2.6 Histology of the heart Flashcards
Describe the pericardium…
The outermost layer of the heart. (A layer of mesothelial cells resting on a thin layer fibrous connective tissue)
Visceral and parietal layers
What does this image show and label what you can see…
The pericardium
Describe the epicardium…
Found between the pericardium and the myocardium.
The underlying adipose connective tissue, vessels and nerves.
Describe the myocardium…
The thickest layer of the heart.
It is specialised cardiac muscle.
What is this image showing and label it…
The myocardium
What is this image showing:
Intercalated discs
What is the function of intercalated discs and what do they contain?
They connect adjacent cardiac myocytes.
They contain:
Gap junctions, adhering junctions and desmosomes.
What is the endomysium?
Loose fibrous connective tissue between the muscle fibres.
What is the image showing:
Endomysium
Describe atrial myocytes
Smaller than ventricular myocytes.
They contain perinuclear neuroendocrine granules (atrial natriuretic peptide).
What is atrial natriuretic peptide and what does it do?
A hormone that is released when cells are stretched excessively.
It increases the excretion of water, sodium and potassium ions in the kidney. It also inhibits renin secretion causing a lowering of blood pressure.
What does this image show and label it…
Atrial myocyte
N - cell nucleus
M - myofibrils
G - small dark staining granules that contain ANP
How are individual myocytes joined?
By intercalated discs
What do the intercalated discs contain:
Desmosomes and adherent junctions that bind the cells together.
Gap junctions that allow the cell to become electrically coupled.
What is this image showing and what are the stains showing?
Green arrows - intercalated discs
Black stain = intercalated disc
Blue - black stain = myofibrils
Red = RBC and mitochondria
Describe the endocardium
The innermost layer of the heart.
Contains a thin layer of fibrous connective tissue and endothelial cells
Label this image:
What are specialised extensions of endocardium?
Valves