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Unit 10 Notes

Unit 10 Notes. Blood Flow of Kidney. Blood comes in via the Renal Artery Branches down into afferent arteriole, which feeds the glomerulus with blood. Blood Flow of Kidney. Blood passes through the glomerular capillary, where filtration occurs

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Unit 10 Notes

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  1. Unit 10 Notes

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

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

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

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

  6. 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

  7. 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

  8. 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)

  9. 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

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

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

  12. 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

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

  14. Urine then continues down to URETERS

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

  16. Urine then heads to the BLADDER

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

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

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

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

  21. 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

  22. Urine then exits the body through the URETHRA

  23. Urethra • Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis • Length • Females – 3–4 cm (1 inch), along wall of vagina • Males – 20 cm (8 inches), through prostate & penis • Function • Females – only carries urine • Males – carries urine and is a passageway for sperm cells

  24. Facts to know about Urinary System… • Each kidney has over ONE MILLION nephrons • It takes about four minutes for all of your blood to be filtered through a kidney • A moderately full bladder holds about 500 mL of urine, but it can hold up to 1 liter • In 24 hours, kidneys filter out 150-180 liters of blood plasma, but only produce about 1-1.8 liters of urine

  25. Remember some of the functions of kidneys… • 1. Excretion of nitrogen-containing wastes (which we discussed last class!) • 2. Maintaining water balance • 3. Regulate blood pressure • 4. Ensuring proper blood pH • We’ve talked about number 1, but we will discuss 2 through 4 today!

  26. Maintaining Water Balance • Normal amount of water in the human body • Young adult females – 50% • Young adult males – 60% • Babies – 75% • Old age – 45% • Water is necessary for many body functions and levels must be maintained

  27. Maintaining Water Balance • Intracellular Fluid • 2/3 of body fluid, found in cells • Extracellular Fluid • 1/3 of body fluid, found outside cells • Includes blood plasma, cerebrospinal fluid, tissue fluid, and others • Ions (Electrolytes) are dissolved in much of this fluid

  28. Maintaining Water Balance • Changes in electrolyte balance causes water to move in and out of the cells • Alters blood volume and blood pressure • Can impair the activity of cells

  29. Maintaining Water Balance • Water intake must equal water output (about 2500 mL / 2.5 L every day) • Sources for water intake • Ingested foods and fluids • Water produced from metabolic processes • Sources for water output • Vaporization out of the lungs • Lost in perspiration • Leaves the body in the feces • Urine production

  30. Maintaining Water Balance • How does your body know that it is lacking water? • How does it fix the problem??? • And how do your kidneys regulate your blood pressure at the same time?

  31. Way #1: ADH • Water loss leads to low blood pressure • …which leads to low filtrate production • …which leads to unusual composition of blood • …which causes your hypothalamus to say, “hey, something’s wrong!” • The hypothalamus then sends out a nerve signal to the pituitary gland • …which releases ADH (antidiuretic hormone) • …which stimulates the kidney’s collecting ducts to reabsorb more water • … which causes blood pressure and volume to rise! (more filtrate will be produced!)

  32. Way #2: Renin-Angiotensin Mechanism • Water loss leads to low blood pressure • …which will stimulate the release of renin (an enzyme) • …which will speed up the production of angiotensin (a hormone) • …which will cause vasoconstriction (higher blood pressure!)

  33. Way #2: Renin-Angiotensin Mechanism • Angiotensin will also stimulate the production of aldosterone • Aldosterone acts on the distal convoluted tubules • …and stimulates them to reabsorb more Na+ and water • …which increases blood pressure and volume!

  34. Maintaining Blood pH • pH is the measure of the concentration of H+ ions • More H+, more acidic • pH level 0-7: acidic • pH level 7-14: basic • pH level at 7: neutral

  35. Maintaining Blood pH • Blood pH must remain between 7.35 and 7.45 to maintain homeostasis • Alkalosis – pH above 7.45 • Acidosis – pH below 7.35 (while not “acidic”, it still has more H+ than normal!)

  36. Maintaining Blood pH • Many metabolic processes will produce acids to throw off this balance! • Lactic Acid in your muscles • Fatty Acids • Carbonic Acid (formed by CO2 and H2O mixing in your blood!) • Your kidneys help your body to maintain its optimal pH by controlling H+ and HCO3- absorption & secretion

  37. Urinary Conditions • Kidney Stones • Also called Renal Calculi • Solid crystals that are formed from ions in urine • Can be the size of grains of sand up to golf-ball sized • As small as 2-3 mm can block the ureters

  38. Urinary Conditions • Kidney Stones, con’t • Usually detected by an X-Ray or Ultrasound • Some small stones may pass on their own • Larger stones must either be broken up with Shock Wave Lithotripsy or be removed with surgery

  39. FYI: Stones can look different depending on what ions precipitated out! • http://www.herringlab.com/photos/

  40. http://www.youtube.com/watch?v=ODL3eEZCY8M&feature=related http://www.youtube.com/watch?v=48AWCOCG5ug&feature=fvw

  41. Urinary Conditions • Urinary Incontinence (UI) • Involuntary leakage of urine • Different Types…

  42. Stress UI • Due to insufficient strength of pelvic floor muscles • In men, is common following removal of the prostate • In women, is common as a result of pregnancy and childbirth • Urge UI • Involuntary loss of urine due to random spasms of the bladder muscles • Can be due to damage of nerves

  43. Functional UI • A person knows they need to go, but cannot make it to the bathroom in time, usually due to some issue with thinking, moving, or communicating • Overflow UI • Because of weak bladder muscles or some sort of nervous system condition, the bladder is never completely emptied • This causes the person to “dribble” out urine

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