11/24/2014 Microscopic Anatomy Blood Vessels II Thomas Poole Flashcards
What is the average diameter of a capillary
5-10 microns
What is the average length of a capillary?
0.05 - 1 mm depending on the organ
Name the intermediate filaments that provide structural support to endothelial cells.
Desmin
Vimentin
What kinds of junctions to endothelial cells make?
Tight junctions or gap junctions, depending on the organ
What “stuff” do endothelial cells produce?
Collagens, is types I, II, IV and V Fibronectin Laminin Coagulants Anticoagulants
What cells share the basal lamina with the endothelial cells?
Pericytes
Pericytes are what shape?
Stellate
Pericytes can serve what function after injury?
They can be stem cells for endothelial cells and smooth muscle cells.
What capillaries have tight junctions?
Continuous capillaries (muscle, nervous, connective tissue, exocrine pancreas)
Where are fenestrated capillaries located?
Pancreas, intestine, endocrine glands
A special type of fenestrated capillaries with no diaphragm is located where?
Renal glomerulus
What is a diaphragm of the capillary?
In fenestrated capillaries, except in the renal glomerulus, the windows in the capillaries have little caps.
About how big is a capillary fenestra?
60-80nm in diameter
What kind of capillaries are found in endocrine glands, liver, bone marrow and spleen?
Sinusoidal capillaries:
Discontinuous in liver and bone marrow;
Venous sinusoids in spleen
What is the difference between fenestrated and sinusoidal capillaries?
In sinusoidal capillaries, the diaphragms are much larger, as to be leaky.
What are the three main methods of transport across a capillary wall?
- Fenestrations
- Pinocytosis
- Trans-Golgi network vesicles
* *2 and 3 are examples of transcytosis
There are two distinct pore systems in endothelial cells: small (9-11nm) and large (50-70nm). The small system is through to be gaps that allow for what kind of transport?
Water and small hydrophilic vesicles
T/F: Arteries are more numerous in the body then veins.
False. Veins are both larger and more numerous in the body, carrying up to 70% of the body’s blood at any given time.
Why do veins have more extensive vasa vasorum and lymphatics?
Because they see less oxygenated blood and need another way to receive nutrients.
__1__ contain more collagen and less elastic substance and smooth muscle than __2__.
- Veins
2. Arteries
Veins owe most of their thickness to what outermost layer of their structure?
Adventitia
What forms the small valves in certain small and medium veins?
Intima infolding, with an elastic tissue core.
In large veins, what structural tissue element is often missing or incomplete?
Media (between intima and adventitia)
Large veins contain a continuous endothelium and basal lamina, but no ____
internal elastic lamina
Large vein adventitia contains what important structures?
- Vasa vasorum
- Lymphatics
- Collagen and elastic fibers
- Smooth muscle, longitudinally-oriented
In arteries, which section is largest, the intima, media or adventitia?
Media
In small and medium veins, in what direction does smooth muscle arrange itself? What layer is smooth muscle found in?
Smooth muscle is found in the media in small and medium veins, and runs circumferentially.
What types of vessel are the preferred location for leukocyte emigration?
Venules
What are the two types of venules?
- Pericytic venules
2. Muscular venules
Where are pericytic venules found?
Post capillary venules that resemble large capillaries, about 10-15 microns in diameter.
Muscular venules received blood from:
pericytic venules and accompanying arterioles
Do muscular venules have smooth muscle?
Yes, 1-2 circular layers of smooth muscle in the media.
What is a portal system?
A portal system carries blood from one capillary bed to another, ie. hepatic portal system.
Arteriovenous anastomoses are direct connections between arterioles and venules. Smooth muscle cells form a ___ that regulates blood flow and allows a bypass of the capillary bed.
sphincter
Large lumens, thin walls, irregular shape, extensive branching. These are all characteristics of?
The lymphatic vessels
How are lymphatic capillaries similar to regular capillaries?
They aren’t, really. They have a discontinuous basal lamina, and are held open by elastic anchoring filaments.
What is a Weibel-Palade body?
Weibel–Palade bodies are the storage granules of endothelial cells, the cells that form the inner lining of the blood vessels and heart. They store and release two principal molecules, von Willebrand factor and P-selectin, and thus play a dual role in hemostasis and inflammation.
