#16 HEART

Question 1

Heart function and characteristics

Answer 1

On average the heart beats 75/minute, 108,000 / day

Average cardiac output is 5.25 L/minute

Functions as a dual pump for the pulmonary and systemic circuit

Question 2

heart location and orientation

Answer 2

Within the mediastinum

Lies on the diaphragm, posterior to the sternum

Base: Posterior and superior surface of the heart (where great vessels are)

Apex: Anterior and inferior, points to the left hip (where there is a point towards left)

Question 3

Three layers of pericardium

Answer 3

fibrous pericardium, visceral serous pericardium, parietal serous pericardium

Question 4

What is the most superficial layer of pericardium?

Answer 4

fibrous pericardium

Question 5

what does the pericardial cavity contain?

Answer 5

serous fluid

Question 6

periacarditis

Answer 6

Inflammation of pericardium

Question 7

What are the three structures of the heart wall?

Answer 7

myocardium, endocardium, epicardium

Question 8

myocardium

Answer 8

Cardiac muscle

Bulk of the heart wall

Myocardial infarctions occur here

Question 9

endocardium

Answer 9

Lines chambers and covers valves

Simple squamous epithelium

Called “endothelium”

Question 10

epicardium

Answer 10

Visceral layer of serous pericardium

Simple squamous epithelium

Question 11

4 heart chambers

Answer 11

Right atrium

Right ventricle

Left atrium

Left ventricle

Question 12

heart chambers and circuits

Answer 12

Atria
Ventricles
Pulmonary circuit
Systemic circuit

Question 13

pulmonary circuit

Answer 13

Carries blood to and from lungs

Right ventricle is the pump

Question 14

systemic circuit

Answer 14

Transports blood to and from the body tissues

Left ventricle is the pump

Question 15

Right Atrium

Answer 15

Receiving chamber for oxygen poor blood from systemic circuit

Superior vena cava (1) 
Inferior vena cava (2)  
Coronary sinus (3)  
Interatrial septum (4)  
Fossa ovalis (5) 
Foramen ovale during fetal circulation  
Pectinate muscles (6)  
Conducting nodes  
Sinoatrial node (7)  
Atrioventricular node (8)  
Right atrioventricular (AV) valve or Tricuspid valve (9)

Question 16

Right ventricle

Answer 16

Pump of the pulmonary circuit ejects oxygen-poor blood into pulmonary trunk (1) 
Trabeculae carneae (2) 
Papillary muscles (3) 
Anchor chordae tendineae 
Chordae tendineae (4) 
Prevent valves from everting 
Pulmonary valve (5)

Question 17

Left atrium

Answer 17

Posterior surface of the heart
Receives oxygen-rich blood from lungs through pulmonary veins
Left atrioventricular (AV) valve or Bicuspid or Mitral valve (1)

Question 18

Left Ventricle

Answer 18

Pump of the systemic circuit
ejects oxygen-rich blood into the aorta (1)
Aortic semilunar valve (2)
Forms the apex and inferior surface of the heart
Most muscular of the chambers
Wall is three times thicker then right ventricle

Question 19

What is the structure of the heart valve?

Answer 19

Structure: composed of dense connective tissue

Two or three cusps

Question 20

the function of the heart valve

Answer 20

Function:
Permit passage of blood in one direction
Prevent backflow of blood.

Question 21

the connective tissue location and function

Answer 21

located between the atria and the ventricles
Functions:
Separates the atria and ventricles (structurally and electrically)
Anchors heart valves
Framework for cardiac muscle attachment

Question 22

structure of cardiac muscle cells?

Answer 22

Fibers are short, branched, striated, and contain 1-2 nuclei
Cells are joined by intercalated discs
Gap junctions: increase flow of electrical current
Desmosomes: prevent cardiac muscle from pulling apart
More mitochondria and ATP than skeletal muscle

Question 23

systole

Answer 23

contraction of a heart chamber

Question 24

Diastole

Answer 24

relaxation of a heart chamber

Question 25

cardiac cycle

Answer 25

period of time from start of one heartbeat to the initiation of the next

Question 26

steps in the cardiac cycle

Answer 26

Atrial systole (both atria contract at the same time) Ventricular systole (both ventricles contract at the same time) Note: Atrial diastole occurs during ventricular systole Ventricular diastole (ventricles relax together)

Question 27

how does the parasympathetic nervous system regulate the heart?

Answer 27

Emerges from the medulla Vagus nerve (CN X) Decreases heart rate

Question 28

How does the sympathetic nervous system regulate the heart?

Answer 28

Emerges from the thoracic spinal cord Synapses in sympathetic chain ganglia Increases heart rate and force of contraction

Question 29

coronary circulation

Answer 29

hearts own blood supply Brings nutrients and oxygen to the heart wall Inadequate circulation causes a heart attack (myocardial infarction)

Question 30

myocardial infarction

Answer 30

results from a lack of blood flow (ischemia) and oxygen (hypoxia) to a region of the heart, resulting in death of the cardiac muscle cells. often occurs when a coronary artery is blocked by the buildup of atherosclerotic plaque consisting of lipids, cholesterol and fatty acids, and white blood cells, primarily macrophages. Or can occur when a portion of an unstable atherosclerotic plaque travels through the coronary arterial system and lodges in one of the smaller vessels. The resulting blockage restricts the flow of blood and oxygen to the myocardium and causes death of the tissue. MIs may be triggered by excessive exercise, in which the partially occluded artery is no longer able to pump sufficient quantities of blood, or severe stress, which may induce spasm of the smooth muscle in the walls of the vessel.

Question 31

heart failure

Answer 31

Progressive weakening of heart Heart can no longer pump enough blood to meet the needs of the body. Weakened ventricles fail to empty completely. They become overfilled and blood backs up into veins behind the ventricle. May result in edema (congestion) in the tissues outside the pulmonary or systemic circuits.