Base
top of the heart where the great vessels emerge
Apex
bottom of the heart
Epicardium
outermost layer of the heart; the coronary arteries run along this layer
Myocardium
middle and thickest layer of the heart; made of pure muscle and is responsible for contracting; damaged most during a heart attack
Endocardium
thin, innermost later that lines the heart chambers and folds back onto itself to form the valves; watertight to prevent leakage of blood into other layers; cardiac conduction system is found in this layer
Pericardium
double walled sac that encloses the heart; serves as support and protection and anchors heart to diaphragm and great vessels
Pericardial fluid
minimizes friction between layers of pericardium
Right Atrium
Receiving chamber for deoxygenated blood returning to the heart from the body; O2 sat @ 60 - 75%, CO2 concentration high
Right Ventricle
Pumps blood to the lungs for fresh supply of O2; O2 sat @ 60 - 75%, CO2 concentration high - relatively low pressure - muscle bulk relatively thin
Left Atrium
Receiving chamber for blood returning to the heart from the lungs; O2 sat almost 100%, CO2 concentration extremely low
Left Ventricle
Pumps blood out to entire body; major pumping chamber of the heart; O2 sat about 100%, CO2 concentration minimal - generates highest pressure - three times muscle bulk since it has to deliver blood to the entire body against BP - plays the most prominent
Atria
primary job: to deliver blood to the ventricles that lie directly below
Ventricles
higher pressure chambers that contract more forcefully to deliver blood into the pulmonary system and systemic circulation
Interatrial septum
muscular band of tissue dividing the heart into right and left sides
Interventricular septum
muscular band of tissue separating the ventricles
Semilunar valves
separate a ventricle from an artery, and have three half-moon shaped cusps
Pulmonic Valve
Semilunar valve located between right ventricle and pulmonary artery
Aortic Valve
Semilunar valve located between the left ventricle and aorta
Atrioventricular Valves
located between an atrium and ventricle; supported by chordae tendonae, which are attached to papillary muscles, and anchor valve cusps to keep the closed AV valves from flopping backward and allowing backflow of blood
Tricuspid Valve
AV valve located between the right atrium and ventricle, as three cusps
Mitral Valve
AV valve, also called bicuspid valve, is located between the left atrium and ventricle, and has two cusps.
Chordae Tendonae
tendenous cords
Papillary Muscles
muscles that outpouch from the ventricular wall
Valve
work based purely on changes in pressure, a structure in the heart that prevents the backflow of blood
Valve Closure
responsible for the sounds made by a beating heart
S1
first heart sound, reflects closure of the mitral and tricuspid valves
S2
second heart sound, reflects closure of the aortic and pulmonic valves
Systole
Heart beats and expels blood, occurs between S1 and S2
Diastole
Heart rests and fills with blood, occurs between S2 and the next S1
Superior vena cava
large vein that returns deoxygenated blood to the right atrium from the head, neck, and upper chest and arms
Inferior vena cava
large vein that returns oxygenated blood to the atrium from the lower chest, abdomen, and legs
Pulmonary artery
large artery that takes deoxygenated blood from the right ventricle to the lungs to load up on oxygen and unload CO2 - only artery that carried deox'd blood
Pulmonary veins
these are large veins that return oxygenated blood from the lungs to the left atrium. They are the only veins that carry oxygenated blood
Aorta
largest artery in the body, takes oxygenated blood from the left ventricle to the systemic circulation to feed all the organs of the body
Cardiac Cycle
mechanical events that occur to pump blood
Rapid-filling phase
first phase of diastole; atria have received and are full of blood and therefore have high pressures, unlike the ventricles, which are freshly empty. AV valves pop open because of the pressure difference and the atrial blood flows down into the ventricles
Diastasis
second phase of diastole, pressure in the atria and ventricles begins to equalize as the ventricles fill and atria empty, and blood flow slows down. TL;DR: slowing blood flow
Atrial kick
last phase of diastole, atria are empty, but there is still a little blood to deliver to the ventricle, so the atria contract and propel the remaining blood into the ventricles. Pressures in the ventricles now are high, and atrial pressures are low. AV ve
Atrial depolarization
delivery of electrical stimulus to the atria; in order for atrial kick to occur, the atria must first have been depolarized.
P Wave
represents atrial depolarization. Normal ___ wave is small, rounded, and upright, but many things can alter the wave shape
Isovolumetric contraction
first phase of systole; ventricles are full but the pressure is not high enough to pop the semilunar valves, so the ventricles squeeze in on themselves without bloodflow occuring.
Ventricular ejection
second phase of systole; ventricular pressure is high enough for the semilunar valves to pop open; half the blood empties quickly and the rest a little slower TL;DR: pumping vigorously
Protodiastole
third phase of systole; ventricular contraction continues but blood flow slows. Aortic and pulmonary arterial pressures rise. Pressures are equalizing between ventricles and aorta and pulmonary artery. TL;DR: pumping less
Isovolumetric relaxation
final phase; ventriuclar pressure is low because all the blood as been pumped out. Pressures drop in the ventricles even further, aorta and pulmonary artery have higher pressues. TL;DR: relaxing, valves closing to end systole
QRS Complex
represents ventricular depolarization. Normal ___ is spiked in appearance, consisting of one or more deflections from the baseline. Most easily ID's structure on the EKG. Shape can vary.
Depolarization
a wave of electrical current that changes the resting negatively charged cardiac cell to a positively charged one. Necessary before any heart tissue can contract
Coronary arteries
rise from the base of the aorta and course along the epicardial surface, and dive into the myocardium to provide blood supply
Left anterior descending (LAD)
a branch off of the left main coronary artery. LAD supplies blood to the anterior wall of the left ventricle
Circumflex
branch of the LMCA, feeds the lateral wall of the left ventricle.
Right coronary artery (RCA)
feeds right ventricle and inferior wall of left ventricle
coronary veins
returns deoxy'd blood to the right atrium after the myocardium has been fed by the coronary arteries
contractile cells
cause the heart muscle to contract, resulting in a heartbeat
conduction system cells
create and conduct electrical signals to tell the heart when to beat.
autonomic nervous system (ANS)
controls involuntary biological functions, subdivided into sympathetic and parasympathetic
sympathetic nervous system
mediated my norepinephrine (released by the adrenal gland) speeds up heart rate, increases blood pressure, causes pupils to dialate, and slows digrestion. Flight or Fight, triggered by stress, exertion, or fear. TL;DR: ACCELERATOR
parasympathetic nervous system
mediated by acetylcholine, slows heart rate, decreases blood pressure, and enhances digestion.
vagus nerve
nerve that travels from the brain to the heart, stomach, and other areas; secretes acetylcholine
syncope
fainting