Chapter 12: The Heart Flashcards
pulmonary circuit
carries blood to and from the exchange surfaces of the lungs
systemic circuit
transports blood to and from the rest of the body
pericardial cavity
contains the heart; lined by serous membrane called the pericardium
pericardium
Double-layered membrane surrounding the heart; visceral and parietal tough, fibrous layer that protects the heart
parietal pericardium
lines inner surface of the pericardial sac and is a dense network of collagen fibers
visceral pericardium
(epicardium)covers the outer surface of the heart
auricle
lumpy, wrinkled flap
coronary sulcus
groove usually filled with fat that marks border between atria and ventricles
apex
inferior, pointed tip of the heart
myocardium
muscular, middle layer of the heartalmost entirely dependent on aerobic metabolism; has many mitochondria, excess myoglobin O2 reserves
endocardium
simple squamous inner lining of the heart
intercalated discs
specialized connections between myocardial cells containing gap junctions and desmosomes
interatrial septum
wall that separates the left and right atria
interventricular septum
wall that separates the left and right ventricles
AV
atrioventricular
superior vena cava
delivers blood to the heart from the head, neck, upper limbs, and chest
inferior vena cava
delivers blood to the heart from the trunk, viscera, and lower limbs
fossa ovalis
small depression at the prior site of the foramen ovale
foramen ovale
connects the two atria in the fetal heart; closes at birth and is permanently sealed within 48 hours
tricuspid valve
right atrioventricular valve
chordae tendineae
“heart strings” are tiny white connective fibers that anchor the cusps to the ventricular walls; originate from the papillary muscles
papillary muscles
cone-shaped projections on the inner surface of the ventricle that contract and pull on chordae tendineae
pulmonary trunk
the start of the pulmonary circuit
pulmonary semilunar valve
heart valve opening from the right ventricle to the pulmonary artery
mitral valve
bicuspid valve (left atrioventricular valve)
aortic semilunar valve
aortic valve
regurgitation
backflow of blood; swirling sound may create soft sound known as a heart murmur
mitral valve prolapse
improper closure of the mitral valve; affects an estimated 10% of normal individuals who are asymptomaticmay stem from improperly sized chordae tendineae or malfunctioning papillary muscles
aortic sinuses
sac-like expansions at the base of the ascending aorta; prevent the cusps of the aortic semilunar valve from sticking to the wall of the aorta when valve opens
fibrous skeleton of the heart
-dense bands of tough, elastic connective tissue that encircle the bases of the large blood vessels
-stabilizes the position of the heart valves and physically isolates atria from ventricles
coronary arteries
-left and right branches originate at the base of the aorta (at aortic sinuses)
-where BP is highest in entire body
right coronary artery
-forms the marginal and posterior interventricular (descending) branches
-provides blood to right atrium
-BOTH ventricles (makes sense bc left ventricle needs more blood)
left coronary artery
forms the circumflex and anterior interventricular (descending) branches
supplies
-blood to left atrium
-left ventricle
-interventricular septum
anastomoses
connections between blood vessels; built-in redundancy that ensures that bloodflow will reach target even in the event of a blockage
arteriosclerosis
hardening of the arteries
Atherosclerosis
a form of arteriosclerosis in which fatty deposits (plaque) build up on the inner walls of the arteries
coronary sinus
large, thin-walled vein in the posterior portion of the coronary sulcus; drains cardiac venous blood into the right atrium
infarct
area of dead tissue caused by an interruption in blood flow
ischemia
lack of blood flow
coronary artery disease
condition characterized by the buildup of fatty deposits in the walls of the coronary arteries
Revascularization
Reestablishment of blood supply to a part of the body
percutaneous transluminal coronary angioplasty (PCTA)
involves introducing a small catheter into the affected artery to increase the size of the vessel lumen
coronary artery bypass grafting (CABG)
major procedure that requires that the sternum be split, the heart stopped, and the patient placed on a bypass pump for the duration of the surgery; part of the saphenous vein is frequently taken from the leg to be sewn into the aorta
cardioplegia
intentional and temporary cessation of cardiac activity, primarily for cardiac surgery
2 types of cardiac muscle cells
conducting system and contractile cells
3 phases of cardiac action potential
rapid depolarization, plateau, repolarization complete process takes 25-30 times as long as in a skeletal muscle fiber
repolarization
calcium leaves the cell to restore the cell to a negative resting membrane potential
nodal cells
responsible for establishing the rate of cardiac contraction; located in SA and AV nodes
conducting cells
distribute the contractile stimulus to the general myocardium; major sites include the AV bundle, bundle branches, and Purkinje fibers
flow of electrical impulse through heart
SA node –> internodal pathways –> AV node –> AV bundle –> bundle branches –> Purkinje fibers
bundle of His
AV bundle
pacemaker cells
nodal cells that reach threshold first
cardiac pacemaker
SA node
SA node
pacemaker of the heart; spontaneously generates 70-80 action potentials per minute
AV node
atrioventricular node; only generates 40-60 action potentials per minute; slows down impulse from SA node to give the atria time to fully contract before ventricular contraction begins
bradycardia
slow heart rate (less than 60bpm)
tachycardia
fast heart rate (more than 100bpm)
ectopic pacemaker
a pacemaker other than the SA or AV node
P wave
depolarization of the atria
QRS complex
depolarization of ventricles
T wave
repolarization of ventricles
cardiac arrythmias
abnormal patterns of cardiac activity
first heart sound
“lubb”produced as AV valves close, semilunar valves open
second heart sound
“dupp”occurs at the beginning of ventricular diastole, when the semilunar valves close
stroke volume
The volume of blood pumped from a ventricle of the heart in a single beat
cardiac output
amount of blood pumped by each ventricle in one minuteCO = SV x HR
myocardial concussion
“commotio cordis”When the heart stops due to a sudden blow to the chest
Bainbridge reflex
“atrial reflex”produces adjustments in HR in response to an increase in venous return
venous return
flow of venous blood to the heart
filling time
duration of ventricular diastole
Frank-Starling principle
As venous return increases, stroke volume in ventricles increases”more in = more out”
cardioacceleratory center
controls sympathetic neurons that increase the heart rate
cardioinhibitory center
controls the parasympathetic neurons that slow the heart rate
hypercalcemia
an abnormally high level of calcium in the blood; heart muscles become extremely excitable
Hypocalcemia
deficient levels of calcium in the blood; heart contractions become very weak and may cease altogether
hyperkalemia
excessive potassium in the blood; cardiac contractions become weak and irregular
hypokalemia
deficient potassium in the blood; heart rate is reduced (bradycardia)
digitalis
works directly on the heart muscle to strengthen and regulate the heartbeat by increasing the Ca+ concentration within myocardium
angina pectoris
severe chest pain that results from temporary ischemia whenever the heart’s workload increases
balloon angioplasty
a technique for reducing the size of a coronary plaque by compressing it against the arterial walls using a catheter with an inflatable collar
carditis
inflammation of the heart
cardiac tamponade
a condition that results from pericardial irritation and inflammation; fluid collects in the pericardial sac and restricts cardiac output
rheumatic heart disease
disorder in which the heart valves become thickened and stiffen into a partially closed position; reduces the efficiency of the heart
valvular heart disease
a disorder caused by abnormal functioning of one of the cardiac valves; severity depends on the degree of damage and the valve involved
rotation of the heart
slightly to the left; right side of heart lays anterior, left side sits posterior
sodium
causes depolarization
three properties of cardiac cells
automaticity, excitability, conductivity
heart dynamics
refers to movements and forces generated in cardiac contractions
Five phases of cardiac action potential
-depolarization (Na+ entry)
-early repolarization
-plateau (Ca+ entry)
-repolarization (K+ loss)
-resting phase (return to normal ionic concentrations)
coronal sinus
cardiac veins return blood here; opens into right atrium
