Muscle 11 Flashcards
What is a Myocyte?
A cardiac muscle cell
What do Cardiac Myocytes look like?
They are short, branched and interconnected to each other end to end
What are Intercalated discs?
The connection of cardiac myocytes to each other
What do intercalated discs do for myocytes?
Increase the surface area of the cells attaching to one another
What is found at the intercalated discs of myocytes?
Desmosomes
What do Desmosomes do?
They mechanically couple one cardiac myocyte to another
Where are Desmosomes important?
In tissues that are subject to considerable stretching
What are Gap junctions found in myocytes?
Transmembrane channels which link the cytoplasm of adjacent cells
What kind of coupling do gap junctions allow for?
Electrical coupling
What are the thin filaments of cardiac muscle formed by?
F actin
What does F actin form in cardiac muscle?
Double stranded alpha helices
What is Tropomyosin in cardiac muscle cells composed of?
Two identical alpha helices
What does Troponin in cardiac muscle consist of?
- TnT
- TnC1
- TnI
What does TnT in cardiac muscle do?
Binds tropmyosin
What does TnC1 do in cardiac muscle?
Binds calcium and troponin I, inhibiting contraction
How are TnI and TnT indicators of damage to the myocardium?
Different levels of these two troponins can be measured in the blood to indicate different types of damage to the heart such as myocarditis and myocardial infarction
What is the difference in nebulin between cardiac muscle and skeletal muscle?
Nebulin in cardiac muscle is smaller
What does the Titin do in cardiac muscle?
Provides elastic recoil
What is contraction of cardiac muscle cells regulated by?
Cytosolic calcium concentration, similar to skeletal muscle
What is the difference between the T tubule system in cardiac and skeletal muscle?
The T tubule system in cardiac muscle is less organize and the T tubules consist of a much wider interface
What is the association between the T tubules and sarcoplasmic reticulum in cardiac myocytes?
There is one T tubule associated with each SR in a diad
What is the heart innervated by?
Both the sympathetic and parasympathetic division of the autonomic nervous system
What is Cardiac contraction triggered by?
A pacemaker
