1. Systems of the Human Body
Chapter 5
Systems of the Human Body

2. Lesson 1 What are the skeletal and muscular systems?
A group of tissues working together form an organ. Organ carry out processes that are needed for life.
Example: Your heart is made of muscles, nerves, and tissues that work together to pump blood.
2. A group of organs working together forms an organ system. If one organ in a system is damaged, the other organs will be affected.

3. Skeletal System
Your skeleton is made mostly of a tissue called bone. Your body cannot stand without its skeletal system.
Your skeleton protects the organs in your body and helps you move.
Calcium is a mineral that helps keep your bones strong and muscles and nerve tissues working properly. Bones store calcium and other mineral for your body.
Bones also produce different kinds of blood cells, which fight bacteria and help stop bleeding.

5. Joints
When one bone attaches to another bone, it is called a joint. There are two types of joint.
Ball-and-socket joints – allow circular movement (shoulders and hips)
Hinge joints – allow back and forward movement or bending (knee)

6. Muscular System
Muscles that move your body are attached to your skeleton (skeletal muscles) and form the muscular system.
You can walk, run, smile, sing, breathe, and swallow because of your muscular system.
Types of Muscles
Voluntary Muscles – you choose when they work and most are skeletal muscles.
Involuntary Muscles – You cannot control. They help you digest food and breathe.

7. What are the respiratory and circulatory systems?
Lesson 2
What are the respiratory and circulatory systems?

8. Lesson 2- Respiratory and Circulatory System
When your body cells use oxygen, they give off carbon dioxide, which leaves your body when you breathe.
Lungs are the main organs in the respiratory system. The diaphragm is the muscle below the lungs that forces air in and out.
**See page 149 for pictures of the parts of the respiratory system!

9. Lesson 2—Respiratory and Circulatory System
Your respiratory and circulatory systems work together to bring oxygen to cells and carbon dioxide away from cells.
Oxygen passes from your lungs to your blood to your heart.
The circulatory system (heart, blood vessels, and blood) has the special job of moving blood through the body.

10. Your Heart ♥
Both sides of your heart work as a pump and collect blood. The right side collects blood from the body and pumps it to your lungs. The left side collects blood filled with oxygen from the lungs and pumps it to the body.
Each side of the heart has two chambers, an atrium and a ventricle.

11. The Heart The atrium receives blood.
The blood passes through a valve (tube) to the ventricle.

12. What are the digestive and nervous systems?
Lesson 3
What are the digestive and nervous systems?

13. Digestive System
Your digestive system breaks food into nutrients that your body can use. This is called digestion. It begins in your mouth.
** See page 153 to see the path food takes through the body.

14. Central Nervous System
Your central nervous system is the control center of your body. It carries signals from one system to another.
This system controls breathing, heart rate, and movements of muscles.
The nervous system handles information from the sense organs.
Example: After touching a hot stove, you feel the heat, and jerk your hand away.

15. Parts of the CNS
The spinal cord is the link between your brain and other parts of your body. Sometimes the spinal cord decides what your body does. Reflexes are controlled by the spinal cord.
The brain is made of billions of nerves cells. It is protected by the skull.

16. How does the body defend itself?
Lesson 4
How does the body defend itself?

17. Lesson 4
Microorganisms can cause diseases in your body if they don’t stay where they belong. They are found on your skin, in your mouth, and in your digestive system. Most of the time, they are harmless.
Your body uses special cells, tissues, organs, and chemicals to keep the bad microorganisms from causing harm.

18. Lesson 4--Fighters
Your skin is your first “fighter.” It provides chemical protection.
Tears help protect diseases from reaching your eyes. Saliva in your mouth, mucus in your throat, and acid in your stomach are other “fighters” found in your body.

19. Lesson 4
Pathogens are organisms that cause diseases. They do not belong in our bodies and can cause infectious diseases, which are contagious.
Bacteria and viruses are parts of pathogens. Bacteria can cause strep throat or food poisoning. Viruses invade your nose, mouth, or throat and can give you a cold.

20. Lesson 4--Fighting Back
Your immune system is made of defensive cells and acts like your body’s army. It protects you from many pathogens.
A vaccine is a kind of medicine that protects you from a disease. They are not available for every disease.