Structure of The Kidney

1. Structure of The Kidney

2. Objectives • Define the termexcretion and explain the importance of removing waste material from the body • Describe the process which forms urea from amino acids • Describe the general structure of the kidney, the nephron, and associated blood vessels

3. Excretion • What waste material do we produce? • CO2 released through lungs • Feces released through digestive tract • Urine released through kidneys • All are poisonous materials (toxins) • Where do they come from? • CO2 cellular respiration • Feces material not absorbed by body • Urine forms from urea; produced by the liver from excess amino acids

4. It All Starts In The Liver • After absorption, food molecules are assimilated • Assimilation to become a useful part of a cell or organ • Roles of the Liver • Glycogen is made from excess blood glucose • Amino acids used to make proteins • Fatty acids/glycerols are made into fat • Form cholesterol from fat • Excess amino acids deaminated; forms urea

5. Deamination: Forming Urea • What are our major sources of energy? • Carbohydrates, Fats, and Proteins • How are carbs and fats stored? Proteins? • Glycogen and fat (adipose tissue) • Deamination removal of for amino group from an amino acid to form a keto acid and ammonia (NH3) • Keto acids can form glucose and fat • Ammonia is toxic

6. Deamination: Forming Urea • To prevent damage from ammonia build up, ammonia instantly combines with CO2and produce urea and H2O • Urea passes from the liver into the blood plasma and then filtered out through the kidneys • Uric Acid minor nitrogenous excretory product made from the breakdown of DNA

7. Structure of the Urinary System • Renal artery takes unfiltered blood to kidneys • Renal vein takes filtered blood from kidneys • Kidney bean-shaped network of filtering units called nephrons • Ureter carries urine from kidneys to bladder • Bladder elastic storage area for urine • Urethra carries urine from bladder to outside the body

8. Layers of a Kidney • 2 main roles of kidneys: • Removal of urea • Regulating water levels, ion levels, and pH of blood (homeostasis) • Capsule tough outer layer to protect kidney from damage • 3 main areas of a Kidney • Cortex contains all glomerulus, renal capsules, and area where ultrafiltation occurs • Medulla contains kidney tubules and collecting ducts, and area where reabsorbtionoccurs • Pelviswhere all collecting ducts meet to carry waste away through ureters

9. Glomeruli K Cortex L Collecting ducts M Medulla N Pelvis O

10. Structure of a Nephron • Nephron(kidney tubule) filtration unit a kidney • Renal (Bowman’s) capsule cup-shaped site where arterial blood is filtered • Blood comes in from arteriole • Glomerulus splitting capillaries in capsule to increase filtering rate • Filtered blood leaves through the arteriole

11. Ultrafiltration • Renal capsule filters urea, H2O, and small molecules from the blood • Reabsorption pulls important molecules and H2O back into blood • 3 layers of Filtration walls inside renal capsule have small gaps; only small molecules get through • Blood cells are too big • Blood pressure helps force waster material through filter and out of the blood (125 ml/min)

12. Reabsorption • What inside the filtrate? • Urea • Water • Glucose • Na + / Cl-; Ions • What do we need back? • Glucose and Ions • Capillaries wrapped about nephronsreabsorb glucose and ions into the blood • Water is reabsorbed in the collecting ducts depending on your blood water levels • Hydrated clear/light yellow • Dehydrated dark yellow

13. Kidney Failure • What happens when the kidneys shut down? • Urea builds up in body • Toxic levels effect organs; death • What can cause kidneys to fail? • Physical damage • Blood clots; blockage in tubes • Kidney Stones • Toxins; Alcohol and Drugs • Genetics; DNA • Disease • How do we know kidneys are damaged? • Blood in urine • Large proteins in urine • Pain and illness

14. Living With One Kidney • What does living with one kidney mean? • More urea in blood • Higher blood pressure • More stress on remaining kidney • Toxins have longer effects; alcohol and drugs • Greater chance of losing other kidney • What options do you have if you lose both kidneys? • Dialysis • Kidney Transplant

15. Kidney Dialysis • Kidney dialysis machine filtering blood outside the body • Machine draws out blood from vein • Inside machine; blood passes by several dialysis membranes; Urea drawn out of blood into dialysis fluid (dialysate). How? • Diffusion 3) Dialysis fluid is contains salt and sugar. Why? • No diffusion; glucose/salts stays in blood 4) Filtered blood returns to body vein • 3-4 hours; 2-3 times a week • What diet must you have? • Low-Protein = Less Urea

16. Kidney Transplant • Kidney Transplant surgically replacing the damaged kidney with the healthy kidney of a donor • What are the major difficulties with transplants? • Donor match kidney must be excepted by body (donor should be related to you or similar in DNA) • Drugs can lower white blood count to help kidney acceptance • Might get really sick • Dangerous surgeries always have a risk of killing the patient • Expensive lots of money needed to get kidney and pay the hospital; plus after hospital care