1. Birds

2. Respiratory System
How do lungs and air sacs work together to obtain oxygen?
The posterior and anterior air sacs expand during inhalation, half the air enters the trachea the other half enters the posterior sac and passes through the lung’s into the anterior sac. The anterior and posterior sac’s don’t play a direct role in gas exchange, but to store air, & helps lungs to maintain a fixed volume with fresh air constantly flowing through.
How is a one-way air flow different then a two-way air flow?
One-way air flow is when you inhale and, then exhale. A two-way air flow is when you inhale and at the same time you are inhaling you are exhaling.
Birds have a high oxygen demand.
Trachea- fresh air flows through the lungs in only one direction.

3. Skeletal Composition
Explain how the bones of a bird are adapted for flight: There wing bones are made very light to make flying easier and their leg bones are heavier then all of there bones to make an easy landing.
Define:
Furcula- important for a birds flight, is formed by the fusion of two collar bones.
Sternum- Muscles in the chest cause the sternum to be pushed outward. This creates a negative pressure in the air sacs, causing air to enter the respiratory system.

5. Response/Nervous Central- Brain & spinal cord
Peripheral- Cranial & spinal cord, ganglia

7. Circulatory System
How many chambers does a birds heart have? & why is this a advantage?
They have a four chambered heart &, it allows for nutrients and, oxygen transports through the body, providing energy to fly and maintain high levels of activity.

9. Digestive system What do birds eat?
Peanuts, seeds, grains, worms.
How do they obtain there food?What special adaptation do they have?
For a example think of a humming birds, they have long thin bills which they insert into flowers to get nectar. Birds that eat meat usually have long, sharp, curved bills Which will help them obtain food.
Describe these functions-
Crop- Softens food, stores food temporarily.
Gizzard-Four muscular bands that rotate and crush food.
Cloacae- where sperm is stored.
Villi – Holds nutrients, is shaped like a mushroom.

10. Reproduction Birds have no external sex organs.
After they male and female mate the female lays a number of eggs in a clutch.
They usually lay from one to twenty eggs each batch.

12. Excretory Why is bird urine different from humans?
The cones of birds are humorous than those of humans. Humans density is 200,000 cones per square milli
For a bird it is 400,000 cones per square milli

13. General Characteristics
Birds only have one kidney.
They have four heart chambers.
Their bones are light weight and usually hollow.
They don’t have a bladder so they don’t have to carry all that extra weight.

14. Habitat They usually are in abandoned fields. Mixed/Coniferous forest.
Desert.
Fresh water marsh.

15. Number of Species 10,000 through out the world Only 925 have been seen
3,200 in Africa,2,900 in Asia,1,700 in Australia and many more in other countries.

16. Body structure
Birds have a bilateral body structure.

17. Bibliography http;//people.eku.edu/ritchisong/ritchsok3/bird.html
http;//encarta.msn.com/encyclopedia