

66. Blood and Cardiovascular Disorders
Red blood cell disorders
Anemias, beta-thalassemias, polycythemia
White blood cell disorders
Infectious mononucleosis, leukemias, lymphomas
Clotting disorders
Hemophilia, thrombus, embolus

67. Blood and Cardiovascular Disorders
Atherosclerosis
Buildup of lipids in the arterial wall that narrows the lumen, may rupture and trigger heart attack

68. wall of artery, cross-section
unobstructed lumen of
a normal
artery
Figure 37.23
Sections from (a) a normal artery and (b) an artery with a lumen narrowed by an atherosclerotic plaque. A clot clogged this one.
Fig a, p. 652

69. atherosclerotic plaque
blood clot sticking to plaque
Figure 37.23
Sections from (a) a normal artery and (b) an artery with a lumen narrowed by an atherosclerotic plaque. A clot clogged this one.
narrowed lumen
Fig b, p. 652

70. Clogged Coronary Arteries

71. coronary artery
Figure 37.24
The photo shows coronary arteries and other blood vessels that service the heart. Resins were injected into them. Then the cardiac tissues were dissolved to make an accurate, three-dimensional corrosion cast.
Fig a, p. 653

72. coronary artery blockage
The sketch shows two coronary bypasses (color-coded green), which extend from the aorta past two clogged parts of the coronary arteries.
aorta
coronary artery blockage
location of a shunt made of a section taken from one of the patient’s other blood vessels
Figure 37.24
The photo shows coronary arteries and other blood vessels that service the heart. Resins were injected into them. Then the cardiac tissues were dissolved to make an accurate, three-dimensional corrosion cast. The sketch shows two coronary bypasses (color-coded green), which extend from the aorta past two clogged parts of the coronary arteries.
Fig b, p. 653

73. Blood and Cardiovascular Disorders
Hypertension – a silent killer
Chronic blood pressure above 140/90
High blood pressure and atherosclerosis increase the risk of heart attack and stroke

74. Arrhythmias – abnormal heart rhythms
Blood and Cardiovascular Disorders
one normal heartbeat
Arrhythmias – abnormal heart rhythms
EKGs record electrical activity of cardiac cycle a
time (seconds)
bradycardia (here, 46 beats per minute) b
tachycardia (here, 136 beats per minute)
Figure 37.25
(a) ECG of one normal beat of the human heart. (b–d) Recordings that identified three types of arrhythmias. c
ventricular fibrillation d
Fig , p. 653

75. Risk Factors
Cardiovascular disorders are the leading cause of death in the United States
Risk factors
Tobacco smoking, family history, hypertension, high cholesterol, diabetes mellitus, obesity, age, physical inactivity, gender

76. Key Concepts When the System Breaks Down
Cardiovascular problems include clogged blood vessels or abnormal heart rhythms
Some problems have a genetic basis; most are related to age or life-style