Vascular bio II Flashcards
What are the three types of capillaries?
Continuous
Fenestrated
Sinusoidal
What type of junction exists between cells of a continuous capillary?
Tight junctions (zonulae occludens)
If a ZO is incomplete, what is it then called?
Fascia occludens
What is the fold that covers up the tight junctions between the cells of continuous capillaries?
Marginal fold
What is present in large amounts in the cytoplasm of continuous capillaries?
Pinocytotic vesicles
How are transendothelial channels formed in continuous capillaries?
Fusion of many pinocytotic vesicles
Where are continuous capillaries found?
Brain Lung Muscle CT Exocrine glands
anywhere where you want specific transport
What are the two types of fenestrated capillaries?
With and without a diaphragm
True or false: the basal lamina is discontinuous in fenestrated capillaries?
False
Where are fenestrated capillaries found?
Kidney
Endocrine glands
Intestines
Glomerulus (diaphragms absent here)
Anywhere where movement of ions is preferred
Do most fenestrated capillaries have diaphragms?
Yes, most do
What is different about the basal lamina in sinusoidal capillaries?
either very discontinuous or absent
Where are sinusoidal capillaries found?
Red bone marrow
Liver
Spleen
Adrenal cortex
Wherever rapid movement is needed
What are the two types of venules?
Pericytic and muscular venules
Where do leukocytes attach in veinules?
At the marginal fold
Why is the tunica media thin in veinules?
Low pressure
What is the thickest layer of veinules?
the tunica adventitia
What are present in veins that are entirely absent in arteries?
valves
What are present in arteries that are entirely absent in veins?
Lamellae
What is characteristic of medium veins, as compared to smaller veins?
Small amount of smooth muscle
What is the defining characteristic of large veins?
Bundles of longitudinally smooth muscles in he tunica adventitia (NOT the tunica media)
What is vasculogenesis?
de novo vessel formation
What is angiogenesis?
Growth of vessels from existing EC derived channels