Body Systems
The body's circulatory system (血液循环系统) includes the heart and blood vessels (血管).
The heart pumps blood to all parts of the body through a network of arteries and veins (动脉和静脉).
The digestive system (消化系统) breaks down (分解) and absorbs food (吸收食物) into the body.
It supplies the energy that the body needs for growth and repair (生长和修复).
After digestion, excess food (多余的食物) is turned into waste and eliminated from the body (被排出体外).
The nervous system (神经系统) includes the brain, spinal cord (脊髓) and nerves (神经).
This is your body's control system.
It controls your muscles and organs, including your circulatory and digestive system.
The respiratory system (呼吸系统) includes the nose and lungs.
It brings air and oxygen (氧气) into the body and removes carbon dioxide (二氧化碳).
The lungs are where oxygen enters the bloodstream (血流), and carbon dioxide is removed.
The immune system (免疫系统) protects the body against infections (感染、传染) and diseases (疾病).
Sneezing (打喷嚏) and fever (发烧) are examples of how the immune system works.
If an infection invades (侵袭，侵入) the body, the immune system attacks it.
Exercise:
1.— Which system circulates blood throughout the body?
— The heart pumps blood and the blood vessels transport the blood throughout the body.
2. — Which system digests food and supplies energy to the body?
— the digestive system
3.— Which system brings air and oxygen into the body?
— the respiratory system
4.— What is your body's control system?
— the nervous system
5.— Which body system protects the body against infections?
— the immune system
6. The heart pumps blood to all parts of the body through a network of
7. The digestive system is where the food is broken down and absorbed into the body.
8. It brings air and oxygen into the body and removes carbon dioxide.
Repeat & Read Sentences:
1. The respiratory system includes the nose and lungs.
2. It brings air and oxygen into the body and removes carbon dioxide.
3. Sneezing and fever are examples of how the immune system works.
4. The body's circulatory system includes the heart and blood vessels.
5. The digestive system breaks down and absorbs food into the body.
Great Discoveries
The controlled use of fire (控制和使用火) allowed people to cook food and survive (幸存) in colder climates.
Fire provided light so that people could work and socialize (参与社交) for longer hours.
With the invention of agriculture (农业的发明), people could grow food and settle into communities (融入群体生活).
By growing food, people could spend less time hunting, and more time for other things such as art.
The domestication (驯养) of animals allowed people to raise and use animals for food and work.
By raising herds of animals (成群的动物) such as sheep, humans had a regular supply of meat and clothing.
The strength of animals such as horses and oxen was used for work and transportation (运输).
The development of tools and machines has resulted in more efficient manufacturing (制造业) and construction (建筑业).
With better tools and machines, work can be done with fewer people and at much lower costs.
The development of science and engineering has improved many things, including communications.
With an understanding of electricity, telephones and radios allow people to communicate over long distances.
Exercise:
1.— What allowed people to cook food?
— The controlled use of fire allowed people to cook food.
2.— What has improved the quality and efficiency in manufacturing and construction?
— The development of tools and machines has resulted in more efficient manufacturing and construction.
3.— What allowed people to take advantage of the strength of animals?
— The domestication of animals allowed people to raise and use animals for food and work.
4.— What helped people to spend less time hunting for food?
— With the invention of agriculture, people became less dependent on hunting for food.
5.— What has changed the way we communicate?
— Science and engineering have changed the way we communicate with each other.
6. Fire provided light so that people could work and socializefor longer hours.
7. The strength of animals such as horses and oxen was used for work and
8. With better tools and machines, work can be done with fewer people and at much lower costs.
Repeat & Read Sentences:
1. With the development of agriculture, people had more time for other activities.
2. Science and engineering have changed the way we communicate with each other.
3. The controlled use of fire allowed people to cook food and survive in colder climates.
4. Science and engineering breakthroughs are rapidly changing the way we live our lives.
