Principles lec 5 2013

Active secretion kidney urine liver bile transporters

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Unformatted text preview: rom blood stream to uinary tract 2. Active secretion (kidney – urine & liver - bile) transporters that use energy and force things out independent of concentration barrier 3. Diffusion into glandular secretions (mammary, sweat, saliva) if soluble and/or small enough you can cross through diffusion without any energy use if fat soluble you can go anywhere good and bad, because you can be removed easily and retaken up easily Can excretion Fail? YES 1. Lipid soluble – Storage – BIOACCUMULATION 2. 3. Reabsorbed – Kidney (Hg-metalothionine) GIT (bile salts) active transport!! Binding – Storage Bioaccumulate (lead) The Kidney very well vascurlized this helps with re-uptake • Nephrons (1 million) glomerulus, high blood flow, leaky podocytes • Spaces 40 Angstroms 1A= 1/100000000 cm • hydrostatic filtration- hydrophilic molecules pushed through •Reabsorption of water, sugars, peptides (transport mediated) • Some transporters- secretion Kidney Toxicant Excretion Not Available can be diffused out into blood stream or transported out most things get filter, or get reabsorbed or excerted Available To T+ To Transporters T+ T+ To To To Reabsorption Eliminated T+ + T After filtration in Glomerulus: T+ - Large water soluble xenobiotics = eliminated in urine - Some reabsoption of large water soluble nutrients (mistakes!) - lipid soluble compounds can diffuse back into the bloodstream Liver Anatomy Liver receives oxygenated blood from the heart (hepatic artery) Also receives blood from the stomach, SI, LI, pancreas, spleen (portal vein) Tissue divided into lobules roughly hexagonal, portal triads on corners Hepatocytes line sinusoids (hepatic capillaries) Bile ducts arranged to collect fat soluble waste, drains to gall bladder Lobules Portal Triad Liver Secretion Liver gets first crack at molecules absorbed from the GI Many xenobiotic transporters filter blood, bring many molecules in: Liver = major site of metabolism Hepatocytes synthesize bile, secrete conjugates into...
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