Transcript Respiratory system - EDF4402Assignment2

Respiration occurs at 2 levels
1/ INTERNAL: At the level of the cell – cellular
respiration
2/ EXTERNAL: At the level of the organisms – getting
oxygen into the cell
1/ Internal respiration: Cellular respiration
Glucose
Water
O2
CO2
ADP
ATP
 All cells need energy in the form of ATP to survive
2/ External Respiration
 An organism must get oxygen into its cells and carbon
dioxide back out.
 This is called EXTERNAL RESPIRATION because the
exchange of gases takes place with the external
environment.
 There is an exchange of oxygen and carbon dioxide
between air and blood and this involves the respiratory
system – group of organs work together.
The need for a respiratory system
 Single-celled organisms – gases exchanged directly
with environment (diffusion)
 Multi-cellular organisms – must have respiratory
system to ensure the effective exchange of gas with the
atmosphere quickly and efficiently to survive.
Mechanism of breathing
Components of the upper
respiratory tract
Nasal Cavity
 Coarse hairs filter our any
large particles.
 Air moistened and warmed
by the mucus membrane and by
blood in capillaries.
 Dry, cold and dirty air would damage lungs
Pharynx
 13cm long
 Transports food and air
 Lined with mucus membrane
Larynx (Voice box)
 Supported by cartilage pieces
 Epiglottis – prevents food entering
the airway (trachea)
 Particles not removed in nasal
cavity are trapped by lining of larynx
Trachea (Wind pipe)
 12cm long.
 Reinforced with incomplete rings of
cartilage so walls do not collapse.
 Lining has goblet cells and cilia that
trap any particles that pass
the larynx.
 Trachea leads directly to
the lungs.
Components of the lower
respiratory tract
Bronchi
 Trachea branches into 2 bronchi
 Each bronchus leads to a lung
 Amount of cartilage reduces
 Smooth muscle in the walls of
tubes increases
Bronchioles
 Further branching of bronchi
 No cartilage
 Smooth muscle on walls
Lungs
 Paired, lobed organs
 Moist soft spongy tissue with
many air-filled sacs (alveoli)
 Extremely large surface area
about 35 times the surface area
of your skin!!!!
Alveoli
 Bronchioles lead to alveolar duct then to an alveolar sac
 This is where gas exchange occurs
across a single layer of thin cells
 Each alveolus surrounded by a
capillary network
 Surfactant (oily) coats alveoli to
decrease surface tension (prevents
Collapse of alveoli)
Alveoli
Gases
 Oxygen carried in haemoglobin in red blood cells
 Carbon dioxide mainly carried in plasma but small
amount combines with haemoglobin
Interactive activity
 42D The Human Respiratory System
 42E Transport of Respiratory Gases
Biozone
 Page 145 + 146 Q 1,2 and 3
Animated tutorial - human
respiratory system
 1/ Airflow in humans enters via the same way that it
leaves (trachea) this is called ______________.
 2/ There are _____ pleural membranes.
 3/ Circle. Lower/Higher pressure in the lungs
causes air to rush in.
 4/ Alveolar pressure: Inhalation causes a ________
in pressure, exhalation causes a _________ in
pressure.
 5/ Pleural cavity pressure is always _________. It
_______ with inhalation and but returns to its
original pressure with exhalation.
We will look at different types of respiratory
systems involved with different groups of
animals:
Fish
Mammals Birds
Insects
STRUCTURE OF THE GAS
EXCHANGE SURFACE
Depends on:
the size of the organism
where it lives – water or land
the metabolic demands of the
organism – high, moderate or low
TYPES OF GAS EXCHANGE SURFACE
THE SOURCE OF OXYGEN
Air
 about 21% oxygen
 thinner at higher altitudes
 easy to ventilate
Water
 amount of oxygen varies but is always much less than
air – 3% to 5% of what’s available in air
 even lower in warmer water
 harder to ventilate
WATER AS A
GAS EXCHANGE MEDIUM
No problem in keeping the cell membranes of the gas
exchange surface moist
BUT
O2 concentrations in water are low,
especially in warmer and/or saltier water
SO
the gas exchange system must be very efficient
to get enough oxygen for respiration
Fish require less energy to maintain its balance
than does land animals therefore they have a
reduced need for oxygen.
GETTING OXYGEN FROM WATER: FISH GILLS
 Gills covered by an operculum (flap)
 Fish ventilates gills by alternately
opening and closing mouth and
operculum
 water flows into mouth
 over the gills
 out under the operculum
 Water difficult to ventilate
 gills near surface of body
GETTING OXYGEN FROM WATER: FISH GILLS
 Each gill made
of four bony
gill arches.
 Gill arches
lined with
hundreds of
gill filaments
that are very
thin and flat.
GETTING OXYGEN FROM WATER: FISH GILLS
 Gill filaments are
have folds called
lamellae that
contain a network
of capillaries.
 Blood flows
through the blood
capillaries in the
opposite
direction to the
flow of water.
ENHANCING THE EFFICIENCY OF FISH GILLS
Fresh water flows over gills in one direction.
COUNTER-CURRENT FLOW: water and blood in the
gills flow in opposite directions
 maintains a favourable concentration gradient
for diffusion of both gases
ENHANCING THE EFFICIENCY OF FISH GILLS
 Gills have a very large surface area:
four arches with flat filaments with lamellae folds
 Gills are thin-walled and in close contact with water:
short distance for diffusion
 Gills have a very high blood supply to bring CO2 and
carry away O2  dark red colour
 Gills are moist: fish live in water!
 Counter-current system – maintains concentration
gradient along the width of the lamellae
THE SOURCE OF OXYGEN
Air
 about 21% oxygen
 thinner at higher altitudes
 easy to ventilate
Water
 amount of oxygen varies but is always much less than
air – 3% to 5% of what’s available in air
 even lower in warmer water
 harder to ventilate
GETTING OXYGEN FROM AIR:
MAMMALS, BIRDS & INSECTS
As a gas exchange medium, air has many advantages over
water:
 Air has a much higher oxygen concentration than
water
 Diffusion occurs more quickly so less ventilation of
the surface is needed
 Less energy is needed to move air through the
respiratory system than water but more energy is
required to maintain balance
GETTING OXYGEN FROM AIR:
MAMMALS, BIRDS & INSECTS
BUT
as the gas exchange surface must be
moist, in terrestrial animals water
is continuously lost from the gas
exchange surface by evaporation
SO
the gas exchange surface is folded
into the body to reduce water loss.
WARM-BLOODED ANIMALS
Warmth speeds up body’s reactions
 enables faster movement etc
BUT
increases evaporation of water from lungs
AND
increases demand for energy to stay warm
SO
higher demand for gas exchange to provide O2 for and
remove CO2 from respiration
BIRD LUNGS
Birds have a high demand for oxygen:
• warm-blooded so metabolism is high
• flight requires a lot of energy
Additional challenge:
• air at higher altitude is
thinner  lower in O2
…yet some species have
been seen flying over
Mt Everest!
Birds have a very efficient gas exchange system to
cope with low O2 supply & high O2 demand
BIRD LUNGS
Birds have lungs and
air sacs:
• air sacs are not sites
of gas exchange
• air sacs enable a
one-way flow of
air through lungs
BIRD LUNGS: VENTILATION
Passage of air through lungs:
1
3
2
4
BIRD LUNGS
Blood capillaries run alongside air capillaries
BUT
blood flows in opposite direction to air flow
COUNTER-CURRENT EXCHANGE of gases
This maintains a concentration gradient
• Air flows in one direction through
lungs regardless of whether the bird is
inhaling or exhaling
Animated Tutorial – Airflow in birds
1/ Birds have __________ as well as lungs.
2/ Circle. Airflow over the lungs is/isn’t
unidirectional
3/ Full cycle of air flow requires _____ breaths
4/ Circle. Air flows first to the posterior/
anterior sac/lungs.
5/ On the second breath (inhalation) air
moves from the __________to the
_____________.
INSECT TRACHEAL SYSTEM
Completely different system!
Air tubules (trachea & tracheoles) throughout the
body which open to the environment via spiracles
INSECT TRACHEAL SYSTEM
•
•
•
•
Trachea kept open by circular bands of chitin
Branch to form tracheoles that reach every cell
Ends of the tracheoles are moist
Oxygen delivered directly to respiring cells –
insect blood does not carry oxygen
ENHANCING THE EFFICIENCY OF
INSECT TRACHEAE
• Oxygen delivered
directly to
respiring cells
• Can pump body to
move air around in
tracheal system
BUT
• Size of animal
limited by relatively
slow diffusion rate
DIVERSITY
fish
gills
bird
lungs
mammal
lungs
insect
tracheae
Biozone
 Gas exchange in animals
 Page 143 and 144