Levels of Organization

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. There are many different types of cells. Their shape and structure depend on their function.

Some examples of cells are… Nerve Cells – need to have “arms” to reach out to other cells to conduct electric signals.

Bone Cells need to be very dense, and have lots of calcium and other minerals inside.

Muscle Cells have to be long and skinny so that they can contract together and make things move.

Red Blood Cells have to be tiny to fit through capillaries . White Blood Cells have to be able to “stick” to germs to destroy them.

Make a “bullseye” diagram on your page. Label the center circle as “cells” because all living things are made of cells. Cells = basic unit of living things

Two or more kinds of cells that work together to do a job are called a tissue.

Some examples of tissues are… Nervous tissue = nerve cells + connective cells

Blood tissue = red blood cells + white blood cells + platelets

Adipose Tissue = lipid cells + connective cells

Esophageal tissue = mucous cells + muscle cells + connective cells

Now add another layer to your bullseye Cells = basic unit of living things Tissue = two or more cell types working together

Two or more kinds of tissues that work together to do the same job are called an organ.

Some examples of organs are… Lungs alveoli tissue + bronchial tissue + connective tissue

Kidneys nephron tissue + tubule tissue + connective tissue + muscle tissue

Bones Osteoblast tissue + Bone marrow + Blood tissue + Nervous tissue + Connective tissue

Skin epidermal tissue + dermal tissue + sweat glands + muscle tissue + adipose tissue Fun fact: skin is the largest organ in the body

Now add another layer to your bullseye Cells = basic unit of living things Tissue = two or more cell types working together Organ = two or more tissue types working together

An organ system is a group of organs working together to perform a function.

Some examples of organ systems are… Digestive System Mouth Esophagus Stomach Liver Small Intestine Large Intestine Anus

Respiratory System nose trachea bronchioles alveoli diaphragm (muscle)

Integumentary System skin mucous membranes hair toenails fingernails eyelashes

Circulatory System heart arteries veins capillaries blood

Now add another layer to your bullseye Cells = basic unit of living things Tissue = two or more cell types working together Organ = two or more tissue types working together Organ System = two or more organs working together

Many organ systems working together meet the needs of an entire organism.

An organism can be as big as a bear with many systems, or as small as a bacterium, that has only a single cell (and no actual systems).

Now add another layer to your bullseye Cells = basic unit of living things Tissue = two or more cell types working together Organ = two or more tissue types working together Organ System = two or more organs working together Organism = living thing that can exist by itself

The needs of each individual cell are met by systems working together The needs of each individual cell are met by systems working together. (write this in your notes) For example, these smooth muscle cells found in the stomach wall… Get the oxygen they need from the respiratory system which absorbs the oxygen in the lungs and the circulatory system which delivers the oxygen in the blood to each cell

The needs of each individual cell are met by systems working together. Get the food they need from the digestive system which breaks food into chemicals and the circulatory system which delivers the chemicals in the blood to each cell For example, these smooth muscle cells found in the stomach wall…

The needs of each individual cell are met by systems working together. Know when to contract and churn because the nervous system sends signals from the brain, along nerves and the muscular system receives the signal and sends calcium to the stomach cells For example, these smooth muscle cells found in the stomach wall…

The needs of each individual cell are met by systems working together. Know when to divide and grow when the endocrine system releases hormones from the pituitary and the circulatory system delivers those hormones to the cell For example, these smooth muscle cells found in the stomach wall…