O Level Science Biology - Respiration in Humans (PDF)

Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Huma...

Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans LN7.1 Respiration in Humans (Human Gaseous Exchange System) Textbook References Biology Matters (3rd edition) by Lam P. K. & Lam Y. L. E. Chapter 7. Pages 137 - 150 Syllabus Learning Outcomes (5088 Syllabus) 6(a) identify the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries and state their functions in human gaseous exchange 6(b) explain how the structure of an alveolus is suited for its function of gaseous exchange 6(c) state the major toxic components of tobacco smoke – nicotine, tar and carbon monoxide, and describe their effects on health Table of Contents 1. Human Respiratory System......................................................................................... 3 1.1 Parts of the Human Respiratory System*....................................................................... 4 1.1.1 Structure & Function of Respiratory Parts*......................................................................... 4 1.1.1.1 Larynx*.............................................................................................................................. 5 1.1.1.2 Trachea*............................................................................................................................ 5 1.1.1.3 Bronchus* [plu: bronchi]......................................................................................................... 6 1.1.1.4 Bronchiole* [plu: bronchioles].................................................................................................. 6 1.1.1.5 Alveolus* [plu: alveoli]............................................................................................................ 6 1.1.1.6 Capillary*........................................................................................................................... 6 1.1.2 Pathway of Air through the Human Respiratory System*................................................. 7 1.1.3 Diameter of Respiratory Parts*............................................................................................. 7 1.2 Characteristics of Alveolus Exchange Surface*............................................................. 8 1.2.1 Adaptations of the Alveolus*................................................................................................. 8 1.2.2 Adaptations of the Exchange Surface*................................................................................ 9 Summary 1: Adaptations of the Alveolus Exchange Surface**............................................... 10 2. Gaseous Exchange...................................................................................................... 11 2.1 Movement of Oxygen Into the Blood from the Alveolar Space*................................ 12 2.2 Movement of Carbon Dioxide from the Blood Into the Alveolar Space*................... 12 2.3 Unpacking the Terms (Breathing, Gaseous Exchange, Respiration) #GTK............... 13 2.3.1 Breathing #GTK....................................................................................................................... 13 2.3.2 Gaseous Exchange #GTK...................................................................................................... 13 2.3.3 (Aerobic) Respiration #GTK................................................................................................... 14 Summary 2: Breathing v.s Gaseous Exchange v.s Respiration #GTK..................................... 14 Greendale Secondary School 1 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 3. Tobacco Smoke & Its Effects..................................................................................... 15 3.1 Major Toxic Components in Tobacco Smoke**............................................................ 16 3.1.1 Nicotine*................................................................................................................................. 16 3.1.1.1 Characteristics & Effects on Health of Nicotine*.............................................................. 16 3.1.1.2 Harmful Effects on Health of Nicotine*............................................................................ 17 3.1.2 Tar*......................................................................................................................................... 17 3.1.2.1 Harmful Effects on Health of Tar*.................................................................................... 17 3.1.3 Carbon Monoxide*................................................................................................................ 18 3.1.3.1 Harmful Effects on Health of Carbon Monoxide*............................................................. 18 Summary 3: Harmful Effects of Toxic Components in Tobacco Smoke*............................... 19 3.2 Respiratory Diseases caused by Tobacco Smoke #GTK........................................... 20 3.2.1 Bronchitis #GTK....................................................................................................................... 20 3.2.2 Emphysema #GTK.................................................................................................................. 20 3.2.3 Lung Cancer #GTK.................................................................................................................. 20 Greendale Secondary School 2 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 1. Human Respiratory System Syllabus Learning Outcomes: 6a Learning Outcomes: Human Respiratory System ¨ identify the parts of the human respiratory system (larynx, bronchi, bronchioles, and alveoli) ¨ describe the functions of the parts of the human respiratory system ¨ explain how the structure of the alveoli is adapted to its function as the site of gaseous exchange Note-taking Greendale Secondary School 3  Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 1.1 Parts of the Human Respiratory System* 1.1.1 Structure & Function of Respiratory Parts* Structure Function larynx protects the trachea 1. secretes mucus to trap dust and moves mucus up the trachea trachea 2. carries air to the lungs bronchus carries air from the trachea into the lung [plu. bronchi] bronchiole carries air into the alveolus [plu. bronchioles] alveolus site of gaseous exchange [plu. alveoli] capillary carries blood to the alveoli / lungs for gaseous exchange to occur Greendale Secondary School 4 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 1.1.1.1 Larynx* Function: protects the trachea ^ Diagram showing how the larynx protects the trachea & the other airways in the human respiratory system. Another structure for protection is through a flap known as the epiglottis. 1.1.1.2 Trachea* Function: 1. secretes mucus to trap dust and moves mucus up the trachea 2. carries air to the lungs ^ Diagram (left) and electron micrograph (right) showing the ciliated epithelial cells & gland cells found in the trachea Greendale Secondary School 5 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 1.1.1.3 Bronchus* [plu: bronchi] Function: carries air from the trachea into the lung 1.1.1.4 Bronchiole* [plu: bronchioles] Function: carries air into the alveolus ^ Diagram showing the branching of the bronchi & bronchioles, and the respective names of the different branches ^ Diagram showing how the bronchi carries air from the trachea into the lungs, and how the bronchioles carry air into the alveoli 1.1.1.5 Alveolus* [plu: alveoli] Function: site of gaseous exchange 1.1.1.6 Capillary* Function: carries blood to the alveoli / lungs for gaseous exchange to occur ^ Diagram showing the alveoli and its associated capillaries. Pulmonary artery carrying deoxygenated blood from the heart to the alveoli in the lungs. Gaseous exchange occurs at the alveoli (site of gaseous exchange) between the blood & alveolar space, where carbon dioxide is removed & oxygen is absorbed. The pulmonary vein then carries oxygenated blood from the alveoli in the lungs back to the heart. Greendale Secondary School 6 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 1.1.2 Pathway of Air through the Human Respiratory System* Air travels from outside the body, to trachea, to bronchus, to bronchiole, then into the alveolus in the lungs Pathway of air: outside air → larynx → trachea → bronchus → bronchiole → alveolus ^ Diagram showing the pathway of air through the human respiratory system 1.1.3 Diameter of Respiratory Parts* As air travels from the trachea to the alveoli, the diameter of respiratory parts decreases largest diameter smallest diameter trachea bronchus bronchiole alveolus ^ Diagram showing the decreasing diameter of the airways as air travels from the outside air into the trachea, bronchi, bronchioles, and the alveoli Greendale Secondary School 7 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 1.2 Characteristics of Alveolus Exchange Surface* The alveolus exchange surface contains the alveolus and associated capillaries. 1.2.1 Adaptations of the Alveolus* There are three adaptations of the alveolus: Adaptation #1: Alveolus has large surface area OR there are numerous alveoli Relation to Function: Increases surface area for higher rate of diffusion of gases during gaseous exchange ^ Diagrams showing the lungs containing numerous alveoli which has large surface area to increase the rate of diffusion of gases during gaseous exchange Adaptation #2: Alveolar wall / epithelium is one-cell thick Relation to Function: Decreases diffusion distance for higher rate of diffusion of gases during gaseous exchange ^ Diagram of one alveolus showing how the one-cell thick alveolar wall can decrease diffusion distance required for the diffusion of oxygen & carbon dioxide gases, therefore increasing rate of gaseous exchange Greendale Secondary School 8 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans Adaptation #3: Thin film of moisture covers the alveolar wall Relation to Function: Allows oxygen to dissolve in the thin film of moisture for diffusion into the blood ^ Diagram showing the alveolar wall at different magnifications, covered with a thin film of moisture to allow gases to dissolve for diffusion during gaseous exchange 1.2.2 Adaptations of the Exchange Surface* Adaptation #4: There is a network of capillaries surrounding alveoli Relation to Function: Provides alveoli walls with constant blood flow, to maintain a concentration gradient of gases for diffusion of gases ^ Diagram showing the network of capillaries associated with the alveoli in lungs. Constant blood flow to and from the heart helps to maintain concentration gradient for the diffusion of gases Greendale Secondary School 9  Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans Summary 1: Adaptations of the Alveolus Exchange Surface** Specialised feature / Relation to Function Adaptation Large surface area / Increases surface area → higher rate of numerous alveoli diffusion of gases Cluster of during gaseous alveoli / Alveolar wall / epithelium Decreases diffusion exchange alveolus is one-cell thick distance features Thin film of moisture Allows oxygen to dissolve in the thin film of covers the alveolar wall moisture for diffusion into the blood Exchange Network of capillaries Provides alveoli walls with constant blood flow surface surrounding alveoli → maintain a concentration gradient of gases features for diffusion of gases Greendale Secondary School 10 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 2. Gaseous Exchange Syllabus Learning Outcomes: 6b Learning Outcomes: Gaseous Exchange o describe the movement of oxygen and carbon dioxide between the alveolar space and the blood at the alveoli exchange surface o understand the differences between breathing, gaseous exchange & respiration Note-taking Greendale Secondary School 11 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 2.1 Movement of Oxygen Into the Blood from the Alveolar Space* ^ Diagram showing how oxygen diffuses from the alveolar space into red blood cells, where oxygen bind to haemoglobin to produce oxyhaemoglobin. O2 in the alveolar space dissolves in the thin film of moisture surrounding the alveolar wall O2 moves from a region of higher concentration, in the thin film of moisture, through the alveolar wall and capillary wall, to a region of lower concentration, in the red blood cells in the capillaries, via diffusion. 2.2 Movement of Carbon Dioxide from the Blood Into the Alveolar Space* ^ Diagram showing how carbon dioxide diffuses from the blood plasma into the alveolar space. #FYI Carbon dioxide is transported in blood plasma mainly by dissolving, but it can also be converted into soluble bicarbonate ions, or be transported by binding to haemoglobin in red blood cells CO2 moves from a region of higher concentration, in the plasma in the capillaries, through the capillary wall and alveolar wall, to a region of lower concentration, in the thin film of moisture surrounding the alveolar wall, via diffusion. CO2 leaves the thin film of moisture and enters the alveolar space Greendale Secondary School 12 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 2.3 Unpacking the Terms (Breathing, Gaseous Exchange, Respiration) #GTK 2.3.1 Breathing #GTK ^ Diagram showing how breathing occurs. Air enters the lungs when the pressure in lungs decreases due to increase in lung volume. Air leaves the lungs when the pressure in lungs increases due to decrease in lung volume. Description Movement of air in and out of lungs Location Occurs at the lungs Occurs due to Occurs because of pressure changes in the lungs 2.3.2 Gaseous Exchange #GTK ^ Diagram showing how gaseous exchange can occur at the body tissues and the alveoli in the lungs Description 1. Absorption of oxygen from the alveolar space into the blood AND 2. Removal of carbon dioxide from the blood Location Occurs at the alveoli in the lungs Note: can also occur between body cells and the blood Occurs due to Occurs due to diffusion Greendale Secondary School 13  Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 2.3.3 (Aerobic) Respiration #GTK ^ Diagram showing how aerobic respiration takes place in the mitochondria of cells. Glucose is chemically broken down in the presence of oxygen to release a large amount of energy Description Oxidation of glucose to release energy, producing water and carbon dioxide Location Occurs in the mitochondria of cells Occurs due to Chemical reactions catalysed by enzymes Summary 2: Breathing v.s Gaseous Exchange v.s Respiration #GTK Gaseous Process Breathing (Aerobic) Respiration Exchange Absorption of oxygen from the alveolar Oxidation of glucose to Movement of air Description space into the blood, release energy, producing in and out of the lungs and removal of carbon carbon dioxide and water dioxide from the blood Occurs at the alveoli Occurs in mitochondria Location Occurs at the lungs of cells of the lungs Occurs because of Occurs due to Chemical reactions Occurs due to pressure changes diffusion catalysed by enzymes in the lungs Greendale Secondary School 14 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 3. Tobacco Smoke & Its Effects Syllabus Learning Outcomes: 6c Learning Outcomes: Tobacco Smoke & Its Effects o state the major toxic components of tobacco smoke – nicotine, tar, and carbon monoxide o describe the characteristics of each component and their harmful effects on human health Note-taking Greendale Secondary School 15 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 3.1 Major Toxic Components in Tobacco Smoke** Smoke is produced when tobacco products are burnt Tobacco smoke contains several toxic components. o There are three major toxic components, which are: 1. nicotine 2. tar 3. carbon monoxide Inhalation of tobacco smoke (not inhalation of cigarettes!) can cause harm to health 3.1.1 Nicotine* 3.1.1.1 Characteristics & Effects on Health of Nicotine* Characteristic #1: Nicotine is a highly addictive drug → causes addiction Characteristic #2: Nicotine is a stimulant drug → increases alertness ^ Nicotine is highly addictive because it causes a large release of ^ Nicotine is a stimulant which increases the number of pleasure-inducing dopamine (hormones), which leads to cravings impulses that is sent to the brain, causing increased and more tobacco use. alertness Characteristic #3: Nicotine causes heart rate and blood pressure to increase > Nicotine in tobacco smoke can cause the vasoconstriction of blood vessels, resulting in increase in blood pressure & heart rate Greendale Secondary School 16 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 3.1.1.2 Harmful Effects on Health of Nicotine* Harmful Effect #1: Nicotine makes blood clotting easier → Blood clots can cause the lumen of coronary arteries to become occluded → Increases risk of coronary heart disease (Refer to Section 5.2 of Ch6 Transport in Humans. Elaborate on full details based on the mark allocation) ^ Nicotine causes the condition called “sticky blood”, where the blood clotting process becomes easier as the clotting proteins are more likely to cause more agglutination of fibrin threads, platelets & red blood cells. This can form dangerous clots. 3.1.2 Tar* 3.1.2.1 Harmful Effects on Health of Tar* Harmful Effect #1: Tar paralyses cilia of the trachea → cilia unable to remove dust trapped in mucus > Tar is accumulated on the cilia of epithelial cells in the trachea, preventing them from moving to sweep trapped dust towards the larynx Harmful Effect #2: Tar leads to bronchitis (inflammation of bronchi) → reduce air flow to and from the lungs ^ Tar accumulates in the airways of the primary & secondary bronchitis, causing them to be inflamed Greendale Secondary School 17 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans Harmful Effect #3: Tar damages walls of the alveoli → increased risk of emphysema (weakening and breakdown of alveolar walls) → reduces surface area to volume ratio of the alveoli → reduced efficiency of gaseous exchange in the alveoli ^ The build-up of tar in the alveoli causes the walls to weaken and breakdown (emphysema), therefore causing a reduction in surface area to volume ratio, reducing gaseous exchange efficiency Harmful Effect #4: Tar causes uncontrolled division of cells in the lungs → increased risk of lung cancer > People that smoke often will get smoker’s lungs, which are often stained black from tar. Smoker’s lungs have tumours. 3.1.3 Carbon Monoxide* 3.1.3.1 Harmful Effects on Health of Carbon Monoxide* Harmful Effect #1: Carbon monoxide binds irreversibly to haemoglobin in red blood cells to form carboxyhaemoglobin → Red blood cells can carry less oxygen → Decreases oxygen carrying capacity of blood to the organs → Tissue cells have insufficient oxygen for aerobic respiration to release energy ^ Blood with carboxyhaemoglobin is pinker ^ Diagram showing how carbon monoxide displaces oxygen than normal oxygenated blood to bind to haemoglobin Greendale Secondary School 18 Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans Summary 3: Harmful Effects of Toxic Components in Tobacco Smoke* (1) Tar paralyses cilia of trachea (2) Tar causes bronchitis (4) Tar causes (3) Tar causes emphysema lung cancer (0) Nicotine increases risk of coronary heart disease Increases heart rate Increases blood pressure (5) Carbon monoxide binds irreversibly to haemoglobin in red blood cells to form carboxyhaemoglobin Red blood cells carry less oxygen, decreasing oxygen carrying capacity of blood to the organs. Tissue cells have insufficient oxygen for aerobic respiration to release energy Greendale Secondary School 19  Lesson Notes (LN) Chapter 7 O Level Science Biology Respiration in Humans 3.2 Respiratory Diseases caused by Tobacco Smoke #GTK 3.2.1 Bronchitis #GTK Bronchitis is the inflammation (swelling) of the bronchi Symptoms: Production of excess mucus, chronic coughing, wheezing, shortness of breath ^ Diagram showing how bronchitis causes inflammation of walls and increased amount of mucus ^Comparison of cross section of a healthy bronchus (left) and an inflamed bronchus (right) 3.2.2 Emphysema #GTK Emphysema is the weakening and breakdown of alveolar walls Symptoms: Production of excess mucus, chronic coughing, wheezing, shortness of breath ^ Picture of lung tissue with emphysema ^ Comparison of cross section of cluster of ^ Comparison of electron micrograph of healthy lung tissue (left) and healthy alveoli (left) and alveoli during lung tissue with emphysema (right) emphysema (right) 3.2.3 Lung Cancer #GTK Lung cancer is the uncontrolled growth of abnormal cells (called tumour) in the lungs > Diagram showing healthy lungs & tumours in lungs at late-stage cancer Greendale Secondary School ^ Spread of cancer cells from lung to other parts of the respiratory system as cancer progresses 20