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Excretory System

Excretory System. Functions of the Kidney. Excretion – Removal from the body of the waste products of metabolic pathways Osmoregulation – Is the control of the water balance of the blood, tissue, or cytoplasm of a living organism. Draw and label a diagram of the kidney. Kidney Structure.

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Excretory System

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  1. Excretory System

  2. Functions of the Kidney • Excretion – Removal from the body of the waste products of metabolic pathways • Osmoregulation – Is the control of the water balance of the blood, tissue, or cytoplasm of a living organism.

  3. Draw and label a diagram of the kidney

  4. Kidney Structure

  5. Nephron – the functional unit of the kidney

  6. Annotate a diagram of a glomerulus and associated nephron to show the function of each part

  7. Ultrafiltration specifics • Production of filtrate from blood • 20% of blood plasma passes through walls of glomerulus; higher than any other cap. bed. • Why? • 1. bp is very high due to diameter differences of the efferent and afferent arterioles • 2. glomerular capillaries are fenestrated • Pores large : all substances can pass through • But basement membrane acts as a filter

  8. Explain the selective reabsorption of glucose, water and salt in the PCT, including the roles of microvilli, osmosis, and active transport • Filtrate at this point contains waste and substances the body needs • PCT consists of a single layer of cuboidal epithelial cells with microvilli = increased SA

  9. PCT cont’d • IMPs all cell over surfaces for AT • Mitochondria in large numbers producing ATP to drive AT

  10. What’s Re-absorbed? • 100% of glucose • 80% of mineral ions (including Na) • AT of solutes makes cell hypertonic which cause water to follow. • 80% of water is re-absorbed; 20% of water remains in the renal tubule and heads towards the LOH

  11. Explain the role of the LOH, medulla, collecting duct (CD) and ADH in osmoregulation • Descending and acsending limbs differ in permeability. • Major role? • To create an area of high solute conc. in the medulla (hypertonic interstitial fluid)

  12. Osmoregulation in the CD • Water conc. in blood too low = • ADH release from pituitary gland in brain = • Increase in aquaporin production in CD cells • CD passes through zone of high solute conc created earlier by the LOH • Hypertonic urine is produced

  13. If water conc in blood is too high (hypotonic blood) = • ADH is not secreted = • Aquaporins are broken down = • CD becomes less permeable to water • Dilute, hypotonic urine is produced

  14. Explain the difference in the conc. of proteins, glucose, and urea between blood plasma, glomerular filtrate and urine • The Urinary System • Plasma, Filtrate, and Urine ComparisonsTable. Average Composition of Blood Plasma, Glomerular Filtrate, and Urine  • Blood PlasmaGlomerular FiltrateUrine • Substance  (total amount) (amount per day) (amount per day) • Water 3 L 180 L 1-2 L • Urea 4.8 g 53 g 25.0 g • Chloride 10.7 g 639 g 6.3 g • Sodium 9.7 g 580 g 4.6 g • Potassium 0.5 g 30 g 2.0 g • Creatinine 0.03 g 1.6 g 1.6 g • Uric acid 0.15 g 8.5 g 0.8 g • Protein 200.0 g 2.0 g 0.1 g • Bicarbonate 4.6 g 275.0 g 0.0 g • Glucose 3.0 g 180.0 g 0.0 g

  15. Explain the presence of glucose in the urine of untreated diabetics

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