Transcript Avian Anatomy - MACCRAY High School

Avian Anatomy
Skeletal System
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Skeleton is very unique and specially adapted
for flight
Very lightweight; yet strong
Most of the long bones are hollow but
reinforced through a honeycombed structure
Flying species have a large keel
Keel - place on the sternum that the flight
muscles attach
Respiratory System
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Different from mammals in many ways.
Bird respiration is much more efficient.
Birds do not have a diaphragm. In mammals
this moves up and down to increase and
decrease the chest cavity.
Birds push the sternum in and out to the
same effect
Hummingbird breathes 143 times per minute
while a turkey breathes 7 times per minute
Rate increases during flight.
Breathing Cycle
Bird lungs are very compact and take up
much less space than mammal lungs
 The air enters through the nostrils, down
the trachea and into the lungs and air
sacs
 Thin-walled air sacs extend through the
body cavity and even into the bones
 Birds can keep a continuous flow of air
through the lungs.
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Digestion
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Birds has special digestive tracts because they
do not chew their food
First the food travels down the esophagus and
into the crop.
The crop is an expanded section of the
esophagus.
It is used as a holding tank for food before it can
enter the proventriculus
The proventriculus produces acid and adds
enzymes which aid in breaking down the food
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The gizzard helps grind food like seeds
The gizzard is highly keratinized to make the
surface rough
Turkey gizzard can crush walnuts and steel
needles
Food then passes through the intestinal tract,
where nutrients are absorbed
Waste is expelled through the cloaca, or vent.
Digestion
Reproductive Tract
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The reproductive organs shrink whenever
birds are not in breeding season
This decreases their weight
Males have 2 testes and females have 1
ovary
Eggs production:
The ovum is fertilized and passes through a
long tube called the oviduct
Each section of the oviduct adds a different
part to the egg, just like an assembly line
The egg assembly
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In the infundibulum the egg stays 20 minutes
before going to the magnum where the egg
white is added
Next the egg goes to the isthmus, where
inner and outer membranes are formed
This process takes about 1 hour
In the uterus the shell and all pigments are
added (20 hrs)
The egg then passes out the cloaca