period between start of one hearbeat & the start of the next
The sodium potasium exchange pump maintains a gradient of sodium & potassium ions accross the cell membrane. _____ is more concentrated inside the cell & _____ is more concentrated outside the cell.
stroke volume (SV)
the amount of blood ejected by a ventricle during a single beat
cardiac output (CO)
amount of blood pumped by each ventricle in one minute
CO = SV * HR
"more in = more out"
output of blood from both ventricles is balanced under a variety of conditions
the more the heart muscle is stretched, the more forcefully (to a point) it will contract, & the more blood it will eject (SV) w/ each beat.
increased venous return increases stroke volume
Heart rate can be modified by the ANS. Both sympathetic & parasypathetic divisions of the ANS innervate the heart.
Postganglionic sympathetic fibers extend from neuron cell bodies located in the crevical & upper thoracic ganglia.
The vagus nerves (N X) carry parasympathetic preganglionic fibers to smal ganglia near the heart.
Both ANS divisions innervate the SA & AV nodes as well as the atrial & vintricular cardiac muscle cells.
1. IVS & SVS
5. Pulmonary Semilunar
6. Pulmonary Trunk/Pulmonary Artery
7. Lungs (oxygenated/decarbonated)
8. Pulmonary Veins
12. Aortic Semilunar
13b. Coronary Sinas
1) right coronary artery (RCA)
2) posterior interventricular branch of RCA
3) marginal branch of RCA
4) left cornonary artery (LCA)
5) circumflex branch of LCA
6) anterior interventricular branch of LCA
7) posterior left ventricular branch of LCA
The pericardium is the serous membrane, which covers the heart. It has two layers, one exposed to the thoracic cavity, the other on the surface of the heart. Name & identify these membranes. ie. which one is on the heart & which one is on the outside.
a. visceral pericardium (on the heart)
b. parietal pericardium (on the outside)
area of dead heart tissue caused by an interruption in blood supply
interconnectons of small tributaries from of the left & right coronary arteries
The sodium-potassium exchange pump maintains gradients by ejecting sodium ions & recapturing lost potassium ions. For each ATP molecule consumed, how many sodium ions are ejected and how many potassium ions are reclaimed by the cell?
3 sodium ions are rejected for every 2 potassium ions relaimed
cardiac action potential steps
1) rapid depolarization
2) the plateau
cause: Na+ entry
ends w/: closure of voltage-regulated sodium channels