pyloric sphincter.

The chemical breakdown of food involves enzymes,

There are eleven distinct organ systems in the human body

There are four basic types of human tissues: connective tissue, which connects tissues; epithelial tissue, which lines and protects organs; muscle, which contracts for movement and support; and nerve, which responds and reacts to signals in the environment.

There are hundreds of types of cells (e.g., red blood cells, nerve cells, skin cells). Each individual cell conducts all the basic processes of life. It must take in nutrients, excrete wastes, detect and respond to its environment, move, breathe, grow, and reproduce. Many cells have a short life span and have to be replaced continually. For example, enterocytes (cells that line the intestines) are replaced every 2-4 days, and skin cells are replaced every few weeks.

While all cells in an individual contain the same DNA, each cell only expresses the genetic codes that relate to that cell’s specific structure and function.

ll matter in the universe is composed of one or more unique elements, such as hydrogen, oxygen, carbon, and nitrogen.

Levels of structural organization of the human body. The organization of the body often is discussed in terms of distinct levels of increasing complexity, from the smallest chemical building blocks to a unique human organism.

Life is extraordinarily complex.

Experiments may not yield the results that we expect, but that can lead to new and important questions.

The basis of what we know about nutrition is derived from research, and the scientific method underlies how research is conducted. The steps of the scientific method include:

Now, more than ever, it’s essential to develop skills in information literacy, including the ability to find information, evaluate whether it is accurate and useful, and apply it effectively.