Natural Science Unit 2

1. Respiratory system

1.1. 1. The air enters through the nose and the mouth

1.2. 2. The air passes through the trachea and then to the bronchi

1.3. 3. Then the bronchi passes the air through the bronchioles

1.4. 4. The bronchioles gives the air to the alveoli

1.5. 5. And then to the capillaries

1.6. Video: https://www.youtube.com/watch?v=TK-b-Ri7IsY

2. Excretory system

2.1. 1. The renal arteries carry the blood to the kidneys

2.2. 2. The kidneys eliminate water and waste product and form urine

2.3. 3. Urine passes through the ureters to the bladder

2.4. 4. When the bladder is half-full it send a message to the brain to go to the toilet

2.5. 5. The bladder is emptied by another tube called urethra

2.6. Vídeo: https://www.youtube.com/watch?v=2_7Q1xQ-NWU

3. Digestive system

3.1. 1. The food mixes with saliva in the mouth

3.2. 2. The food passes down the oesophagus

3.3. 3. The stomach digests the food using gastric juices.

3.4. 4. The nutrients are absorbed in the small intestine

3.5. 5. Waste product is expelled through the anus

3.6. Video: https://www.youtube.com/watch?v=VwrsL-lCZYo

4. Circulatory system

4.1. 1. The blood passes from the right atrium to the right ventricle and now to the lungs

4.2. 2. Blood returns to the heart through the pulmonary artery

4.3. 3. The blood flows into the left atrium and then into the left ventricle

4.4. 4. The aorta carries the blood into small arteries

4.5. 5. The blood passes from the capillaries to the small veins

4.6. Video: https://www.youtube.com/watch?v=_eVG45_iF9U