GASEUOS EXCHANGE In

your Body

Created by D.T NyalungaUniversity of JohannesburgCopyrights (2012)

Why do we have to breathe?You have to breathe because all the cells in your body require oxygen. Without oxygen, your body wouldn’t move. It would be like a parked car without a battery.

The cycle of breathing

lungsTrachea

O2

Nose air O2

Air Co2 from lungs

Exhaled out

O2

Co2

Requirements for gaseous exchange

The must be a large surface area, in man this is created by the presence of the alveoli. (We focus on it later.)

The must a thin moist layer for the diffusion of gases, The surface must be adequately ventilated. For effective

mechanism of inhalation and exhalation Camphell & Reece (2010). The gaseous exchange must be richly supplied with blood vessels,

for transport The organ must be properly protected , in man the lungs are

situated in an airtight chest cavity and are well protected by the ribs and sternum Mader s.s (2008).

The organs of the breathing system

Table adopted from senior biology 2005

Organ Function

1.Nasal passage For Inhalation (Oxygen) and exhalation (carbon dioxide).

2.pharynx Contain epiglottis which closes the food passage when breathing

3.Trachea C-shaped cartilage rings, for moistening the air and trapping dust.

4.Bronchi and bronchioli Convey air to the lungs

5. Lungs Its moist to facilitated the diffusion of gases, between lungs and the blood capillaries.

The breathing system

The structure of the lungsThe lungs are two grey, spongy, elastic organs situated in the chest

cavity. They are protected by the ribs and sternum. The lower section consist of diaphragm, surrounded by a double membrane called pleura membrane. The right lung is divided into three while the left is divided into two.

The lungs and the alveolus

Transportation of oxygen and carbon dioxide in the alveolus.We, and all respiring organisms, need oxygen to live. When we breathe in air, alveoli in our lungs exchange carbon dioxide for oxygen, as shown here in this diagram

transportationOxygen can only be transported in two ways.

1. A small percentage is conveyed in solution in the blood plasma.

2. Most of the oxygen transported in a form of oxyhaemoglobin.

Carbon dioxide can be transported in three ways.

3. Small percentage is transported in a solution in the blood plasma.

4. Some transported as carbamino haemoglobin.

5. Most carbon dioxide is transported as Bicarbonate Ions in the erythrocytes.

Pulmonary Diseases1Bronchitis cigarette smoke and other pathogens irritants the movement of cilia. Which lines the bronchial tubes. Thus mucus blocks the bronchial tubes and then infections develops.

2.Emphysema repeated coughing due to aveola bust. when a lot of alveola destroyed the heart does not get enough oxygen, therefore it could result to cardiac arrest.

3. Asthma causes by irritants such as smoke, pollen, dust and allergies. The air ways become narrow which make breathing difficult.

4. Cancer is the most known respiratory diseases which affects our life daily. Hence there many types of cancer but it is known that smoking is the most cause of cancer.

PNEUMONIA