Download Chapter 6, lesson 2

Chapter 6, lesson 2
Respiration and Circulation
In order to obtain (get) energy in
food, animals must carry out
chemical reactions:



Food molecules join with oxygen (O2).
Energy is released when molecules
are broken apart (bonds broken).
Carbon dioxide (CO2) is a waste
product
Animals must take in (respire)
oxygen and eliminate (give off)
carbon dioxide.

Process of gas exchange =
respiration.
Cellular respiration
Respiration that occurs inside the cell to
break apart molecules with oxygen to
release energy that can be used by the
cell to do work.
Formula for cellular respiration:
C6H12O6 + 6O2  6CO2 + 6H2O +
energy
1 Glucose + 6 oxygens yields (=) 6
carbon dioxides + 6 waters + energy
Cellular respiration
Respiration happens differently for
different animals.
How does the oxygen get in and
the carbon dioxide get out?
Gas Exchange in Simple
Animals:
Sponges and cnidarians = simple
animals

Body wall is two cell layers thick.
 Water outside touches one layer, water
inside (the animal) touches the other
layer.

Both layers get oxygen (O2) and get rid of
carbon dioxide (CO2) by diffusion. (known as
simple diffusion)
Diffusion
Diffusion = movement of
molecules from an area of high
concentration to an area of low
concentration.
O2 outside is at higher concentration in
the water than inside the cells  O2
diffuses from water into cells.
CO2is at a higher concentration inside
the cells than in the water  CO2
diffuses from the cells into the water.
Diffusion also happens in
flatworms because they also have
2 cell layers.
Gas Exchange in Other
Animals:
Most animals contain many cells
(many layers thick)


Cannot simply exchange gases with
environment.
They have special organs for
respiration.
Animals that live in water
 gills.
Gills = feathery structure that
provides a large surface area that
allows diffusion to happen quickly.


O2 in and CO2 out.
Examples: fish, tadpoles, lobsters,
clams.
Land animals: exchange
gases with the air.
Insects  system of tubes that
carry air into and out of body.

Air enters and leaves through small
openings (spiracles) scattered over
the body.
Other land animals 
lungs.
Lungs = balloon like structure
inside body.


Inhale = breathe in, draws air into
lungs
Exhale = breathe out, pushes air out
of lungs.
Lungs provide a large surface area
for O2 to diffuse into bloodstream
and CO2 to diffuse out of the
bloodstream.
How does the Oxygen get to the
rest of the body and the carbon
dioxide get back to the lungs from
the cells?
Circulatory Systems:
Animals must transport (move) O2
from the gills or lungs to the rest
of the body and transport CO2
from the body to the gills or lungs.

This is the job of the Circulatory
sytem:
 “circulatory” = flowing in a circle.
Moves blood through the
body
As blood circulates it delivers O2 and
picks up CO2 .
Blood also carries
nutrients from the
digestive tract to the
cells to be broken down
by cellular respiration.
Oxygen is carried by hemoglobin (made
of iron) inside a red blood cell.


Red blood = oxygenated (with oxygen)
Blue blood = deoxygenated
(without oxygen)
All circulatory systems
have:
A set of tubes = blood vessels.

Carries the blood.
One or more pumps =
hearts.
 When heart contracts
(squeezes), pushes blood
through blood vessels.
Two types of circulatory
systems:
Open circulatory system
Closed circulatory system
1. Open circulatory
system:
blood leaves the vessels and
enters the spaces around organs.
(leaks out and surrounds organs)

blood flows slowly and makes direct
contact with cells.
 Examples: arthropods and most
mollusks.
2. Closed circulatory
system:
blood stays inside the vessels at all
times.


Smallest vessels (capillaries) have very thin
walls so the O2 can diffuse out of blood and
into the cell and CO2 can diffuse out of the
cell and into the blood.
Blood cells don’t cross, just the gases and
nutrients.
 Examples: Annelids, vertebrates, and some
mollusks.
Open
Closed
Vertebrate Circulatory
Systems:
Single heart.

Divided into chambers = enclosed
spaces.
 Atria (atrium = singular)= chambers
that receive blood that returns to the
heart (enter only).
 Ventricles = chambers that pump the
blood out of the heart (exit only).
Different classes =
different # of chambers
Fish: one atrium and one
ventricle.
Amphibians and most reptiles: two
atria and one ventricle.
Birds, mammals, and some
reptiles: two atria and two
ventricles.
How does blood circulate through
the body of a bird or mammal?
Left atrium: receives blood from the
lungs that is rich in oxygen with very
little carbon dioxide (red blood =
oxygenated).
 Left ventricle: pumps blood to rest
of body (arteries carry oxygenated
blood away from the heart).
 the oxygen rich blood (in capillaries)
delivers the oxygen to the cells and
picks up carbon dioxide from the cells
(waste from cellular respiration)
the oxygen poor blood (blue blood =
deoxygenated) or carbon dioxide rich
blood returns to the heart (veins carry
blood to the heart)
 blood returns to and enters the right
atrium: very little oxygen but a lot of
carbon dioxide.
 Right ventricle: pumps the blood to
the lungs.
 at the lungs, the deoxygenated
blood gets rid of carbon dioxide
(the waste) and picks up more
oxygen.
 the oxygenated blood returns to
the left atrium and begins the
cycle again.