Living Organisms: Organization, Functions & Structure

Lesson Transcript
Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Living organisms are things that respond to stimuli, grow, reproduce, and maintain homeostasis. Explore the organization, functions, and structure of living organisms, and learn about the roles of cells, tissues, and organs as components of larger living organisms. Updated: 11/12/2021

How Are Living Organisms Organized?

You are a living organism, but so is every other animal and plant on Earth. An organism is a living system that can respond to stimuli, grow, reproduce, and maintain a consistent state (homeostasis). Or at least that's our current definition of a living organism; there is definitely room for debate. But we're pretty sure we know a living organism when we see it in most cases. Living organisms include animals, plants, fungi, and microorganisms.

But how are living organisms structured? What makes them up? Living organisms have lots of parts and those parts combine together to form a whole that works seemingly as one. It's an amazing system, especially in the case of plants and animals. Plants and animals are structured into cells, tissues, organs, and organ systems. Those organ systems together form the whole organism.

Cells are the basic unit of life - they are the smallest functional units of an organism and are microscopic objects which contain cytoplasm and a nucleus surrounded by a cell membrane. Microscopic organisms are often just a single cell: in that case that's the whole organism. But humans have trillions of cells.

Tissues are groups of cells of the same type or from the same place that accomplish a particular task. For example, humans have muscle tissue, connective tissue, nervous tissue and others.

Organs are part of an organism that's usually self-contained and has a specific purpose or function. For example, the human heart is an organ with the function of pumping blood around the body.

An organ system is a group of organs that collectively do a particular job or function. For example, the digestive system contains the stomach, esophagus, small intestine, large intestine, pancreas, liver, gallbladder, rectum, and anus. An organ can be part of multiple organ systems.

So that's how organisms are organized. But how those individual parts structured? And how are the functions of organisms achieved?

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Environmental Changes & Adaptation in Organisms

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:05 How Are Living…
  • 2:17 Structure and Function
  • 3:25 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it now
Create an account to start this course today
Used by over 30 million students worldwide
Create an account