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BIPN100 A - Blood Volume Factors that change blood volume 1...

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Blood Volume Factors that change blood volume: 1. ADH (vasopressin) increases water reabsorption in the kidney increase vasoconstriction - due to increase osmolarity in blood - responds to change in blood volume detected by baroreceptors. - Counteracts loss in blood volume like hemorrhage 2. Natriuretic Peptides increase loss of Na+ in urine increase osmotic contribution in urine increase loss of water and decrease blood volume a. Atrial NP (ANP) secreted by heart (endocrine gland) stretch Receptors activated in atria due to increase venous return vasodilation and decrease Na+ absorption. b. Brain NP (BNP) same effects as ANP c. These NPs are meant to decrease blood volume and thus decrease blood pressure. They suppress secretion of ADH from the hypothalamus. - In the kidney, they prevent Na+ and Cl- absorption= Na+, Cl-, H20 in urine. - They inhibit secretion of aldosterone by inhibiting renin release, increase glomerulus filitration rate, and stimulate the cardiovascular center of the medulla oblongata to decrease Blood pressure from decrease sympathetic output. RAAS- Renin-Aldosterone Activating System responds to decrease BP, stimulated by sympathetic system. - Renin secreted by juxtaglomerular apparatus secrete renin acts on angiotensinogen converted to angiotensin I ACE converts this to angiotensin II a potent vasoconstrictor that stimulates secretion of aldosterone this acts on distal tubule and collecting duct to increase absorption of Na+ to increase Blood Volume. - Also, there is K+ excretion - Aldosterone is a steroid hormone stimulated by increase K+ in plasma or decrease Na+ in plasma - This hormone increases Na+/K+ channels time and makes new Na+/K+ channels and pumps. Capillaries - single endothelial cell with junctions between them, has pores to allow H2O and small molecules move between blood space and ECF. - O2 and CO2 can diffuse across cap. walls. - Works by transcytosis of molecules - Driving force of gradient is the hydrostatic pressure. Eqn for Outward (filtration) flow: K (Pcap- Pif) - But also need return of fluid done by osmotic pressure Eqn for Inward (absorption) flow: σ (Пcap – Пif) - This change in osmotic pressure is caused by solutes like albumin and gamma- globulins impermeable macromolecules.
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- σ represents the permeability of the molecules σ = 1 for impermeable and = 0 for fully permeable. Net Flow = Outward Flow- Inward Flow Diagram: Fig 15-18 - Lack of protein in diet hepatic cirrhosis/ protein deficiency not enough osmotic pressure due to say lack of albumin in blood increase pressure in hepatic vein increase hydrostatic pressure fluid accumulates in abdomens swelling due to increase accumulation of ascites fluid. Lymphatic System
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BIPN100 A - Blood Volume Factors that change blood volume 1...

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