6.3 Heart Anatomy Flashcards
What are the base and the apex of the heart?
Base- superior
Apex- point, inferior
From out to in, what are the layers of the covering of the heart?
Fibrous pericardium Pareital layer of serous pericardium Pericardial space Visceral layer of serous pericardium/ epicardium Myocardium Endocardium
What are epicardium, myocardium, and endocardium?
epicardium: aka visceral layer of serous pericardium, also contains fat.
myocardium: cardiac muscle, connective tissue, electrical tissue
endocardium: squamous epithelial with connective tissue lining inside of heart, similar to endothelium of an artery
In general, what is the path of blood through the heart?
R atrium R ventricle Pulmonary artery Lungs Pulmonary vein L atrium L ventricle
What are the heart valves? Where are they?
Tricuspid Valve/R AV: between R atrium and ventricle
Mitral/Bicuspid/L AV: between L atrium and ventricle
Pulmonary semi-lunar- R ventricle and pulmonary trunk
Aortic semi lunar- between L ventricle and aorta
When are AV valves open/closed?
open when heart is filling
closed when heart is pumping (blood goes to lungs/tissues not back to atria)
What are the chord tendinae and papillary muscles?
collagen cords “heart strings” attached to AV valves anchor the cusps of the valve to the ventricles
papillary muscles: protruding muscles on the ventricle wall attach to the chordae tenidinae
How do AV valves open?
Blood fils atria, increased pressure in the atria causes valve to open
As ventricle fills, AV flaps hang into ventricle
Atria contract, pushing more blood past open valves
How do AV valves close?
Ventricle contracts- pushing blood against cusps
Blood pushes valve closed
Papillary muscles contract, pull on chordae tendinae, preventing valve failure
How do semilunar valves function?
Semilunar valves open when ventricle pressure is high, so blood can leave the heart through the aorta and pulmonary trunk
When the heart is filling, semilunar valves close to prevent blood from backing up into the ventricles
What are common causes of valvular heart disease?
Congenital malformation of valve leaflets
history of myocardial infarction (MI), especially if damages papillary muscle or chordae tendinae
arteriosclerosis, calcification of valves with aging
trauma
infection, rheumatic fever, infective endocarditis
What are common clinical consequences of valvular defect?
dysrhythmia, ischemia, stroke, pulmonary edema, heart failure
What is valve stenosis?
narrowed valve that does not open properly
high resistance, turbulent flow, low efficiency, excess volume left behind
What happens with mitral valve stenosis?
left atrium becomes overloaded, overstretched
What happens with aortic valve stenosis?
left ventricle hypertrophy, inadequate coronary blood flow, ischemia
What is a regurgitant valve?
incompetent, insufficient valve that does not close properly
leakage, turbulent backflow, less blood ejected, stasis of blood
What happens with mitral valve insufficiency?
left atrium becomes overloaded, overstretched
What causes rheumatic fever? What is the most serious complication?
Strep a (GABHS strain) Rheumatic heart disease --> mitral valve stenosis
What comes off the left main coronary artery?
left anterior interventricular “descending” artery (LAD): left ventricle
circumflex artery: left atrium, left ventricle
What comes off the right main coronary artery?
marginal artery: right side
posterior interventricular “descending” artery: ventricle walls, apex
How does venous return from the heart work?
to the right atrium via the coronary sinus
great cardiac vein: anterior
middle cardiac vein: posterior
small cardiac vein: right margin
What is ischemic heart disease? Possible causes?
caused by lack of blood flow to the myocardium
coronary artery atherosclerosis, thrombus obstructs arteries, coronary artery vasospasm, and anemia result in inadequate oxygen delivery
inadequate blood supply (ex: during exertion) leads to anaerobic metabolism, increased adenosine and lactic acid
What is temporary ischemia? S/A?
lack of circulation, then perfusion returned, risk for reperfusion injury
What is angina pectoris?
chest pain caused by lack of blood flow to myocardium, can be stable/chronic or unstable/acute (**medical emergency)
What is the functional “syncytium”
“domino effect” all activate at same time via intercalated disks = atria/ventricles contract AS A UNIT
What are the 2 main differences between cardiac and skeletal muscle?
NO RECRUITMENT:
skeletal muscles can recruit additional motor units to increase strength of contraction
cardiac muscle pumping needs to be reliable and forceful, contraction is ALL IN, due to gap junctions, instead it is modulated by stretch of wall.
NO TETANY:
skeletal muscle produces sustained contractions via tetany (continued stimulus without relaxation)
the heart needs to pump, fill, pump, fill so NO TETANY is allowed, this is achieved by a very long refractory period.
Describe the flow of electrical impulse in the heart. Where are the autorythmic cells located?
SA Node: upper right atrium
AV Node: right atrioventricular junction
AV Bundle (Bundle of His): interventricular septum
Right and Left Bundle Branches
subendocardial conducting network (Purkinje fibers): ventricle walls
