4. DSA Cardiac Electrochemical Coupling Flashcards Preview

085. Cardiopulmonary Exam 2 > 4. DSA Cardiac Electrochemical Coupling > Flashcards

Flashcards in 4. DSA Cardiac Electrochemical Coupling Deck (9)
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1
Q

What are the 5 steps involved in cardiac muscle contraction?

A
  1. cardiac action potential
  2. Ca2+ enters cell during plateau
  3. Ca2+-induced Ca2+ release from SR
  4. Ca2+ binds to troponin C
  5. Cross-bridge cycling = TENSION
  6. Alternate pathway: Cross bridge cycling can lead to Ca2+ accumulation in SR causing relaxation
2
Q

The cardiac muscle is arranged just as skeletal muscle. It is composed of sarcomeres that run from z to z line. Composed of thick and thin filaments. What makes up each?

A

Thick: myosin, globular heads with actin binding sites and ATPase activity

Thin: actin, tropomyosin, and troponin (troponin removes tropomyosin from binding site, allowing actin and mysoin to bind)

3
Q

Contraction occurs via the sliding filament model which states?

A

when cross bridges form between myosin and actin and then break, the thick and thin filaments move past each other = tension

4
Q

Transverse (T) tubules invaginate cardiac muscle cells at Z lines and function to carry action potentials to the cell interior. The T tubules form what?

A

Dyads with the sarcopaslmic reticulu, which is the site of storage and release of Ca2+ for excitation contraction coupling.

5
Q

Contactility or inotropism is the intrinsic ability of myocardial cells to develop force at a given muscle cell length. Agens that produce an increase in contractility are said to have positive inotropic effects. Positive inotropic effects increase both…?

A

the rate of tension development and the peak tension

6
Q

Agents that produce a decrease in contractability are said to have negative inotropic effects. These agents cause?

A

a decrease in both the rate of tension development and the peak tension

7
Q

Do cardiac glycosides have positive or negative inotropic effects?

A

Positive: increase rate of tension development and peak tension

8
Q

How does cross bridge cycling work?

A

It is fueled by ATP and continues as long as intracellular Ca2+ concentration is high enough to occupy the Ca2+ binding sites on the troponin C

9
Q

What important to remember about intracellular Ca2+ and the magnitude of tension developed by myocardial cells?

A

The more Ca2+ in the cell, the larger the magnitude of the tension of the cell