Download PP_Gas Exchange and Respiratory System

Gas Exchange in animals
Consider the following
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What is gas exchange?
Why do animals need to exchange
gases with the environment?
By what process does gas enter a
cell?
But what process does gas leave a
cell?
Breathing Systems
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Diffusion: single celled organisms such
as euglena or ameoba as well as more
simple multicellular organisms such as
jelly fish. But note; all organisms use
diffusion in some form
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Lungs:mammals, birds, reptiles
Gills: fish, Axolotl, lobster
Tracheae: insects
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Amoeba
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Single celled organism
Small: large surface area to volume
ratio
Gas exchange across the membrane
of the cell directly into cell cytosol
Axolotl
Mexican walking fish
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External Gills
An axolotl has three pairs of featherlike gills at the back of its head. As
water passes across the gills, the
axolotl takes in the oxygen from it and
carbon dioxide passes into the water
Gills of Fish
Gills
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Thin surface thus short diffusion
pathway
Blood supply close by; other side of
exchange surface
Gill Filaments are separated from each
other by the buoyancy of water they
have a large surface area
Gills of Fish
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Often counter current
pathways exists to
increase the rate of
diffusion
Tracheal system
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Insects
Opening called
spiracles lead to tubes
called trachea
Air is usually drawing
into trachea, it passes
down tracheal tubes
and directly into tissues
Characteristics common to
Respiratory Surfaces
The surface must be very thin
 The surface must be moist
 It must have a fresh/renewed source of oxygenit must be able to maintain a concentration
gradient along which gases can diffuse
 Extensive: A large surface area over which gas
exchange can occur.
In large multicellular organisms such as humans:
 This surface must be in contact with a transport
system
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Gas Exchange in Mammals
Life’s so hard!
Its breathe, breathe,
breathe
all the time!
Inhaling and Exhaling
INHALING
EXHALING
RIB CAGE
INTERCOSTAL
MUSCLEs
DIAPHRAGM
MUSCLE
Ventilation of the LUNGS
Inhalation/Inspiration
Thoracic cavity is increased in
volume due to:
Exhalation/Expiration
Thoracic cavity is decreased in
volume due to:
Rid cage rises
Rid cage lowers
Diaphragm flattens
Diaphragm domes upwards
Air pressure in the cavity falls
Air pressure in the cavity rises
air moves into lungs
air moves out of lungs
Nasal cavity
pharynx
epiglottis
larynx
Trachea
Bronchiole
Lung(right lobe)
Right Bronchus
Secondary Bronchi
rib
Pleura
Intercostal
muscle
Diaphragm muscle
Nose
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Filters air:
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Warms air:
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Coarse hairs
Lots of surface
capillaries carrying
warm blood
Moistens air:
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Goblet cells mucus:
evaporation of water
from mucus helps
moisten air entering
lungs
Trachea
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Goblet cells
mucus
Mucus traps dust
and bacteria
Cilia beat
rhythmically to
move mucus (with
trapped particles)
upwards to pharynx
Changing Structure of Lung plumbing
Terminal Bronchioles
Respiratory Bronchioles
ALVEOLI
Transport of gases in mammals
Oxygen + Haemoglobin oxyhaemoglobin
Oxyhaemoglobin Oxygen + Haemoglobin
Transport of Oxygen
~ 98% of oxygen(MOST): binds
with haemoglobin to form
oxyhaemoglobin; transported via
red blood cells
~2% of oxygen: dissolved as
oxygen gas in plasma
Transport of Carbon Dioxide
~70% of carbon dioxide(MOST): as
Bicarbonate ions in the plasma
~23% of carbon dioxide: combined
with haemoglobin to form
carbohaemoglobin and carried on red
blood cells.
~7% of carbon dioxide: transported in
plasma as dissolved carbon dioxide
gas
You don’t need to know all of
the chemistry on the picture
slides following.
This is for your interest.
At lungs
carbohemoglobin
Carbonic acid
Oxygen +
Haemoglobin
bicarbonate
Oxyhaemoglobin
At Tissues
carbohemoglobin
Carbonic acid
bicarbonate
Surfactant
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Phospholipid and
protein
Produced by alveolar
cells
Prevents collapsing
of lung at end of
expiration
Assists with
expansion of lungs