Heart

Question 1

How do the heart muscles contract together like one muscle?

Answer 1

Gap junctions allow them to function as a syncytium

Question 2

What are gap junctions? How do they relate to cardiac muscle?

Answer 2

Special intracellular connections that allow ions to pass and help send signals to other cells to contract cardiac muscle.

Question 3

What do desmosomes do in cardiac muscle?

Answer 3

Maintain structural integrity and anchor the cells together.

Question 4

What are intercalated discs and what do they do in cardiac muscle?

Answer 4

• Specialized structures that connect adjacent cardiac muscle cells together.
• Contain specialized junctions like desmosomes and gap junctions.

Question 5

How big is the heart?

Answer 5

Approximately the size of a fist.

Question 6

Where is the heart located?

Answer 6

In the mediastinum

Question 7

What is the heart enclosed in?

Answer 7

Pericardium

Question 8

What protects, anchors and prevents overfilling in the heart?

Answer 8

Superficial Fibrous Pericardium

Question 9

How many layers does the serous pericardium have? What are they? Where are they located?

Answer 9

• 2
• Parietal Layer: lines internal surface of fibrous pericardium
• Visceral Layer: lines external surface of heart

Question 10

What is the visceral layer also known as? Where is it located?

Answer 10

• Epicardium
• On external surface of heart

Question 11

What separates the parietal and visceral layer? What is the function of this?

Answer 11

• Pericardial cavity
• Contains serous fluid which lubricates pericardium and reduces friction as heart beats.

Question 12

What are the layers of the heart (innermost-outermost)? And their functions?

Answer 12

Endocardium - contains endothelial cells for smooth surface that allows blood to flow easily through heart

Myocardium - contain cardiac muscle cells, anchors cardiac muscle fibers, supports great vessels and valves

Epicardium - visceral pericardium, CT for protection and support, contains blood vessels and nerve fibers to supply heart with O2 and nutrients.

Question 13

What are the chambers of the heart?

Answer 13

2 atrium (left and right), 2 ventricles (left and right)

Question 14

What encircles the junction of the atria and ventricles?

Answer 14

Coronary sulcus (atrioventricular groove)

Question 15

What vessels enter the right atrium? Left atrium?

Answer 15

• Superior Vena Cava, Inferior Vena Cava, Coronary sinus
• Right and left pulmonary veins

Question 16

What vessel leaves the right ventricle? Left ventricle?

Answer 16

• Pulmonary trunk
• Aorta

Question 17

What is the trabeculae carneae?

Answer 17

Ridges in the walls of ventricles that give structural support and prevent ventricle walls from collapsing during ventricular contraction.

Question 18

Which side of the heart is the pump for pulmonary circuit?

Answer 18

Right side

Question 19

Which side of the heart is the pump for systemic circuit?

Answer 19

Left side

Question 20

What is the pulmonary circuit?

Answer 20

Circulation of blood from the heart to the lungs

Question 21

What is systemic circulation?

Answer 21

Circulation of blood from the heart to every tissue in the body

Question 22

Which circuit is high pressure and which is low? Pulmonary circuit or systemic circuit? Why?

Answer 22

• Systemic circuit is high pressure and pulmonary circuit is low pressure.
• It takes a lot more energy and pressure to pump blood to all the bodies tissues compared to pumping blood to the lungs, therefore systemic circuit has higher pressure.

Question 23

Why are the left ventricle walls thicker than the right ventricle?

Answer 23

It takes a lot of work and energy to pump blood for systemic circulation (which is what left ventricle pumps to), so its walls a thicker to accommodate amount of energy needed to pump.

Question 24

What is coronary circulation? Why is it important?

Answer 24

• Circulation of blood to the heart
• It’s important for the function of the heart and heart muscle

Question 25

What are collateral routes and anastomoses? Why do we need them?

Answer 25

Collateral routes - natural connections between adjacent blood vessels Anastomoses - surgical or natural connections between two blood vessels - We need them because they allow blood to continue to reach tissues and organs even if a blood vessel is partially or completed blocked

Question 26

What are the major arteries in the heart? (hint: 6)

Answer 26

(slide 25 CVS1) - Right/left coronary artery - Right marginal artery - Posterior interventricular artery - Anterior interventricular artery - Circumflex artery

Question 27

What are the major cardiac veins?

Answer 27

(slide 26 CVS1) - Small cardiac vein - Middle cardiac vein - Great cardiac vein

Question 28

What is angina pectoris?

Answer 28

Thoracic pain due to fleeting deficiency in blood delivery and O2 supply to the myocardium

Question 29

What is myocardial infarction?

Answer 29

Heart attack; prolonged coronary blockage - areas of cell death can be repaired with non contractile scar tissue

Question 30

Which is long term and which is short term? Angina pectoris or myocardial infarction? Why?

Answer 30

- Myocardial infarction is long term and angina pectoris is short term - Angina pectoris is only fleeting deficiency of blood while myocardial infarction is a prolonged blockage of blood supply

Question 31

What are the atrioventricular (AV) valves?

Answer 31

Tricuspid valve: right Mitral (bicuspid) valve: left

Question 32

What are heart valves for?

Answer 32

Ensure unidirectional blood flow through the heart

Question 33

What are the chordae tendineae and papillary muscles for?

Answer 33

- Chordae tendineae anchor AV valve cusps to papillary muscles - Papillary muscles pull on chordae tendineae to open and close valves

Question 34

What are the semilunar (SL) valves?

Answer 34

- Aortic semilunar valve - Pulmonary semilunar valve

Question 35

What is the pathway of blood through the heart?

Answer 35

Superior/inferior vena cava —> right atrium —> tricuspid valve —> right ventricle —> pulmonary semilunar valve —> pulmonary trunk —> pulmonary arteries —> lungs —> pulmonary veins —> left atrium —> bicuspid valve —> left ventricle —> aortic semilunar valve —> aorta —> systemic circulation

Question 36

Why does cardiac muscle have large mitochondria? How much of cell volume do they take up?

Answer 36

- The heart is constantly functioning, therefore they need bigger mitochondria for more energy - 25-35% of cell volume

Question 37

What are T-tubules for? Why are they wide?

Answer 37

- Allow rapid and efficient transmission of electrical impulses throughout the cardiac muscle cell - Synchronize the contraction of the entire muscle cell - They are wide in order to allow electrical signals to pass through at a higher rate

Question 38

What are some characteristics of cardiac muscle cells?

Answer 38

Striated, short, fat, branched, interconnected