LESSON 3The Circulatory System

人体血液循环系统

The circulatory system:Comprises of the heart and the network blood vessels.

Main Functions:1. Supply oxygen to all parts of the body.2. Distribute heat3. Distribute （ 分配） the absorbed nutrients.4. Collect and carry waste materials to the organs concerned with their

discharge.( 排出）

Position and structure of the heart Position:1. lies in the chest cavity between two lungs.

Structure :2. muscular muscle,acts as double pump.3. Divided into left and right side.(right : upper

collecting , left : lowers pumping)

The Average heartbeat Adult :60~80/min children:80~100/min Infant:100~120/min

The Factor which increase the heartbeat1. Exercise2. Fever3. Emotional Stress4. The comsumption of alcohol5. Several bleeding

The structure and function of blood vessels and Blood

Arteries( 动脉） * 有氧• Strongest blood vessels• Carry blood away from heart.

Capillaries( 微血管）• Very small blood vessels• Exchange of fluids and gases to and from tissues of body.

Veins( 静脉） * 无氧• Very small vessels.• Returninng blood to right chamber heart.

Blood• Red ,white corpuscles and platelets.• Blood carry nutrient from digestive organs and carry waste

products to excretory(排泄） organs.**Red cells carry oxygen**white cells remove germs and dead cells.**platelets help blood clot.

The pulseCarotid (颈动脉）Brachial （上臂脉）RadialFemoral（大腿内侧）