KNES 260 Lecture Notes - Osmosis, Allergen, Mast Cell
Document Summary
Epinephrine released from adrenal medulla primarily acts on beta-2 type adrenergic receptors found mostly in heart and skeletal muscle: activation of beta 2 receptors results in vasodilation. Beta-2 adrenergic receptor activation: epinephrine is a hormone, epinephrine creates an increase in blood supply, depending on where, epinephrine can cause vasodilation (in heart and skeletal muscles) and vasoconstriction (digestive tract) Active hyperemia: a local reflex: increase in blood flow to a tissue in response to increase metabolites (co2 and lactic acid) in the interstitial fluid of that tissue, depletion of o2 also causes active hyperemia, norepinephrine=neurotransmitter, epinephrine=hormone (blood circulation) Microcirculation and exchange across capillary walls: metarteriole is a shunt, precapillary sphincters open in response to local factors like increase in co2 and lactic acid and increase in. O2: most capillary beds (about 90%) in muscle tissue are closed under resting conditions, blood is shunted through metarterioles to venules when the pre-capillary sphincters are closed.