Levels of Organization in Human Biology

Basic Units of Matter and Life

• Atoms are the smallest unit of any pure substance.
• Cells are the smallest independently functioning unit of a living organism.
• Organisms are typically categorized as complex units composed of various interacting systems.

Chemical Foundations

• Elements serve as the chemical building blocks for all body structures and include unique pure substances like oxygen, carbon, and hydrogen.
• Atoms consist of subatomic particles: protons, neutrons, and electrons.

Tissue and Organ Structures

• Tissues are groups of similar cells that perform a specific function.
• Muscle tissue is made up of specialized cells that have the ability to contract and relax, enabling movement.
• Epithelial tissue covers body surfaces and performs protective and regulatory functions.
• Connective tissue provides support, binds other tissues together, and stores energy, including fat in adipose tissue.

Organ Systems and Organizational Hierarchy

• An organ is a structure composed of multiple types of tissues working together for a specific function.
• Organ systems are groups of organs that cooperate to perform complex functions for the body.
• The highest level of organization in an organism is the organism itself, integrating all lower levels—cells, tissues, and organs—into a functional whole.

Functions of Various Tissues

• The primary functions of connective tissue include storage of energy, supporting other tissues, and facilitating transport within the body.
• Adipose tissue's primary function is energy storage and insulation.
• Muscle tissue functions to facilitate movement through contraction and relaxation.

Cellular Component Overview

• Organelles are specialized structures within a cell that perform distinct functions, crucial for the cell's operations.