Heart Chp. 18 Flashcards
What is a circulatory system?
blood within the heart and blood vessels throughout the body.
What is the cardiovascular system?
passages through which blood flows. heart and blood vessels. (arteries, veins, and capillaries)
What is the pulmonary circuit?
right side of the heart. the blood goes to the lungs.
What is the systemic circuit?
the left side of the heart. the blood goes to the body.
What is the location of the heart in the thoracic cavity?
lies within the mediastinum, 2/3 lay to the left of the midline. the apex points downward at the diaphragm.
Identify the pericardium and what is its purpose?
visceral - inner layer; parietal - outer layer.
The purpose is to protect the heart. It anchors it to the surrounding structures. and it prevents over filling the heart with blood.
What are the three layers of the heart?
Epicardium- visceral layer
Myocardium- muscle layer
Endocardium- inner, endothelium
What is the flow of blood through the heart?
superior/inferior vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonary semilunar valve -> pulmonary trunk -> right and left pulmonary arteries -> lungs -> right and left pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic semilunar valve -> ascending aorta -> aortic arch -> aorta
What is coronary circulation?
the hearts own blood supply via coronary arteries branched from the ascending aorta.
What are the branches of the left and right coronary arteries?
right coronary artery: posterior interventricular artery and marginal artery.
left coronary artery: anterior interventricular artery and circumflex artery.
Identify venous drainage of the heart.
20% of coronary blood empties into the right atrium and right ventricle.
80% returns to right atrium via 1) great cardiac vein-anterior 2) middle cardiac vein-posterior 3) small cardiac vein-posterior
all three converge in the coronary sinus
What are intercalated discs?
they are complex joining structures.
1) gap junctions- electrical junctions
2) interdigitating folds- increase surface area between adjacent cardiac cells
3) desmosome- mechanical junction (anchor)
What is pacemaker potential?
1% of cardiac muscle doesn’t have a stable resting membrane potential. potential is always drifting upward- graded potential.
what is the conduction system of the heart?
The sinoatrial (SA) node generates the impulses, the impulses pause at the atrioventricular (AV) node, the atrioventricular (AV) bundle connects the atria to the ventricles, the bundle branches conduct the impulses through the interventricular septum, the subendocardial conducting network (or purkinje fibers) depolarizes the contractile cells of both ventricles.
Why is the SA node is the primary pacemaker of the heart?
it is the primary pacemaker because it initiates the heart beat - sinus rhythm
What events correlate with the electrical excitation of the heart with the waveform of an EKG?
P- atrial depolarization
QRS- ventricular depolarization begins at apex, atrial repolarization occurs.
T- ventricular repolarization begins
What are the four phases of the cardiac cycle?
1) ventricular filling
2) ventricular systole
a) isovolumetric contraction phase
b) ventricular ejection phase
3) isovolumetric relaxation
What happens in ventricular filling?
occurs in ventricular diastole. atrioventricular valves open while the semilunar valves are closed. 80% of ventricular filling occurs before atrial systole.
1st 1/3 of filling = rapid ventricular filling
2nd 1/3 of filling = diastasis
3rd 1/3 of filling = atrial systole
What happens in isovolumetric contraction phase during ventricular systole?
volume doesn’t change. start of ventricular systole. all four valves are closed.
What happens in ventricular ejection phase during ventricular systole?
ventricles still contracting. pressure in left ventricle = ascending aorta. semilunar valves open. blood leaves.
What happens in isovolumetric relaxation?
early diastole. all valves are closed. no change in volume. pressure decreases.
What is systole?
contraction
What is diastole?
relaxation
What is rapid ventricular filling?
rapid blood flow into the ventricles
What is diastasis?
slow ventricular filling
What is end diastolic volume?
The ventricles have the maximum volume of blood they will contain in a cycle
What is end systolic volume?
when ventricles relax, the remaining blood in the chambers
What is stroke volume?
the amount of blood ejecting during ventricular systole
What are the structures involved in creating the first heart sound (S1)?
closure of the AV valves (tricuspid & bicuspid)
What are the structures involved in creating the second heart sound (S2)?
closure of the semilunar valves (aortic & pulmonary)
What is a murmur?
an abnormal heart sound.
caused by: 1) narrowed valves - stenosis
2) regurgitation- backflow, leaky valves
3) hole in septum, foramen ovale
What is cardiac output?
measure of the pumping ability of the heart
What is the formula used to calculate cardiac output?
heart rate x stroke volume = cardiac output
beats/min x volume of blood/beats = CO
What is normal heart rate?
adult- 68-75 bpm
infant- 120 bpm
What is tachycardia?
high heart rate; >100 pbm
What is bradycardia?
low heart rate;
What is angina pectoris?
chest pain. increased physical demands on heart. stress induced spasms of coronary arteries. weakened cardiac cells.
What are some risk factors of angina pectoris?
age, male, heredity, hypertension, obesity, diet, stress, smoking.
What is the treatment for angina pectoris?
nitroglycerin-vasodilator (temporary)
if myocardial infarction: angioplasty- balloon, laser.
stent, mesh, coronary bypass surgery.
What is congestive heart failure?
failure of either ventricle to eject blood effectively.
in left ventricle: blood backs into lungs - pulmonary edema
in right ventricle: blood backs into vena cava - systemic/peripheral edema.
What are some risk factors of congestive heart failure?
myocardial infarction- weakened heart. chronic hypertension, valve problems, congenital defects, atherosclerosis.
What is the treatment for congestive heart failure?
fix initial problem if possible.
drugs- digitalis to increase contractility
diuretics- reduce edema
decrease blood pressure
