Histology: Cardiac Histology

Question 1

What chamber of the heart has the thickest layer?

Answer 1

Left Ventricle

Question 2

What chamber of the heart has the thinnest layer?

Answer 2

Right Atrium

Question 3

What is the endocardium and what makes it up?

Answer 3

• Innermost layer
• Composed of:
– Simple squamous epithelium (endothelium)
– Connective Tissue
– Subendocardium: in contact with cardiac muscle and contains small vessels, nerves, and Purkinje Fibers.

Question 4

What are the Purkinje-Fibers?

Answer 4

• Impulse conducting fibers

* Large modified muscle cells

Question 5

What is the thickest part of the heart wall?

Answer 5

Myocardium

Question 6

What are intercalated disks?

Answer 6

– Junctional complexes that contain fascia adherens, desmosomes, and gap junction to provide connection and communication.
– Bind myocytes and allow ion exchange to facilitate electrical impulses to pass

Question 7

What is the epicardium and what is it composed of?

Answer 7

• Outermost layer of the heart
• Composed of connective tissue with nerves, vessels, adipocytes and an outer layer of mesothelium
• Mesothelium secretes pericardial fluid
• Covers and protects the heart

Question 8

What are the AV valves?

Answer 8

– 2 AV (mitral and tricuspid) in the chambers

Question 9

What are the semilunar valves?

Answer 9

– 2 semilunar (aortic /pulmonary)

Question 10

What are the 3 layers that comprise the cardiac valves?

Answer 10

– Spongiosa: loose collagen
– Fibrosa: dense core of connective tissue
– Ventricularis: dense connective tissue with many elastic and collagen fibers