1 / 26

Human Health & Physiology

11.3 – The kidney. Human Health & Physiology. Kidney Structure & Function. Excretion: the process of removing metabolic waste from the cells, tissue fluid, and blood of living organisms The main organ of excretion in mammals is the kidney

verena
Download Presentation

Human Health & Physiology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 11.3 – The kidney Human Health & Physiology

  2. Kidney Structure & Function • Excretion: the process of removing metabolic waste from the cells, tissue fluid, and blood of living organisms • The main organ of excretion in mammals is the kidney • Osmoregulation: the control of water balance of the blood, tissue or cytoplasm of a living organism

  3. Kidney Structure & Function • Functions: • Produces urine • Maintain water balance • Maintain blood pH • Maintain blood pressure • The functional unit of the kidney is the nephron • There are more than 1 million nephrons in a human kidney • On average 120mL/min of fluid passes through the kidney

  4. Kidney Structure & Function • Roles of the nephron: • Ultrafiltration • Reabsorption • Secretion • For the kidney you should be able to label: • Cortex • Medulla • Pelvis • Ureter • Renal blood vessels

  5. Nephron Structure & Function • Afferent arteriole: brings blood into the glomerulus from the renal artery • Efferent arteriole: takes blood out of the glomerulus into the surrounding capillary network and then into the renal vein • Glomerulus: a ball of capillaries that are fenestrated (have pores) and are surrounded by a basement membrane that filters what passes through into the filtrate

  6. Nephron Structure & Function • Bowman’s capsule: a cup shaped structure at the end of the nephron that surrounds the glomerulus and collects the filtrate • Proximal convoluted tubule (PCT): lined with microvilli to increase surface area and has many mitochondria to provide ATP for active transport

  7. Nephron Structure & Function • Loop of Henle: carries the filtrate from the PCT to the DCT • The loop of Henle descends into the medulla of the kidney • The concentration gradient of salt increases as you move down the medulla of the kidney

  8. Nephron Structure & Function • Distal convoluted tubule (DCT): conducts urine from the loop of Henle to the collecting duct • It is the final place where blood pH and ions are balanced • Collecting duct: collects urine and carries it into the renal pelvis to the ureter • This is where the final water balance of the blood occurs

  9. Formation of urine • Blood enters the glomerulus through the afferent arteriole under high pressure • This forces water, amino acids, small proteins, glucose, and ions into the Bowman’s capsule • The product is the filtrate that enters the nephron • Filtrate flows into the PCT • Glucose, amino acids, and ions are reabsorbed into the bloodstream through active transport • Small proteins are reabsorbed by pinocytosis

  10. Formation of urine • Filtrate flows into the descending loop of Henle • The descending loop is permeable to water but not to salt • The loop of Henle is hypotonic (higher salt/urea concentration outside) to the medullary fluid • Water moves out of the nephron by osmosis • Therefore the filtrate becomes more concentrated and hypertonic

  11. Formation of urine • The ascending loop of Henle is permeable to salt, but not to water • As the filtrate moves up the ascending loop, salt (Na+ and Cl–) moves out passively at first, then is actively pumped out at the top of the loop • Filtrate passes into the DCT where it is adjusted to balance blood pH (by secretion of H+) and ion composition • More water is also reabsorbed

  12. Formation of urine • Filtrate moves into the collecting duct, where water may be further reabsorbed if needed • This is controlled by anti-diuretic hormone (ADH) • ADH is secreted by the pituitary gland and increases the permeability of the DCT and collecting duct to water

  13. Formation of urine • If blood is low in water content, ADH is secreted and more water is reabsorbed from the collecting duct into the blood • Concentrated urine is formed and water is conserved • If blood is high in water content, ADH is not secreted and no more water is reabsorbed • Dilute urine is formed

  14. Comparing Solute Concentrations

  15. Diabetes & Glucose in Urine • People with uncontrolled diabetes can have a large amount of glucose in their blood • Glucose enters the glomerular filtrate and is reabsorbed by active transport • There is a maximum rate at which reabsorption can occur • If there is too much glucose in the blood, reabsorption of all glucose from the glomerular filtrate cannot be achieved

  16. Nephron Structure & Function

  17. Nephron Structure & Function

  18. Nephron Structure & Function

  19. Nephron Structure & Function

  20. References • Damon, A., McGonegal, R., Tosto, P., & Ward, W. (2007). Higher Level Biology. England: Pearson Education, Inc. • Raven, P.H., Johnson, G.B., Losos, J.B., Mason, K.A., & Singer, S.R. (2008). Biology. (8th ed.). New York: McGraw-Hill Companies, Inc.

More Related