A 90-year-old woman has been a patient of the Beacham Ambulatory Care Center since 2000. Chronic conditions are pernicious anemia, osteoarthritis, and urinary incontinency. She is fully functional and fully independent. She provides care for the homebound husband who has severe COPD. They live in a row home specifically "close to the hospital" to ensure access to house calls for her husband.

In September 2000, the husband dies as a result of respiratory arrest. Her only relative is a nephew who talks with her about once a month. In October 2002, her home is broken into and our patient is raped and robbed. She was taken to a local hospital specializing in rape. Here, she is distressed, delusional, and is reported to be very emotionally distraught.

1. What are the main morphological features of birds?

2. In which habitat do birds live?

3. What adaptations for flight are present in birds?

4. What are pneumatic bones?

5. How is the respiratory system of birds characterized?

6. How is the circulatory system of birds characterized?

7. Which type of nitrogen waste do birds produce? Why is this feature, in addition to being an adaptation to the terrestrial environment, also an adaptation to flight?

8. What similarities are present in birds and reptiles regarding external coverage, reproduction and excretion?

9. How do birds reproduce?

10. Is embryonic development in birds direct or indirect?

Answer:

1 Birds are animals with aerodynamic bodies covered with feathers, anterior limbs transformed into wings, pneumatic bones and horny (corneous) beaks.

2 Birds are terrestrial animals but the majority of them also explore the aerial environment by flying.

3 The features of birds that allow them to fly are: wings attached to a well-developed pectoral musculature, pneumatic bones, less accumulation of feces in the bowels due to the absence of the colon, the absence of a bladder (no urine storage), an aerodynamic body and lungs with specialized air sacs.

4 Birds have lightweight bones with internal spaces filled with air. These bones are called pneumatic bones. This feature reduces the density of body of the animal, facilitating flight.

5 Like reptiles and mammals, they carry out gas exchange through lungs.

6 Birds, like every vertebrate, have a closed circulatory system. Their heart is similar to the heart of mammals, as it has four chambers (two atria and two ventricles) and no mixture of venous and arterial blood. (In mammals, however, the aorta curves down to the left and in birds it curves down to the right).

7 Birds are uricotelic, meaning that, like reptiles, they excrete uric acid. This substance needs less water to be eliminated and it helps to reduce body weight, making flight easier.

8 Regarding external coverage, birds are similar to reptiles in that they present impermeable keratinized outside. Concerning reproduction, fertilization is internal in both and the embryo develops within a shelled egg. Regarding excretion, both excrete uric acid.

9 Birds, like every vertebrate, use sexual reproduction. Their embryos develop within shelled eggs containing extraembryonic membranes. Therefore, their embryonic development occurs outside the mother's body.

10 Embryonic development in birds is direct. There is no larval stage.