The Cardiovascular System: The Heart Flashcards
Heart Wall
Epicardium - outer layer
Myocardium - cardiac muscle
Endocardium - thin layer of endothelium
heart wall outer layer
epicardium
- thin layer of endothelium
-provides a smooth lining for the chambers of the
heart and covers the valves of the heart.
Endocardium
an inflammation of the myocardium that usually occurs as a complication of a viral infection, rheumatic fever, or exposure to radiation or certain chemicals or medications.
Myocarditis
refers to an inflammation of the endocardium and typically involves the heart valves. Most cases are caused by bacteria (bacterial endocarditis).
Endocarditis
intravenous antibiotics
Tx
2 upper chambers
Atria
2 lower chambers
ventricles
receive blood from blood vessels returning blood to the heart, called veins
Atria
eject the blood from the heart into blood
vessels called arteries
Ventricles
thin partition between the right left atrium
interatrial septum
blood passes from the right atrium into the right ventricle
Tricuspid valve
A prominent feature of interatrial septum is an oval depression
fossa ovalis
Forms the right border of the heart and receives blood from three veins: the superior vena cava, inferior vena cava, and coronary sinus.
Right Atrium
three veins
the superior vena cava,
inferior vena cava, and
coronary sinus.
forms most of the anterior surface of the heart.
Right ventricle
inside of the right ventricle contains a series of ridges formed by raised bundles of cardiac muscle fibers called
Trabeculae
separate right ventricle from the left ventricle
interventricular septum
receives blood from the lungs through four pulmonary veins.
Left atrium
the thickest chamber of the heart, averaging 10–15 mm
Left ventricle
Depolarize spontaneously
pacemaker
Fastest one run runs the heart
pacemaker
a device that sends out small electrical currents to stimulate the heart to contract.
artificial pacemaker
consists of a battery and impulse generator and is usually implanted beneath the skin just inferior to the clavicle.
pacemaker
if the pacing rate is so slow (20–35 bpm) that blood flow to the brain is
inadequate
Recording of currents from cardiac conduction on skin
electrocardiogram
a composite record of action potentials produced by all the heart muscle fibers during each heartbeat.
ECG
electrocardiogram
3 waves
P wave = represents atrial depolarization
QRS complex = rapid ventricular depolarization
T-wave = ventricular repolarization
represents atrial depolarization
P wave
rapid ventricular depolarization
QRS complex
ventricular repolarization
T-wave
adheres tightly to heart
Inner visceral layer
fused to fibrous pericardium
Parietal layer
Inelastic and anchors heart in place
Fibrous pericardium
Designed to prevent back flow in responseto pressure changes
Valves
scar formation or a congenitaldefect causes narrowing of the mitral valve.
mitral stenosis
narrowing of a heart valve opening that restrictsblood flow
stenosis
backflow of blood fromthe left ventricle into the left atrium
Mitral valve prolapse (MVP)
aortic valve is narrowed, and inaortic insufficiency there is backflow of blood from theaorta into the left ventricle.
aortic stenosis
acute systemic inflammatory disease that usually occurs after a streptococcal infection of the throat.
Rheumatic fever
Recording of currents from cardiac conduction on skin
electrocardiogram (EKG or ECG)
indicate enlargement of an atrium
Larger P waves
may indicate a myocardial infarction
Enlarged Q wave
generally indicates enlarged ventricles.
Enlarged R wave
lengthens in coronary artery disease and rheumatic fever
P–Q interval
elevated in acute myocardialinfarction and depressed when the heart musclereceives insufficient oxygen
S–T segment
may be lengthened by myocardial damage, myocardial ischemia (decreased blood flow), or conduction abnormalities.
Q–T interval
includes all the events associated with one heartbeat.
single cardiac cycle
consists of systole and diastole ofthe atria plus systole and diastole of the ventricles.
cardiac cycle
lasts about 0.1 sec, the atria are contracting (P -wave). The ventricles are relaxed(diastole).
atrial systole
lasts about 0.3 sec, the ventricles are contracting. The atria are relaxed in (atrial diastole).
ventricular systole
the volume ejected per beatfrom each ventricle
Stroke volume
the volume of blood ejectedfrom the left ventricle (or the right ventricle) into theaorta (or pulmonary trunk) each minute.
Cardiac output (CO)
Three factors regulate SV (Stroke Volume)
preload,
contractility,
afterload,
the degree of stretch on the heart before it contracts
preload
the forcefulness of contraction of individual ventricular muscle fibers;
contractility
the pressure that must be exceeded before ejection of blood from the ventricles can occur
afterload
substances that increase contractility
positive inotropic agents
decrease contractility
negative inotropic agents
reduce Ca2+ inflow
Calcium channel blockers
ACh slows
Parasympathetic
Norepinephrine speeds
Sympathetic
loss of pumping efficiency by the heart
Congestive Heart Failure
Causes of Congestive Heart Failure
coronary artery disease, congenital defects,long-term high blood pressure, myocardial infarctions,and valve disorders.
Two important functions of Conduction System
they act as a pacemaker
they form the cardiac conduction system,
Blood flow through vessels in myocardium
coronary circulation
