Levels of Organization
Living Things
You already know that everything
that is alive or was once alive is made
of cells
(these are cells in the stem of a plant)
Cells are the basic unit of living
things
(Draw this diagram on your page in the center. You will need
the entire page for today’s model)
Cells - Layers of
Organization
All living things are
organized into various
levels with the cell
being the basic level of
organization.
Cells
In unicellular (one
celled) organisms, the
cell performs all of it’s
life functions.
Because of this, there is
no need to have multiple
levels of organization.
Cells
In a multi-cellular (many
celled) organism, there are
many other levels of
organization that can be
found.
These different levels
of organization each work
together to carry out the daily
functions needed to keep the
organism alive by taking care of
specific functions and through
teamwork.
Some examples of cells are…

Nerve Cells
Some examples of cells are…

Bone Cells
Some examples of cells are…

Muscle Cells
Some examples of cells are…

Blood Cells
Tissues
Tissues are the 2nd level
of organization.
Within a multi-cellular
organism, groups of cells
with similar functions
combine to make tissues.
Two or more kinds of cells that do
the same job are called a tissue
(Draw this diagram on your page in the center)
Tissues

A tissue is a group of cells
that work together to
perform a specific activity.

Examples of tissues include:
blood, nervous, bone,
muscle.

Humans have 4 main types
of tissue: connective,
muscle, nervous, and
epithelial
Some examples of tissues are…

Brain tissue = nerve cells + connective cells
Some examples of tissues are…

Blood tissue
=
red blood cells +
white blood cells +
platelets
Some examples of tissues are…

Adipose Tissue = lipid cells + connective cells
Some examples of tissues are…

Esophagus tissue =
mucous cells +
muscle cells +
connective cells
Organs

Organs are the 3rd
layer of organization in
a multi-cellular
organism.

A group of tissues
that work together
and have similar
functions combine to
make up organs.
Two or more kinds of tissues that do
the same job are called an organ
(Draw this diagram on your page in the center)
Organs

Some examples of
organs are:
Heart
Brain
Skin
Can you think of any
other organs?
Some examples of organs are…

Lungs = alveoli tissue +
bronchial tissue +
connective tissue
Some examples of organs are…

Kidneys =
nephron tissue +
tubule tissue +
connective tissue +
muscle tissue
Some examples of organs are…

Bones =
Osteoblast tissue +
Bone marrow +
Calcium +
Connective tissue
Some examples of organs are…

Skin =
epidermal tissue +
dermal tissue +
sweat glands +
muscle tissue +
adipose tissue
skin is the largest organ in the body
Organ Systems

The 4th Layer of
organization in a
multi-cellular
organism are organ
systems.

A group of organs
working together
combine to make
up an organ
system.
Two or more organs that work
together on the same job are called
an organ system
Organ Systems

Some examples of organ
systems that can be found in the
human body include:
circulatory system
nervous system
skeletal system
The human body has 11
organ systems. What are
some of the others that we
have not mentioned?
Are you familiar with some of
the organs that make those
systems up?
Some examples of organ systems
are…

Digestive System
Mouth
Esophagus
Stomach
Liver
Small Intestine
Large Intestine
Anus
Some examples of organ systems
are…

Respiratory System
nose
trachea
bronchioles
alveoli
diaphragm (muscle)
Some examples of organ systems
are…

Integumentary System
skin
mucous membranes
hair
toenails / fingernails
eyelashes
Some examples of organ systems
are…

Circulatory System
heart
arteries
veins
capillaries
blood
Organism

An organism is the 5th
and final level of
organization in a multicellular organism.

Several organ systems
working together
combine to make up
an organism.
Many organ systems working
together meet the needs of an entire
organism.
Organism

An organism is an
entire living thing that
can carry out all of
life’s basic processes.
An organism can be as big as a bear
with many systems, or as small as a
bacteria, that has only a single cell (and no
actual systems.)
Organisms
Organisms can:






Take in materials
Release energy from
food (respiration)
Release wastes
Grow
Respond to the
environment
Reproduce
Organisms
Examples of organisms
include:






Bacteria
Amoeba
Mushroom
Sunflower
Human
Monkeys
Note: While an organism
may be unicellular, most
organisms are made up of
more than a single cell