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81 Cards in this Set

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What is the objective of the vascular system?
To mainatin the QUALITY and VOLUME of the extracellular fluid.
Where is the site of exchange for replenishing oxygen and nutrients in the EC space?
In the Microvascular capillary bed of each tissue
How close to a nurturing capillary are all cells?
Within 200 um
How many "tunics" in vessels?
3
What are the 3 tunics of blood vessels?
1. Tunica Adventitia
2. Tunica media
3. Tunica intima
What is the outermost covering of blood vessels? What is it made of?
Tunica adventitia - made of connective tissue.
2 Important structures housed within the Tunica Adventitia:
-Vasa vasorum
-Nervi vascularis
What is Vasa Vasorum?
The vasculature of the vasculature - the blood supply to the vessels themselves.
What is Nervi vascularis?
The blood vessel's nerve supply
What is Tunica Media? What is it made up of?
The most variable layer - made up of Smooth muscle cells + CT
What is the Tunica Media made of it it's in the heart?
Cardiac myocytes + CT
What is the innermost covering of the blood vessel?
Tunica intima
What does the tunica intima consist of? (3 things)
-Endothelium
-Basal lamina of the endothelium
-some CT
What type of epithelium is the endothelium of tunica intima?
Simple squamous
What feature of the tunica intima endothelial cells KEEPS blood IN the tube vessel?
Tight junctions
How does the tunica intima change at the capillary beds?
The tight junctions become leaky to allow exchange of fluids.
What are the three very highly modified vascular tunics in the heart called?
-Epicardium
-Myocardium
-Endocardium
What is the Epicardial layer made up of in the heart? (cell types)
Simple squamous mesothelium + some CT
Why is the epicardium important?
Because innervation and coronary vessels enter the heart here.
What 2 cell types make up the myocardium?
-Cardiac myocytes
-Cardiac fibroblasts
What type of cells make up the cardiac endocardium?
Simple squamous endothelium + basal lamina + some CT
What important component of the heart is located in the sub-endocardium?
Purkinje fibers - the conduction system.
Which has a thicker wall; arteries or veins?
Arteries
Why are the walls of arteries thicker?
They have a more highly developed tunica media
What fiber is prominent in the tunica media of arteries?
Elastin
How is the lumen different in arteries versus veins?
It's smaller in arteries
What is the thickest layer in veins in contrast to arteries?
The tunica ADVENTITIA is thickest in veins; and their lumen is much larger than arteries.
What are the arrangements of elastin fibers in large vessels called?
lamellae
3 important features of the Tunica Intima in large vessels:
-Tight junctions
-Pinocytotic vesicles
-EC cells that secrete Fx VIII
Function of the large arteries:
To maintain BP during diastole
What is an Aneurysm?
Outpocketing of the tunica media in large arteries
What distinguishes large veins from large arteries?
Their thick tunica adventitia
What are the 2 prominent features that distinguish MEDIUM ARTERIES?
-Prominent layer of 40 SMCs in the tunica media
-Internal lamina is ELASTIC
Function of the medium arteries?
To regulate blood pressure
What pathology develops in medium arteries?
Atherosclerosis
2 Cell types that form atherosclerotic plaques:
-Macrophages
-Smooth muscle cells
How do macrophages form atherosclerotic plaques?
They ingest lipid and become lodged in the endothelial wall.
How do SMCs form atherosclerotic plaques?
They migrate to the tunica intima, proliferate, and take up LDL.
What is the combination of Lipid-laden Macrophages and SMCs called?
Foam cells
Aside from simply blocking the arteries, what do foam cells do?
Bind platelets - form pathological thrombosies that cause STROKE and/or MI
What feature of Medium AND small veins allows them to direct the flow of blood to the heart?
Valves
What are the valves in medium and small veins made of?
Infoldings of the tunica intima.
How wide are SMALL blood vessels? How many RBCs can fit through?
Less than 50 um in diameter
Allows ~6-7 RBCs to pass through at a time.
What is the prominent layer in small arteries/arterioles?
Their tunica media
How many layers of SMCs are in
-Arteries?
-Arterioles?
Arteries = 8 layers

Arterioles = 2 layers
What results when SMCs in the media wall of small arteries and arterioles take up lipid?
Hypertension
What is the function of the small arteries and arterioles?
To regulate bloodflow to the vascular capillary bed.
What important inflammatory process occurs at venules?
Diapedesis of leukocytes
How are capillaries prominently different from all other vessels?
They have no tunica adventitia or media - only the intima
How wide in diameter are capillaries?
~10 um
So how many RBCs can fit through a capillary at one time?
1-2
What is a capillary composed of?
A single layer of endothelial cells + its basal lamina
Are capillaries active or passive?
Very active
What makes capillaries tissue specific?
Expression of tissue-specific growth factors
3 morphological types of capillaries:
-Continuous
-Fenestrated
-Sinusoidal
4 tissues that have Continuous capillaries:
-Heart
-Skeletal muscle
-CNS
-Lung
What makes these capillaries "continuous"?
Tight junctions
How do continuous capillaries transport stuff from the vessel lumen to connective tissue?
Via pinocytosis
Do CNS vessels have pinocytosis?
No
What tissues have Fenestrated capillaries (3)?
-Endocrine organs
-GI tract
-Kidneys
What is the predominant feature of fenestrated capillaires?
100 nm wide windows that allow passage of large molecules
Where are Sinusoidal capillaries found? (3 places)
-bone marrow
-liver
-spleen
What are sinusoidal capillaries for?
Letting whole RBCs pass through.
What is the function of capillaries in general?
Exchange of gases and nutrients.
What size of molecules can pass through the intercellular junctions of endothelial cells in capillaries w/out needing transporters/pinocytosis?
<10,000 kDa
Do endothelial cells in capillaries just exchange gases and nutrients?
No; they also SECRETE STUFF.
What are some things that capillary endothelial cells secrete?
-Endothelin (vasoconstrictor)
-Nitric oxide (vasodilator)
-Growth factors
-PDGF
-Interleukins
Where are LYMPHATICS present?
Everywhere except bone marrow and the CNS
What is special about lymphatic vessels?
they are very very very very very leaky
What is the function of lymphatics?
One way drainage of lymphatic fluid to veins and venules.
What is lymphatic fluid composed of?
WBCs and Lipid
How is lymphatic fluid circulated?
By skeletal muscle contractions
What is vasculogenesis?
Development of blood vessels in the embryo
What is angiogenesis?
REgeneration of blood vessels in adults.
What vascular Endothelial cell receptor is necessary for angiogenesis?
VEGEF (thank you deb donahoe)
Well actually 3 receptors needed for angiogenesis:
-VEGEF receptor
-FGFR (fibroblast grwth factor)
-TIE2
What do VEGEF, FGF, and TIE2 do?
Stimulate angiogenesis
What inhibits angiogenesis? (2 things)
Angiostatin
Endostatin
When would you want to stimulate angiogenesis?
After an MI or in diabetics with ischemic tissue diseases.
When would you want to inhibit and prevent angiogenesis?
In tumor situations
Other than directly inhibiting angiogenesis with Angiostatin or Endostatin how can you limit tumor angiogenesis?
By giving an antibody against VEGF.