The Heart part 2

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

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.

cardiac excitation begins here. They do not have a stable resting potential, rather they repeatedly depolarize to threshold spontaneously. creating pacemaker potentials

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

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

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.

is a recoding of electrical signals produced by the propagation of action potentials