Cardiac Disorders: Physiology and Pharmacology

Question 1

orientation of the heart in the mediastinum

Answer 1

weighs 300g, cone- shaped, tilted forward and to the left, apex or tip of cone is that the hearts bottom and left of the midline, base of heart is at the top

Question 2

heart as a pump

Answer 2

two pumps working together simultaneously, right side generates the pressure to propel O2-poor blood through pulmonic circulation, left side propels O2 rich blood to the remainder of the body through the systemic circulation, at rest heart pumps ~5L of blood per minute

Question 3

layers of the heart: endocardium

Answer 3

innermost layer, thin endothelial tissue lining the inner chambers and the heart valves

Question 4

layers of the heart: myocardium

Answer 4

middle layer, striated muscle fibers forming interlaced bundles, contracting muscle of the heart

Question 5

layers of the heart: epicardium

Answer 5

(visceral pericardium) covers the outer surface of the heart

Question 6

parietal pericardium

Answer 6

tough, loose-fitting, fibrous outer membrane

Question 7

pericardial space

Answer 7

between the visceral pericardium and the parietal pericardium

Question 8

pericardial fluid volume

Answer 8

5 to 20ml

Question 9

purpose of pericardial fluid

Answer 9

fluid lubricates pericardial surfaces as they slide over each other when the heart beats

Question 10

pericarditis

Answer 10

(pericardial frictions rub): inflammation of fluid surrounding heart (pericardial sac) – leathery rubbing sound

Question 11

chambers of the heart

Answer 11

Right and Left Atria, upper collecting chambers
Right and Left Ventricles, pumping chambers
The left ventricle is the most muscular chamber and pumps blood against high resistance into the systemic circulation

Question 12

cardiac valves

Answer 12

Delicate, flexible structures that consist of endothelium covered by fibrous tissue
Allows for unidirectional blood flow through them
Open and close passively, depending on pressure gradients
-Close tightly once blood flows though

Question 13

which heart valve is replaced most often?

Answer 13

aortic valve

Question 14

Atrioventricular valves (A-V)

Answer 14

between the atria and ventricles

• tricuspid (R side)
• bicuspid/ mitral (L side)

Question 15

Semilunar valves

Answer 15

lie between the ventricles and great vessels

• aortic
• pulmonic

Question 16

Chordae Tendineae

Answer 16

strong, fibrous filaments that arise from the papillary muscle and attach to the valves

Question 17

Papillary Muscle

Answer 17

arise from the ventricular walls

Question 18

relationship of papillary muscle and chordae tendineae

Answer 18

Papillary muscle and chordae tendineae work together to prevent A-V valves from bulging back into the atria during vent. contraction

Question 19

“Leaky” valves

Answer 19

valves do not seal well when closed, called regurgitant or incompetent valves

• May cause heart murmur
• Best place to listen to aortic valve: 2nd intercostal space to right of the sternal border

Question 20

“Stiff” valves

Answer 20

valves that cannot open correctly are called stenotic

Question 21

mitral regurgitation

Answer 21

backflow into the atria

Question 22

Semilunar (half-moon) Valves

Answer 22

Both have three cup-like cusps that open during ventricular contraction (systole) and close to prevent backflow of blood into the ventricles during relaxation (diastole)

Question 23

aortic stenosis

Answer 23

• narrow outflow

- Aortic stenosis is the most common valve dysfunction in the US and is considered a disease of “wear and tear”

Question 24

Trabeculae Carneae

Answer 24

Irregular bands and bundles of muscle projecting from the inner surface of the ventricles
Pacemaker wire tips are directed into the trabeculae of the right ventricle to help keep the tip near the ventricular wall

Question 25

cardiac blood supply

Answer 25

The heart itself requires a rich oxygen supply to meet it’s own metabolic needs Coronary arteries, right and left, branch off the aorta, just above the aortic valve (ostia: openings) Encircle the heart, penetrate the myocardium