Heart (Ch 19)

the heart

a muscular double pump

• pulmonary circuit

• systemic circuit

• atria

• ventricles

Pulmonary circuit

receives oxygen-poor blood from the body and pumps it to the lungs; from the heart to the lungs and back

Systemic circuit

receives oxygenated blood from lungs and pumps throughout the body; from the heart to body tissues and back

atria

receive blood from the pulmonary and systemic circuits; blood entering the heart

ventricles

the pumping chambers of the heart, sending blood out of the heart

the heart is the largest organ of?

the mediastinum; located between the lungs

• apex lies to the left of the midline

• base is the broad posterior surface

layers of the heart wall

• epicardium

• myocardium

• endocardium

epicardium

visceral layer of the serous pericardium

myocardium

consists of cardiac muscle; arranged in circular and spiral patterns

endocardium

Lines the internal walls of the heart; endothelium resting on a layer of connective tissue

heart chambers

• right atrium

• right ventricle

• left atrium

• left ventricle

right atrium

Receives oxygen-poor blood from systemic circuit through these vessels: Superior vena cava, Inferior vena cava, Coronary sinus

fossa ovalis

Depression in interatrial septum; remnant of foramen ovale

right ventricle

Receives blood from right atrium through the right atrioventricular (AV) valve (tricuspid valve); Pumps blood into the pulmonary trunk passing through the pulmonary semilunar valve

Left atrium

Receives oxygen-rich blood from lungs through pulmonary veins; opens into the left ventricle through the left AV valve (bicuspid valve, mitral valve)

left ventricle

Pumps blood through systemic circuit via the aortic semilunar valve internal divisions

Atrioventricular (AV) valves

Between atria and ventricles

• right AV valve= tricuspid valve

• left AV valve= bicuspid (mitral valve)

chordae tendineae and papillary muscles help to?

prevent AV valves from everting into atria

aortic and pulmonary valves (semilunar valves) help to?

prevent backflow into ventricles

systole

contraction of a heart chamber

diastole

expansion of a heart chamber

systole and diastole also refer to

Stage of heartbeat when ventricles contract and expand

structure of heart wall

walls differ in thickness

• atria— thin walls

• ventricles— thick walls

left ventricle

three times thicker than right ventricle; exerts more pumping force; (thicker because all the blood needs to pump to the whole body)

Myocardium

Striated, like skeletal muscle; contractions pump blood through the heart and into blood vessels

cardiac muscle cells join at the?

intercalated discs— contract as one unit without info from the CNS

conducting system

A series of specialized cardiac muscle cells

• sinoatrial node (SA node)

• atrioventricular node (AV node)

sinoatrial node (SA node)

cardiac pacemaker; sets the heart rate

Atrioventricular node (AV node)

controls and establishes the rate of contractions

blood supply to the heart

• coronary arteries

• cardiac veins

coronary arteries

Blood supply to the muscular walls and tissues of the heart

• Right coronary artery

• Left coronary artery

Cardiac veins

Carry deoxygenated blood from the heart wall to the right atrium via the coronary sinus

disorders of the heart

• heart failure

• congestive heart failure (CHF)

• arrhythmias

heart failure

progressive weakening of the heart; can’t meet body’s demand for oxygenated blood

congestive heart failure (CHF)

heart enlarges

arrhythmias

abnormal heartbeat