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Unit 9 Notes

Unit 9 Notes. Urinary System. Functions of the Kidneys include…. Filter fluid from the bloodstream Eliminate nitrogenous wastes, toxins, and drugs from the body Regulate aspects of homeostasis Water, electrolyte, and pH balance of blood Blood pressure Red blood cell production

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Unit 9 Notes

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  1. Unit 9 Notes Urinary System

  2. Functions of the Kidneys include… • Filter fluid from the bloodstream • Eliminate nitrogenous wastes, toxins, and drugs from the body • Regulate aspects of homeostasis • Water, electrolyte, and pH balance of blood • Blood pressure • Red blood cell production • Activation of vitamin D

  3. Major organs of Urinary System • Kidneys – filter blood, form urine • Ureters – carries urine to… • Bladder – stores urine • Urethra – carries urine out of body

  4. Location of Kidneys • Right is lower than left due to liver crowding • Against the dorsal body wall • Partially in rib cage

  5. Hilus of Kidney • Medial indentation • Where ureters, renal blood vessels, and nerves enter/exit the kidneys

  6. Capsules of Kidneys • Renal capsule • Surrounds each kidney • Adipose capsule (FAT) • Surrounds the kidney • Provides protection to the kidney • Helps keep the kidney in its correct location

  7. Parts of Kidney • Renal cortex: • Outer portion • Contains the blood supply to each nephron • Contains bulk of nephrons

  8. Parts of Kidney • Renal medulla: • Deep to cortex • Contains some Loop of Henles • Contains collecting ducts

  9. Parts of Kidney • Medullary Pyramids • Triangular regions of renal medulla • Renal Columns • Extensions of cortex tissue

  10. Parts of Kidney • Renal Pelvis: • Where urine is dumped into ureter

  11. Parts of Kidney • Calyces: • Cup-shaped areas that collect urine from pyramids and dump into renal pelvis • Calyx: singular

  12. Let’s look closer at a Medullary Pyramid…

  13. Look at all those tubes! • More tubes… more surface area… more filtration of blood! • The tubes form structures called NEPHRONS

  14. Nephron • The structural and functional units of the kidneys • Responsible for forming urine

  15. Nephron • Main 2 structures of a nephron include… • Glomerulus: a knot of capillaries, where blood comes in to be filtered! • Renal tubule: drainage/filtration tube

  16. Glomerular Capsule • AKA Bowman’s Capsule • Surrounds glomerulus • Beginning of renal tubule • Filtrate formed here from stuff coming out of blood!

  17. 3 Divisions of Renal Tubule • Proximal Convoluted Tubule: closest to glomerulus • Loop of Henle • Distal Convoluted Tubule • Let’s look at the parts in more detail!

  18. Parts of Nephron Glomerular Capillaries: where blood comes in to be filtered

  19. Parts of Nephron Bowman’s Capsule: site of filtration, contains glomerulus

  20. Parts of Nephron Proximal Convoluted Tubule: secretion, reabsorption

  21. Parts of Nephron Loop of Henle: reabsorption

  22. Parts of Nephron Distal Convoluted Tubule: secretion, reabsorption

  23. Parts of Nephron Collecting duct: carries urine to renal pelvis, secretion, reabsorption

  24. Nephrons • Nephrons can be named based on where they are located! • Cortical nephrons • Located entirely in the cortex • Includes most nephrons • Juxtamedullary nephrons • Loop of Henle dips from cortex down into medulla

  25. Blood Flow of Kidney • Blood comes in via the Renal Artery • Branches down into afferent arteriole, which feeds the glomerulus with blood

  26. Blood Flow of Kidney • Blood passes through the glomerular capillary, where filtration occurs • Blood leaves the glomerulus through the efferent arteriole

  27. Blood Flow of Kidney • Blood continues to peritubular capillaries, where reabsorption and gas exchange occurs • Blood leaves through branched veins, and eventually renal vein

  28. Urine Formation • Occurs through three processes… • Filtration • Reabsorption • Secretion

  29. Filtration • Happens at glomerular capillaries • Includes… • Blood plasma without blood proteins or RBC’s • Water • Small Solutes • Blood pressure must be good for filtrate to pass through capillary walls! • Approx. 1 L of blood passes through kidney per minute… of this, about 120-125 mL is filtered out

  30. Reabsorption • Most happens at Proximal Convoluted Tubule, but can happen all along renal tubule! • Reabsorbed back into Peritubular Capillaries • Mostly done by active transport (exception is water: passive transport) • Includes… • Water • Glucose • Amino Acids • Ions (H+, K+, Na+, Cl-, HCO3-) • Some of these substances will be left in the urine – if the body doesn’t need them to maintain homeostasis

  31. Reabsorption • Nitrogen wastes tend NOT to be reabsorbed (or poorly if they are) • Urea: Formed by the liver (protein breakdown) • Uric Acid: Nucleic acids metabolized • Creatinine: Muscle metabolism • Also, excess water is not reabsorbed • All are found in high amounts in urine • Approx. 99% of filtrate is reabsorbed (taken back from filtrate to blood)

  32. Secretion • Some substances are secreted by the Peritubular Capillaries back into the renal tube • Includes… • Creatinine • H+, K+ ions • Drugs • Any materials left move out the collecting duct, through the renal pelvis, and down the ureter to the bladder

  33. http://www.argosymedical.com/Urinary/samples/animations/Urine%20Formation/http://www.argosymedical.com/Urinary/samples/animations/Urine%20Formation/

  34. So, anything that’s left after filtration, absorption, and secreting by the kidney tubules is then called URINE.

  35. Urine • Yellow in color • Color due to urochrome (pigment resulting from destroying hemoglobin); more solutes (less water/solvent) yields deeper color • Has an odor, but becomes more “ammonia” smelling if allowed to stand

  36. Urine • pH slightly acidic • More dense than distilled water (water + solutes) • Common solutes include H+ & K+ ions, urea, uric acid, creatinine, ammonia, and HCO3-

  37. Urine then continues down to URETERS

  38. Ureters • Ureters travel down toward bladder • Peristalsis aids gravity in urine transport

  39. Urine then heads to the BLADDER

  40. Bladder • Smooth, collapsable sac • Stores urine temporarily • Flaps of bladder mucosa cover the ureter openings to prevent backflow of urine

  41. Bladder • Trigone – three openings of the bladder • Two from the ureters • One to the urethra

  42. Bladder Wall • Three layers of smooth muscle (detrusor muscle) • Also, transitional epithelium – which has the unique characteristic of being able to stretch and slide

  43. Bladder • Sphincters • Internal Urethreal: involuntary, keeps urethra closed • External Urethral: lower, formed by skeletal muscle, voluntary

  44. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter27/animation__micturition_reflex.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter27/animation__micturition_reflex.html

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