Cardiac Muscle Structure & Function Flashcards Preview

CV Unit I > Cardiac Muscle Structure & Function > Flashcards

Flashcards in Cardiac Muscle Structure & Function Deck (11):
1

What are the specialized features of cardiac muscles?

- Striated
- Not under direct neural control
- Shorter, narrower, richer in mitochondria than skeletal muscles
- ATPase activity of cardiac myosin slower than skeletal muscle but faster than SM
- Ca++ binds to troponin => regulates actin-myosin interaction

2

Describe myosin

a

3

Describe actin

a

4

Describe troponin C

- Contains 1 Ca++ binding site

5

Describe troponin I

- Contains 2 PKA phosphorylation sites (critical for adrenergic response)
- Interacts with TnC but released with phosphorylation

6

Describe troponin T

- Binds tropomyosin
- Regulates isoform expression

7

Describe tropomyosin

- Only alpha isoform in heart

8

Describe the basic contraction-relaxation cycle

- AP leads to Ca++ release
- Ca++ binds to TnC
- Tn complex undergoes conformation change => moves tropomyosin out of way
- Myosin binds actin and cross bridge moves
- Ca++ is released from TnC => tropomyosin reblocks binding site => relaxation

9

Describe the mechanisms of altering cross-bridge cycling in cardiac muscle

- many ways to regulate Ca++ flow
- Depolarization opens L-type calcium channels => calcium influx
- Calcium influx triggers more Ca++ release from SR via RyR2
- Ca++

10

Describe the length-tension relationship (Frank-Starling) in cardiac muscle

a

11

Identify sarcomeric changes associated with heart failure

a