Cardio 1C

Question 1

What are the key anatomical features present in both cardiac and skeletal muscle cells?

Answer 1

Sarcolemma, T-tubules, Sarcoplasmic reticulum, Terminal Cisternae, Mitochondria, Myofibrils, Sarcomeres

Question 2

What is the thick filament called?

Answer 2

Myosin

Question 3

What is the thin filament called?

Answer 3

Actin

Question 4

What are the other components of actin?

Answer 4

Troponin and tropomyosin

Question 5

Which filament contains the heads?

Answer 5

Myosin

Question 6

What are the 7 steps of cardiac muscle contraction?

Answer 6

1. Action potential spreads from the sarcolemma into the T-tubules
2. During plateau phase of action potential Ca channels open and Ca enters the cell from ECF
3. Ca entry from ECF triggers release of Ca from sarcoplasmic reticulum
4. As a result of Ca release ICF Ca rises significantly
5. Ca binds to troponin C and tropomyosin is moved out of the way
6. Actin and myosin bind, thick and thin filaments slide past each other, cardiac muscle cell contracts (force is proportional to ICF [Ca])
7. Relaxation occurs when Ca is re-accumulated by the sarcoplasmic reticulum and moved back to the ECF from the ICF

Question 7

What are intercalated discs?

Answer 7

They are dark staining junctions in cardiac cells formed by the fusion of the plasma membranes of adjacent cardiac muscle cells

Question 8

What is the purpose of desmosomes?

Answer 8

Prevent adjacent cardiac cells from separating during contraction

Question 9

What is the purpose of gap junctions?

Answer 9

Allow ions to pass freely from cell to cell directly transmitting the depolarizing current across the entire heart

Question 10

What is the purpose of the intercalated disc?

Answer 10

They ensure that cardiac muscle contracts in a certain sequence so that blood moves in the right direction

Question 11

Define functional syncytium?

Answer 11

The entire myocardium behaves as a single coordinated unit because cardiac fibers are electrically coupled by the gap junctions

Question 12

What are the three proteins of the cardiac troponin complex?

Answer 12

• Cardiac Troponin C (cTnC)
• Cardiac Troponin I (cTnC)
• Cardiac Troponin T (cTnT)

Question 13

What is C (cTnC)?

Answer 13

Cardiac Troponin Calcium binding

Question 14

What is C (cTnI)?

Answer 14

Cardiac Troponin Inhibitory

Question 15

What is C(cTnT)?

Answer 15

Cardiac Troponin Tropomyosin binding

Question 16

What causes angina and myocardial infarction?

Answer 16

Myocardial eschemia (decreased blood flow right and/or left coronary arteries) which is most common caused by atherosclerosis

Question 17

What is the direct cause of chest pain in angina or MI?

Answer 17

Build up of lactic acid

Question 18

Generally what is the cause of angina?

Answer 18

Exertion, emotion, eating, and cold

Question 19

What is usually given to relieve angina?

Answer 19

Nitroglycerine

Question 20

What is the key difference between angina and MI?

Answer 20

No cell death in angina (NTG restores blood flow before damage to myocardium)

Question 21

What causes cell death in MI?

Answer 21

Mismatch of supply and demand of oxygen and myocardial tissue becomes hypoxic

Question 22

What can follow a MI?

Answer 22

Death, arrhythmias, heart failure, myocardial rupture

Question 23

What cardiac troponins rise after MI?

Answer 23

Troponin Inhibitory (cTnI) or Troponin Tropomyosin binding (cTnT)