Why is the inner surface of the small intestine lined with villi and microvilli?

If the lower esophageal sphincter fails to close properly, what might the patient experience?

A patient has a puncture wound that causes air to enter the pleural cavity. What will likely happen to the lung on that side, and why?

 A patient complains of feeling full quickly, and an X-ray reveals delayed gastric emptying. What part of the digestive tract is most likely involved?

A person has extremely low stomach acid due to chronic antacid use. What nutrient absorption will most likely be impaired?

Why are the alveoli lined with simple squamous epithelium rather than a thicker tissue type?

The medical term that describes spongy bone is:

Which burn degree classification involves erythema  without blisters? 

Which of the following ligaments of the knee keeps the femur from sliding posteriorly on the tibia and prevents hyperextension of the knee?

Which of the following minerals is stored in the bones and is constantly being removed to maintain necessary blood levels?