1. Ch. 44 Warm-Up Draw and label the parts of a nephron.
What are the 4 main functions of a nephron?
Where does each function in #2 above occur in a nephron?
In the glomerulus, which substances are filtered? Which substances remain in the blood?

2. Controlling the Internal Environment
Chapter 44

3. What you must know:
Three categories of nitrogenous waste, which animal groups produce each, and why.
The components of a nephron, and what occurs in each region.
How hormones affect water balance by acting on the nephron.

4. Osmoregulation: control solute concentrations and balance water gain/loss
Excretion: removal of nitrogenous wastes from body
Types of Nitrogenous Wastes:
Ammonia – water soluble, very toxic; aquatic animals
Urea – produced by liver; less toxic, conserves water; most vertebrates
Uric acid – excreted as paste or crystals; birds & reptiles

5. Types of Nitrogenous Wastes

6. Various forms of excretory systems
Protonephridia - Platyhelminthes (Planaria)
Metanephridia - Annelida
Malpighian tubules – Insects, arthropods
Kidneys - Vertebrates

7. How to make urine:
Water and solutes enter filtrate; blood cells and proteins remain in body fluid.
Reclaim glucose, vitamins, hormones
Add toxins and excess ions
Filtrate leaves body as urine

8. Mammalian Excretory System

9. Nephrons: functional units of the kidney
Glomerulus: filtrate forced into Bowman’s capsule.
Blood cells and proteins DO NOT enter filtrate

10. Processing of blood filtrate:
Proximal tubule: secretion & reabsorption change volume and composition of filtrate
Bicarbonate, NaCl, water is absorbed
Descending loop of Henle: reabsorb water
Ascending loop of Henle: reabsorb salt
Distal tubule: K+ and NaCl levels regulated
Collecting duct: filtrate becomes more concentrated; minimize water loss

11. From blood filtrate to urine
SECRETION
FILTRATION
REABSORPTION
EXCRETION

12. Hormones
Antidiuretic Hormone (ADH):  urine concentration, reduce H2O loss
Also called vasopressin
Renin/angiotensin II: raise blood pressure
Aldosterone:  Na+ reabsorption,  H2O retention, blood volume, pressure

13. Blood Pressure Regulation

14. Urine exits kidney through Ureters
Bladder: stores urine
Urethra: urine exits body

15. Believe it or not…
Your kidneys are only 4 in long and weigh about 5 oz (weight of ½ unfinished can of pop)
Usually we urinate liters/day
44 gallons of blood is filtered by kidneys everyday-2 bathtubs full
Fresh urine is cleaner than spit, cleaner than your hands after they have been washed and cleaner than the sandwich you will eat for lunch
Gandhi drank urine every day (Tantric Yoga practice)
Gladiators brushed their teeth with it
Colonial housewives cleaned their home with it
1st football=pig bladder