BIOL 2050U Lecture Notes - Tunica Externa, Tunica Media, Simple Squamous Epithelium

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29 Jan 2013

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Lymphocytes (6-18µm)
Spherical nucleus and shape, very little cytoplasm
Memory cells have specific antigen receptors on the cell surface
Lymphocytes vary in life span. Some live few days, others many years
Only white blood cells that return to blood stream after migrating to tissues
Monocytes (12-20µm)
Oval, horseshoe or kidney shaped nucleus; more cytoplasm than lymphocytes
Nucleus does not stain as darkly as lymphocytes in blood smears
After leaving circulatory system, they differentiate into macrophages in connective
Lobed nucleus and granular cytoplasm
Different functions: some engulf bacteria; others are involved with allergies and
Blood clotting
If blood vessels are damaged a series (cascade) of enzyme-control reactions occurs to
form a clot
o Prevents further blood loss
o Prevents invasion by pathogens
IMG 3-12-3
Clotting depends on clotting factors which are plasma enzymes
They are present as an inactive form in blood plasma
They are named with roman numerals e.g. Factor V
Haemophilia is an inherited disease. Patients make non functional Factor VIII
Serotonin causes smooth muscle of the arterioles to contract / narrows blood vessels,
cutting off the blood flow to damaged area
Blood vessels
Pulmonary artery
o Transport deoxygenated blood from the right ventricle into lungs
Systemic arteries
o Transport oxygenated blood from left ventricle to body tissues
o About 10% of total blood volume is in systemic arterial system at any given time
o Blood is pumped from the left ventricle into large elastic arteries
o Elastic arteries become smaller muscular arteries
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