Levels of Organization in the Body and Examples

Amanda Robb, Angela Hartsock
  • Author
    Amanda Robb

    Amanda has taught high school science for over 10 years. They have a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. They also are certified in secondary special education, biology, and physics in Massachusetts.

  • Instructor
    Angela Hartsock

    Angela has taught college microbiology and anatomy & physiology, has a doctoral degree in microbiology, and has worked as a post-doctoral research scholar for Pittsburgh’s National Energy Technology Laboratory.

Learn levels of organization in the body. See examples of different levels of organization in the human body, like cellular and tissue levels of organization. Updated: 07/13/2021

Table of Contents


The Human Body

How is the human body organized? The levels of structural organization in the human body start with atoms, as all matter on Earth is made of these. There are several elements in particular that makeup living things:

  • Carbon
  • Hydrogen
  • Nitrogen
  • Oxygen
  • Phosphorus
  • Sulfur

These types of atoms make up most of the molecules in our body. Those molecules form the basic units of life, cells. Cells come together in different levels of organization in the human body to form an entire organism or living thing.

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  • 0:00 Levels of Organization
  • 0:36 Organism Level
  • 0:48 Organ System Level
  • 1:27 Organ Level & Tissue Level
  • 3:22 Cellular Level
  • 4:49 Lesson Summary
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Levels of Organization in the Human Body

All matter in the universe is made of atoms, which are made of sub-atomic particles, like neutrons, protons, and electrons. Atoms are organized into molecules, and molecules are organized into cells, the basic units of life, which make up the organization of the human body. The levels of organization in anatomy and levels of organization examples include the following:

Organization Level Example
Cells Cardiomyocyte
Tissues Muscle
Organs Heart
Organ systems Cardiovascular system
Organism Human

The levels of organization from cell to organism in a mouse.

the levels of organization in the body of a mouse

Organism Level

The highest level of organization in the body is the organism level. This is the entirety of a living thing, such as the entire human body.

Organ System Level of Organization

An organ system is a collection of organs in the body that works together to perform a function. There are eleven examples of organ systems in the human body including:

  • Cardiovascular system
  • Nervous system
  • Respiratory system
  • Endocrine system
  • Reproductive system
  • Digestive system
  • Immune system
  • Integumentary system
  • Muscular system
  • Skeletal system
  • Excretory system

For example, the job of the cardiovascular system is to pump blood around the body to distribute oxygen and nutrients and remove metabolic waste, such as carbon dioxide. The main organs of the cardiovascular system are the heart, blood, and blood vessels, like arteries, veins, and capillaries. The cardiovascular system is essential for distributing oxygen and nutrients to cells all over the body. Cells require oxygen to make energy. Thus, without the cardiovascular system, there won't be enough oxygen, and thus not enough energy for the cells and they will die. This is what happens during a heart attack. The heart stops working and the body doesn't get oxygen or nutrients and can die.

Another example of an organ system is the nervous system. The nervous system is responsible for electrochemical communication in the body. The main organs in the nervous system are the brain, spinal cord, and nerves. The nervous system is important for the organism to be able to detect changes in the surroundings and within the body itself. It also is responsible for our thoughts, feelings, and actions. For example, when we feel something too hot or too cold, the nervous system registers this and processes the information in the brain. The brain then sends signals that allow the body to shiver or sweat and take conscious action to change our temperature.

Organ Level of Organization

An organ is a biological unit made up of tissue and independently performs a specific function for the body. Some examples of organs in the body include:

  • Brain
  • Heart
  • Liver
  • Stomach
  • Uterus
  • Intestines

For example, the heart is the main organ of the cardiovascular system. It is made mostly of muscle tissue and acts as a pump. Sending blood to the lungs to get oxygenated and out to the body to deliver that oxygen and important nutrients. The brain is the main organ of the nervous system. It is made of neurons and other connective tissue and is the main processing center for information in the body.

Tissue Level of Organization

Tissue is a biological unit made up of several cells acting in conjunction with each other. What are the four levels of organization in an organism? There are four main types of tissue level of organization in the body:

  • Epithelial
  • Connective
  • Muscle
  • Nervous

Epithelial tissue forms the covering of the body and organs. Its main function is to offer protection and separation from the environment. Connective tissue binds, connects, and cushions the body. Muscle tissue is for contraction and movement. Nervous tissue is for communication. The table below details the different functions of the four tissues in the body and examples.

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Frequently Asked Questions

What are the six levels of organization in the body from simplest to most complex?

The six levels of organization in the body from simplest to most complex are:

  1. Molecules
  2. Cells
  3. Tissues
  4. Organs
  5. Organ system
  6. Organism

What are the 12 levels of biological organization?

The twelve levels of biological organization are:

  1. Atoms
  2. Molecules
  3. Cells
  4. Tissues
  5. Organs
  6. Organ systems
  7. Organisms
  8. Population
  9. Community
  10. Ecosystem
  11. Biome
  12. Biosphere

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