Nota Sains: Bab 18. Respiration

Nota Sains Tingkatan 3:

18: Respiration

RESPIRATION

· Definition : a process in breaking of glucose ( food ) with the presence of oxygen to produce energy / oxidation of food process.

· During respiration, humans obtain oxygen which at the same time remove carbon dioxide and water vapour through the respiratory system.

· Oxygen is obtains through breathing.

HUMAN BREATHING MECHANISM

STRUCTURE	FUNCTION
NASAL CAVITY	Air entering from the nostrils is led to the nasal cavity
TRACHEA	An airway through which respiratory air travels. The rings of cartilage within its walls keep the trachea open.
BRONCHUS	Passage divided from trachea [ singular = bronchus, plural = bronchi ]
BRONCHIOLE	A narrow tube inside the lungs that branches off the main air passages bronchi
ALVEOLUS	Place where exchange of gases take place
RIB CAGE	To protect the lungs and help in breathing mechanism
LUNG	A respiratory organ
INTERCOSTAL MUSCLES	Antagonistic muscles that help the movement of rib cage for breathing mechanism
DIAPHRAGM	A muscular membrane that separates the thoracic cavity and the abdominal cavity

BREATHING MECHANISM

INHALATION = a process when air is force into the lungs		EXHALATION = a process when air is force out of the lungs
External intercostal muscle contract, while internal intercostal muscle relax	Intercostal muscle		External intercostal muscle relax, while internal intercostal muscle contract
Moves upwards and outwards	Rib cage		Move downwards and inwards
Contract and become flat	Diaphragm		Relax and become “dome” shape
Volume increase	Thoracic cavity		Volume decrease
Decrease	Air pressure in the lung		Increase
Air from outside enters the lungs	Air movement		Air is force out of the lungs

**** You just need to memorize 1 process because the other part is just the OPPOSITE

· Pathway taken by air during inhalation:

Nostril ---> Nasal cavity--> Trachea--->Bronchus---->Bronchiole--->Alveolus

· Pathway taken by air during exhalation:

Alveolus

--->

Bronchiole

-->

Bronchus

--->

Trachea

---->

Nasal cavity

--->

Nostril

Transport of oxygen in human body

v Exchange of gases takes place in the alveoli by diffusion.

v Characteristics of alveoli that help exchange of gases to take place effectively:

Ø Has one-cell thick wall ( very thin) Ø Inside surface has thin film of moisture Ø Huge number of alveoli Ø Network of blood capillaries surround each alveoli

TRANSPORTATION OF OXYGEN

1. Oxygen dissolves in the moist lining of the alveolus
2. Then, oxygen diffuses into the blood capillaries
3. Blood inside the capillaries contains red blood cells that are rich with haemoglobin
4. Oxygen combines with haemoglobin to form oxyhaemoglobin
5. Oxyhaemoglobin is transported in the blood to heart and then pump to all parts of the body
6. Oxyhaemoglobin breaks down, oxygen diffuses into the cells, at the same time carbon dioxide diffuses into the blood

EFFECTS OF OTHER AIR POLLUTANTS

CHEMICAL SUBSTANCE	SOURCES	DAMAGING EFFECTS
Carbon monoxide	Car exhaust	Reduces amount of oxygen in the food
Sulphur dioxide	Industry, vehicles	Damages lung tissues
Hydrocarbons	Industry, vehicles	Cause cancer
Nitrogen oxide	Industry, vehicles	Interacts with hydrocarbons to form haze
Haze	Industry, vehicles, open burning	Causes breathing difficulties