BIOL 1344 Lecture 20 Outline of Last Lecture I. The Urinary SystemA. Anatomy of the KidneyB. Kidney DiseasesC. Functions of the KidneyOutline of Current Lecture II. Structure of KidneyIII. Blood Supply and Cell TypesIV. Urine Formation Current LectureStructure of Kidneys: 8-15 lobes of the renal pyramids, renal papillae, minor calyces, major calyces, renal pelvis, ureter, urinary bladder. Each kidney contains about 1 million nephrons. Thegeneral structural flow in the kidney goes from the Bowman’s capsule to the proximal convoluted tubule, and thick descending loop of Henle which is permeable to water and sodium, a thin ascending loop of Henle permeable only to sodium, distal convoluted tubule, collecting tubule, collecting duct, papillary duct, then finally the minor calyx. Leading from the other side of the Bowman’s capsule are efferent and afferent arterioles. There are two types of nephrons in the kidneys. Cortical nephrons make up 85%, are in the short loop of Henle, and are normally used to produce urine. Juxtamedullary nephrons make upthe remaining 15%, are in the long loop of Henle, and are used in stressful situations creating highly concentrated urine, more than 4 times the plasma concentration which is 300 mOsmols. Blood Supply – 250 ml/min to the kidneys. Blood flow path is abdominal aorta, renal artery, segmental artery, interlobar artery, arcuate artery, interlobular artery, afferent arteriole, glomerulus, efferent arteriole, interlobular vein, interlobar vein, renal vein, vena cava, then to the heart. Cell Types within the Kidney: in the proximal convoluted tubule and the thick loop of Henle it is cuboidal epithelium with microvilli for reabsorption. In the thin loop of Henle it’s simple squamous epithelium without microvilli. In the distal convoluted tubule it is cuboidal with fewermicrovilli. In the collecting tube and duct there are principle cells which emit aldosterone and intercalated cells which have the A Type and B Type cells which regulate acids and bases. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Urine Formation:1. Filtration – blood filtered in glomeruli, creates glomerular filtrate which is similar to plasma in its makeup – glucose, amino acids, albumins, vitamins B and C, water, and ionssuch as sodium, potassium, chlorine, phosphate)2. Reabsorption – 99.5% percent of this filtrate is reabsorbed3. Secretion – secreted in distal convoluted tubule and collecting
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