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Lecture 11

ANAT 261 Lecture Notes - Lecture 11: Arteriole, Adventitia, Venule

Anatomy & Cell Biology
Course Code
ANAT 261
Jason Young

of 3
ANAT 261 October 7, 2010
Dr. Mandato Lecture 12
ANAT 261
· The circulatory system consists of the heart (which pumps in a
rhythmic and involuntary fashion), efferent (out of) and afferent
blood vessels.
oEfferent : arteries – blood diffuses at the level of capillaries.
oAfferent : veins go to heart with CO2 and waste products
· Lymphatic system is separate from the circulatory system. It starts
as blind capillaries larger lymphatic vessels drain into larger
veins such as the superior vena cava.
oLymph is made of plasma and immunoglobulins.
Right side - afferent system, Left – efferent system
· Each box on both sides (in the above diagram) are parallel because
they go together (i.e an arteriole and a venule, large vein and a
large artery, etc.)
· Larger arteries and veins are easy to distinguish because only a
piece of their walls are seen under a light microscope.
· When observing blood vessels (both veins and arteries) there are 3
layers – Intima (closer to lumen), media (larger for an artery),
adventitia (connective tissue around the structure).
· The media of muscular artery contains more than four layers of
muscle cells (spindle shaped smooth muscle cells).
· Both media contain reticular fibres, proteoglycans, and sometimes
external elastic membrane.
· Adventitia of blood vessels contains dense irregular tissue, and
vasa vosorum (blood vessel within a blood vessel).
ANAT 261 October 7, 2010
Dr. Mandato Lecture 12
· Vasa vosorum exists to supply blood for the other parts of the blood
vessel wall.
· Genetic defect of reticular fibers – aneurysm
· Atherosclerosis of large veins and arteries – infiltration of intimal
media with foam cells (similar to macrophages).
Intima of the Muscular Artery
· The structure closest to the lumen – endothelial layer which is a
squamous simple epithelium (flat cells) that rests on a basement
oNote – all epithelium rest on a basement membrane.
· Sub endothelial layer – at the beginning it is made of connective
tissue which eventually disappears leaving extracellular matrix.
· Interelastic limiting membrane (IELM) – elastic membrane
oWavy in cross section because when tissue is fixed arteries
contract, and go closer to the lumen.
oElastin is found in this structure
Middle Size Vein
Intima – no IELM
ANAT 261 October 7, 2010
Dr. Mandato Lecture 12
Media contains one or two layers of muscle cell
The vein appears collapsed because it has a thin wall, and
doesn’t have blood to keep it inflated.
Elastic Artery
Has elastic membranes in between which are smooth muscle
The membrane appears black under an electron microscope.
The muscle cells run in different directions (which in muscular
artery they run in a circular direction)
The muscle cells have vimentin rather than desmin intermediate