Chapter022

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Timby/Smith: Introductory Medical-Surgical Nursing, 10/e

Timby/Smith: Introductory Medical-Surgical Nursing, 10/e

Chapter 22: Introduction to the Cardiovascular System


Anatomy and Physiology Anatomy and Physiology • Cardiovascular System

– Comprises heart, major blood vessels, and a vast network of smaller peripheral blood vessels

– Five qualities unique to cardiac tissues

• Heart Chambers

– Four-chambered muscular pump

• Upper chambers: Right, left atria

• Lower chambers: Right, left ventricles

– Thick septum separates the right heart from left heart


Anatomy and Physiology Anatomy and Physiology

• Cardiac Tissue Layers

– Heart wall: Three distinct layers of tissue —epicardium; myocardium; endocardium

– Pericardium: Sac-like structure; Surrounds and supports the heart; Two membranous layers

• Heart Valves

– Membranous structures: Ensures one-way flow of blood; Forward direction

– Two atrioventricular valves: Separate the atria from the ventricles


QuestionQuestion

Is the following statement true or false?

The cardiac wall has three distinct layers of tissue.


AnswerAnswer

True.

The cardiac wall has three distinct layers of tissue: the epicardium, the myocardium, and the endocardium.



• Heart Valves (Cont’d)

– Cusped Valves: Tricuspid; bicuspid

– Chordaea Tendineae: Papillary muscles contract to prevent eversion of valves, regurgitation of blood

– Semilunar Valves: Prevents blood from flowing back into the ventricles after the heart contracts

– Pulmonary Valve; Aortic valve



• Arteries and Veins

– Arteries: Carry oxygenated blood from heart

– Veins: Return deoxygenated blood to heart

– Arterioles: Smallest arteries; Branch into capillaries

– Capillaries: Connecting network between arterioles and venules; Deliver O2, metabolic substances to blood, cells

– Venules: Smallest veins

– Consist of three layers


QuestionQuestion

Is the following statement true or false?

The arteries carry oxygenated blood to the heart.


AnswerAnswer

False.

The arteries carry oxygenated blood from the heart; the veins return deoxygenated blood to the heart.



• Cardiopulmonary Circulation

– Inferior, superior venae cavae: Bring venous blood from all areas of body into right atrium

– Pulmonary artery: Branches to deliver venous blood to right, left lungs

– Pulmonary veins: Bring oxygenated blood into left atrium; Leave left atrium through bicuspid, mitral valves

– Left ventricle pumps blood through the aorta to all body cells, tissues


Anatomy and Physiology Anatomy and Physiology • Blood Supply to the Heart

– Left, right coronary arteries: Supply oxygenated blood to cardiac muscle

– Myocardium: First tissue supplied with oxygenated blood

– Left coronary artery, branches: Maintain pumping function of heart

– Right coronary artery, branches: Maintain heart rhythm

– Coronary veins: Empty into the coronary sinus in right atrium

– Blood from inferior, superior venae cavae: Recirculated to lungs


QuestionQuestionIs the following statement true or false?

The left coronary artery and its branches supply blood to support the pumping function of the entire heart.


AnswerAnswerTrue.

The left coronary artery and its branches supply blood to support the pumping function of the entire heart. The right coronary artery and its branches supply blood to support the maintenance of cardiac rhythm.



• Cardiac Cycle

– Contraction, relaxation of both atria and ventricles

– Contraction of left ventricle: Wave-like impulse in peripheral arteries

– Auscultated “lub-dub” sounds: Valves alternately snap shut

– Starling’s law



• Conduction System

– Sustains the electrical activity of the heart

– Sinoatrial (SA) node: Pacemaker of the heart

– Atrioventricular (AV) node: Impulse delayed a few hundredths of a second

– Normal sequence of events of the cardiac impulse

– Bundle of His; Bundle branches; Purkinje fibers


Anatomy and Physiology Anatomy and Physiology • Conduction System (Cont’d)

– Polarization; Depolarization

– Repolarization; Refractory period

– Normal ranges of potassium and calcium ions

– ECG: Record of electrical changes caused by depolarization or repolarization



• Regulation of Heart Rate

– Fluctuates per: Stimulation from Autonomic nervous system; Baroreceptors; Chemoreceptors

– Autonomic nervous system: Sympathetic, parasympathetic nervous system innervation; Increased heart rate

– Parasympathetic innervation: Vagus nerve; Decreased heart rate

– Responses to baroreceptors

– Chemoreceptors



• Cardiac Output

– Amount of blood pumped out of the left ventricle each minute

– Cardiac output = heart rate x stroke volume

– Heart adjusts cardiac output to body’s changing needs

– Two ways of increasing cardiac output

– Stroke volume: Amount of blood pumped per cardiac contraction


AssessmentAssessment• History

• Physical Examination

– General appearance; Pain; Vital signs

– Cardiac rhythm; Heart sounds

– Peripheral pulses

– Peripheral edema

– Weight; Jugular veins

– Lung sounds; Sputum

– Mental status


Cardiac DiagnosticsCardiac Diagnostics• Laboratory Tests: Blood chemistry; Serum enzymes;

Isoenzymes

• Radiograph; Radionuclide Studies

• Magnetic Resonance Imaging (MRI)

• Echocardiography

– Transesophageal echocardiography

• Electrocardiography

• Cardiac Catheterization

• Arteriography; Aortography

• Nursing Management


End of Presentation

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