Building Blocks
This is the smallest unit of life in all living things.
Cell
This system breaks down food into nutrients for your body.
Digestive System
The main job of any muscle in the body is to do this.
contract (or tighten)
This is the largest organ in the human body.
skin
These two systems work together to help your body move around.
skeletal and muscular systems
This level of organization is made of many of the same kind of cells working together.
Tissue
This system uses the heart and blood vessels to move materials around the body.
Circulatory System
These specific blood cells carry oxygen from your lungs to the rest of your body.
red blood cells
These are the two main organs of the Central Nervous System (CNS).
brain and spinal cord
Muscles get their energy from oxygen and these, which come from the digestive system.
carbohydrates
These are the five levels of organization in order from simplest to most complex.
cells, tissues, organs, organ systems, and organisms
This system is the "control center" that sends and receives messages.
Nervous System
These blood cells are responsible for fighting off infections.
white blood cells
Most of the nutrients from your food are absorbed into the blood in this organ.
small intestine
This gas is a waste product that the lungs remove from the body.
carbon dioxide
This tissue type covers the body as skin and lines the inside of your organs.
epithelial tissue
This system helps you breathe in oxygen and breathe out carbon dioxide.
Respiratory System
These tough structures attach your muscles to your bones.
tendons
These two bean-shaped organs filter your blood to make urine.
kidneys
The circulatory system works with this system to get oxygen to all your cells.
respiratory system
This simple aquatic animal has cells but no tissues or organ systems.
A Sponge
This system removes liquid waste (urine) from your body.
Excretory System
This thick liquid is formed in the stomach after food is mixed with acid.
chyme
These are the tiniest blood vessels where oxygen is swapped for carbon dioxide.
capillaries
This system coordinates all the other systems to make sure they work together.
nervous system