arteries from largest to smallest
elastic artery
muscular artery
arteriole
continuous capillary
veins from largest to smallest
large vein
medium sized vein
venule
fenestrated capillary
what is the basic structure of a capillary
simple squamous epithelium is the endothelium
basal lamina
pericytes possibly on outside
what is the function of pericytes
stem cell properties- would repair and angiogenesis
contractile function- regulates flow through the capillaries
what are the two methods of capillary exchange
transcytosis and between the cells
what is transcytosis and how can it be done
through the endothelial cell
done via: diffusion, active transport, pinocytosis, or fenestrations
what allows substances to pass between capillary endothelial cells
junctional complexes with occluding junctions, adherent junctions, and gap junctions
what induces junctional complexes to open
inflammation
what are the 3 types of capillaries
continuous
fenestrated
sinusoid
describe continuous capillaries and where are they found
have continuous endothelium and basal lamina
most common type
least penetrable
found in the muscle, brain, and lung
describe fenestrated capillaries and where are they
have holey endothelium with continuous basal lamina
fenestrations may have diaphragms
permeable
found in endocrine glands, intestine, kidney
describe sinusoidal capillaries and where are they
discontinuous endothelium and basal lamina (or no basal lamina)
allow faster exchange
found in blood forming organs (bone marrow, liver, spleen)
what do endothelial cells synthesize and release
coagulation factors antithronmbogenic factors vasoactive factors immune response factors growth factors oxidative enzymes
what coagulation factor is released by endothelial cells
von Hillebrand factor- stored as Weibel-Palade bodies
what are antithrombogenic factors for
prevent clots from on the vessel wall
what is the main growth factor released by endothelial cells
VEGF
what are the 3 layers of a blood vessel
tunica intima
tunica media
tunica adventitia
what layers and cell types are in the tunica intima
endothelium- simple squamous epithelium
subendothelium- loos connective tissue
myointimal cells- properties of smooth muscle, fibroblasts, and phagocytes
what blood vessel layer is the same in all vessels
tunica intima
what is in the tunica media
concentric layers of smooth muscle
internal and external elastic membranes with fenestrations
what is in the tunica adventita
loose connective tissue
possible elastic fibers
what layer of blood vessel is thicker in veins
tunia adventitia
what layer of blood vessel is thicker in arteries
tunica media
what layer do blood vessels, nerves, and lymph vessels run in
tunica adventitia
what does the tunica media of large elastic arteries look like
smooth muscle
elastic fibers
internal and external elastic lamina blend in- not visible
what does the tunica adventitia of large elastic arteries look like
thin
vasovasorum present
what are examples of large elastic arteries
aorta
pulmonary trunk
renal arteries
what does the tunica media of a muscular artery look like
4-40 layers of smooth muscle
distinct internal and external elastic membranes
what does the tunica adventitia of a muscular artery look like
thicker than large elastic arteries
what are examples of muscular arteries
most named arteries
what does the tunica media of arterioles look like
1-3 layers of smooth muscle
what does the tunica adventitia of arterioles look like
very thin
what are examples of arterioels
precapillary sphincters
what does the tunica media of venues look like
0-2 smooth muscle layers
may have elastic lamina
what does the tunica adventitia look like in venules
absent or very thin
what type of vessel may have periocytes
venules
which vessel has a large collapsed lumen
venules
what two types of blood vessels travel together
venules and arterioles
what does the tunica media of veins look like
thin
may have internal elastic lamina
what does the tunica adventitia of veins look like
very thick
which type of vessel has valves
veins
what are examples of veins
most named veins
what does the tunica media of large veins look like
thin
what does the tunica adventitia of large veins look like
thickest layer
longitudinal bundles of smooth muscle
vasovasorum
what are examples of large veins
superior and inferior vena cava
what determines the flow of blood in capillary beds
metabolic needs of the tisseu
where and what are pre capillary sphincters
junction of arteriole with the capillary
smooth muscle in arterioles regulates blood entering capilaries
what are metarterioles
cross between an arteriole and venule that acts as the main route through the capillary bed with branches with sphincters coming off
what are arteriovenus anastamoses and what is their main purpose
connect the arteriole directly to the venule
used for thermoregulation to direct blood away from the capillaries
what are two other uses of arteriovenus anastamoses
direct blood away from the penis when it is not erect
in the uterine endometrium to reduce blood loss during menses
what are the two types of specialized areas in blood vessels
baroreceptors
chemoreceptors
what are baroreceptors and where are they found and why are they special
monitor blood pressure
in the carotid and aortic sinuses
have a thin tunica media so the walls can extend and a thick tunica adventitia with lots of nerve endings
what are chemoreceptors and where are they found and why are they special
monitor changes in blood gasses and pH
in the carotid and aortic bodies
what are the special structures in chemoreceptors and what are their roles
gloms cells- detect blood pH
sheath cells- surround gloms cells and have nerve endings
what happens during normal aging of blood vessels
lose elastic and have more collagen resulting in weaker, stiffer vessels
how does an aneurism form
weakened vessel walls dilate
what is arteriole tonus
level of constriction to maintain peripheral resistance
what happens in hypertension
increased arteriole tons leads to smooth muscle hypertrophy and activation of the RAAS
what is arteriosclerosis and what is it associated with
thickening of tunica media due to constant vessel smooth muscle contraction
loss of wall elasticity
associated with hypertension and diabetes
what is athersclerosis and describe the disease process
thickening of tunica intima due to defects in endothelium that let lipids through which accumulate in the tunica intima
lipids are phagocytosed by macrophages and myointimal cells which leads to plaque production
plaques disrupt the endothelial cells on the vessel wall which decreases antithrombotic factors (thicks the walls are damaged, so it wants clots to form)–> clots
tunica intima fibrosis and tunica media atrophy
what is a haemangioma
benign mass of blood vessels visible through the skin
what is angiosarcoma
malignant tumor of endothelial cell origin
what is kaposi’s sarcoma
small malignant tumors in the s kin, muscle and internal organs of endothelial origin
associated with viral infections
what is vasculogenesis
production of new blood vessels, occurs mostly in embyo
describe the process of vasculogenesis
mesenchymal cells secrete VEGF and differentiate into angioblasts which proliferate and form tubes
what is vasculogenesis regulated by
VEGF and VEGF receptors
what is angiogenesis and when does it happen
sprouting of new blood vessels off of existing vessels
occurs in embryos, the uterus, wound healing, and inflammation
what are the steps of angiogenesis
- hole made in exsiting vessel
- area missing basal lamina buds
- endothelial cells proliferate and migrate out
- tube formed
- basal lamina assembled and cells are recruited to form the layers
what prevents over proliferation during angiogenesis
apoptosis
what cells are recruited during angiogenesis
pericytes
fibroblasts
smooth muscles
what controls antiogenesis
VEGF angiopoeitin Tie- tyrosine kinase with immunoglobulin like EGF apoproteins notch receptor signaling
what does Tie do
modulates induction and inhibition of endothelial cell proliferation
what do apoproteins do
contribute to vessel stability
what do notch receptors do
activate VEGF and inhibit endothelial cell apoptosis
what type of tissue is endocardium
simple squamous epithelium
sub endothelium of loose connective tissue with collagen, elastic fibers, and smooth muscle cells
what are the 3 types of cardiac muscle
contractile
conducting cells
endocrine type cells (secrete hormones)
what are the layers of the epicardium made of
outer- simple squamous epithelium
inner- loose ct with veins, nerves and adipose
what are the main conducting areas of the heart
SA and AV nodes
atrioventricular bundle of his
purkinje fibers
what is the fibrous skeleton of the heart
dense irregular ct surrounding the valves and great vessel bases and forms the intramembranous septum
what is the purpose of the fibrous skeleton
structure and anchoring for valves and the leaflets
what is the structure of heart valves
atrial side- loose CT for shock absorption
ventricular side- dense CT with elastic fibers covered by endothelial tissue
how does inflammation affect heart valves
increased collagen fibers which increases stiffness
stimulates angiogenesis which makes valves fragile
what is a cardiac infarct
loss of blood flow to the heart from a blockage in coronary vessels
what is inflammation of the valve
vavulitis
what is rheumatic fever
group A beta hemolytic streptococci
can lead to mitral valve defect
what do lymphatic capillaries look like
blind ended
no occluding junctions
discontinuous or missing basal lamina
what do lymphatic vessels look like
similar to veins
blended layers
what do lymphatic ducts look like
have circular and longitudinal smooth muscle
what is edema
interstitial fluid volume is greater than drainage capacity OR the lymphatic vessels are blocked
what is lymphedema
damaged or abdormal lymphatic vessels leading to inflammation or fibrosis
common after lymph node removal (mastectomies)