Cardiac Histology Flashcards
Are cardiac muscle cells striated or non-striated? Voluntary or involuntary?
Striated and involuntary.
Are smooth muscle cells striated or non-striated? Voluntary or involuntary?
Non-striated and involuntary.
Smooth muscle cells occur as what?
Bundles or sheets of elongated fusiform cells with finely tapered ends
What kind of nucleus do smooth muscle cells have?
Centrally located (n=1)
Do smooth muscle cells have visible striations?
No, they are smooth
What are smooth muscle cells interconnected with?
gap junctions
What is special about smooth muscle contraction?
The contractions are long, rhythmic, continuous and of low force.
Ex. The uterus during labor
Are smooth muscle cells responsive to ANS stimulation?
Yes
What are smooth muscle contractile apparatus’ anchored to? What does this allow?
They are anchored to cytoplasmic densities/dense bodies. This allows cells to contract all together at once from an elongated to flat shape.
What is the general shape of cardiac muscle cells?
Short, branched, and y-shaped
What are intercalated discs?
Transverse junctions at the end of cells that allow passage of electrical current
What are purkinje cells?
Modified cardiac muscle cells that act as a pacemaker for the heart and allow rapid conduction of electrical stimulus
What is the fibrous pericardium?
The outer covering of dense connective tissue
What are the two layers of serous pericardium?
Parietal and visceral
The visceral layer of serous pericardium is the same as what layer of the heart?
The epicardium
Why is the endothelium of blood vessels smooth and made up of simple squamous epithelium?
So blood can easily flow over it
What is the thickest layer of the heart?
Myocardium
What are the main characterizations of myocardium?
- Striations
- Intercalated discs
- Dyad T-Tubule system
- Many mitochondria
- Lipofuscin granules
- Atrial granules
What are intercalated discs?
Specialized, interdigitating junctions between cardiomyocytes
Where do intercalated discs always coincide?
Z lines
What do intercalated discs allow?
The transmission of contraction and they allow the spread of excitation
What are the two components of the transverse region of intercalated discs?
- ) Fascia adherens
2. ) Desmosomes
What are intercalated discs?
Specialized junctions that bind cells and allow the spread of excitation
In what layer of the heart are intercalated discs present?
Myocardium
