Cellular Organization

Five Levels of Organization Within the Human Body

The Benefits of Being Multicellular•Larger size

▫The larger you are, the less predators you have, and you can eat larger prey!

•Longer life▫Longer life-span than unicellular

organisms.•Specialization

▫Each type of cell has a particular job.▫This makes the organism more efficient.

Levels of Organization

• From smallest to largest:

Cells

Tissues

Organs

Organ systems

Organism

Cells

•Cell – basic unit of structure and function in a living thing

Tissues

•Tissue – group of similar cells that perform the same function.

•Most animals (including humans) have four basic types of tissue:▫Muscle tissue▫Nerve tissue▫Connective tissue▫Protective tissue

Muscle Tissue

•Muscle tissue – makes parts of your body move by contacting (or shortening)

Nerve Tissue

•Nerve tissue – carries messages back and forth between the brain and every other part of the body.

Connective Tissue

•Connective Tissue – provides support for your body and connects all its parts.▫Ex:

Bone – supports & protects Fat – insulation & energy storage Blood

Protective Tissue

•Also known as epithelial tissue – covers the surfaces of your body (inside & out).

Plant Tissues

•Plants have three types of tissues:1. Transport tissue - moves water and

nutrients throughout the plant2. Protective tissue – covers the plant; helps

the plant retain water & protects it from damage

3. Ground tissue – tissue where photosynthesis occurs

Organs•Organ – structure

composed of different kinds of tissue working together ▫Each organ performs a

specific job.▫Ex:

Heart – pumps blood throughout the body

Stomach – breaks down food so that it can be absorbed by the intestines.

Organ Systems

•Organ system – a group of organs that work together to perform a major function.▫Ex:

Circulatory system – heart, blood vessels, blood

Organism

•Organism - a living thing

Structure & Function•Structure - the arrangement of parts in

an organism▫Includes the shape of a part and the

material from which it is made.•Function - the job the part does

▫Ex: structure of lungs (spongy sac) is related to its function

Homeostasis

•The different organ systems work together and depend on one another.▫Ex:

Respiratory, digestive & circulatory systems work together to fuel muscles with the energy they need.

•The systems of the human body work together to maintain homeostasis.