Histology Flashcards
What are the three layers of the heart from outer to inner?
Epicardium
Myocardium
Endocardium
What is the structure of the endocardial layer?
Simple squamous epithelium
Basal lamina
Dense connective tissue
What is the structure of the myocardial layer?
Thick cardiac muscle layer
What is the structure of the epicardial layer?
Simple squamous epithelium (mesothelium)
Basal lamina
Connective tissue layer (sometimes with substantial adipose tissue)
What is the pericardial sac lined by?
Serous layer that faces the heart and is lined by mesothelium with a basal lamina
The outer coat is tough connective tissue (fibrous pericardium)
Thin layer of fluid between them
What represents the visceral pericardium?
Epicardium
What is the heart’s fibrous ‘skeleton’?
Layer found between the atria and ventricles
Provides attachment for the cardiac muscle and supports valves
It is composed of non-excitable connective tissue and so prevents direct spread of excitation from the atria to the ventricles
What is the structure of the valves?
Covered in epithelium
Dense core of connective tissue (lamina fibrosa) that is continuous with the fibrous skeleton
What anchor the AV valves?
Bands of collagenous tissue called chord tendinae anchor the valves to the papillary muscles
What is the difference between the structure of pacemaker cells and typical cardiac myocytes?
Smaller and found in SA and AV nodes
What are the features of the Purkinje fibres?
Large muscle cells
Have fewer contractile filaments
Appear pale
Found in the subendocardium
