View
218
Download
0
Category
Tags:
Preview:
Citation preview
Histology for PathologyCardiac System
Theresa Kristopaitis, MDAssociate Professor
Director of Mechanisms of Human Disease
Kelli A. Hutchens, MD, FCAPAssistant Professor
Assistant Director of Mechanisms of Human Disease
Loyola Stritch School of Medicine
Objectives1. Identify the 3 layers of the heart – endocardium, myocardium, epicardium2. Differentiate cardiac, skeletal and smooth muscle on H&E stained slides citing the key distinguishing morphologic features3. Define “intercalated disc”4. Name the layer of the heart in which Purkinje fibers are found and describe their function5. Explain which chamber of the heart has the thickest layer of myocardium vs the thinnest6. Explain the general histologic structure of a cardiac valve
Endocardium• Innermost layer• Composed of:– Simple squamous
epithelium (endothelium) – Connective Tissue– Subendocardium: in
contact with cardiac muscle and contains small vessels, nerves, and Purkinje Fibers.
Purkinje Fibers• Impulse conducting fibers• Large modified muscle
cells– Cluster in groups together– 1-2 nuclei and stain pale
due to fewer myofibrils• Terminal branches of the
AV bundle branches located in the subendocardial connective tissue
Myocardium• Thickest layer of the heart• Thickest in left ventricle because must
pump hard to overcome high pressure of systemic circulation
• Right atrium the thinnest because of low resistance to back flow
• Consist of cardiac muscle cells = myocytes– Different from smooth or skeletal
muscle cells due to placement of nuclei, cross striations, and intercalated disks• Intercalated disks
– 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
Smooth MuscleLong, slender central nuclei, lying within narrow, fusiform cells.No cross striations
Skeletal muscleFibers with cross-striations and
peripheral nuclei.
Epicardium
• 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
Cardiac Valves• 4 valves– 2 AV (mitral and tricuspid) in the
chambers– 2 semilunar (aortic /pulmonary)
• Composed of connective tissue layers covered by endothelium on each side; 3 layers– Spongiosa: loose collagen– Fibrosa: dense core of connective
tissue– Ventricularis: dense connective
tissue with many elastic and collagen fibers
Recommended