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-
- 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