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Flashcards in Histology Deck (18)
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Where is most of the blood in the body held?

Peripheral veins


What is the inner layer of blood vessels?

Tunica intima - a single layer of squamous epithelial cells supported by a basal lamina and a thin layer of connective tissue


What is the middle layer of blood vessels?

Tunica media - made up predominately of muscle (in some areas there is a significant amount of elastic tissue) - this layer varies tremendously and in some cases virtually disappears


What is the outer layer of blood vessels?

Tunica adventitia - supportive connective tissue


Why are the largest arteries termed "elastic arteries"?

They have many elastic sheets in their tunica media to allow elastic recoil


What is the vascular supply to the large arteries called?

Vasa vasorum


What are pericytes and where are they found?

Connective tissue cells that have contractile properties that are found at intervals just outside the basal lamina of capillaries


What are fenestrated capillaries and where are they found?

Capillaries with ~50nm pores in the walls
Found in mucosa of gut, endocrine glands, glomeruli of kidneys


What are sinusoidal capillaries and where are they found?

They have large gaps through which macromolecules, and in some cases even cells, can pass
Found in liver, spleen and bone marrow


Which type of capillary lacks a basal lamina?

Sinusoidal capillaries


What structures at the beginning of capillaries help control blood flow through the network?

Precapillary sphincters


What is the structure of the endocardium of the heart?

Basal lamina
Thin layer of collagen fibres
Layer of denser connective tissue


What is the structure of the myocardium of the heart?

Bundles and layers of contractile cardiac muscle fibres
Individual muscle fibres are surrounded by delicate, collagenous connective tissue with a rich network of capillaries


Histologically, what is the fibrous pericardium?

A sac of tough fibrocollagenous connective tissue


What does the serous pericardium consist of?

Made up of a layer of simple squamous epithelium (termed mesothelium), backed by a basal lamina and connective tissue


What is the function of the serous pericardium?

Lines the inner surface of the fibrous pericardium (where it is termed the parietal serous pericardium), and covers the surface of the heart (where it is termed the visceral serous pericardium)


What is the name given to the core of dense connective tissue in the heart valves and what structure is it related to?

Lamina fibrosa, in continuation with the cardiac skeleton


Where are the Purkinje fibres found?

The subendocardial layer, just deep to the endocardium