In studying more complex multicellular organisms like ourselves, there are 5 basic
levels of organization we use.
The most basic level of organization is individual cells.
Groups of similar cells which work together are called tissues. Muscle and bone are
examples of tissues.
Different types of tissues combine to form organs. Each organ performs a specific job in
the body, such as pumping blood or filtering urine.
Groups of organs working together form organ systems. Each organ system performs a
general function for the body, such as digestion or respiration.
And finally, the total combination of all the cells, tissues, organs and organ systems is
the whole organism. We’ll take a closer look at all of these levels.
neuron
The cell is the basic biological unit for all living things. (click) One example of a cell is a
neuron or nerve cell
neuron
muscle cell
Another type of cell is a muscle cell.
neuron
muscle cell
bone cell
Here’s a bone cell
neuron
muscle cell
bone cell
skin cell
And here’s a skin cell.
nerve tissue
Tissues are made up of similar cells, all working together. (click) here is some nerve
tissue
nerve tissue
muscle tissue
Here is some muscle tissue
nerve tissue
muscle tissue
skeletal tissue
Our bones are made up of skeletal tissue
nerve tissue
muscle tissue
skeletal tissue
epithelial tissue
Epithelial tissue covers all the surfaces in our body, inside and out.
brain
Organs are made up of groups of different tissues that work together to perform a specific activity or set of
activities. (click) The brain is one organ. It has a lot of nerve tissue, but also contains other types of tissue.
brain
heart
The heart is another organ. It is made up largely of muscle tissue, but also has nerve
tissue, connective tissue, and epithelial tissue, and others.
brain
heart
liver
Another important organ is the liver. Like all organs, the liver is made up of a number
of types of tissue.
digestive
system
An organ system is a group of two or more organs that work together to perform a general function in the body.
(click) For example, the digestive system is a group of organs that break down our food and deliver its nutrients to all
cells of the body.
digestive
system
respiratory system
And the respiratory system is a group of organs which extracts oxygen from the air and
deliver it to all of the cells in our body.
An organism is a complete individual animal or plant, including all of it’s cells, tissues,
organs, and organ systems. (click) Here’s a cute organism
And here’s a pretty one!
Acknowledgements for Images Used
License: CC0 Public Domain / FAQFree for
commercial use / No attribution required
Thank you Nemo
License: CC0 Public Domain / FAQFree for
commercial use / No attribution required
Thank you Gerd Altmann
Acknowledgements for Images Used
License: CC0 Public Domain / FAQFree for commercial use /
No attribution required. Thank you Nemo.
"Heart anterior exterior view" by Patrick J. Lynch, medical
illustrator - Patrick J. Lynch, medical illustrator. Licensed
under CC BY 2.5 via Wikimedia Commons http://commons.wikimedia.org/wiki/File:Heart_anterior_ext
erior_view.jpg#mediaviewer/File:Heart_anterior_exterior_vi
ew.jpg
Acknowledgements for Images Used
License: CC0 Public Domain / FAQFree for
commercial use / No attribution required.
Thank you Nemo
Acknowledgements for Images Used
"Respiratory system complete en" by LadyofHats - The image i did
myself as sources i used the books: Sobotta "atlas der anatomie
des menschen" ISBN. 3 541 02828 9 , Churchill livingstone "gray's
anatomy" ISBN. 0 433 01505 8, Interamericana. McGraw-hill
"atlas forografico de anatomia del cuerpo humano" ISBN. 968 25
1677 3. Also used several online diagrams like ([1] and [2]) Image
renamed from Image:Respiratory system complete.svg. Licensed
under Public Domain via Wikimedia Commons http://commons.wikimedia.org/wiki/File:Respiratory_system_co
mplete_en.svg#mediaviewer/File:Respiratory_system_complete_
en.svg