CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 23 The Cardiovascular System

CHAPTER

© 2011 The McGraw-Hill Companies, Inc. All rights reserved.

23The Cardiovascular

System


23-2

Learning Outcomes

23.1 Describe the structure of the heart and the function of each part.

23.2 Trace the flow of blood through the heart.

23.3 List the most common heart sounds and what events produce them.

23.4 Explain how heart rate is controlled by the electrical conduction system of the heart.


23-3

Learning Outcomes (cont.)

23.5 List the different types of blood vessels and describe the functions of each.

23.6 Define blood pressure and tell how it is controlled.

23.7 Trace the flow of blood through the pulmonary and systemic circulation.

23.8 List the major arteries and veins of the body and describe their locations.


23-4


23.9 List and describe the components of blood.

23.10 Give the functions of red blood cells, the different types of white blood cells, and platelets.

23.11 List the substances normally found in plasma.

23.12 Explain how bleeding is controlled.

23.13 Explain the differences among blood types A, B, AB, and O.


23-5


23.14 Explain the difference between Rh-positive blood and Rh-negative blood.

23.15 Explain the importance of blood typing and tell which blood types are compatible.

23.16 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the cardiovascular system.


23-6

Introduction • The cardiovascular system consists of heart

and blood vessels

• Sends blood to– Lungs for oxygen– Digestive system for nutrients

• Also circulates waste products to certain organ systems for removal from the blood


23-7

Structures of the Heart• Cone-shaped organ

about the size of a loose fist

• In the mediastinum • Extends from the

level of the second rib to about the level of the sixth rib

• Slightly left of the midline


23-8

Structures of the Heart (cont.)

Heart is bordered: Laterally by the lungs Posteriorly by the vertebral

column Anteriorly by the sternum

Rests on the diaphragm inferiorly


23-9


• Heart coverings– Pericardium

• Covers the heart and large blood vessels attached to the heart

• Visceral pericardium

– Innermost layer

– Directly on the heart

• Parietal pericardium

– Layer on top of the visceral pericardium

• Heart walls:– Epicardium

• Outermost layer• Fat to cushion heart

– Myocardium • Middle layer • Primarily cardiac muscle

– Endocardium • Innermost layer• Thin and smooth• Stretches as the heart

pumps

Click for Larger View


23-11


• Four chambers– Two atria

• Upper chambers• Left and right• Separated by

interatrial septum

– Two ventricles• Lower chambers• Left and right• Separated by

interventricular septum

Click for View of

Heart

Atrioventricular septum separates the atria from the ventricles


23-12


• Tricuspid valve – prevents blood from flowing back into the right atrium when the right ventricle contracts

• Bicuspid (mitral) valve – prevents blood from flowing back into the left atrium when the left ventricle contracts

• Pulmonary semilunar valve – prevents blood from flowing back into the right ventricle

• Aortic semilunar valve – prevents blood from flowing back into the left ventricle

Click for View of

Heart


23-14

Blood Flow Through the Heart

Deoxygenated blood in from

bodyOxygenated blood

in lungs

Atria Contract Ventricles Contract

Deoxygenated blood out to lungs

Oxygenated blood out to

body


23-15

Blood Flow Through the Heart (cont.)

Right Atrium

Right Ventricle

PulmonarySemilunar

Valve

Left Atrium

BicuspidValve

Left Ventricle

PulmonaryValve

TricuspidValve

LungsBody

AorticSemilunar

Valve


23-16

Cardiac Cycle

• Right atrium contracts– Tricuspid valve opens – Blood fills right ventricle

• Right ventricle contracts– Tricuspid valve closes– Pulmonary semilunar valve

opens– Blood flows into pulmonary

artery

• Left atrium contracts – Bicuspid valve opens – Blood fills left ventricle

• Left ventricle contracts– Bicuspid valve closes– Aortic semilunar valve

opens– Blood pushed into aorta

One heartbeat = one cardiac cycle Atria contract and relax Ventricles contract and relax


23-17

Cardiac Cycle (cont.)

• Influenced by– Exercise– Parasympathetic nerves– Sympathetic nerves– Cardiac control center– Body temperature– Potassium ions– Calcium ions


23-18

Heart Sounds

• One cardiac cycle – two heart sounds (lubb and dubb) when valves in the heart snap shut– Lubb – first sound

• When the ventricles contract, the tricuspid and bicuspid valves snap shut

– Dubb – second sound • When the atria contract and the pulmonary and

aortic valves snap shut


23-19

Cardiac Conduction System• Group of structures that send electrical impulses through

the heart

• Sinoatrial node (SA node)– Wall of right atrium– Generates impulse– Natural pacemaker– Sends impulse to AV node

• Atrioventricular node (AV node)– Between atria just above ventricles– Atria contract– Sends impulse to the bundle of His

• Bundle of His– Between ventricles– Two branches – Sends impulse to Purkinje

fibers

• Purkinje fibers– Lateral walls of ventricles– Ventricles contract

Click the i below for a Diagram


23-20

Cardiac Conduction

System

Back


23-21

Apply Your Knowledge

Match the following:

__ Tricuspid valve A. Two branches; sends impulse to Purkinje fibers

__ Bicuspid valve B. Covering of the heart and aorta

__ Pericardium C. Between the right atrium and the right ventricle

__ SA node D. In the lateral walls of ventricles

__ Bundle of His E. Natural pacemaker

__ Purkinje fibers F. Between the left atrium and the left ventricle D

A

E

B

F

C

ANSWER:


23-22

Blood Vessels

• Closed pathway that carries blood from the heart to cells and back to the heart

• Types– Arteries– Arterioles– Veins

– Venules– Capillaries


23-23

Arteries and Arterioles • Strongest of the

blood vessels• Carry blood away

from the heart• Under high pressure

– Vasoconstriction– Vasodilation

• Arterioles– Small branches of

arteries

• Aorta– Takes blood from the

heart to the body

• Coronary arteries– Supply blood to heart

muscle


23-24

Veins and Venules • Blood under no pressure

in veins

– Does not move very easily

– Skeletal muscle contractions help move blood

– Sympathetic nervous system also influences pressure

• Valves prevent backflow

• Venules

– Small vessels formed when capillaries merge

• Superior and inferior vena cava

– Largest veins

– Carry blood into right atrium


23-25

Capillaries• Branches of arterioles

• Smallest type of blood vessel

• Connect arterioles to venules

• Only about one cell layer thick

• Oxygen and nutrients can pass out of a capillary into a body cell

• Carbon dioxide and other waste products pass out of a body cell into a capillary


23-26


How do arteries control blood pressure?

ANSWER: The muscular walls of arteries can constrict to increase blood pressure or dilate to decrease blood pressure.


23-27

Blood Pressure• Force blood exerts on the inner walls of blood vessels

– Highest in arteries – Lowest in veins

• Systolic pressure – Ventricles contract– Blood pressure in arteries is at its greatest

• Diastolic pressure – Ventricles relax– Blood pressure in arteries is at its lowest

• Reported as the systolic number over the diastolic number


23-28

Blood Pressure (cont.)

• Control is based mainly on the amount of blood pumped out of the heart

• The amount of blood entering should equal the amount pumped from the heart

• Starling's law of the heart – Blood entering the left ventricle stretches the wall of the ventricle– The more the wall is stretched

• The harder it will contract and • The more blood it will pump out


23-29

Blood Pressure (cont.)

• Baroreceptors – Also help regulate blood pressure

– Located in the aorta and carotid arteries

– High blood pressure in aorta message to cardiac center in brain decreases heart rate lowers blood pressure

– Low blood pressure in aorta message to cardiac center in the brain increases heart rate increases blood pressure


23-30


What is the difference between the systolic pressure and diastolic pressure?

ANSWER: Systolic pressure is the result of the contraction of the ventricles increasing the pressure in the arteries. Diastolic pressure is the result of the relaxation of the ventricles lowering the pressure in the arteries.

Good Answer!


23-31

Circulation

• Pulmonary circuit right atrium right ventricle pulmonary artery trunk pulmonary arteries lungs

pulmonary veins heart (left atrium)

• Systemic circuitleft atrium left ventricle aorta arteries

arterioles capillaries venules veins vena cava heart (right atrium)


23-32

Circulation (cont.)

• Arterial system– Carries oxygen-rich

blood away from the heart

– Pulmonary arteries carry oxygen-poor blood

– Paired – left and right artery of the same name


23-33

Circulation (cont.)

• Venous system– Carries oxygen-poor

blood toward the heart

• Except pulmonary veins

– Most large veins have the same names as the arteries they are next to

Hepatic portal system Collection of veins

carrying blood to the liver

Click for Larger View


23-35


ARTERIES: Pulmonary arteries carry oxygen-poor blood.

Do pulmonary arteries carry blood with high levels of oxygen or low levels of oxygen?


23-36

Blood

• A type of connective tissue

– Red blood cells (erythrocytes)

– White blood cells (leukocytes)

– Platelets – cell fragments

– Plasma – fluid part of blood

Average-sized adult has 4 to 6 liters of blood

Amount depends on: Size of person Amount of adipose tissue Concentrations of ions Females have less than

males

Average-sized adult has 4 to 6 liters of blood

Amount depends on: Size of person Amount of adipose tissue Concentrations of ions Females have less than

males


23-37

Blood Components

• Hematocrit – The percentage of

red blood cells– Normal is about

45%

• White cells and platelets = 1%

• Plasma = 55% © Cre8tive StudiosAlamy RF


23-38

Red Blood Cells• Erythrocytes • Transport oxygen throughout the body• Small biconcave-shaped cells • Hemoglobin is a pigment in RBCs

– Oxyhemoglobin carries oxygen; bright red – Deoxyhemoglobin does not carry oxygen; darker

red • Carries carbon dioxide, so also called carboxyhemoglobin

– Anemia – low RBC count• Erythropoietin – regulates production of

RBCs


23-39

Red Blood Cells (cont.)

© Cre8tive StudiosAlamy RF


23-40

White Blood Cells • Granulocytes

– Neutrophils (55%) –destroy bacteria, viruses, and toxins in the bloodstream (phagocytes)

– Eosinophils (3%) – get rid of parasitic infections such as worm infections

– Basophils (1%) – control inflammation and allergic reactions

• Agranulocytes– Monocytes (8%) – destroy bacteria, viruses, and

toxins in blood – Lymphocytes (33%) – provide immunity for the body


23-41

White Blood Cells (cont.)

• WBC count normally 5000 to 10,000 cells per cubic millimeter of blood– Leukocytosis

• Elevated WBC count• Usually due to infection

– Leukopenia • Low WBC count• Some viral infections and other conditions


23-42

Platelets

• Fragments of cells found in the bloodstream

• Also called thrombocytes • Important in the clotting process of blood• Normal count

– 130,000 to 360,000 platelets per cubic millimeter of blood


23-43

Plasma• Liquid portion of blood

composed mostly of water

• Proteins– Albumins

• Smallest plasma proteins

• Pull water in to help maintain blood pressure

– Globulins – transport lipids and fat-soluble vitamins

– Fibrinogen – needed for blood clotting

• Nutrients– Amino acids– Glucose– Nucleotides– Lipids from the

digestive tract

• Gases – oxygen, carbon dioxide, and nitrogen

• Electrolytes• Waste products


23-44

Bleeding Control• Hemostasis – the control of bleeding

• Three processes of hemostasis– Blood vessel spasm– Platelet plug formation– Blood coagulation


23-45

Platelet plug formation:


23-46

Blood Types

• Types are distinguished by antigens and antibodies

• Agglutination– Clumping of red blood

cells – Antigens on surface of

RBCs bind to antibodies in plasma


23-47

Blood Types (cont.)

Blood Type Antigen Present

Antibody Present

Blood That Can Be Received

A A B A and O

B B A B and O

AB AB None A, B, AB, and O

O None A and B O


23-48

Blood Types (cont.)

• Rh antigen – protein on RBCs

• Rh-positive– RBCs contain the

Rh antigen

• Rh-negative – RBCs do not contain

the Rh antigen

• Rh-positive blood is

given to Rh-negative person– Antibodies form

• If Rh-negative person receives more Rh-positive blood– Antibodies bind to the

donor cells – Agglutination occurs


23-49


True or False:

__ Hematocrit is the percentage of WBCs in the blood.

__ Neutrophils destroy bacteria, viruses, and toxins in the bloodstream.

__ Platelets are important to the clotting process.

__ Albumin is a small plasma protein that pushes water out of the bloodstream.

__ Hemostasis is the control of bleeding.

__ A person with type AB blood can only receive type AB blood.

__ Blood should be matched for Rh factor.

pulls water into

RBCs

receive any type of blood

T

T

F

T

F

T

F

ANSWER:


23-50

Chest Pain

• Cardiac– Myocardial infarction– Angina– Pericarditis– Coronary spasm

• Non-cardiac– Heartburn– Panic attacks– Pleurisy– Costochondritis – Pulmonary embolism– Sore muscles– Broken ribs

Take all complaints of chest pain seriously!


23-51

Chest Pain (cont.)

• Determine cause– Electrocardiogram– Stress tests– Blood tests– Chest x-ray– Nuclear scan– Coronary

catheterization– Echocardiogram – Endoscopy


23-52

Diseases and Disorders of the Cardiovascular System

Disease Description

Anemia The blood does not have enough red blood cells or hemoglobin to carry an adequate amount of oxygen to the body’s cells

Aneurysm A ballooned, weakened arterial wall

Arrhythmias Abnormal heart rhythms

Carditis Inflammation of the heart

Endocarditis Inflammation of the innermost lining of the heart, including valves


23-53

Diseases and Disorders of the Cardiovascular System (cont.)

Disease Description

Myocarditis Inflammation of the muscular layer of the heart

Pericarditis Inflammation of the membranes that surround the heart (pericardium)

Congestive heart failure

Weakening of the heart over time; heart is unable to pump enough blood to meet body’s needs

Coronary artery disease (CAD)

Atherosclerosis; narrowing of coronary arteries caused by hardening of the fatty plaque deposits within the arteries


23-54


Disease Description

Hypertension High blood pressure; consistent resting blood pressure equal to or greater than 140/90 mm Hg

Leukemia Bone marrow produces a large number of abnormal WBCs

Murmurs Abnormal heart sounds

Myocardial infarction

Heart attack; damage to cardiac muscle due to a lack of blood supply


23-55


Disease Description

Sickle cell anemia

Abnormal hemoglobin causes RBCs to change to a sickle shape; abnormal cells stick in capillaries

Thalassemia Inherited form of anemia; defective hemoglobin chain causes, small, pale, and short-lived RBCs

Thrombophlebitis

Blood clots and inflammation develop in a vein

Varicose veins

Twisted, dilated veins


23-56


ANSWER: Anemia is a condition in which a person does not have enough red blood cells or hemoglobin in the blood to carry an adequate amount of oxygen to body cells.

The doctor has told your patient she has anemia. How would you explain this to her?

Bravo!


23-57

In Summary

23.1 The structures of the heart include the pericardium, epicardium, myocardium, and endocardium.

– The chambers of the heart consist of the upper atria and the lower ventricles.

– The septums are interatrial, interventricular, and atrioventricular.

– The four valves within the heart are tricuspid, bicuspid, pulmonary semilunar valve, and the aortic semilunar valve.


23-58

In Summary (cont.)

23.2 Superior and inferior vena cavae → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → right and left pulmonary arteries → the lungs → pulmonary veins → left atrium → bicuspid valve →left ventricle → aortic semilunar valve → aorta → body organs and tissues.

23.3 Heart sounds are described as lubb dubb. Lubb is created when the ventricles contact and the tricuspid and bicuspid valves snap shut. Dubb occurs when the atria contract and the pulmonary and aortic semilunar valves snap shut.


23-59

In Summary (cont.)

23.4 The sinoatrial node generates an impulse to the atrioventricular node. The AV node then sends the impulse to the bundle of His. The bundle splits into the left and right bundle branches and sends the impulse to the Purkinje fibers in the ventricles.

23.5 The arterial system is composed of the aorta, arteries, and arterioles (largest to smallest) bring blood from the heart to the body. The capillaries act as the connectors between the arterioles and venules. From the venules, blood returns to the heart via the veins to the superior and inferior vena cavae.


23-60

In Summary (cont.)

23.6 Blood pressure is the force exerted on the inner wall of blood vessels by blood as it flows through vessels. It is highest in arteries and lowest in veins.

Clinically, BP refers to the force of blood within the arteries.

Blood pressure is largely controlled by the amount of blood pumped out of the heart, but various other events may also raise and lower BP.


23-61

In Summary (cont.)

23.7 Pulmonary circulation: right atrium→ tricuspid valve → right ventricle→pulmonary semilunar valve → pulmonary trunk→pulmonary arteries→lungs→pulmonary veins→left atrium.

Systemic circulation: left atrium→bicuspid valve→left ventricle→aortic semilunar valve → aorta → arteries → arterioles→capillaries→venules→veins→vena cavae→right atrium.


23-62

In Summary (cont.)

23.8 The largest artery in the body is the aorta. Other major arteries include lingual, facial, occipital, maxillary, ophthalmic, axillary, brachial, ulnar, radial, intercostals, lumbar, external iliac, common iliac, femoral, popliteal, and tibial.

The largest veins in the body are the superior and inferior vena cavae. Other major veins are jugular, brachiocephalic, axillary, brachial, ulnar, radial, intercostals, azygos, gastric, splenic, mesenteric, hepatic portal, hepatic, iliac, femoral, popliteal, and saphenous.


23-63

In Summary (cont.)

23.9 The components of blood are red blood cells (RBC), white blood cells (WBC), platelets, and plasma.

23.10Red blood cells carry oxygen and carbon dioxide throughout the body. White blood cells are divided into two types: granulocytes and agranulocytes. Granulocytes include neutrophils, eosinophils, and basophils. Agranulocytes include lymphocytes and monocytes. Platelets are essential in the blood clotting process.

23.11Plasma contains three major proteins: albumins, globulins, and fibrinogen.


23-64

In Summary (cont.)

23.12Hemostasis is bleeding control. When a blood vessel breaks, the vessel wall spasms and reduces blood loss.

Platelets stick to the broken area and to each other, forming a platelet plug.

A blood clot occurs when fibrinogen converts to fibrin, which sticks to the damaged area of the blood vessel, creating a meshwork to trap blood cells and platelets, which will remain while tissues repair themselves.


23-65

In Summary (cont.)

23.13Blood types are named for the antigen present on the cell surfaces. The “opposite” letter is the name of the antibody present. Blood type A has antigen A and antibody B; blood type B has antigen B and antibody A; blood type AB has antigens A and B and 0 (zero) antibodies; Blood type O has no antigens present and both A and B antibodies.

23.14Rh-positive blood contains the Rh antigen on its RBCs. Rh-negative blood carries no such antigen.


23-66

In Summary (cont.)

23.15Due to the antibodies present on different blood types, it is important for blood typing to be done prior to any transfusion.

It is equally important to know if a patient’s blood type is positive or negative for the same reason.

A negative blood type will “fight” the positive antigen found on a positive blood type.

An Rh-negative woman carrying an Rh-positive fetus will develop antibodies against the child’s blood type.


23-67

In Summary (cont.)

23.16Many different types of cardiac and blood diseases are described in this chapter. The signs, symptoms, and treatments are as varied as the diseases themselves. The Pathophysiology section of this chapter outlines the most common of these diseases, their signs and symptoms, as well as the treatments.


23-68

Your work is to discover your world and then with all your heart give yourself to it.

~ Buddha

End of Chapter 23

Documents

CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 23 The Cardiovascular System