blood passes from the right ventricle through this into a large artery called the pulmonary trunk, which divides into the right and left pulmonary arteries which take blood away from the heart
forms most of the base of the heart. It receives blood from the lungs through four pulmonary veins
blood passes from the left atrium into the left ventricle through this which has two cusps
is the thickest chamber of the heart and forms the apex. Like the right, the left contains trabeculae cornea and has chordea tendinae that anchor the cusps of the bicuspid valve to papillary muscles
blood passes from the left ventricle through this into the ascending aorta
the aortic and pulmonary valves
they are located between an atrium and a ventricle. They include the tricuspid valves and the bicuspid valves
the left side of the heart is the pump for this system. It receives bright red oxygen enriched blood into the aorta and from here pumps it to the rest of the body
the right side of the heart. it receives dark red, deoxygenated blood returning from the systemic circulation. From here it flows into the lungs
coronary and cardiac circulation
the myocardiums own network of blood vessels that supplies all the layers of cells that make up the heart wall
branch from the ascending aorta and encircle the heart.
after blood passes through the arteris of the coronary circulation, it flows into capillaries, where it delivers oxygen and nutrients to the heart muscle and collects waste
most of the deoxygenated blood from the myocardium drains into a large vascular sinus in the coronary sulcus on the posterior surface of the heart. It thens flows into the right atrium
the discs of cardiac muscle fibers contain these. They connect the fibers together.
a network of specialized cardiac fibers. they are self excitable. they repeatedly generate action potentials that trigger heart contractions
autorhythimic fibers act as this. Setting the rhythm of electrical excitation that causes contraction of the heart
cardiac action potentialspropagatethrough this network. a network of specialized cardia fibers that provide a path for each cycle of cardiac excitation to progress through the heart.
Sinoatrial (SA) node
cardiac excitation begins here. They do not have a stable resting potential, rather they repeatedly depolarize to threshold spontaneously. creating pacemaker potentials
Atrioventricular (AV) node
the action potential reaches here. , located in the interatrial septum just anterior to the opening of the coronary sinus
from the AV node the action potential enters her. This is the only site where action potentials can conduct from the atria to the ventricles
right and left bundle branches
after propagating along the Av bundles the action potential enters both of these. They extend through interventricular septum toward the apex of the heart
finally these large diameter fibers rapidly conduct the action potential beginning at the apex of the heart upward to the remainder of the ventricular myocardium. Then the ventricles contract pushing the blood upward toward the semilunar valves.
can restore normal heart rhythm. A device that sends out small electrical currents to stimulate the heart to contract.
the working atrial and ventricular muscle fibers. They have a stable resting membrane potential
voltage gated fast Na + channels
when a contractile fiber is brought to threshold by an action potential from neighbouring fibers these channels open and quickly
inflow of Na+ down the electrochemical gradient produces this. Within a few millisecond the Na+ channels open then quickly close.
a period of maintained depolarization Ca+ channels open allowing them in and K+ channels open letting potassium out of the cell. This balances the cell and maintains depolarization.
the recovery of the resting membrane potential
is the time interval during which a second contraction cannot be triggered. In a cardiac fiber it lasts longer than the contraction itself. Maintained contraction or tetanus can not occur.
Electrocardiogram or ECG
is a recoding of electrical signals produced by the propagation of action potentials