CHAPTER 1: RESPIRATION Human Breathing Mechanism 1.
Breathing is a physical process in which air is inhaled or taken in and exhaled or given out by a living body (Draw figure 1.1) 2. Breathing involves two phases: Inhalation rib cage moves upwards and outwards diaphragm contracts, moves downwards and flatten thoracic cavity becomes bigger (causes air pressure to decrease) higher air pressure outside forces the air into the lungs Exhalation rib cage moves downwards and inwards diaphragm expands and curves upwards thoracic cavity becomes smaller (causes air pressure to increase) higher air pressure in the lungs forces the air out
(Draw Figure 1.2)
(Draw Figure 1.3)
Activity 1.1 AIR PRESSURE IN THE THORACIC CAVITY AND THE PROCESS OF INHALATION AND EXHALATION (Draw figure 1.4) Model of the human respiratory system can be used to show the action of the diaphragm during breathing. Inhalation Exhalation (draw figure 1.5 pg 4) (draw figure 1.6 pg 4) Thin rubber sheet is pulled downwards Thin rubber sheet is pushed upwards (diaphragm flatten) (diaphragm curves upwards) The volume of bell jar (thoracic cavity) The volume of the bell jar (thoracic cavity) increase decrease Air pressure inside the bell jar decrease Air pressure inside the bell jar increase Air from outside is sucked into the ballons Air inside the balloons is pushed out The structure of the lungs: ( Draw figure 1.7 ) The flow of air from the nose to the alveolus in the lungs is : Nose Trachea Bronchus Bronchiole Alveolus
Transport of Oxygen in the Human Body Diffusion: the movement of molecules from a region of higher concentration of the molecules to a region of lower concentration of the molecules Characteristics of alveoli one cell thick wall moist Present in large numbers(offering a large surface for difussion) Well covered by blood capillaries 1. When we inhale, more oxygen is present in the inhaled air than in the blood. Alveoli (inhaled air) (higher concentration of oxygen ) Blood capillaries (lower concentration of oxygen ) ( Draw figure 1.8 )
2. So oxygen diffuses through the thin walls of alveoli and then the capillary wall into the blood. 3. Now the blood capillaries that surround the alveoli have a higher concentration of oxygen. Red blood cells contain a dark red compound called haemoglobin. Haemoglobin combines with the oxygen to form oxyhaemoglobin. Haemoglobin + Oxygen Oxyhaemoglobin. ( dark red ) (bright red ) 4. The blood containing oxyhaemoglobin is transported from the lungs to other parts of our body. Oxyhaemoglobin is an unstable compound . It breaks down and release its oxygen at places where the oxygen concentration is low Blood capillaries (oxyhaemoglobin) (higher concentration of oxygen ) Body cells (lower concentration of oxygen )
5. The cells surrounding the blood capillaries usually have a lower oxygen concentration. So oxyhaemoglobin breaks down into haemoglobin and oxygen. The oxygen then diffuses through the blood capillaries into the cells
The Importance of a Healthy Respiratory System 1. Substances which are harmful to the respiratory system: Harmful Source Effect substances Tar Cigarette smoke -kills cells in the air passages and the lungs -increases production of mucus and phlegm in the lungs -causes lung cancer Irritants Cigarette smoke -irritate the air passages and alveoli in the lungs -kill cells on the surface on the air passages and lungs -cause smokers cough and lung cancer Carcinogens Cigarette smoke -cause various types of cancer Nicotine Cigarette smoke -cause addiction -damages brain tissue -causes blood to clot more easily which may lead to stroke -hardens walls of arteries which may cause heart attacks Carbon Cigarette smoke, smoke -prevents haemoglobin from transporting oxygen around the monoxide from vehicle body -causes the lack of oxygen in our body which may lead to headaches, brain damage or even deaths Sulphur dioxide Haze Burning of coal and oil at factories and power stations Exhause fume of vehicle, open burning, forest fires Cigarette smoke, exhaust fume of vehicle and burning of fuels. -irritates our air passages, causing coughs, breathing difficulties, bronchitis and lung cancer -irritates the respiratory system. -causing respiratory disorders such as asthma -lead poisoning that kills our cells -damage our lungs and brain -make us cough -cause lung diseases such as emphysema
Toxins (lead compound, oxides of nitrogen)
2. Diseases of the Respiratory System: a) Asthma Caused by inhaling dust , cigarette smoke and industrial fumes Symptoms : shortness of breath , wheezing or coughing b) Bronchitis Inflamation of the bronchi Caused by tar and the irritants in cigarette smoke Symptoms : continuous coughing (called smokers cough) , Constant breathlessness , sleeplessness c) Emphysema Alveoli of the lungs are enlarged and damages Caused by harmful air pollutants especially in the cigarette smoke Symptoms : shortness of breath , feeling pain while breathing , exhaustion even from doing light work
