Histo 1 Flashcards
Smooth Muscles: Key features
- No striations
2. Fusiform cells with centrally located nucleus
How are smooth muscle cells connected?
Gap junctions; allows rhythmic contraction
Hallmarks of cardiac tissue
- Intercalated discs
2. Purkinje cells
What cells act as pacemakers for the heart?
Purkinje cells
What are the two areas of the Transverse region?
- Fascia Adherens
2. Desmosomes
Fascia Adherens
- actin filaments at the ends of terminal sarcomeres insert into the junction
- transmit contractile forces between cells (ensure no tearing with contractile force)
- most predominant
Desmosomes
- provide anchorage for the intermediate filaments of the cytoskeleton
- ensure no tearing with contractile force
What do we find in the Longitudinal region?
- Gap junctions
* sites of low electrical resistance that allows excitation to pass between cells/uniform contraction
Lipofuscin Granules
-small bodies that accumulate with age in stable non-dividing cells
Where do we find the most atrial granules? What are they?
- right atria
2. contain precursor of atrial natriuretic factor (ANF)
Atrial Natriuretic Factor
Targets kidney to decrease Na+ and H2O retention
What’s unique about the endocardium of the ventricles?
they contain a subendocardial layer (thin layer of CT with smooth muscle that contains purkinje fibers)
What’s unique about the Purkinje fibers in the atria?
they are often closer to the endothelium, and are intermixed with the myocardium
What are nodal cardiomyocytes?
modified cells within the SA/AV nodes that initiate/relay electrical signals (normal HR)
*lack intercalating discs
What do Purkinje fibers mostly lack?
T tubules
