Unit 2

INTRODUCTION AND QUESTIONS REVIEW OF CIRCULATORY SYSTEM PLAYING FOR KUDOS

Slide 1

Unit 2

Chapter 12The Circulatory System

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HEARTSlide 3

• Location, size, and position• Triangular organ located in mediastinum with two

thirds of the mass to the left of the body midline and one third to the right; the apex on the diaphragm; shape and size of a closed fist (Figure 12-1)

• Cardiopulmonary resuscitation (CPR)—the heart lies between the sternum in front and the bodies of the thoracic vertebrae behind; rhythmic compression of the heart between the sternum and vertebrae can maintain blood flow during cardiac arrest; if combined with artificial respiration procedure, it can be life saving

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HEARTSlide 5

• Anatomy• Heart chambers (Figure 12-2)

• Two upper chambers • Two lower chambers• Wall of each heart chamber is composed of cardiac

muscle tissue called myocardium• Endocardium—smooth lining of heart chambers—

inflammation of endocardium called endocarditis• Covering sac, or pericardium

• Pericardium is a two-layered fibrous sac with a lubricated space between the two layers

• Inner layer called • Outer layer called

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Slide 6

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HEARTSlide 7

• Anatomy• Heart action

• Contraction of the heart • Relaxation is called • Heart valves (Figure 12-3)• Valves keep blood flowing through the heart and

prevent backflow • Consist of two atrioventricular, or AV, and two

semilunar (SL) valves• Tricuspid—at the opening of the right atrium into the

ventricle• Bicuspid (mitral)—at the opening of the left atrium into

the ventricle• Pulmonary semilunar—at the beginning of the pulmonary

artery• Aortic semilunar—at the beginning of the aorta

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HEARTSlide 9

• Heart sounds• Two distinct heart sounds in every heartbeat

or cycle—“lub-dub”• First sound (lub) -the vibration and closure of

AV valves during contraction of the ventricles• Second sound (dub) -the closure of the

semilunar valves during relaxation of the ventricles

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HEARTSlide 10

• Blood flow through the heart (Figure 12-4)• The heart acts as two separate pumps—the right

atrium and ventricle performing different functions from the left atrium and ventricle

• Sequence of blood flow: venous blood enters the right atrium through the

superior and inferior venae cavaeo passes from the right atrium through the tricuspid

valve to the right ventricleo from the right ventricle it passes through the

pulmonary semilunar valve to the pulmonary artery to the lungs

o blood moves from the lungs to the left atrium, passing through the bicuspid (mitral) valve to the left ventricle

o blood in the left ventricle is pumped through the aortic semilunar valve into the aorta and is distributed to the body as a whole

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Slide 11

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HEARTSlide 12

• Blood supply to the heart muscle

• coronary circulation• myocardial infarction (heart attack)• Angina pectoris• Coronary bypass surgery

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HEARTSlide 15

• Conduction system of the heart (Figure 12-7)

• Intercalated disks are electrical connectors • SA (sinoatrial) node, the • AV (atrioventricular) • AV bundle (bundle of His• Purkinje fibers

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Slide 16

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HEARTSlide 17

• Electrocardiogram (Figure 12-8)• Specialized conduction system structures

generate and transmit the electrical impulses that result in contraction of the heart

• These tiny electrical impulses can be picked up on the surface of the body and transformed into visible tracings by a machine called an electrocardiograph

• The visible tracing of these electrical signals is called an electrocardiogram, or ECG

• The normal ECG has three deflections or waves • P wave—associated with depolarization of the atria• QRS complex—associated with depolarization of the

ventricles• T wave—associated with repolarization of the

ventricles

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Slide 18

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BLOOD VESSELSSlide 19

• Types• Arteries—carry blood away from the heart• Veins—carry blood toward the heart• Capillaries—carry blood from the arterioles to

the venules

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BLOOD VESSELSSlide 20

• Structure (Figure 12-9)• Arteries

• Tunica intima—inner layer of endothelial cells• Tunica media—smooth muscle with some elastic

tissue, thick in arteries; important in blood pressure regulation

• Tunica externa—thin layer of fibrous elastic connective tissue

• Capillaries—microscopic vessels with only one layer—tunica intima

• Veins• Tunica intima—inner layer; valves prevent retrograde

movement of blood• Tunica media—smooth muscle; thin in veins• Tunica externa—heavy layer of fibrous connective

tissue in many veins