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UH BIOL 1344 - Final Exam Study Guide
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BIOL 1344 Exam # 3 Study Guide Lectures: 19 - 27Lecture 19The Urinary System: kidneys – ureter – urinary bladder – urethraKidneys - paired organs, outside peritoneal cavity, surrounded by fibrous capsule, perinephric fat, renal fascia, and paranephric fat which protects from mechanical shock. Unilateral renal agenesis – one kidney fails to develop, bilateral renal agenesis – neither developPtosis – when the kidneys drop causing a kink in the ureter due to loss of adipose connective tissue usually in anorexics or old people. Can result in renal failure Renal Calculi (Kidney Stones) – causes radiating, acute pain, and a burning sensation while urinating, can contain oxlate, phosphates, and sulfates. Stones don’t cause pain until they start moving. Treatment can include lithotripsy (pulverizes stones through an ultrasound type machine). Chronic Renal Failure: must get dialysis or a kidney transplant. Intravenous Pyelography (IVP) uses radioactive dye to measure kidney function. Dye flows with the blood to healthy areas of the kidney so whatever part of the kidney appears darker is the healthy area. Functions of the Kidney:1. Removing nitrogenous wastes2. Blood Cell Formation – kidneys secrete erythropoietin hormone to stimulate production3. Osmoregulation: regulates levels of water, electrolytes, and ions in the body4. Bone Health – calcium reabsorption, phosphate excretion, trigger vitamin D3 synthesis. Lecture 20Kidney Structure: 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.Structural flow in the kidney goes Bowman’s capsule, proximal convoluted tubule, thick descending loop of Henle (permeable to water and sodium) a thin ascending loop of Henle (permeable only to sodium) distal convoluted tubule, collecting tubule, collecting duct, papillaryduct, 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 - 85%, in the short loop of Henle, normally used to produce urine. Juxtamedullary nephrons - 15%, in the long loop of Henle, used in stressful situations creating highly concentrated urineUrine 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 ductLecture 21Filtration – small substances (glucose, amino acids, urea, potassium, chlorine, calcium, and bicarbonate) are freely filtered. Large sized particles (red and white blood cells) are not filtered. Regulated filtration is based on physiological need such as water needs.Nephritis - inflammation of the kidneys, blood cells can enter the urine, this is called pyuria Net Filtration Pressure – simple diffusion due to blood pressureGlomerular Filtration Rate (GFR) = (urine concentration (mg/ml) X urine flow (ml/min))/ plasma concentration (mg/ml). about 125 ml/min or 180 L/day but 99% of this is reabsorbed back into the body rather than being secreted as urine. There is intrinsic and extrinsic control of GFR. 1. Intrinsic mechanisms– myogenic regulation which controls smooth muscles of afferent and efferent arterioles through vasoconstriction and vasodilation. 2. Extrinsic mechanisms – neural control: sympathetic input (epinephrine and norepinephrine secreted during stress, the fight or flight response). These bind with alpha and beta receptors. Alpha causes vasoconstriction while beta causes vasodilation. Lecture 22Obligatory water resorption – inside tubule of kidney is hypotonic so water goes outOsmotic diuresis – large volumes of water are lost through diluted urineHormonal diuresis – no ADH or aldosterone is maintaining water homeostasis Osmolarity – solute concentration/liter of solutionOsmolality – solute concentration/ kg of solvent (solvent is always water) Reabsorption: simple diffusion, facilitated diffusion (glucose flows from filtrate through PCT cell into blood), primary active transport (potassium/sodium pump), secondary active transport (SGLT or sodium dependent glucose transporter)Tubuloglomerular regulation – macula densa cells detect concentration of filtrate, if too concentrated this means flow through the nephron is too fast and the GFR is high. To solve, glomerular shrinks, reducing filtration surface area and GFR decreases. Reverse also happens.Lecture 23Transport Maximum (Tm)- amount of substance reabsorbed per minute. Renal Threshold: physiological limit of reabsorption, if a substance goes over this limit, it spills out with the urine. Blood Flow through the kidneys: 1250 ml/min but only plasma gets filtered so this is about 700 ml/min going through glomerulus. Because of GFR about 125 ml/min actually gets filteredCounter Current Mechanism: blood flow goes opposite of urine flow. Micturition: this is the act of passing urine and it is controlled by T11-L2 and the sympathetic nerve fibers. There is the internal urethral sphincter which opens and closes involuntarily through the sympathetic nervous system. Then the external urethral sphincter is voluntary because it is controlled by skeletal muscles and the parasympathetic spinal nerves. When the bladder fills to 300 ml there is a desire to void the urine. If the person does not urinate at this point, the urge passes and the volume can then get up to 600-700 ml through distending the bladder. Any more than this volume results in involuntary urination. Lecture 24Fluids: body is average 65% water by weight. Most of this is in skeletal muscles. 2/3rds of water weight is intracellular fluid (ICF) and the other third is extracellular fluid (ECF). 2/3rds of the ECF is interstitial fluid while the other third is blood plasma. Edema is the accumulation of water outside the cells. Kwashiorkor is a condition which results ina swollen pot belly due to lack of proteins in the blood creating a hypotonic state. This means that water leaves the blood and enters interstitial fluid creating edema. Water Intake: approximately 700 ml from food, 1600 ml from drinking, 200 ml produced in the body from metabolic processes. Water Loss: approximately 500 ml from sweating, 300


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UH BIOL 1344 - Final Exam Study Guide

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