Excretory & Respiratory Systems

Lungs and Kidneys

Gas Exchange: oxygen & CO2

• Earliest type: Simple diffusionType 1

Diffusion = movement of particles to equilibrium!

Gas exchange: simple diffusion• Protists: amoebas etc• Plants: through stomata

Examples of organisms that

use simple diffusion

Gas exchange: skin• Some amphibians, worms• Skin must be moist to open

pores!

Gas exchange: insects

• Tracheal tubes

Tubes open to outside of body, allow passive diffusion of gas

SPIRACLES are valves that open and close

special openings to let in oxygen: SPIRACLES

not lungs!!!!

Interesting idea: ancient giants• What was different about

earth’s atmosphere that would let insects grow so big?

more oxygen!!

Now, oxygen is at 21%

Then, it was at 30%!!!

http://www.astrobio.net/pressrelease/2431/attack-of-the-giant-insects

Gas exchange: Gills• Thin layers of tissue

letting oxygen diffuse out of water into bloodletting CO2 diffuse out of blood into water

Gills “counter-current exchange”

Fish, (bony & cartilaginous), Mollusks80% efficiciency rate

oxygenoxygen

carbon dioxide

carbon dioxide

water

blood

Lungs + Air Sacs: Birds• Birds have so

many air sacs, they can get fresh oxygen while inhaling OR exhaling!

Mammals: nose or blowhole• Sinus cavities to filter air• Tissue to warm air

Trachea: tube for air• Cartilage rings around it

keeps it from collapsing

Choking: blockage of trachea

Bronchi: branches into lungs• Looks like a

branching tree

By the way: bronchitis is inflammation (swelling) of the bronchi

• Usually due to infection or allergies

Asthma:

Lungs: amphibians, reptiles, mammals

• Concurrent exchange system

Lungs: getting oxygen from air• Expanding lungs =

contracting diaphragm

Take a closer look at lungs:• ALVEOLI: small sacks

Ocean mammals:• Lungs

• Nose or blowhole

Smoker’s Lung:

Excretion: water balance!• Urinary Tract: filters liquid

wastes from body, balances water in blood

RemovesNITROGEN ous

WASTES

Also: sweating!

Kidney: contains NEPHRONS• Units of

tubing that remove excess water and liquid wastes from blood

General idea of a nephron:• In the

glomerulus, blood is passed near the tubules to exchange materials

Glomerulus• Blood can

exchange wastes with liquid

• Excess water will diffuse out of blood into renal tubule

Wastes pass through URETER• To be stored in

bladder

• Passed out urethra to outside of body

• Exit controlled by sphincter

Sphincters: open and close• Muscular “lock”

Potty training kids: • Wait for nervous system to

reach voluntary sphincters• 13 months – 36 months

Kidney Stones

Mineral deposits in kidneys or ureter

Painful!

UTI: urinary tract infection• Bacterial infection• Can spread to kidneys if left

untreated

Control of Water Balance:• Brain hormone ADH keeps

balance• HOMEOSTASIS

BEWARE!You can drink too much waterYou can drink too little water

You can kill babies by giving them too much water in their formula!

What is dialysis? • When kidney’s fail, we have

to do their job with machines.• USE DIFFUSION!