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GAS EXCHANGE
GAS EXCHANGE
As you recall, all the cells of organisms carry out
aerobic cellular respiration in order to release energy
from food.
Remember?
C6H12O6 + O2
(glucose)
(oxygen)
CO2 + H2O + ATP
(carbon dioxide)
(water)
(energy)
C6H12O6 + O2
(glucose)
(oxygen)
CO2 + H2O + ATP
(carbon dioxide)
(water)
(energy)
• Oxygen is needed for this process.
• Carbon dioxide is released from this system.
• To survive, organisms must take in oxygen and
expel carbon dioxide from their bodies.
• This is accomplished through a process called
GAS EXCHANGE
Review of the eight life processes:
1.
2.
3.
4.
5.
6.
7.
8.
Respiration
Reproduction
Regulation
Growth
Excretion
Nutrition
Transport
Synthesis
VOCABULARY
• Respiration: the process of releasing
chemical energy stored in foods
• Gas exchange: the physical methods that
organisms have for obtaining oxygen from
their surroundings and removing excess
carbon dioxide
• Respiratory surface: surface through
which gas exchange occurs between an
organism and its environment
Characteristics of a Respiratory
Surface
1. Thin walled for diffusion
2. Must be moist (oxygen and carbon
dioxide are dissolved in solution)
3. Must be in contact with the source of
oxygen
4. Must be in contact with the transport
system so gases can get to all cells
Gas exchange occurs by
diffusion
• As cells use up the oxygen from cellular
respiration, the concentration of oxygen in
the cell is low
• The capillaries carry oxygen rich blood
from the respiratory surface so the
concentration of oxygen in the blood is
high.
Therefore oxygen diffuses from the blood to
the cells (high to low concentration)
Therefore oxygen diffuses from the
blood to the cells
(high to low concentration)
O2
O2
O2
O2
Gas exchange occurs by
diffusion
• The cells build up carbon dioxide as a
waste product of cellular respiration
• The blood has a low concentration of
carbon dioxide
Therefore the carbon dioxide diffused from
the cells to the blood
(high to low concentration)
Therefore the carbon dioxide
diffused from the cells to the blood
(high to low concentration)
CO2
CO2
CO2
CO2
The greater the surface area of the
respiratory surface, the greater the
rate of gas exchange.
Protists have direct exchange
between the cell and the
environment
Multicellular organisms have
specialized organs and organ
systems for gas exchange.
PROTISTS:
Diffusion directly through the cell
membrane
CO2
CO2
o2
o2
HYDRA
• Diffusion directly from
the environment to the
cells of the
gastrovascular cavity
and into the endoderm
• Diffusion directly from
the fresh water into the
cells of the ectoderm
CO2
O2
CO2
O2
CO2
O2
GRASSHOPPER
Blood does not carry gases
System of branching tubes carry air to the cells
• Air enters 10 pair of openings called spiracles
• Tracheal tubes branch into smaller tubes and
into fluid filled ends where there can be contact
with the body cells
– Here oxygen and carbon dioxide can diffuse
• Air is pumped in and out of tracheal system by
muscle contraction
• Air sacs (connected to tubes) help pump air in
and out
GRASSHOPPER
EARTHWORM
Skin is the respiratory surface
• Skin is thin and specialized cells secrete mucus
• Just beneath the skin is a large number of
capillaries
Capillaries pick up oxygen and carry it to all the
cells
Oxygen is deposited and carbon dioxide gets
picked up and returned to the skin
• If the skin dries out – they suffocate
• If there is flooding rain – they drown
EARTHWORM
MULTICELLED ANIMALS:
air breathers (air is 21% oxygen)
• must keep the respiratory surfaces moist
• must have respiratory surfaces extending
inside to protect surfaces and decrease
water loss by evaporation
• most have respiratory pigments in the
blood to allow the blood to carry more
gases than water
• hemoglobin is the most common
respiratory pigment
MULTICELLED ANIMALS:
water breathers (water
has less than 1%
oxygen)
• less oxygen available
and oxygen diffuses
more slowly in water
• therefore large amounts
of water must pass over
the respiratory surface
GAS EXCHANGE IN GILLS
• Gas exchange organ of
water living organisms
are gills
• As water passes over,
oxygen diffuses across to
the blood vessels
• A great deal of water
must pass over them
ORGANISM
ORGAN WHERE
GAS EXCHANGE
TAKES PLACE
PROTISTS
(AMOEBA and
PARAMECIUM)
Cell
membrane
ADAPTATIONS
OR
SPECIALIZED
STRUCTURES
FUNCTION OF SPECIAL
STRUCTURES
none
Endoderm to
gastrovascular
HYDRA
(cell membrane)
none
Ectoderm
to fresh water
EARTHWORM
Skin
Specialized
cells
Blood
GRASSHOPPER
Spiracles
to
tracheal tubes
to
air sacs
Air sacs
Cell secrete mucus to
keep skin moist
Hemoglobin so blood
carries more O2 than
water
Where diffusion of gases
occurs
Body movements squeeze
air sacs and help move air
in and out of the body
General Structure
• Lungs fill a large part of the chest cavity
• Chest and abdomen are separated by the
diaphragm
• Lungs are enclosed by the pleura
Structures
The Nose
• Air enters through the nostrils
• Mucous membrane and cilia
trap small particles of bacteria
and dust
• Blood vessels are close to the
surface
The nose
1. Filters air
2. Moistens air
3. Warms air
The Pharynx
• The throat – common passage from the
nose and the mouth
The Larynx
• The voice box is made of cartilage
• Contains two pair of vocal cords
• Controlled vibrations make a variety of
sounds
• The epiglottis blocks the larynx from food
during swallowing
The Trachea
• 12 cm long and 2.5 cm
wide
• Kept open by horseshoe
shaped rings of cartilage
• Ciliated mucous
membranes push
particles up into the throat
• Smoking stops cilia from
moving and increases
production of mucous
Bronchi
• Two cartilage
ringed tubes that
branch off the
trachea to the
lungs
• Cilia lines the tubes
• Branch into the
bronchial tubes in
the lungs
Bronchioles (tiny tubes)
• The smallest branches of the bronchial
tubes that lead to the alveoli
BRONCHIOLE
The Alveoli
• Tiny air chambers one cell
thick
• Walls are moist and
surrounded by capillaries
• Site of gas exchange or
external respiration
• 300,000,000 alveoli
• 70 square meters of
surface area (40 x’s the
surface area of the skin)
Fill in the diagram on page 10. in
the packet
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Nose
Nasal passage
Pharynx
Epiglottis
Larynx
Esophagus
Trachea
Lung (or pleura)
Pleura
Bronchi
11.Bronchioles
12.Diaphragm
13.Alveoli (air sacs)
14.Capillaries (blood
vessels)
15.Capillary beds
16.Bronchioles
17.Alveoli
RESPIRATORY SYSTEM PARTS AND FUNCTIONS
Nose
• Air enters
• Hair filters out dust, dirt, and bacteria
Nasal chamber
• Warms and moistens air
Pharynx (throat)
• Passage to the trachea
Epiglottis
• Flap that closes over trachea
• Keeps food and liquid out of the lungs
Esophagus
• Tube to the stomach
RESPIRATORY SYSTEM PARTS AND FUNCTIONS
Trachea (wind pipe)
• Tube that carries air from the pharynx to the
bronchi
• Ciliated and has cartilage rings
Bronchi (2 bronchi)
• Short tubes from the trachea into the right and
left lungs
Bronchioles
• Tiny tubes
• Carry air from the bronchi to the alveoli
Lung
• Main organ of respiration
• Contains tiny air sacs (alveoli) and capillaries
RESPIRATORY SYSTEM PARTS AND FUNCTIONS
Diaphragm
• Muscle below the chest cavity
• Moves down with inhalation (contracts)
• Moves up with exhalation (relaxes)
Capillaries
• Surrounds the alveoli
• SITE OF GAS EXCHANGE
Alveoli
• Air sacs
• SITE OF GAS EXCHANGE
THE FOUR PHASES
OF
HUMAN RESPIRATION
THE FOUR PHASES OF
HUMAN RESPIRATION
I. BREATHING
II. EXTERNAL RESPIRATION
III. INTERNAL RESPIRATION
IV. CELLULAR RESPIRATION
I. BREATHING
Movement of air into and out of the lungs
 Inhalation:
• Ribs up and out
• Diaphragm pulls down
• Air rushes in
 Exhalation
• Ribs relax and drop down
• Diaphragm moves up
• Air pushed out
No muscles in the lungs, they are elastic and air is moved
due to pressure changes
Breathing controlled by
• Respiratory center in the brain
• Sensors in the aorta and other arteries that sense gas
levels
II. EXTERNAL RESPIRATION
Exchange of oxygen and carbon dioxide
between lungs (alveoli) and blood
• Air flow moves with the concentration
gradient
III. INTERNAL RESPIRATION
Exchange of oxygen and carbon dioxide
between blood and tissues (body cells)
• Exchange by diffusion
III. INTERNAL RESPIRATION
Exchange of oxygen and carbon dioxide
between blood and tissues (body cells)
Exchange by diffusion
O2
CO2
O2
CO2
O2
CO2
O2
CO2
IV. CELLULAR RESPIRATION
Using oxygen, the cells release energy
(ATP) from food (glucose)
TRANSPORT OF GASES IN
BLOOD
Oxygenated blood
must be transported
from the lungs to all
the cells of the body
TRANSPORT OF OXYGEN
• Hemoglobin (Hb) carries O2 on red blood
cells
• Hb + O2 = oxyhemoglobin (HbO2) with a
loose bond
• CO has a stronger bond with hemoglobin
than O2 therefore cigarette smokers’ blood
carries less O2 than non-smokers’ blood
TRANSPORT OF CARBON
DIOXIDE
 70% carried by water
CO2 + H2O
H2CO3
H2CO3
H + HCO3
 20% carried by hemoglobin
Hb + CO2
HbCO2
 10% dissolves in plasma
PHASES OF RESPIRATION
BREATHING AIR → EXT. RESP → TRANSPORT → INT. RESP → CELL RESP
ALVEOLI – CAPILLARY
CAPILLARY – TISSUES
O2 in / CO2 out
BLOOD
AEROBIC RESP
BREATHING AIR →
EXT. RESP → TRANSPORT → INT. RESP →
O2 in / CO2 out ALVEOLI –CAPILLARY
CAPILLARY – TISSUES
→ CELLULAR RESPIRATION
BLOOD FLOW
BREATHING
INHALATION
DIAPHRAGM
RIB CAGE
SIZE OF CHEST CAVITY
AIR MOVEMENT
PRESSURE
EXHALATION
INHALE
CONTRACTS / MOVES DOWN
UP AND OUT
INCREASES
INTO LUNGS
LOWER IN LUNGS
EXHALE
RELAXES / MOVES UP
DOWN AND IN
DECREASES
OUT OF LUNGS
HIGHER IN LUNGS
DISEASES OF THE
RESPIRATORY SYSTEM
ASTHMA
• Chronic inflammation of the bronchi
• Response to irritants with shortness of
breath, coughing, and wheezing
• Treated with medications and inhalers
Asthma
BRONCHITIS
• Inflammation of the lining of the lower
respiratory passages (bronchi and
bronchioles)
• Mucus production increases and impairs
breathing
• Risk of lung infection (pneumonia)
increases
Chronic Bronchitis
EMPHYSEMA
• Alveoli enlarge as the walls between the
alveoli break down (airways collapse)
• Chronic inflammation causes lungs to
lose elasticity
• It takes a large amount of energy just to
breath
• Over inflation of the lungs leads to a
permanently expanded barrel chest
emphysema lungs
A normal lung
PNEUMONIA
• Infection in the lungs
• Caused by
– Bacteria (treatable with antibiotics)
– Virus
– fungus
Pneumonia
LUNG CANCER
• Accounts for 1/3 of all cancer deaths in the
United States
• Second-hand smoke is the third leading
cause of preventable death in America
• Many have no symptoms in the early
stages
• Increased incidence associated with
smoking (8 out of 10 lung cancers are
caused by smoking)
Lung Cancer