Paneth cells are specialized immune cells that are found in the gastrointestinal tract. Paneth cells act as anti-microbial defence for our bodies. It is found in the crypts of the intestine. It is also responsible for the renewal of epithelial layer cells which keep bacteria from entering the intestines.
The ridge of a birds breastbone is called a keel
Sneezing is an involuntary action because it's something we cannot control.
In my Biology Honors Class, they taught about gastric juice, or also known as (p H) which is formed by stomach glands, is very acidic and can seriously mess up enzyme trypsin functions. After all, enzymes are a type of catalyst that help break down food, which means that enzymes are a sort of digestive acid as well. Hope this helps!