Histology of the Cardiovascular System Flashcards
Briefly describe the histological morphology of the epicardium and myocardium.
Epicardium:
☯ mesothelium (remember this is simple squamous epithelium of mesodermal origin forming lining of body cavities in this case, visceral pericardium)
☯ subepithelial layer composed of dense fibrocollagenous tissue, adipose and coronary neurovasculature
Myocardium:
☯ Has cardiac myocytes
☯ Striated in nature; state other characteristics of cardiac myocytes
☯ Extensive capillary network-for perfusion
Further notes:
In connective tissue between aorta and pulmonary artery about the level of semilunar valves are scattered islands of chromaffin tissue.
The endocardium is homologous with the tunica intima and comprises three layers. Name them, stating what they are comprised of.
☯ Outer layer (subendocardial), continuous with connective tissue in the myocardium
☯ Middle layer composed of some smooth muscles and loose connective tissue
☯ Inner layer comprising of the endothelium and subendothelial connective
[Slide 1] [Slide 2] [Slide 3]
Note that the subendocardium is part of the endocardium, the inner layer of tissue that lines the heart’s chambers. The subendocardium is found between the endocardium and myocardium and contains the cardiac conduction system.
Make notes on the cardiac skeleton.
☯ This is the supporting skeleton of the heart to which cardiac muscle and valves are attached.
☯ It is made of dense connective tissue.
☯ Consists of 4 rings at the main openings, 2 fibrous trigones between the rings and a membranous interatrial and interventricular septae.
☯ The valves consist of a central portion of dense fibrous aponeurosis-like tissue lined on both sides by an endothelial layer.
The cardiac conducting system consists of: (name them respectively).
SAN, internodal tracts (anterior, middle and posterior), AV node, AV bundle (of His), the bundle branches, and the Purkinje fibers.
State the features of the nodes (note these nodes consist of a mass of small spindle-shaped specialized muscle cells embedded in connective tissue).
☯ large nuclei and often binucleate
☯ pale cytoplasm with a few myofibrils arranged irregularly between sarcolemma
☯ cytoplasm rich in glycogen and mitochondria
State distinctive features of Purkinje fibers.
☯ they are larger than ordinary cardiac fibers and bundle fibers
☯ they may be binucleate, have few myofibrils, and have a vacuous cytoplasm (normally filled with glycogen)
☯ they have a subendocardial location
The blood vessels consist, except for the smallest of the vessels, of three layers namely the tunica intima, tunica media and tunica adventitia. State the three parts of the tunica intima.
endothelium, sub-endothelial layer, internal elastic lamina
How are arteries classified according to the organisation of their tunica media?
They are classified into elastic, transitional and hybrid arteries.
(a) Giving a reason, identify the type of artery in the slide shown: [Slide].
(b) List four arteries that present this kind of histological organisation.
(a) elastic artery
(b) aorta, pulmonary artery, brachiocephalic artery, left common carotid artery, left subclavian artery, common iliac arteries
