21-Blood Vessels and Hemodynamics Flashcards
Layers of all blood vessels - 3
Tunica interna - Endothelium, elastic lamina for diffusion
Tunica Media - Smooth muscle, vasoconstriction, elastic lamina
Tunica Externa - contains nerves and blood vessels (vaso vasorum), anchors to surrounding tissue
Main blood vessel types - 5
Arteries - take blood away from heart Arterioles - arteries to capillaries, controls blood pressure Capillaries - nutrient and gas exchange Venules - capillary to vein Veins - take blood to the heart
6 Elastic arteries
Aorta Pulmonary Trunk Brachiocephalic Subclavian Common Carotid Common iliac
Arteriole functions - 4
Regulate blood flow into capillary
Regulate resistance, therefore BP, using sphincter. Vasomotion.
Metarteriole tapers to capillary
Vasoconstriction, vasodilation changes BP
More capillaries needed where, amount typically in use at a time
More needed for high metabolic demands (brain, liver, kidney)
25%
3 capillary types based on leakiness
Continuous - CNS, lungs, skin, muscle - no proteins cross
Fenestrated - small holes, kidneys, sm. intestines, endocrine glands
Sinusoids - large holes, proteins and RBCs can cross - red marrow, liver, spleen
Types of Venules - 2
Postcapillary - allows white blood cell migration, nutrient exchange
Muscular - Reservoir for large amount of blood storage
Osmosis - 3 things needed
3 types of pressure
Water movement, through a membrane, from lower to higher solute concentration
Osmotic pressure - due to different solute concentrations, solute Pulls the water
Hydrostatic pressure - Like BP, Pushes the water
Filtration pressure - Osmotic plus Hydrostatic summed
Capillary Exchange occurs 3 ways
Diffusion - with concentration gradient
Transcytosis - endocytosis and exocytosis
Bulk Flow - Pressure driven flow, liquids and solutes
Bulk Flow parts and process - 7
Blood contains Albumin protein, does not pass membrane
On arteriole side, BP pushes liquids and ions and nutrients to ISF due to Hydrostatic. Can also be some osmotic pushing same way. Filtration.
On veinous side, BP lower, osmotic pressure pushes liquids and “wastes” ISF to blood. Reabsorption.
Left over fluids go into lymph. If lymph cannot handle all, Edema.
Systemic Edema - why
Reduced Albumin protein in blood, so Hydrostatic pressure pushes fluids out of blood, but Osmotic pressure does not pull enough back into blood. Lymph is overwhelmed.
Blood flow - 2 factors, 3 reasons for one, SVR
Pressure difference
Resistance - lumen size, blood viscosity, vessel length
Systemic Vascular Resistance - arterioles more than other vessels
Venous return - 3 factors
Left Ventricle - pressure pushes blood around
Skeletal muscle pumps - legs major factor
Respiratory pump - lungs
Varicose veins - 3
Incompetent valves
Physical activity best way to hold off
Great Saphenous Vein likely - little muscle to pump, longest vein in body
Circulation Time, and define circulation
Circulation is drop of blood starting at right Atrium, traveling to foot, and back to right Atrium.
One minute.