Lec 1C: Cardiac Muscle Contraction

Question 1

Thick Filament?

Answer 1

myosin

Question 2

Thin Filament?

Answer 2

Actin, tropomyosin, and troponin:ICT

Question 3

Sarcolemma

Answer 3

plasma membrane around skeletal muscle cell

Question 4

Terminal Cisternae?

Answer 4

terminal of SF: Storage of calcium

Question 5

Sarcomere?

Answer 5

Unit within a myofibril

Question 6

Intercalated discs?

NAme the two associated with cardiac muscle.

Answer 6

1) desmosomes: connect the cells together during contraciton so they don’t seperate
2) Gap junctions: allows ions to pass through freely from cell to cell, directly transmitting the depolarizing current across the entire heart.

Question 7

What is functional syncytium?

Answer 7

in cardiac muscles, the cardiac fibers are electrically coupled by gap junctions, therefore, the entire myocardium behaves as a single coordinated unit.

Question 8

Troponin: 3 sites and functionality.

Answer 8

I: inhibitory. where trophomyosin blocks
C: where calcium binds
T: tropomyosin binding so contraction can occur.
- Skeletal and cardiac troponin T and I isoforms differ from each other in amino acid sequence.

Question 9

What is atherosclerosis?

Answer 9

Hardening of the arteries.

Question 10

What’s the preferred markers for detecting myocardial cell injury?

Answer 10

Cardiac troponins. C, I ,T . Cardiac isoforms are very specific for cardiac injury and are not present in blood of healthy people. So troponin I and T are the forms frequently assessed.

• I and T both rise after 2-6 hours, both peak at 12-24 and CTn
• TROPONIN I rises. most important distiction to know that there’s a heart problem.
• so when cardiac muscle cells die… thing things in sides of it leak out. and goes into the interstitial fluid. Such as troponin. This is why we see a rise in troponin if something bad is happening
• on the graph. At 0–> that’s when you notice the chest pain.