CHAPTER 49 Circulatory Systems

Chapter 49: Circulatory Systems

CHAPTER 49Circulatory Systems


Chapter 49: Circulatory SystemsCirculatory Systems: Pumps, Vessels, Circulatory Systems: Pumps, Vessels,

and Bloodand Blood

Vertebrate Circulatory SystemsVertebrate Circulatory Systems

The Human Heart: Two Pumps in OneThe Human Heart: Two Pumps in One


Chapter 49: Circulatory SystemsThe Vascular System: Arteries, Capillaries, and Veins

Blood: A Fluid Tissue

Control and Regulation of Circulation Control and Regulation of Circulation


Circulatory Systems: Pumps, Vessels, and Blood• Metabolic needs of the cells of small

aquatic animals are met by direct exchange of materials with the external medium.

• Those of the cells of larger animals are met by a circulatory system that transports nutrients, respiratory gases, and metabolic wastes throughout the body.

Review Figure 49.14


49.1

Figure 49.1

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Circulatory Systems: Pumps, Vessels, and Blood• In open circulatory systems the blood

or tissue fluid leaves vessels and percolates through tissues.

Review Figure 49.2

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49.2

Figure 49.2

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Circulatory Systems: Pumps, Vessels, and Blood• In closed circulatory systems the blood

is contained in a system of vessels.

Review Figure 49.3

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49.3

Figure 49.3

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Vertebrate Circulatory Systems• The circulatory systems of vertebrates The circulatory systems of vertebrates

consist of a heart and a closed system consist of a heart and a closed system of vessels containing blood separate of vessels containing blood separate from tissue fluid. from tissue fluid.

• Arteries and arterioles carry blood Arteries and arterioles carry blood from the heart; from the heart;

• Capillaries are the site of exchange Capillaries are the site of exchange between blood and tissue fluid; between blood and tissue fluid;

• Venules and veins carry blood back to Venules and veins carry blood back to the heart.the heart.

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Vertebrate Circulatory Systems• The vertebrate heart evolved from two The vertebrate heart evolved from two

chambers in fishes to three in chambers in fishes to three in amphibians and reptiles and four in amphibians and reptiles and four in crocodilians, mammals, and birds. crocodilians, mammals, and birds.

• This progression has led to an This progression has led to an increasing separation of blood flow to increasing separation of blood flow to the gas exchange organs and to the the gas exchange organs and to the rest of the body.rest of the body.

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Vertebrate Circulatory Systems

• In birds and mammals, blood In birds and mammals, blood circulates through the pulmonary circulates through the pulmonary circuit and the systemic circuit.circuit and the systemic circuit.

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The Human Heart: Two Pumps in One

• The human heart has four chambers. The human heart has four chambers.

• Valves prevent the backflow of blood. Valves prevent the backflow of blood.

Review Figure 49.4Review Figure 49.4

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49.4

Figure 49.4 – Part 1Figure 49.4 – Part 1

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• The cardiac cycle has two phases: The cardiac cycle has two phases: systole, in which the ventricles contract; systole, in which the ventricles contract; and diastole, in which they relax. and diastole, in which they relax.

• Sequential heart sounds are made by Sequential heart sounds are made by heart valves closing. heart valves closing.


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Figure 49.5Figure 49.5

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• Blood pressure can be measured using Blood pressure can be measured using a sphygmomanometer and a a sphygmomanometer and a stethoscope. stethoscope.


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49.6


figure 49-06.jpg


The Human Heart: Two Pumps in One• The autonomic nervous system The autonomic nervous system

controls heart rate. controls heart rate.

• Sympathetic activity increases it, Sympathetic activity increases it, parasympathetic activity decreases it. parasympathetic activity decreases it.

• This is due to the effects of This is due to the effects of norepinephrine and acetylcholine on norepinephrine and acetylcholine on the depolarization rate of the the depolarization rate of the membranes of pacemaker cells. membranes of pacemaker cells.


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• The sinoatrial node controls the The sinoatrial node controls the cardiac cycle by initiating a wave of cardiac cycle by initiating a wave of depolarization in the atria, which is depolarization in the atria, which is conducted to the ventricles through conducted to the ventricles through the atrioventricular node. the atrioventricular node.


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• The EKG records electric potentials The EKG records electric potentials resulting from contraction and resulting from contraction and relaxation of cardiac muscles. relaxation of cardiac muscles.


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The Vascular System: Arteries, Capillaries, and Veins• Arteries and arterioles have many Arteries and arterioles have many

elastic fibers enabling them to elastic fibers enabling them to withstand high pressures. withstand high pressures.

• Abundant smooth muscle cells allow Abundant smooth muscle cells allow them to contract and expand, altering them to contract and expand, altering their resistance and thus blood flow. their resistance and thus blood flow.


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49.10


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The Vascular System: Arteries, Capillaries, and Veins• Capillary beds are the site of exchange Capillary beds are the site of exchange

of materials between blood and tissue of materials between blood and tissue fluid.fluid.

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The Vascular System: Arteries, Capillaries, and Veins• Fluid exchange between blood and

tissues is determined by the balance between blood pressure and osmotic potential in the capillaries.

Review Figure 49.12

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49.12


figure 49-12.jpg


The Vascular System: Arteries, Capillaries, and Veins• The ability of a specific molecule to The ability of a specific molecule to

cross a capillary wall depends on cross a capillary wall depends on

– Capillary architecture, Capillary architecture,

– type of substance, and type of substance, and

– concentration gradient between the concentration gradient between the blood and tissue fluid.blood and tissue fluid.

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The Vascular System: Arteries, Capillaries, and Veins• A separate system of vessels, the A separate system of vessels, the

lymphatic system, returns the tissue lymphatic system, returns the tissue fluid to the blood.fluid to the blood.

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The Vascular System: Arteries, Capillaries, and Veins• Veins have a high capacity for storing Veins have a high capacity for storing

blood. Aided by gravity, contractions of blood. Aided by gravity, contractions of skeletal muscle, and the actions of skeletal muscle, and the actions of breathing, they carry blood back to the breathing, they carry blood back to the heart. heart.


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49.13


figure 49-13.jpg


The Vascular System: Arteries, Capillaries, and Veins• Cardiovascular disease is responsible Cardiovascular disease is responsible

for about half of all deaths in the U.S. for about half of all deaths in the U.S. and Europe. and Europe.

• Atherosclerosis and thrombus Atherosclerosis and thrombus formation can lead to potentially fatal formation can lead to potentially fatal conditions such as heart attack and conditions such as heart attack and stroke. stroke.

• Diet and behavior are the keys to good Diet and behavior are the keys to good cardiovascular health.cardiovascular health.

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• Blood can be divided into a plasma portion and a cellular portion.

• All of the cellular components are produced from stem cells in the bone marrow.

Review Figure 49.15

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49.15

Figure 49.15

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• Red blood cells transport respiratory gases.

• Their production in the bone marrow is stimulated by erythropoietin, which is produced in response to hypoxia in the tissues.

Review Figure 49.16

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49.16

Figure 49.16

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• Platelets, along with circulating proteins, are involved in clotting responses.

Review Figure 49.17

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49.17 – Part 1

Figure 49.17 – Part 1

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Figure 49.17 – Part 249.17

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Figure 49.17 – Part 2



• Plasma is a complex solution containing gases, ions, nutrient molecules, proteins, and other molecules.

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Control and Regulation of Circulation

• Blood flow through capillary beds is controlled by local autoregulation mechanisms, hormones, and the autonomic nervous system.

Review Figure 49.18

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49.18

Figure 49.18

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• Blood pressure is controlled in part by the hormones vasopressin and angiotensin, which stimulate contraction of blood vessels.

Review Figure 49.19

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49.19

Figure 49.19

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• Heart rate is controlled by the autonomic nervous system.

• It responds to information about blood pressure and blood composition that is integrated by the brain’s regulatory centers.

Review Figure 49.20

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Figure 49.20

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• Diving mammals conserve blood oxygen stores by slowing the heart rate during dives.

Review Figure 49.21

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Figure 49.21

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CHAPTER 49 Circulatory Systems