6.3 Heart Anatomy

Question 1

What are the base and the apex of the heart?

Answer 1

Base- superior

Apex- point, inferior

Question 2

From out to in, what are the layers of the covering of the heart?

Answer 2

Fibrous pericardium
Pareital layer of serous pericardium
Pericardial space
Visceral layer of serous pericardium/ epicardium
Myocardium
Endocardium

Question 3

What are epicardium, myocardium, and endocardium?

Answer 3

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

Question 4

In general, what is the path of blood through the heart?

Answer 4

R atrium
R ventricle
Pulmonary artery
Lungs
Pulmonary vein
L atrium
L ventricle

Question 5

What are the heart valves? Where are they?

Answer 5

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

Question 6

When are AV valves open/closed?

Answer 6

open when heart is filling

closed when heart is pumping (blood goes to lungs/tissues not back to atria)

Question 7

What are the chord tendinae and papillary muscles?

Answer 7

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

Question 8

How do AV valves open?

Answer 8

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

Question 9

How do AV valves close?

Answer 9

Ventricle contracts- pushing blood against cusps
Blood pushes valve closed
Papillary muscles contract, pull on chordae tendinae, preventing valve failure

Question 10

How do semilunar valves function?

Answer 10

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

Question 11

What are common causes of valvular heart disease?

Answer 11

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

Question 12

What are common clinical consequences of valvular defect?

Answer 12

dysrhythmia, ischemia, stroke, pulmonary edema, heart failure

Question 13

What is valve stenosis?

Answer 13

narrowed valve that does not open properly

high resistance, turbulent flow, low efficiency, excess volume left behind

Question 14

What happens with mitral valve stenosis?

Answer 14

left atrium becomes overloaded, overstretched

Question 15

What happens with aortic valve stenosis?

Answer 15

left ventricle hypertrophy, inadequate coronary blood flow, ischemia

Question 16

What is a regurgitant valve?

Answer 16

incompetent, insufficient valve that does not close properly

leakage, turbulent backflow, less blood ejected, stasis of blood

Question 17

What happens with mitral valve insufficiency?

Answer 17

left atrium becomes overloaded, overstretched

Question 18

What causes rheumatic fever? What is the most serious complication?

Answer 18

Strep a (GABHS strain)
Rheumatic heart disease --> mitral valve stenosis

Question 19

What comes off the left main coronary artery?

Answer 19

left anterior interventricular “descending” artery (LAD): left ventricle
circumflex artery: left atrium, left ventricle

Question 20

What comes off the right main coronary artery?

Answer 20

marginal artery: right side

posterior interventricular “descending” artery: ventricle walls, apex

Question 21

How does venous return from the heart work?

Answer 21

to the right atrium via the coronary sinus
great cardiac vein: anterior
middle cardiac vein: posterior
small cardiac vein: right margin

Question 22

What is ischemic heart disease? Possible causes?

Answer 22

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

Question 23

What is temporary ischemia? S/A?

Answer 23

lack of circulation, then perfusion returned, risk for reperfusion injury

Question 24

What is angina pectoris?

Answer 24

chest pain caused by lack of blood flow to myocardium, can be stable/chronic or unstable/acute (**medical emergency)

Question 25

What is the functional “syncytium”

Answer 25

“domino effect” all activate at same time via intercalated disks = atria/ventricles contract AS A UNIT

Question 26

What are the 2 main differences between cardiac and skeletal muscle?

Answer 26

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.

Question 27

Describe the flow of electrical impulse in the heart. Where are the autorythmic cells located?

Answer 27

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