Lecture AP Biology Chapter 44 Controlling the internal environment

After studying this chapter you will be able to understand: Three categories of nitrogenous waste, which animal groups produce each, and why; the components of a nephron, and what occurs in each regionl; how hormones affect water balance by acting on the nephron.

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?

Chapter 44

Controlling the Internal

Environment

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

Types of Nitrogenous 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)

Malpighian tubules – Insects, arthropods

Metanephridia - Annelida

Kidneys - Vertebrates

 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

How to make

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

change volume and composition of filtrate

 Bicarbonate, NaCl, water is absorbed

2. Descending loop of Henle : reabsorb water

3. Ascending loop of Henle : reabsorb salt

4. Distal tubule : K+ and NaCl levels regulated

5. Collecting duct : filtrate becomes more

concentrated; minimize water loss

From blood filtrate to urine

FILTRATION

REABSORPTION

SECRETION

EXCRETION

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

Hormones

Blood Pressure Regulation

 Urine exits kidney

urine

exits body

Believe it or not…

5 oz (weight of ½ unfinished can of pop)

everyday-2 bathtubs full

your hands after they have been washed and cleaner than the sandwich you will eat for lunch

practice)