Blood Pathway
Some blood from the left ventricle goes to supply the heart tissue through here, the rest goes into the aortic arch & descending aorta to supply the body
Coronary arteries
Serves most of the body
Systemic
Side of heart responsible for pulmonary circuit, blood ejected from this side's ventricle flows to pulmonary trunk, which branches into pulmonary arteries that branch to the left and right lung
Right side of heart
Make up the myocardium, similar to those in skeletal muscle, a bit shorter & more branched
Cardiac muscle fibers
Nerve impulse reaches here, located in the septum between the two atria
Atrioventricular node
When atria contract, blood is forced through here and into the ventricles; when ventricles contract, the cusps of these are forced upward & the tension from the chordae tendinae keeps them from being forced open the wrong way
AV valves
Circulates blood back & forth between lungs and heart
Pulmonary
Smaller air tube that branches off the left or right bronchi
Bronchiole
Ends of cardiac muscle fiber cells connect to each other from here, which helps hold the cell together. Channels in here allow cells to communicate & for nerve impulses to spread fast from cell to cell
Intercalated discs
Nerve impulse enters here, and the impulse then travels through both the left and right bundle branches that are located in the interventricular septum
Atrioventricular bundle (bundle of His)
Made of 3 crescent moon shaped cusps, forced open when ventricles contract; when ventricles relax, blood starts to flow backwards, but fills these and they close tightly
Aortic & pulmonary semi-lunar valves
Smaller versions of arteries
Arterioles
Air sacs, site of gas exchange in lungs
Alveoli
Cardiac myocarditis fibers are ____, meaning they can generate action potentials that trigger heart contractions (also means that heart will beat even when cut from body with all nerves cut)
Autorhythmic
Impulse travels through here to the apex of the heart and upwards. Both ventricles contract (aka ventricular systole)
Purkinje fibers
Located on the ascending aorta
Right and left coronary arteries
Nutrient and gas exchange happens through the walls of these (O2 unloaded into tissue, CO2 picked up to return to heart)
Capillaries
Oxygen-rich blood returns to this side of the heart via pulmonary vein, and the trip to the systemic circuit repeats
Left side of heart
Group of autorhythmic fibers, aka sinoatrial node (SA), forms conduction system that allows contraction to progress through the heart
Pacemaker
From the CNS and hormones, these modify the timing and the strength of each heartbeat, but do NOT establish the fundamental rhythm
Nerve impulses
Delivers oxygenated blood to left atrium, THE ONLY VEIN THAT DELIVERS OXYGENATED BLOOD
Pulmonary vein
Smaller versions of veins, usually blood passes through one capillary bed and then enters a systemic ___, these carry nutrient & oxygen poor blood away from tissues
Venule
Part of the systemic circuit, blood doesn't diffuse through chambers of heart tissue and needs its own supply, so coronary arteries branch from ascending aorta & encircle the heart
Coronary circulation
Excitation begins here, located in the right atrium wall. Impulse from here spreads through both atria via gaps in intercalated discs, and both atria will contract simultaneously (aka atrial systole)
Sinoatrial node
These are generated as nerve impulses travel through the heart, and can be detected on the body surface
Electrical currents