1. Structure of The Kidney

2. Objectives
Define the term excretion 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 CO2 and 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 reabsorbtion occurs
Pelvis where all collecting ducts meet to carry waste away through ureters

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

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? What do we need back?
Urea
Water
Glucose
Na + / Cl-; Ions
What do we need back?
Glucose and Ions
Capillaries wrapped about nephrons reabsorb 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