Cell Respiration - A food oxidization process in body cells to produce energy - Occurs (happens) in animal cells and plant cells Notes : Metabolic Reactions in Gaseous Exchange CELL RESPIRATION Photosynthesis - Uses energy to produce glucose and oxygen - Occurs in plant cells only Glucose + Oxygen Carbon Dioxide + Water + Energy C6H12O6 + 602 6CO2 + 6H20 + energy PHOTOSYNTHESIS Carbon Dioxide + Water + Energy (Sunlight) Glucose + Oxygen 6CO2 + 6H20 + energy C6H12O6 + 602 Page 1 of 7 1. Glucose (from food) is oxidized (combined with oxygen) to produce carbon dioxide, water and energy in respiration 2. The energy from sunlight, carbon dioxide and water is used to produce glucose and oxygen in photosynthesis
The Human Respiratory System Nasal Cavity - Space in the nose air passes through Page 2 of 7 - Functions to warm, moisten and filter fine particles (dust) Trachea - A channel that branches into two - Each branch is a bronchus which enters into the lungs - Has C-shaped rings (cartilage rings) to prevent it from collapsing Bronchiole - Small channel that branches from bronchus - Each ends with an alveolus Alveolus - Has thin, moist walls with a large network of blood capillaries Intercostal Muscles - Situated between the ribs - Contract and relax to help the breathing process - Two types : Internal and External Intercostal Muscles Ribs - Protect the lungs and internal organs (heart) Diaphragm - Piece of muscle situated at the bottom of the lungs - Separates the thorax and the abdomen Pathway of Airflow : Nostrill Nasal Cavity Trachea Bronchus Bronchiole Alveolus
Page 3 of 7 Breathing Mechanism Inhalation - External intercostal muscles contract and internal relaxes - Ribs (hard bones) are raised - Chest is pushed out (upwards) - Diaphragm (elastic piece of muscle) contracts and flattens - Volume (space) of thoracic cavity increases - Air pressure becomes lower than the surrounding - Air flows in (through the nose) Exhalation - External intercostal muscles relax and internal contracts - Ribs (hard bones) are descends - Chest is pulled in (upwards) - Diaphragm (elastic piece of muscle) relaxes and curves up - Volume (space) of thoracic cavity decreases - Air pressure becomes higher than the surrounding - Air flows out (through the nose) Comparison between the Model and Actual Human System Simple Model to Show the action of the Diaphragm - When diaphragm is pulled, the balloons inflate - When diaphragm is released, the balloons deflate - This is because the volume (space) in the glass jar increases - This is because the volume (space) in the glass jar decreases - Thus, the pressure decreases and air is forced into the balloons - Thus, the pressure increases and air is forced out of the balloons Balloons - Lungs Y-Shaped tube Bronchus Glass Tube Trachea Rubber Sheet - Diaphragm Bell Jar Rib Cage Air space inside bell jar Thoracic Cavity
Page 4 of 7 Transport of Oxygen in the Human Body - Oxygen diffuses into the blood capillaries - Carbon Dioxide diffuses out of the blood capillaries - Oxygen is carried to the body cells - Carbon Dioxide is carried into the alveolus to be eliminated Reasons alveolus is efficient in gaseous exchange : - Moist (enables gas to dissolve) - Millions of alveoli (increase surface area) - Large network of blood capillaries How does oxygen and carbon dioxide undergo diffusion in the alveolus? i) Inhaled air will reach the alveolus through the breathing channel ii) High concentration of carbon dioxide in the blood forces it into the alveolus to be eliminated iii) Low concentration of oxygen in the blood helps the oxygen from the air to dissolve into the blood Transport of Oxygen in the Blood - Red blood cells contain haemoglobin which is made of iron - These cells react with oxygen to form oxyhaemoglobin - When the red blood cell reaches other cells, it will decompose and supply oxygen to them Haemoglobin + Oxygen Oxyhaemoglobin / Hb + 4O2 HbO8
Illnesses of the Respiratory System Lung Emphysema Page 5 of 7 - Abnormal growth of cells blocking air channels in the lungs - Caused by certain chemical substances in cigarette smoke - Carbon dioxide get trapped and eventually the alveoli would swell then burst, leaving large spaces in the lungs - The bursting cannot be repaired and reduces surface area for gaseous exchange - Symptoms : breathing difficulty, tiredness, excessive coughing Bronchitis - Inflammation of the epithelium (cell layer) of the bronchus - Causes by fine particles that float in the air or in cigarette smoke - Breathing channel of the patient will be lined by mucus - Symptoms : high fever, breathing difficulty, tiredness, weight loss, chest pains, continuously heavy coughing, phlegm changes from white to yellow or green Lung Cancer - Caused by unusual cell growths in the lungs and smoking is a major cause because of its carcinogens (causes cancer) - Does not show symptoms in the early stage (normally) : - Symptoms : fever, breathing difficulty, weight loss, wheezing, chest pains, coughing blood, continuous coughing, weight loss Asthma - Inflammation of the breathing channel because it is very sensitive to certain allergens (cause allergy) - The channel will become narrow and cause breathing difficulties - Causes : dust (air pollutant), smoking or cigarette smoke - Symptoms : Breathing difficulties, wheezing, tightness in the chest, coughing (especially at night/ cold weather)
Effects of Cigarette Smoke on the Lungs Experiment Observations - The cotton wool becomes darkish yellow - The temperature in the conical flask increases Page 6 of 7 - The universal indicator solution turns from green to red - If hydrogen carbonate indicator is used, red to yellow - If litmus solution is used, purple to red Notes - Tobacco tar blackens the lungs, causes them to be less efficient, damages alveolus and lung cells as well as causes lung cancer - Nicotine causes addiction and illnesses like bronchitis, throat cancer and lung cancer - Acid corrodes the lung cells and cells that line the breathing channel as well as causes illnesses like coughing, asthma and bronchitis - Carcinogen stimulates the growth of cancer cells, causing lung and throat cancer Other Harmful Gases - Acidic gas from factories (Sulphur and nitrogen dioxide) damages breathing channel and lungs as well as causing breathing difficulties - Vehicle fumes (carbon monoxide) reduces the ability of blood to transport oxygen because it binds easier with haemoglobin than oxygen - Burning forest or garbage (haze) damages the lungs and causes breathing difficulties - Burning plastic material (emits hydrogen chloride, ammonia and hydrogen cyanide) corrodes the breathing channel
Page 7 of 7 Ways to Improve Air Quality Install catalyst converters on vehicle exhaust pipes to reduce the release of dangerous gases (carbon monoxide, hydrocarbon and nitrogen oxide) Use air cleaning system to dissolve toxic hases (Sulphur dioxide and nitrogen dioxide) in water before it is released into the atmosphere Install tall chimneys so that dangerous substances are kept at a higher level in the atmosphere Install electrostatic precipitors in factory chimneys to remove pollutants before smoke is released Stop smoking to prevent the release of cigarette smoke into the environment Burn garbage in special places like the incinerator