F2 1st Term IS WS 12 Answers

7.6       Breathing and breathing system

             in humans

C. Our breathing mechanism

i      Words to know:

	English term	Write the words again	Chinese term
1	Diaphragm		橫膈膜
2	Intercostal muscle		肋間肌
3	Rib		肋骨
4	Chest		胸腔
5	Volume		體積
6	Pressure		壓力
7	Contract / Relax		收縮 / 放鬆
8	Upwards / Downwards		向上 / 向下
9	Inwards / Outwards		向內 / 向外

i      Fill in the blanks:

1       Breathing is brought about by the actions of diaphragm / intercostal muscles, the ribs and the Intercostal muscles / diaphragm.

2       Breathing involves changes in volume and pressure inside the chest.

3       Fill in the table to show how our body works on breathing.

	Breathing in	Breathing out
Diaphragm	move upwards / downwards	Move upwards
Intercostal muscles	contract	contract / relax
Ribs move	Upwards / downwards and outwards / inwards	Downwards and inwards
Volume inside the chest	increases	increases / decreases
Gas pressure inside the chest	increases / decreases	increases
Air flows	Into the lungs	Into / out of the lungs

i      Writing:

1      During the process of breathing in, the diaphragm becomes flat. The intercostal         muscles contract, causing the ribs to move upwards and outwards. The volume inside the chest increases, and the gas pressure inside decreases. Thus air flows into the lungs.

         the lungs.

2      When we breathe out, the diaphragm moves upwards. The intercostal muscles relax, causing the ribs to move downwards and inwards. The volume inside the chest decreases, and the gas pressure inside increases. Thus, air flows out of the lungs.