Lecture AP Biology Chapter 44 Controlling the internal environment

Ch. 44 Warm-Up
1. Draw and label the parts of a

nephron.
2. What are the 4 main functions of a
nephron?
3. Where does each function in #2
above occur in a nephron?
4. In the glomerulus, which
substances are filtered? Which
substances remain in the blood?


Controlling the Internal
Environment
Chapter 44


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.


 Osmoregulation: control solute

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


Types of Nitrogenous Wastes


Various forms of excretory
systems

Protonephridia - Platyhelminthes (Planaria)
Metanephridia - Annelida

Malpighian tubules – Insects, arthropods

Kidneys - Vertebrates


How to make
 Water and solutes enter filtrate; blood
urine:

cells and proteins remain in body
fluid.

 Reclaim glucose, vitamins,
hormones

 Add toxins and excess ions

 Filtrate leaves body as urine


Mammalian Excretory
System


Nephrons: functional units of the
kidney

• Glomerulus: filtrate forced into
Bowman’s capsule.
• Blood cells and proteins DO
NOT enter filtrate


Processing of blood filtrate:
1. Proximal tubule: secretion & reabsorption

2.
3.
4.

5.

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


From blood filtrate to urine

SECRETION

FILTRATION

REABSORPTION

EXCRETION


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


Blood
Pressure
Regulation


 Urine exits kidney

through Ureters
 Bladder:
Bladder stores
urine
 Urethra:
Urethra urine
exits body


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 1.5-2.5 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