2From Cell to OrganismOrganismOrgan systemOrganTissuesCell
3The Integumentary System Skin, hair, and nails are the main organs of this system.
4Our skeleton is very important to us. It does three major jobs. It protects our vital organs such as the brain, the heart and the lungs.It gives us the shape that we have. Without our skeleton, we would just be a blob of blood and tissue on the floor.It allows us to move. Because our muscles are attached to our bones, when our muscles move, they move the bones, and we move.
5Muscles allow us to move Muscles allow us to move. Muscle actions can be voluntary or involuntary. Involuntary muscles, such as the heart, diaphragm and intestines, are automatically controlled by the brain. You don't have to think about making them work. Voluntary muscles, such as your arms and legs can be controlled by your thoughts.
6Three types of muscle:Cardiac (only in the heart)Skeletal (attached to bones so you can move)Smooth (parts of organs that work involuntarily like in the digestive system)
7Muscles work together in pairs. When one contracts, the other relaxes.
8The Excretory SystemThe main function of the excretory system is to collect and remove wastes from the body.
9The kidneys remove urea (nitrogen) and excess water The kidneys remove urea (nitrogen) and excess water. The skin removes chemical wastes and some water during perspiration.
10The body has several sets of defenses against germs The body has several sets of defenses against germs. These include the skin, the moist germ-trapping linings of the breathing and digestive passageways, the way blood clots to seal wounds and leaks, white blood cells, and other substances in the blood. Together, all these parts form the body's immune defense system.
11The skin is the first line of defense against germs The skin is the first line of defense against germs. It keeps disease causing micro-organisms out of the body.
13The blood is the transport system by which oxygen and nutrients reach the body's cells, and waste materials are carried away.
14The heart is the pump that keeps this transport system moving.
15Blood vessels that carry blood away from the heart are called arteries Blood vessels that carry blood away from the heart are called arteries. Blood vessels that carry blood back to the heart are called veins.
16When the ventricles contract, the blood is pumped out of the heart.
18The respiratory system takes in the oxygen that the body needs and removes the carbon dioxide that it doesn't need. The large muscle that allows us to breathe in and out is the diaphragm.
19Inside the lung are small air sacs called alveoli.
20The main organs of the respiratory system are the lungs, trachea, and diaphragm.
21The Nervous System is the communication system The Nervous System is the communication system. At the center of the nervous system is the brain. The brain sends and receives messages through a network of nerves. This network of nerves allows the brain to communicate with every part of the body. Some nerves carry information to the brain. This allows us to see, hear, smell, taste and touch. Other nerves carry information from the brain to the muscles to control our body's movement.
22The Central Nervous System is made up of the brain and the spinal cord.
23Food provides us with fuel to live, energy to work and play, and the raw materials to build new cells. All the different varieties of food we eat are broken down by our digestive system and transported to every part of our body by our circulatory system.
24The villi in the small intestine greatly increase the surface area thereby enabling greater absorption of nutrients.