Lecture3

Lecture3 - Review: Purpose of excretory system = filtration...

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1 Review: •Purpose of excretory system = filtration and maintain osmotic balance (osmoregulation) •Requirements and mechanisms vary depending on environment (osmoconformers vs. osmoregulators, need to conserve solutes vs water) •Nitrogenous wastes must be excreted and/or detoxified •Nephron is functional unit of vertebrate kidney •Each kidney contains ~1 million nephrons, regularly arranged Key concepts: •characteristics of cells engaged in absorption (high SA/vol) •countercurrent exchange •mechanism for altering permeability to water “Well, this is getting nowhere fast.” The nephron is the functional unit of the vertebrate kidney 3 major parts of nephron: 1) renal corpuscle = glomerulus + Bowman's capsule = site of filtration 2) renal tubule = site of tubular secretion and absorption, surrounded by capillaries 3) collecting duct = site of urine processing, e.g. concentration or dilution Nephron arrangement within kidney: •Glomeruli in cortex •Some renal tubules loop through medulla •Collecting ducts start at cortex, pass through medulla, empty into ureter
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Renal corpuscle structure/function Glomeruli are highly permeable capillary beds Bowman’s capsule cells surround the glomeruli Podocytes are surface cells of the Bowman’s capsule Blood pressure forces water and small molecules from glomerulus into Bowman's capsule Cells and large molecules are retained in blood Renal tubule structure/function Nephron tubules may loop across the kidney Each tubule has several specialized zones: •Proximal convoluted tubule •Loop of Henle •Distal convoluted tubule •Collecting duct Cell structure in the different zones of the renal tubules reflects function Structure/function of proximal convoluted tubule cells Function: •major site of reabsorption of NaCl, glucose, and aas; water
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This note was uploaded on 04/07/2008 for the course MCDB 1B taught by Professor Weimbs during the Winter '08 term at UCSB.

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Lecture3 - Review: Purpose of excretory system = filtration...

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