Histology Flashcards
What are the three basic layer structures to the blood vessels
Tunica intima, Tunica media, Tunica adventitia (Inside to outside)
Structure of the Tunica Intima
Tunica intima, a single layer of squamous epithelial cells termed endothelial cells supported by a basal lamina and a thin layer of connective tissue.
Structure of the Tunica media
Tunica media, made up predominately of smooth muscle. Thickness of this layer varies tremendously.
Structure of the Tunica adventitia
Tunica adventitia, made up of supporting connective tissue.
What seperates the tunica intima and tunica media
Internal elastic membrane
What seperates the tunica media and tunica adventitia
External elastic membrane
What are elastic arteries?
The very largest arteries (e.g. aorta) are termed elastic arteries because they have many sheets of elastic fibres in their tunica media to provide elastic recoil.
What is vasa vasorum?
In large vessels, only the inner part of the wall can obtain nutrients from the lumen, therefore these vessels will have their own vascular supply: the vasa vasorum.
What are capillaries composed of
Capillaries are essentially composed of endothelial cells and a basal lamina.
They have a diameter of 4-8µm. (compare that to the dia. of an RBC - 7)
What are pericytes
Pericytesare contractile cells that wrap around the endothelial cells that line the capillaries and venules throughout the body. They are found at intervals just outside basal lamina
Three types of capillaries
Continuous, fenestrated and discontinuous
What help control flow through the capillary network
Precapillary sphincters
What has a thinner tunica media, artery or veins?
Veins
Layers of the heart
Endocardium, myocardium and epicardium (Inside to outside)
What does the subendocardium compose of
Subendocardium of loose connective tissue containing small blood vessels and nerves and the branches of the impulse conducting system such as Purkinje fibres
Function of intercalated discs
Acts to attach cells but also allows spread of electrical activity
Parts of the pericardium
Fibrous and serous pericardium
What is the fibrous pericardium
Fibrous pericardium is a sac of tough fibrocollagenous connective tissue
What is the serous pericardium made of
Serous pericardium is made up of a layer of simple squamous epithelium (termed mesothelium), backed by a basal lamina and connective tissue.
What is the epicardium
The epicardium is the visceral layer of the serous pericardium
Structure of heart valves
Layer of collagen and elastin fibres. A core of dense irregular connective tissue, called the lamina fibrosa, that is in continuity with the fibrous skeleton. The leaflets of the valves separating the atria from the ventricles (the mitral and tricuspid) are anchored to papillary muscles in the wall of the ventricle by collagenous strands called the chordae tendineae, which merge with the lamina fibrosa
Types of cardiac muscle cells
Contractile muscle cells
Pacemaker cells
Conducting cells
What is the size relation of purkinje fibres when compared of normal cardiac cells
Unlike the small pacemaker and bundle fibres, the Purkinje fibres are larger than normal cardiac muscle cells.
What produces flow in lymphatic vessels
Lymphatic vessels have no central pump, but smooth muscle in walls, hydrostatic pressure in the tissue and compression of the vessels by voluntary muscle, combined with valves in the vessels, produces flow.
