Structures and Functions in the Human Body

Amanda Robb, Angela Hartsock, Amanda Robb
  • Author
    Amanda Robb

    Amanda has taught high school science for over 10 years. She has a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. She is also 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.

  • Expert Contributor
    Amanda Robb

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

Understand more about human anatomy and physiology. Learn about the human body, its structure, and its functions. Discover how organs interact with each other. Updated: 01/13/2022

Table of Contents


Anatomy and Physiology

Anatomy and physiology are the study of the human body. Anatomy is the study of body parts and their structures. Physiology is the study of the functions of the structures of the body. What is body structure? Body structures are the physical parts of the body. Examples of structure and function in the human body include the following:

Bone - made from hard tissue and used for structure and support

Brain - made of electrochemical cells capable of sending messages over long distances

For example, the anatomy of a bone explains the physical structures that make it up, whereas the physiology defines the function, such as providing structure and support.

Anatomy can be divided into two parts: gross and microscopic. Gross anatomy studies the large scale structures of the body, whereas microscopic anatomy studies the microscopic structures such as tissues and cells. Physiology studies the function of the parts of living systems. Most physiology is centered around maintaining homeostasis, or a balance in the body. All living things must have a specific set of balanced conditions to survive, collectively known as homeostasis.

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Human Body Structure

Human body parts and their functions can be best understood by understanding the organization of the body. All living things are made of six main elements:

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

These elements create molecules that create the basic structures of the body. The body is highly organized to create body structures that carry out specific functions.

Levels of Structural Organization of the Human Body

There are six main levels of organization within the human body:

  • Atoms
  • Molecules
  • Cells
  • Tissues
  • Organs
  • Organ System

As discussed above, there are six elements that comprise most of the atoms in the human body. These atoms are organized into molecules. There are four main categories of molecules in living things:

  • Proteins - Create structures and carry out enzymatic reactions
  • Lipids - Store energy and create the cell membrane
  • Carbohydrates - Create structures and create quick energy
  • Nucleic acids - Store genetic information

These molecules collectively make up cells. There are hundreds of types of cells in the human body, all working together to maintain a balanced and stable internal state, called homeostasis. Cells are membrane bound compartments that contain the machinery necessary to carry out metabolic reactions and other functions necessary for life.

Human Body Tissues

Cells and their products work together to form tissues. There are four main types of tissues in the human body:

  • Nervous
  • Connective
  • Epithelial
  • Muscular

Nervous tissue is the main tissue in the nervous system. Cells that make up nervous tissue allow for electrochemical signaling necessary for controlling body functions and processing incoming stimuli. Connective tissue helps provide structure and support for the body. Adipose cells and bone cells are two examples of cells that make up connective tissue. Epithelial tissue forms barriers on the outside of organs and helps separate them from the rest of the body. Muscular tissue is capable of contraction and allows for movement of the body.

The human body structure is made from the four tissue types

tissue types

Human Organs and Organ Systems

Organs are collections of two or more tissues and the cells they are made of. Organs help carry out a specific process in the body. A system is a collection of components that can carry out complex functions when the parts interact. Thus, an organ system is a collection of organs working together for a larger purpose. There are 11 main organ systems in the human body:

  1. Cardiovascular system
  2. Respiratory system
  3. Digestive system
  4. Integumentary system
  5. Muscular system
  6. Reproductive system
  7. Endocrine system
  8. Nervous system
  9. Immune system
  10. Skeletal system
  11. Excretory system

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  • Activities
  • FAQs

Human Body Analogy

In this writing activity, students will be creating an analogy for the six categories of functions in the human body. Analogies are comparisons that challenge student's creativity and writing skills. For example, a student might compare the human body to a city. The protection of the human body, like the integumentary system, is analogous to the walls of a city. The maintenance of the human body, carried out by homeostasis, might be like the city workers, like garbage men, construction workers, and plumbers that keep the city running. The transport, or cardiovascular system, is like a highway in the city, and the control, the nervous and endocrine system is like the mayor or the government. The reproductive system might be like city planners, who help build suburbs and new additions to the city.

Student Instructions

In this activity, you'll be creating an analogy for the human body and the six categories of functions in it as explained in the lesson: movement and support, protection, maintenance, transport, control, and reproduction. You should choose a system with many different parts, just like the human body has. For example, you might choose to compare the human body to a city, a sports team, or a school. You should include how each of the six categories of function relate to your analogy. To make sure you meet all the requirements, check out the criteria for success below.

Criteria for Success

  • Analogy compares the human body to another system
  • All six of the main functions of the human body are explained
  • Analogy is at least 500 words
  • Analogy is scientifically accurate

What are body parts and their functions?

Body parts are organ systems that perform functions to keep the body at homeostasis. Some examples of organ systems and the functions they perform are the nervous system performing electrochemical communication, the excretory system regulating salt and water balance, and the skeletal system providing structure and support.

What are the structures and functions of the human body?

The main structures of the human body are organs. Each organ has a unique function and works within an organ system to carry it out. Some examples of organ system functions are:

  • Respiratory system - gas exchange
  • Cardiovascular system - pump blood
  • Digestive system - Break down food and absorb nutrients

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