The human body is organized from tiny chemical components into increasingly complex structures. Understanding these levels helps explain how individual parts combine to perform the functions needed for life.
Matter is made of elements, which are pure substances such as hydrogen, oxygen, carbon, nitrogen, calcium, and iron. The smallest unit of an element is an atom. Atoms contain smaller subatomic particles, including protons, neutrons, and electrons.
All flashcards
What is an atom?
An atom is the smallest unit of an element. Atoms contain subatomic particles such as protons, neutrons, and electrons.
What is a molecule?
A molecule forms when two or more atoms combine. Examples in living things include water, proteins, and sugars.
How are cells and tissues related?
A cell is the smallest independently functioning unit of a living organism. A tissue is a group of similar cells, or related cell types, that work together for a specific function.
What defines an organ system?
An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body.
How do biological sex and gender identity differ?
Biological sex refers to characteristics such as chromosomes, hormones, and organs. Gender identity is a person's sense of their gender; the two concepts are distinct and may not align for some people.
Quiz questions
What is the smallest unit of an element?Answer: An atom
How does a cell differ from a tissue?Answer: A cell is an independently functioning unit; a tissue is a group of cooperating cells.
Which description best defines an organ?Answer: An anatomically distinct structure made of two or more tissue types.
Why can assigning an organ to only one organ system be imprecise?Answer: Many organs contribute to the functions of multiple systems.
A collection of organs works together to meet a major physiological need. What level of organization does this describe?Answer: An organ system
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.