3.1 Anatomy of Cardiac Muscle Flashcards
What separates the fibrous pericardium and the parietal pericardium
A layer of connective tissue
How can we subdivide the visceral serous pericardium from the parietal serous pericardium
Visceral pericardium is a single layer of mesothelium that sits on top of the epicardium
Why do some stains show a lighter area around the nucleus of cardiomyocytes in histological section?
- Other organelles surround the nucleus
- Endoplasmic reticulum, golgi body etc.
What type of junctions are in intercalated discs
- Adherens junctions (bind to actin in cytoskeleton)
- Gap junctions (made of conexins, allow APs to spread)
Describe the arrangement of heart muscles around the apex
They spiral down toward the apex
What are sarcomeres?
A single contractile unit of actin and myosin filaments
How long are sarcomeres?
2 micrometers
Where does the depolarization of a cardiomyocyte begin? What is the technical name for this?
- Begins in cell membrane
- AKA sarcolemma
What does “sarco” mean?
Meat
Summarise cardiomyocyte contraction
- Action potential depolarises sarcolemma
- Depolarization travels through the Transerve Tubules
- Calcium travels into cell
- Triggers release of calcium from sarcoplasmic reticulum
How is calcium returned to the sarcoplasmic reticulum during cardiac recovery?
ATP-dependent pumps
How is calcium removed back into the external environment around cardiomyocytes?
Sodium-calcium pump; sodium is pumped in, calcium is pumped out
What is a diad in a cardiomyocyte?
Join between sarcoplasmic reticulum and transverse tubule
What % volume of cardiomyocytes is mitochondria?
40%
Why do Purkinje fibres have more gap junctions than cardiomyocytes?
Because their job is to transport action potentials throughout the heart; they need to be able to transport ions quickly.
