Cardio 2 histo (physio) Flashcards
The walls of medium and large blood vessels are generally described in terms of 3 concentric layers or tunics. Starting from the innermost layer, these tunics are:
- Tunica Intima
- Tunica Media
- Tunica Adventitia
Tunica Intima is the thinnest layer. It is comprised of………….., which is a layer of simple squamous epithelium, and…………., which is a thin loose connective tissue layer with occasional smooth muscle cells.
Endothelium
Sub endothelial connective tissue
Each endothelial cell is arranged in……………. to the lumen of the vessel, and are attached to one another by tight junctions and occasional gap junctions. The endothelium rests on a……………..
parallel
basal lamina
Tunica Media is the middle layer. What is it comprised of?
- circumferentially arranged smooth muscle cells
- extra cellular matrix components
- elastic fibers
Tunica Adventitia covers the outer surface of blood vessels and is primarily composed of what 3 things?
- collagen fibers
- elastic fibers
- fibroblasts
What are the FUNCTIONS OF ENDOTHELIUM?
- Endothelium is specialized epithelium that acts as a semipermeable membrane between blood and the interstitial fluid.
- The endothelium presents a non thrombogenic surface.
- The endothelial cells regulate local vascular tone and blood flow by secreting a number of factors that stimulate smooth muscle contraction (ex: ACE) or relaxation (ex: NO).
- Under various conditions it secretes various growth factors , including proteins that promote proliferation of specific white blood cell lineages and cells that make up the vascular wall.
The endothelium presents a………………… surface.
non thrombogenic
Nitric oxide (NO) causes…………………. of blood vessels.
dilation/relaxation
Arteries carry blood from the heart to the body tissues. They are classified according to their size into what 3 categories?
- Large elastic arteries
- Muscular arteries
- Arterioles
Which are the large elastic arteries?
Include aorta, large branches from the aortic arch (common carotid and subclavian ), common iliac arteries and pulmonary trunk.
Large elastic arteries are conducting vessels, bringing blood to periphery or the lungs. The presence of……………….. helps withstand the……….. pressure , thereby preventing excessive blood pressure in the arterial system.
elastic fibers
systolic
When ventricular pressure decreases during diastole, the elastic recoil of the………………. of large elastic arteries helps maintain arterial pressure.
elastic lamellae
Regarding the layers of large elastic arteries, tunica intima, tunica media, and tunica adventitia, which is the thickest?
tunica media
The tunica intima of large elastic arteries consists of………. and a……………………. of loose connective tissue with occasional smooth muscle cells, both oriented longitudinally .
The………………… marks the outermost boundary of intima and is a signature characteristic of arteries . It is composed of elastin and is fenestrated to permit diffusion of nutrients. It is specifically prominent in large arteries.
endothelium
sub endothelial layer
Internal elastic lamina
The tunica media of large elastic arteries is a thick layer with up to 70…………. arranged………………. lamellae, which increases with age. Elastic tissue is present in abundance, and gives it a yellowish appearance in situ.
Smooth muscle cells are………….. arranged and extra cellular matrix separates each lamella .
concentrically
fenestrated elastic
circularly
The tunica adventitia of large elastic arteries is typically about half of the thickness of the tunica media and is composed of a…………… arrangement of………….. and……….. fibers.
Fibroblasts and……………. are also present.
loose, irregular
elastic and collagen
vas vasorum
Muscular arteries are……………. arteries.
distributing
The tunica intima of muscular arteries consists of the endothelium, plus a thin…………… layer with a few smooth muscle fibers.
sub endothelial