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Copyright © 2011 Pearson Education, Inc.

Chapter 17 Overview

Layers of heart tissue

Heart Chambers

Valves

Heart contraction


Heart Anatomy• Fist sized organ

• Located in mediastinum

• between 2nd and 5th rib

• 2/3 to the left

• Enclosed by pericardium, a double-walled sac

Diaphragm

Sternum

2nd rib

Midsternal line


Pericardium

• Outer fibrous layer

• Anchors heart

• Parietal layer lines fibrous layer

• Visceral layer (epicardium) contacts heart

• Separated by pericardial fluid


Layers of the Heart Wall

1. Epicardium — inner pericardium layer

2. Myocardium - cardiac muscle layer

3. Endocardium - inner layer of heart

Fibrous pericardium

Parietal pericardium

Pericardial cavity

Epicardium(visceral pericardium)

Myocardium

Endocardium

Pulmonarytrunk

Heart chamber

Heartwall

Pericardium

Myocardium


Chambers of the Heart

• Four chambers

• Two atria (patient’s right and left)

• Two ventricles (patient’s right and left)

• Separated by septum

• interatrial

• interventricular

Copyright © 2011 Pearson Education, Inc. Figure 17.4b

(b) Anterior view

Right atrium

Right ventricleLeft ventricle

Left atrium


Atria: The Receiving Chambers

• Right atria

• Low O2 blood

• Blood from:

• Sup. & inf. Vena cava

• Coronary sinus

• Left atria

• High O2 blood

• Blood from:

• R & L pulmonary veins

• From lungs

Right atria

Left atria

L. Pulmonary vein

R. pulm. vein

Inf. Vena cava

Sup. Vena cava


Ventricles: The Discharging Chambers

• Right ventricle

• pumps blood to the lungs

• Via pulmonary trunk

• Left ventricle

• Pumps blood to the body

• Via the aorta

Pulmonary trunk

Aorta

Right ventricle Left

ventricle


Heart Valves• Ensure unidirectional flow

• Two major types

1. Atrioventricular valves

2. Semilunar valves


Heart Valves1. Atrioventricular (AV) valves

• Separates atria from ventricles

• Tricuspid valve (right side)

• Mitral valve (left side)

• a.k.a bicuspid valve

Tricuspid valve

Mitral valve


Heart Valves

Pulmonary SL

Aortic SL

• Semilunar (SL) valves

• Separate ventricles from circulation

• Aortic semilunar valve

• Left ventricle / aorta

• Pulmonary semilunar valve

• Right ventricle / pulmonary trunk

Copyright © 2011 Pearson Education, Inc. Figure 17.4e

Left atrium

Mitral (bicuspid)valve

Aortic valve

Pulmonary valveLeft ventricle

Papillary muscle

(e) Frontal section

Right atrium

Tricuspid valveRight ventricle

Chordae tendineae


PATHWAY OF BLOOD


Pathway of Blood Through the Heart

• The heart is basically two pumps

• Right side

• Pulmonary circuit

• to the lungs

• Left side

• Systemic circuit

• to the body



• R. atrium tricuspid valve R. ventricle pulmonary valve pulmonary trunk pulmonary arteries lungs

• Blood through R. atrium & ventricle is low O2

• In lungs becomes high O2



• High O2 blood enters left atrium

• Lungs pulmonary veins L. atrium bicuspid valve L. ventricle aortic semilunar valve aorta systemic circulation

Copyright © 2011 Pearson Education, Inc. Figure 17.5

Oxygen-rich,CO2-poor bloodOxygen-poor,CO2-rich blood

Capillary bedsof lungs wheregas exchangeoccurs

Capillary beds of allbody tissues wheregas exchange occurs

Pulmonary veinsPulmonary arteries

PulmonaryCircuit

SystemicCircuit

Aorta and branches

Left atrium

Heart

Left ventricleRight atrium

Right ventricle

Venae cavae




• Left ventricle pumps blood through entire body

• Thick myocardium, to generate large force

• Right ventricle pumps blood to lungs

• Thinner myocardium


Coronary Circulation

• Supplies the heart with blood

• The heart is a muscle that requires its own blood supply

• Arteries

• Right and left coronary arteries

• Veins

• Coronary sinus, drains blood into the right atrium


Coronary vessels

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heart high o2 blood

heart wall

atrium ventricle

pumps right

blood supply arteries

atrium bicuspid valve

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