�

� Incase you didn’t notice already, lots of these

mechanisms of response to change are

common among similar organisms.

�Example?

�How come?

�Organisms can not survive without

mechanisms for homeostasis.

�Common homeostatic mechanisms can be

traced through common ancestryo Evolution

�Changes that have arisen have been in

response to a variety of environmental

conditions - divergence

o Natural selection at work

� Examples?

�Organisms must have methods to obtain

needed materials and eliminate waste

o They are similar across animal species

�Breathing

�Why do we need to breathe?

�How are gases captured?

� How are gases captured?

o Diffusion

� Gases first have to dissolve in water

o Respiratory surfaces are moist

� Respiratory systems must be adequate for the size

and oxygen demand of the organism

o Endotherms need larger respiratory surfaces

� All animals have common characteristics because

they have to breathe!

� Look up an animal from each of the following respiratory

system types and research how they respireo In one sentence, describe what the system type is like

o List similarities and differences (compare and contrast) between the

system types

� System Type 1: Simple animals- sponges, cnidarians,

flatworms, roundworms

� System Type 2: Annelids- Segmented worms like

earthworms

� System Type 3: Crustaceans, Aquatic Molluscs and Fish

� System Type 4: Insects

� System Type 5: Terrestrial Vertebrates

� For simple organisms, cells are close enough to the external environment - gases will diffuse across the plasma membrane of individual cellso Sponges, cnidarians, flatworms, roundworms

� Some animals use their skin as their respiratory surfaceo Moist skin, capillaries beneath the skin

• Earth worms and some amphibians

�Larger animals need more efficient structures

�Gills- outfolding of the body surface

o Collect O2 from water

o Problem: O2 concentrations in water are naturally low

o Solution: ventilation- animal passes water over the

gills

o

� Gills are efficient

� Lots of surface area and countercurrent exchange

o

�O2 gradient is always favorable for O2 uptake

�Respiration in air is easier

o Higher O2 concentration

o Faster diffusion

o Problem: respiratory surfaces dry out-

evaporation

o Solution: respiratory surfaces are folded

inside the body

� Tracheal systems in insects

o A system of tubes run through

the body, branching and getting

smaller

• Bring O2 within a very short

distance of all cells

• O2 diffuses into cells, circulatory

system not involved

• Air sacs near large organs

� Lungs

o Internal organs, found in one place- need circulatory

system

o Dense capillary system- respiratory surface

o Found in spiders, terrestrial snails and vertebrates

• Spiders: book lungs- stacks of membranes in an internal

chamber

o Some animals have lungs but also rely on skin breathing

• Frogs and other amphibians, turtles

� Air enters the nasal or oral passageways, travels through

the pharynx and larynx, into the lungs- trachea, bronchi

bronchioles

� Bronchioles end in small sacs called alveoli (alveolus) which

are the site of gas exchange

�What are the similarities across all of

these different systems?

�What are the differences?

�Why are there differences?

�Methods of gaining materials and

eliminating waste are similar.

�Not only are the methods similar, but the

regulation of those methods are also similar

o Homeostasis is accomplished in similar ways

�Since our cells live in an “aquatic”

environment, the balance between water

and solutes needs to be maintained

o Why?

o Both are constantly lost or gained

�Also, normal metabolism produces waste,

which needs to be removed

�Osmoregulation- balance of solutes and the

gain/loss of water

�Excretion- body rids itself of nitrogen-based

waste

�Osmoregulation and excretion are processes

of homeostasis

�Nitrogenous waste has to be dissolved in

water in order to be removed from the body

o That means the water balance is upset as waste

is removed

�The metabolism of

proteins and nucleic

acids results in

ammonia (NH3)

o Ammonia is TOXIC!

o Must be converted to

other substances to

reduce toxicity

�Every animal has to do it, even those

that live in water

� Dehydration in humans

o Death at 12% water loss

� Body coverings reduce

water loss

o Adaptations: Layers of skin,

shells, waxy exoskeleton in

insects

� Most water lost in urine,

feces and skin

o Adaptations: Eat moist foods,

use metabolic water

�What types of

actions are

happening in

the excretory

system?

� Now that we know what osmoregulation and

excretion are, what can we expect to find as we

look at the following animal groups?

� Common Characteristics?

� Flatworms

� Earthworms

� Insects

� Vertebrates

�Filtration

�Re-absorption

�Secretion

�Excretion

� Flatworms: Flatworms: Flatworms: Flatworms: ProtonephridiaProtonephridiaProtonephridiaProtonephridia---- flame bulb systems flame bulb systems flame bulb systems flame bulb systems

o Tubes and bulbs branch through the body

o Beating cilia in the bulbs pull water and solutes into

tubes

o Drains out through pores (nephridiopore)

� Annelids, like earthworms: Annelids, like earthworms: Annelids, like earthworms: Annelids, like earthworms:

MetanephridiaMetanephridiaMetanephridiaMetanephridia

o Fluids enter the

metanephridia for filtration.

o Water and waste are stored

in a bladder and leave the

body through a pore

(nephridiopore)

o Each worm segment has a

pair of metanephridia

� Arthropods, like insects: Arthropods, like insects: Arthropods, like insects: Arthropods, like insects: MalpighianMalpighianMalpighianMalpighian tubulestubulestubulestubules

�Malpighian tubules project from the digestive tract

and collect water and waste from the circulatory fluido Waste added to digestive waste

o Effective at conserving water

� KidneysKidneysKidneysKidneys---- Vertebrate AnimalsVertebrate AnimalsVertebrate AnimalsVertebrate Animals

� Made of organized tubules connected to capillaries

o Nephron - individual filtering unit

� Function in osmoregulation and excretion- water and waste

� Blood is filtered

o H20, NaCl (other salts),

HCO3- H+, Urea, K+

Glucose, Amino Acids ,

Some drugs and nutrients

� The Proximal tubule

reabsorbs stuff the body

still needs, continuing

through the Loop of

Henle, the Distal tubule

and Collecting duct

� All based on

concentration gradients!

� ADH

�What are the similarities across all of

these different systems?

�What are the differences?

�Why are there differences?

�Similarities indicate common ancestry

o Animals have adapted to their environments

o Evolution has occurred