Flashcards in Blood Vessels (Vascular System) Deck (24):
What is the mission of the vasculature?
Maintain quality & volume of ECF
How far does the cell have to be from a capillary?
Where do the lymphatics drain from?
Where do the lymphatics drain to?
Drain from small vessels (arterioles, venules, capillaries)
Drain to large veins
What are the layers of the BV walls and what do they consist of?
Tunica Adventitia: Outer Layer; CT (connective tissue)
Tunica Media: Most variable; Smooth Muscle Cells (SMCs) & CT
Tunica Intima: Inner layer; Endothelial Cell layer (Simple squamous with basal lamina)
What is PECAM?
Platelet Endothelial Cell Adhesion Molecule aka CD31
Marker for vascularization
What are the heart's tunica layers called and what is special about each of them?
T. intima - Endocardium
T. media - Myocardium
Contains myocytes & fibroblasts
T. adventitia - Epicardium
Also might possibly include niche of adult resident cardiac stem cells?
What is the developmental role of epicardial cells?
What cell types do epicardial cells give rise to?
During development epicardial cells grow over the surface of the heart as a mono-cellular layer.
Epicardial cells give rise to:
Coronary arteries - Endothelial cells, SMCs
Maybe cardiac myocytes?
Layers of Elastic Arteries
Adventitia: External Elastic Membrane
Media: Thickest layer, circular SMCs with 40-70 elastic lamellae
Intima: Tight junctions & pinocytotic vesicles
What is the function of large vessels? What is a clinical finding for this vessel?
Function: Elastic recoil to maintain BP during diastole
What is different between large veins and large arteries?
Thin walled compared to arteries
Adventitia is the thickest tunic
What is special about the medium artery layers?
Adventitia: Nothing special
Media: Prominent, has 40 layers of SMC, almost no elastin
Intima: Internal elastic lamina as a unique marker
What is the function of middle vessels?
What is a clinical finding for this vessel, and what is the pathophys of this finding?
SMC regulate Blood Pressure
Athrosclerosis are intimal plaques from foam cells (macrophages and SMCs)
These plaques calcify, have platelets attach, form a thrombus, and lead to an MI/Stroke
What is different between middle arteries and veins?
Veins have much less media and lack an internal elastic lamina
What is the composition of the small arteries and arterioles?
T. media: 8 layers of SMC in small artery down to 2 layers of SMC in arterioles
What is the function of small vessels?
What is the clinical finding for these vessels?
SMC regulates bloodflow to capillary beds
Lipid uptake by SMCs narrows the lumen
What is the structure of a capillary?
The diameter of the lumen accepts 1 RBC: 7.5 μm
Single endothelial cell can make up a tube
Simple squamous endothelium with basal lamina (no media, no adventitia)
What are the types of capillaries and their structures?
Type I: Continuous
10 μm diameter
Tight junctions which admit proteins smaller than 10 kDa and pinocytotic vesicles which permit passage of proteins > 10 kDa
Type II: Fenestrated
10 μm diameter
100 nm windows which serve as permanent pinocytotic vesicles
Type III: Sinusoidal
30 μm diameter
Where are continuous capillaries located and what do they transport?
CNS, Heart, Skeletal Muscle, Lung
Where are fenestrated capillaries located and what do they transport?
Endocrine Glands - Hormones
GI Tract - Nutrients
Kidneys - Ions
Where are sinusoidal capillaries located and what do they transport?
Bone marrow, spleen, liver
What are the function of endothelial cells?
1. Exchange gases & nutrients
Gases thru cell membrane, nutrients thru pinocytotic vesicles, fenestrations, discontinuities
2. Secrete regulatory molecules
Vasoactive factors: Endothelin (vasoconstrictor), NO (vasorelaxant)
Growth factors: FGF, PDGF, VEGF to activate angiogenesis
Angiogenic activating factors (w/ receptors) and inhibiting factors
Activating: VEGF (VEGFR), FGF (FGFR), Angiopoietin-1 (TIE-2)
Inhibitors: Angiostatin, Endostatin
What diseases are there clinical therapies for using angiogenic factors? (Pro-angiogenic vs anti-angiogenic)
Pro-angiogenic: Ischemia in heart & extremities
Anti-angiogenic: Combat tumors (Single endothelial cell can support 50 tumor cells)