project into ventricular cavity​

Papillary muscles

are attached to heart valves​

chordae tendineae

Pumps blood into pulmonary trunk​

Right ventricle ​

Pumps blood into aorta

Left ventricle ​

located between atria and ventricles​

Atrioventricular valves (AV vales)

located between ventricles and major arteries​

Semilunar valves

No valves are found between

major veins and atria

• Thoracic pain caused by fleeting deficiency in blood delivery to myocardium​
• Cells are weakened​

• Angina pectoris​

• Prolonged coronary blockage​
• Areas of cell death are repaired with noncontractile scar tissue​

• Myocardial infarction (heart attack)​

visceral layer of serous pericardium​

Epicardium

circular or spiral bundles of contractile cardiac muscle cells ​

Myocardium

crisscrossing, interlacing layer of connective tissue

Cardiac skeleton

• Receives blood returning from systemic circuit​

Right atrium

• Receives blood returning from pulmonary circuit​

Left atrium​

• Pumps blood through pulmonary circuit​

Right ventricle​

• Pumps blood through systemic circuit​

Left ventricle​

prevent backflow from major arteries back into ventricles​

Two semilunar (SL) valves

located between right ventricle and pulmonary trunk​

Pulmonary semilunar valve

located between left ventricle and aorta​

Aortic semilunar valve

everything exiting

artery

everything coming in

vein

short distance travel

pulmonary circuit

long distance travel

Systemic circuit

receiving blood comes from

atrium

Pumping blood comes from

ventricles

returns blood from body regions above the diaphragm

Superior vena cava

returns blood from body regions below the diaphragm

Inferior vena cava

returns blood from coronary veins​

Coronary sinus

irregular ridges of muscle on ventricular walls​

Trabeculae carneae

anterior interventricular sulcus​

Great cardiac vein

posterior interventricular sulcus​

Middle cardiac vein

inferior margin​

Small cardiac vein

collect blood from capillary beds​

cardiac veins

Open and close in response to pressure changes​

heart valves

Heart depolarizes and contracts without

nervous system stimulation, although rhythm can be altered by autonomic nervous system​

conduction system​

Intrinsic cardiac

action potential is initiated by

pacemaker cells

Generates impulses about

75/minute (sinus rhythm)​

Inherent rate of

100/minute tempered by extrinsic factors​

inferior interatrial septum​-

Atrioventricular (AV) node​

superior interventricular septum​-

1. Atrioventricular (AV) bundle (bundle of His)​

Right and left bundle branches have Two pathways in

interventricular septum​,toward apex

Subendocardial conducting network​ Also referred to as

Purkinje fibers​

To reach ventricles, impulse must pass through

AV node​

If AV node is defective, may cause a

heart block

Heartbeat modified by ANS via cardiac centers in

medulla oblongata​

sends signals through sympathetic trunk to increase both rate and force​

Cardioacceleratory center

parasympathetic signals via vagus nerve to decrease rate​ ; Inhibits SA and AV nodes via vagus nerves​

Cardioinhibitory center

AP in skeletal muscle lasts

1–2 ms

in cardiac muscle it lasts

200 ms

Contraction in skeletal muscle lasts

15–100 ms

can detect electrical currents generated by heart​

Electrocardiograph

depolarization of SA node and atria​

P wave

beginning of atrial excitation to beginning of ventricular excitation​

P-R interval

entire ventricular myocardium depolarized​

S-T segment

beginning of ventricular depolarization through ventricular repolarization​

Q-T interval

period of heart contraction ​

Systole

period of heart relaxation​

Diastole

blood flow through heart during one complete heartbeat​

Cardiac cycle