Transcript Gas Exchange - Mrs. Feigenbaum`s Science Classes

Gas Exchange
Chapter 11
What is gas exchange?
Gas Exchange:
The physical methods of obtaining oxygen
from the surroundings and removing
excess carbon dioxide.
Gas Exchange is not Cellular Respiration.
Oxygen is needed for cellular respiration.
CO2 is produced during cellular respiration.
Respiratory Surfaces
The respiratory system must contain a
respiratory surface.
O2 or CO2 must diffuse through a
membrane or boundary surface.
This surface must be:
thin-walled to allow for rapid diffusion
moist – the gases must be dissolved first.
in contact with a source of O2 in surroundings
in contact with transport system (if multicellular) so blood can obtain O2 to carry it
around.
Diffusion of gases:
Gases move from high to low concentration. As O2
is used up inside organism, more diffuses in.
When excess CO2 is formed inside, it diffuses out.
More gases can diffuse if the respiratory surface is
greater (meaning: a greater surface area)
Small organisms (protists, hydra) can exchange
gases directly from the environment.
Large organisms need a system since:
not all their cells are in contact with the environment
they have protective coverings (feathers, skin, fur) that
block air flow.
Protists and Hydras
CO2
O2
Paramecium
1. Cells are in contact with source of oxygen dissolved in water.
2. Oxygen enters the organism through the body surface (cell
membrane).
3. Carbon dioxide diffuses out.
4. The cell membrane is the respiratory surface.
5. No special structures are needed.
Problems with Larger Organisms
Larger organisms can NOT use just diffusion:
They need larger amounts of oxygen.
They need a respiratory system to reach all cells.
Respiratory surfaces must be kept moist. Having
the system inside the body prevents evaporation.
Animals living in water have more problems:
The percentage of oxygen in water is much lower (1%)
than the percent of oxygen in the air (21%).
Oxygen diffuses more slowly in water than in air.
Respiratory Pigments:
Chemicals that have a color that carry
oxygen and carbon dioxide between the
respiratory surface and the body cells.
These pigments allow blood to carry much
more gas than would normally dissolve.
Compare:
100mL of water carries 0.2mL O2 and 0.3 mL CO2
100mL of blood carries 20mL O2 and 30-60mL CO2
Gas Exchange in the Earthworm
Respiratory Surface is the skin.
They have many capillaries just below the skin.
Oxygen diffuses from the air through the skin into
the capillaries.
Blood, which contains hemoglobin, picks up the
oxygen.
Transport system takes oxygen to body cells
where cellular respiration occurs and carbon
dioxide is produced and carried to the capillaries in
the skin.
Carbon dioxide diffuses from the capillaries
through the skin, into the air.
Gas Exchange in the Earthworm
Earthworm Issues
Earthworms must be kept moist, but not
soaked!
When it rains, the worms must leave the
soil because they get their oxygen from air
in the soil, not water. (Remember: water
does not contain enough oxygen.) If they
stay in the soaked ground, they will drown.
When exposed to air for too long, the skin
dries out and they suffocate.
Gas Exchange in the Grasshopper
Gas exchange in the grasshopper is
separate from the transport system.
This is because the blood does not
have hemoglobin, so it doesn’t carry
O2 or CO2.)
Parts of the system
Tracheal tubes: - branching air tubes. They
branch smaller and smaller and end in a
fluid-filled area where gas exchange occurs
with body cells.
Spiracles: Openings to let air in and out.
There are 10 pairs of spiracles; the front 4
let in air, the back 6 let out air.
Air sacs: Balloon-like chambers help pump
air in and out.
How it works
Contractions of muscles expand the area
around the tracheal tubes and air enters
through the front 4 pairs of spiracles into
the tracheal tubes.
Air enters air sacs which help pump air in
and out of tubes.
When the area around the tracheal tubes
contracts, four pairs of spiracles close, and
the rear six pairs are used to release air
from the grasshopper..
Gas Exchange Through Gills
Gills: respiratory structures specialized for gas
exchange in water.
Fish gills can extract more than 80% of the oxygen
dissolved in water.
Fish gills contain many thin layers of tissue, called
filaments, that increase their respiratory surface area.
Gills contain many small water-bearing channels
surrounded by capillaries. Because the water channels
and capillaries are so close to one another, O2 and
CO2 readily diffuse between the blood and water.
Gills
Human Respiratory System
System consists of:
Lungs and system
of tubes to carry O2
and CO2 to and
from the lungs.
The Nose
Air enters through nostrils into nasal passages.
The nose has hair, mucous membranes and
capillaries near the surface so that the it can filter,
moisten and warm the air.
Hairs and cilia - prevent foreign matter from entering
lungs (filter).
Mucous membranes –
trap bacteria and dust.
Moisten the air.
Capillaries - warm the air.
Breathing through your mouth does not
accomplish these things
Then the air goes to the….
Pharynx: - back of throat
Larynx: voice box, made of cartilage.
Contains two pairs of membranes
stretched across – called the vocal
cords. When air passes by, they
vibrate. Epiglottis prevents choking
during eating.
Larynx and vocal cords
vocal cords
pharynx
Trachea
The windpipe - 12cm
long and 2.5cm wide.
Kept open by cartilage in
the walls.
Lined with ciliated
mucous membranes.
Cilia moves mucus with
trapped particles to
pharynx to be coughed
out or swallowed.
Bronchus (bronchi (pl.):
First two branches
of trachea leading
to lungs
Contain cilia and
branch into smaller
bronchial tubes.
Bronchial
tubes
Lungs
Coated with a 2-layered membrane –
called the pleura. One covers lungs,
other connect to diaphragm.
The diaphragm is a muscle that
moves to help you breathe.
The lungs contains bronchial tubes ,
bronchioles, and alveoli (air sacs).
Bronchioles
Smallest branches
of bronchial tubes
that end in alveoli
Alveoli
Tiny air chamber with walls
one cell thick
Surrounded by capillaries
Respiratory surface
Lungs contain approx. 300
million alveoli
Increases the surface area
Oxygen and carbon dioxide
move between the alveoli
and the blood in capillaries.
Overall Diagram
Lungs
Four Stages of Gas Exchange
Stage 1: Breathing:
Movement of Gases into and out of lungs.
Stage 2: External Respiration:
Exchange of gases between blood and lungs
(alveoli)
Stage 3: Internal Respiration:
Exchange of gases between blood and body
cells
Stage 4: Oxygen & Carbon Dioxide
Transport
Movement of gases between lungs and other
body parts.
Stage 1: Breathing:
Movement of Gases into and out of lungs.
Involves two processese
Inhalation:
Moving air into lungs
This is the Active Phase
Exhalation:
Moving air out of lungs
This is the Passive Phase
Inhalation
As the ribs expand
and are pulled up and
out.
The diaphragm is
pulled downward.
This increases chest
cavity area.
Pressure in the chest
cavity decreases so
air is forced into the
lungs.
Exhalation
The diaphragm relaxes
and moves up.
Rib muscles relax,
causing ribs to drop.
This decreases chest
cavity area.
Pressure in the chest
cavity increases so air is
forced out of the lungs.
Animation of Breathing
Stage 2: External Respiration:
Exchange of gases between blood and lungs
After inhalation, oxygen in
alveoli is greater than in
blood. Oxygen dissolves into
the moist lining of the alveoli
and diffuses into the blood.
Blood coming from body cells
contains high concentrations
of carbon dioxide, which
diffuses from the blood into
the alveoli. It is then
exhaled.
Stage 3: Internal Respiration:
Exchange of gases between blood and body cells
In the capillaries, oxygen diffuses from the
blood to the intercellular fluid to the body cells.
Carbon dioxide produced in the cells diffuses
from the cells to the intercellular fluid to the
capillaries.
Oxygen and Carbon Dioxide
Transport
Movement of gases between lungs and organs
This is the actual method that gases
are carried by the blood.
Two Types:
Oxygen Transport
Carbon Dioxide Transport
Oxygen Transport
Most oxygen is carried by
hemoglobin.
Very little is dissolved in plasma.
Oxygen bonds loosely with
hemoglobin making oxyhemoglobin,
which is bright red.
Carbon Dioxide Transport
70% is carried by combining with
water to form carbonic acid which
quickly turns into bicarbonate ions.
20% is carried by combining with
hemoglobin to make
carboxyhemoglobin.
10% is dissolved in the plasma.
Diseases of the Respiratory
System
Asthma – severe allergic reaction- causes
wheezing, coughing, breathing difficulties.
Bronchioles spasm and squeeze air passages.
Bronchitis – bronchial tubes get irritated and
swollen. Alveoli may swell and clog with mucus.
Causes difficulties with breathing.
Emphysema – lungs lose elasticity. Alveoli are
damaged. Causes shortness of breath. Damage
can not be reversed or cured.
Pneumonia – alveoli fill with fluid preventing gas
exchange.
Lung Cancer – tumors grow in the lungs.
Asthma
Bronchitis
Emphysema
Pneumonia
Lung Cancer
Effects of smoking:
Stops cilia movement – one cigarette stops cilia
from moving for 20 minutes
Increases amount of mucus in trachea
Causes particles to get stuck in alveoli – resulting
in inelastic scars to form.
Extra tissue forms. Result: less functioning
respiratory surface – emphysema
Smoke containing carbon monoxide binds to
hemoglobin instead of oxygen. Result: Less
oxygen is carried by the blood - shortness of
breath.
Greater risk of bronchitis and lung cancer.