Heart and Vessels Ketchum Flashcards
what does the cardiovascular system arise from>
angiogeneic cell clusters of the mesoderm
what is the order of blood vessels
arteries arterioles capillary venule vein
what do arteries do?
carry blood from heart to capillary beds
what do veins do
carry blood from capillary beds to heart
what is the function of capillaries
site of exchange:
nutrients
oxygen
waste
SMALLEST blood vessels
what is the structure of capillaries
what surrounds the capillary
single layer of simple squamous epithelium (endothelium)
surrounded by basement membrane
what is the average diameter of the capillary
8 microns
how can you tell apart lymphatic vessels and blood capillaries
blood capillaries have uniform vessel diameter
lymphatic capillaries have variable size lumen and incomplete basement membrane
what is simple squamous epithelium
endothelium which all vessels are lined with
most interchange between capillary lumen and extravascular space results from …
BUT how else can this exchange occur?
simple diffusion
(water, gases, salts and nutrients)
can also occur via active transport using PINOCYTOSIS (transports soluble high MW molecules across endothelial wall)
we aren’t bloated b/c there is fluid movement inside and outside
what does the rate of simple diffusion in capillary depend on?
blood and colloid osmotic pressure
how do cells cross endothelium? (such as white blood cells or macrophages)
pass endothelium by movement known as diapedesis (squeeze through the endothelial cells)
squeeze through tight junctions
what is the function of tight junctions in the capillary
prevent fluid loss BUT aren’t a strong adhesion so this is where diapedesis occurs
what are fenestrae
windows (pores) that are closed by diaphragm thinner than unit membrane
what are the support cells of the capillaries (pericytes) function?
these are basically inside the basement membrane and are closely associated with the capillary
they have a role in angiogenesis and vessel repair
in injury repair they can transform:
they can become vascular smooth muscular
augment BM production
function as fixed macrophages
what is the application of adipose-derived adult stem cells regarding pericytes
adipose-derived adult stem cells assume perictye-like morphology which may play a role in wound healing and angiogenesis
these cells developed greater cross-sectional vascular areas
involved in new vessel growth and enlargement of already existing vessels
what are the 3 types of capillaries
continuous capillary
fenestrated capillary
discontinuous capillary (sinusoid)
What are sinusoids
how do they differ from true capillaries
specialized enlarged capillary-like vascular channels
Differ:
larger than capillaries with irregular lumen up to 30 microns
the endothelium is discontinuous (gaps) and possess’ a discontinuous basement membrane
where are sinusoids located usually
exist in places where you need excessive exchange (liver, spleen, bone marrow)
allows direct communication and free movement of material