Bio Ch3 Notes PDF

Respiration Process: The oxidation of foods (like glucose) to release energy. Requirement: A continuous supply of oxygen from the blood for aerobic respiration. Waste Removal: Carbon dioxide produced during respiration needs to be removed from the body. Exchange: In h...

Respiration Process: The oxidation of foods (like glucose) to release energy. Requirement: A continuous supply of oxygen from the blood for aerobic respiration. Waste Removal: Carbon dioxide produced during respiration needs to be removed from the body. Exchange: In humans, this gas exchange occurs between the blood and the air in the lungs. Breathing vs. Respiration Breathing: The mechanical process of moving air into and out of the lungs. Respiration: The chemical process of releasing energy from food. Confusion: The terms "respiratory system" and "gas exchange system" are often used interchangeably, but the latter is more accurate. The Structure of the Gas Exchange System Enclosed: The lungs are contained within the chest or thorax by the ribcage and the diaphragm. Diaphragm: A muscular sheet of tissue that separates the thorax from the abdomen. It has a dome shape with a fibrous center and muscular edges. Intercostal Muscles: Muscles between the ribs that aid in breathing movements. Gas Exchange: The lungs facilitate the exchange of oxygen and carbon dioxide between the blood and the air. Animal Physiology: Breathing and Gas Exchange Breathing and gas exchange are crucial processes in the human body, allowing the exchange of gases (oxygen and carbon dioxide) between the air and the blood. This process occurs in the respiratory system, which includes the lungs, bronchi, bronchioles, trachea, and alveoli. Structure of the Respiratory System: 1. Lungs: ○ The lungs are two large spongy organs located in the chest, enclosed within the pleural membranes. ○ Each lung contains bronchi (plural for bronchus), bronchioles, and millions of tiny air sacs called alveoli, where gas exchange occurs. ○ The right lung consists of three lobes (superior, middle, and inferior), while the left lung has two lobes (superior and inferior). ○ The main muscle aiding lung function is the diaphragm, a dome-shaped muscle located beneath the lungs. 2. Bronchial Tree: ○ Trachea (windpipe) extends from the larynx to the chest and divides into the left and right bronchi.  ○ The bronchi branch off into smaller bronchioles, which further subdivide until they end at tiny air sacs called alveoli. ○ Cartilage rings support the trachea and bronchi, helping them remain open during inhalation and exhalation. Gas Exchange Process: The alveoli are key structures in the lungs where the exchange of gases takes place. Oxygen from inhaled air passes through the alveolar walls into the capillaries, while carbon dioxide from the blood is expelled into the alveoli to be exhaled. The large surface area of the alveoli, along with their thin walls and rich blood supply, ensures efficient gas exchange. Air Passage: 1. Trachea: A tube made of cartilage rings that keeps the airway open. 2. Bronchi: These branch into smaller tubes called bronchioles. 3. Bronchioles: These small air passages deliver air to the alveoli. 4. Alveoli: Tiny air sacs where oxygen diffuses into the blood, and carbon dioxide diffuses out of the blood. Ventilation of the Lungs: Ventilation involves moving air into and out of the lungs. The mechanics of ventilation are driven by changes in air pressure: Inhalation (inspiration): ○ When we breathe in, the diaphragm contracts (flattens) and the external intercostal muscles (muscles between the ribs) contract, lifting the ribcage up and out. ○ This increases the volume of the chest cavity, lowering the pressure inside the lungs. As a result, air is drawn in. Exhalation (expiration): ○ When we breathe out, the diaphragm and intercostal muscles relax, causing the chest cavity to decrease in volume, and air is pushed out of the lungs. ○ Internal intercostal muscles contract only during forced exhalation, which assists in pushing more air out. Keeping the Airways Clean: The trachea and large airways are lined with cells that produce mucus, which traps dust and bacteria. The trachea also contains cilia, which are small hair-like structures that move in a wave-like fashion to sweep mucus and trapped particles towards the throat to be swallowed or coughed out. This defense mechanism is essential for preventing infections and maintaining clean airways. Role of Cartilage:  The trachea and bronchi are supported by rings of cartilage, which ensure that these structures remain open, preventing collapse. Cartilage is strong but flexible, allowing the airways to remain stable while enabling movement during breathing. Mechanics of Breathing: Breathing is controlled by the respiratory muscles, particularly the diaphragm and the intercostal muscles: External Intercostal Muscles: Contract to lift the ribcage during inhalation. Internal Intercostal Muscles: Contract during forced exhalation, reducing the volume of the chest cavity and expelling more air. Ventilation and Pressure: The air pressure inside the chest cavity plays a key role in moving air into and out of the lungs. Negative pressure (lower pressure than the atmosphere) draws air in, while positive pressure pushes air out. Extension Work and Additional Information: The document contains sections on extension work, focusing on specific exercises to explain the role of the diaphragm and intercostal muscles during breathing. It highlights how different muscle groups are engaged during normal and forced breathing, and how these muscles affect the movement of air and the volume of the chest cavity. Mechanics of Breathing: The process of breathing is divided into two phases: inhalation and exhalation. These processes are driven by the movements of the diaphragm and the intercostal muscles. 1. Inhalation (Breathing In): ○ When we inhale, the external intercostal muscles contract, pulling the ribs upwards and outwards. ○ The diaphragm contracts and flattens, increasing the volume of the chest cavity. ○ As the volume of the chest cavity increases, the pressure inside the lungs drops below atmospheric pressure, causing air to rush into the lungs. 2. Exhalation (Breathing Out): ○ During exhalation, the external intercostal muscles relax, and the ribs move downwards and inwards. ○ The diaphragm relaxes, moving back to its dome shape, decreasing the volume of the chest cavity. ○ This causes the pressure in the lungs to rise above atmospheric pressure, and air is pushed out. Key Point on Breathing Mechanics: Breathing works on the principle of pressure differences. For example, when you use a bicycle pump, air is forced out when you push down due to increasing pressure inside the pump. The lungs function similarly; as the chest expands during inhalation, air enters due to lower pressure in the lungs compared to outside. During exhalation, the pressure inside the lungs increases, forcing air out. Gas Exchange in the Alveoli: Alveoli are the microscopic air sacs in the lungs where gas exchange takes place. Each alveolus is surrounded by a dense network of capillaries, which facilitate the exchange of gases between the air inside the alveoli and the blood in the capillaries. When blood reaches the alveoli, it is deoxygenated (low in oxygen and high in carbon dioxide). Oxygen diffuses from the alveoli into the blood, while carbon dioxide diffuses out of the blood and into the alveoli to be exhaled. Components of the Air and Gas Exchange: The air we breathe contains approximately 78% nitrogen, 21% oxygen, and a small percentage of carbon dioxide (~0.04%). The air we exhale contains less oxygen (~16%) and more carbon dioxide (~4%), as some oxygen is absorbed by the blood, and carbon dioxide is expelled from the blood during gas exchange. Water vapor is also a significant component of exhaled air. The amount of water vapor in the air varies depending on the temperature and humidity. Detailed Process of Gas Exchange in the Alveoli: 1. Oxygen Diffusion: ○ Oxygen molecules in the air inside the alveoli diffuse across the thin alveolar walls and into the capillaries, where they bind to hemoglobin in red blood cells. This oxygenated blood is then carried to the heart and pumped throughout the body. 2. Carbon Dioxide Diffusion:  ○Carbon dioxide, a waste product from cellular respiration, is carried by the blood back to the lungs. It diffuses from the blood into the alveoli, where it is expelled during exhalation. ○ Carbon dioxide is mainly transported in the blood in the form of bicarbonate ions, which are converted back to carbon dioxide in the lungs. 3. Blood Flow in the Alveoli: ○ The alveoli are richly supplied with blood from the pulmonary artery, which carries deoxygenated blood from the right side of the heart. ○ As the blood passes through the capillaries surrounding the alveoli, it absorbs oxygen and releases carbon dioxide. ○ The oxygen-rich blood then flows back to the heart via the pulmonary veins, ready to be pumped to the rest of the body. Alveolar Structure and Function: Each alveolus is surrounded by a network of capillaries that facilitate the exchange of gases. The walls of the alveoli and capillaries are extremely thin (only one cell thick), allowing for efficient diffusion of oxygen and carbon dioxide. The combined surface area of all the alveoli in the lungs is extremely large (about the size of a tennis court), providing ample space for gas exchange. Layers of the Alveoli: 1. Alveolar Epithelium – A thin layer of cells lining the inside of the alveolus. 2. Capillary Endothelium – A thin layer of cells lining the capillaries surrounding the alveolus. 3. Interstitial Fluid – A thin layer of fluid between the alveolar epithelium and the capillary endothelium, which facilitates the diffusion of gases. Hints for Understanding Gas Exchange: Be careful when interpreting the percentages of gases, as the atmosphere is a mixture of gases, and the total volume of gas must equal 100%. Thus, the composition of exhaled air (more carbon dioxide, less oxygen) is always different from that of inhaled air. Students often confuse the role of alveoli as "walls." In reality, alveoli are clusters of tiny sacs that provide a large surface area for gas exchange. Extension Work: The moist surface of the alveoli is essential for gas exchange. Oxygen dissolves in the thin layer of fluid that lines the alveoli before diffusing into the blood. Similarly,  carbon dioxide dissolves in the fluid before diffusing out of the blood and into the alveoli. The efficiency of gas exchange depends on maintaining a steep concentration gradient. This is achieved by continuously ventilating the lungs (bringing in fresh air with high oxygen levels) and ensuring the blood flow in the capillaries quickly carries away the absorbed oxygen and brings in carbon dioxide for removal. Here is a detailed breakdown of the notes from the new image you provided, focusing on practical experiments related to breathing and gas exchange, along with the effects of smoking on the lungs: Animal Physiology: Breathing and Gas Exchange Activity 1: Practical - Comparing the Carbon Dioxide Content of Inhaled and Exhaled Air Apparatus Setup: The experiment in Figure 3.8 illustrates a method to compare the amount of carbon dioxide in inhaled and exhaled air. A person breathes gently through the apparatus: Inhaled air is drawn through one tube, passing through limewater or hydrogen carbonate indicator solution. Exhaled air is drawn through a different tube into another container of limewater or indicator solution. If limewater is used, the exhaled air turns it cloudy more quickly than the inhaled air, indicating a higher carbon dioxide content in the exhaled air. If hydrogen carbonate indicator solution is used, the solution will change color to show the difference in carbon dioxide levels. Safety Note: Wear eye protection and handle the apparatus carefully. Ensure a clean mouthpiece is used for each individual during the experiment. Activity 2: Practical - Investigating the Effect of Exercise on Breathing Rate This experiment investigates how exercise affects breathing rate. Procedure: 1. Students sit quietly for a few minutes, ensuring they are relaxed.  2. Measure and record their resting breathing rate by counting the number of breaths they take in one minute. 3. Next, the students perform vigorous exercise for three minutes (e.g., running on the spot or star jumps). 4. After completing the exercise, they sit down and immediately begin recording their breathing rate every minute until it returns to normal. Data Recording: The table on the right shows the results of an investigation into the breathing rates of two subjects, A and B, before and after exercise. Time from Start of Experiment (min) Breathing Rate (breaths per minute) Subject A 1 13 2 13 3 14 4 12 Subject B 7 28 8 17 9 24  10 13 Students should plot a line graph of the results, using the same axes for both subjects. Use the data points during exercise (minutes 7, 8, 9) and leave a gap during the period before exercise (when no readings were taken). They should then answer these key questions: ○ Why does the breathing rate need to rise during exercise? ○ Explain the difference in the breathing rates of the two subjects after exercise. Which one recovers more quickly, and why? Effects of Smoking on the Lungs and Respiratory System: In order for the lungs to work effectively in gas exchange, the air passages must remain clear. This allows air to come into contact with the blood and facilitates the efficient exchange of gases. Harmful Effects of Smoking: 1. Smoking and Lung Diseases: ○ Smoking is strongly linked to lung diseases such as lung cancer, bronchitis, and emphysema. It also contributes to other conditions, such as coronary heart disease, and ulcers in the stomach and intestines. ○ Women who smoke are more likely to give birth to underweight babies. 2. Coronary Heart Disease: ○ Smoking is one of the major contributing factors to coronary heart disease, which is discussed further in Chapter 5. 3. Damage to the Respiratory System: ○ Smoking severely affects the cilia lining the trachea and bronchi, which are tiny hair-like structures responsible for sweeping away dust and particles from the lungs. The chemicals in cigarette smoke destroy these cilia, leading to a build-up of harmful substances in the respiratory system. 4. Increased Risk of Infections: ○ With damaged cilia, the lungs become vulnerable to infections as they are unable to clear away bacteria and particles effectively. This increases the risk of respiratory diseases and infections in smokers. Effects of Smoking on the Lining of the Air Passages: The cilia in the air passages (trachea and bronchi) are responsible for clearing out particles of dirt and bacteria.  In smokers, the chemicals in cigarette smoke destroy these cilia, which leads to the accumulation of harmful particles and bacteria in the lungs, increasing the risk of infections and diseases. Breathing and Gas Exchange The respiratory system is vital for exchanging oxygen and carbon dioxide between the body and the environment. Efficient gas exchange depends on the proper function of the alveoli, airways, and the lungs. Damage to the lungs from diseases like emphysema, bronchitis, and lung cancer impairs this process. 1. Cilia and Mucus in the Airways: ○ Cilia are hair-like structures lining the airways. They help sweep away mucus and trapped particles from the lungs. ○ In smokers, fewer cilia are present, which allows mucus to build up in the airways. This makes it harder to expel mucus, increasing the risk of infection and damage. ○ Irritation in the bronchial tubes, caused by smoking, can result in bronchitis, which inflames the airways and restricts airflow, making it harder to breathe. Emphysema Emphysema is a chronic lung disease that causes the destruction of the alveoli (tiny air sacs) in the lungs, leading to breathing difficulties. Causes: Smoking is a primary cause of emphysema. It damages the walls of the alveoli, reducing their surface area, which decreases the amount of oxygen entering the bloodstream. In Figure 3.9, the comparison of a healthy and damaged alveolus illustrates how smoking reduces the surface area available for gas exchange. Symptoms: People with emphysema often experience breathlessness. As the alveoli are damaged, the lungs can no longer function efficiently, resulting in less oxygen being available to the body. Patients may also struggle with everyday tasks, as they cannot inhale enough oxygen to meet the body’s demands. Progression: Over time, emphysema patients may lose a significant amount of lung function, requiring supplemental oxygen. Patients typically die after a long, distressing illness due to oxygen deprivation. Lung Cancer Lung cancer is closely linked to smoking, with its first association noted in the 1950s. By studying different populations, researchers have found a strong correlation between smoking and the occurrence of lung cancer. Causes: The primary cause of lung cancer is smoking. Inhalation of tobacco smoke exposes the lungs to numerous carcinogens, which can trigger mutations in lung  cells, leading to the development of cancer. In Figure 3.11, an image shows a lung affected by cancer, with blackened, deteriorated tissue due to the disease. Comparison: Table 3.2 compares the smoking habits of lung cancer patients with those of patients who do not have lung cancer. It shows that a higher percentage of lung cancer patients smoked more than 15 cigarettes a day compared to non-smokers, establishing a significant link between heavy smoking and lung cancer. Did You Know: Studies show that the type of cigarette smoked does not greatly affect lung cancer risk. However, the duration and frequency of smoking significantly increase the chances of developing lung cancer. As Figure 3.12 indicates, the more cigarettes smoked per day, the higher the risk of developing lung cancer. Additional Risk Factors: Lung cancer can also be caused by exposure to other carcinogens, such as asbestos and radon. However, smoking remains the leading cause of the disease. Even those who do not smoke but are exposed to second-hand smoke have an increased risk. Extension Work COPD (Chronic Obstructive Pulmonary Disease): COPD includes a range of lung diseases, including emphysema and chronic bronchitis, that cause breathing difficulties. There is no cure for COPD, but treatment can help manage symptoms. Carbon Monoxide in Smoke One of the harmful chemicals in cigarette smoke is carbon monoxide, a poisonous gas. Effect on the Body: When inhaled, carbon monoxide enters the bloodstream and interferes with the blood’s ability to carry oxygen. Oxygen in the blood binds to a protein called hemoglobin to form oxyhemoglobin, which transports oxygen throughout the body. Carbon monoxide binds more tightly to hemoglobin than oxygen, forming carboxyhemoglobin. This prevents oxygen from being carried to cells, tissues, and organs. Impact on Health: Over time, this lack of oxygen can result in serious health problems, including heart disease. For pregnant women, carbon monoxide can affect the growth and development of the fetus, leading to lower birth weights, as the developing baby receives less oxygen. Smoking Statistics There are over 1 billion smokers worldwide, and in 2014, smokers consumed about 6 trillion cigarettes. Deaths: Every year, nearly 6 million people die from smoking-related illnesses. By 2030, this number is expected to rise to 8 million, with 80% of these deaths occurring in developing countries. Health Impact:  ○ Smoking causes about 80% of deaths from lung cancer and 14% of deaths from heart disease. ○ Smoking also leads to COPD (Chronic Obstructive Pulmonary Disease), which further contributes to respiratory problems and death. Trends: ○ The demand for tobacco has remained stable in developed countries, but consumption is increasing in developing regions, especially in parts of Asia, Africa, and Eastern Europe. Giving Up Smoking Most smokers are aware of the health risks but find it difficult to quit due to nicotine’s highly addictive nature. Nicotine withdrawal causes cravings, irritability, and other unpleasant symptoms. Nicotine Replacement Therapies (NRTs): ○ Methods like nicotine patches, nicotine gum, and e-cigarettes provide controlled amounts of nicotine without the harmful chemicals found in cigarettes. They help reduce cravings and gradually reduce nicotine dependence. Varenicline: Another method involves using a medication like varenicline, which reduces the brain’s response to nicotine, making smoking less satisfying. Over time, this helps the smoker quit by reducing the desire to smoke. Behavioral Support: Combining nicotine replacement with cognitive-behavioral therapy or support groups can help address the psychological aspects of quitting smoking. Impact of Smoking in China China's Smoking Population: China has around 350 million smokers, making up about one-third of all cigarette consumption globally. Tobacco companies have long targeted the Chinese market, and as a result, smoking-related deaths in China are expected to rise sharply by 2025. Economic and Social Impact: In developing countries, where many people spend significant amounts of their income on cigarettes rather than on essential needs like food and education, the effects of smoking are not just medical but also economic. Tobacco Farming: The demand for tobacco also affects agriculture. Large amounts of land are dedicated to growing tobacco instead of food crops. In 2012, approximately 3.9 million hectares of land in China were used for tobacco cultivation. Word meanings; 1. Cellular Respiration: The biochemical pathways involved in energy production. 2. Lung Anatomy: The detailed structure of the lungs, including the bronchi, bronchioles, and alveoli. 3. Breathing Mechanics: The role of muscles and nerves in controlling breathing. 4. Respiratory Disorders: Conditions that affect the respiratory system, such as asthma, bronchitis, and pneumonia. 5. Trachea – The windpipe; a large membranous tube reinforced by cartilage rings, conveying air to and from the lungs. 6. Bronchi – The major air passages that branch off from the trachea into the lungs. 7. Bronchioles – Smaller branches of the bronchi that lead to the alveoli. 8. Alveoli – Tiny air sacs at the end of bronchioles where gas exchange occurs. 9. Pleura/Pleural membranes – Thin layers of tissue that cover the lungs and line the chest cavity. 10. Diaphragm – A dome-shaped muscular partition separating the thorax from the abdomen; it plays a major role in breathing. 11. Intercostal muscles – Muscles located between the ribs that play a role in ventilation by helping move the ribcage. 12. Cartilage – A firm, flexible connective tissue that supports parts of the body, like the airways. 13. Inhalation/Inspiration – The process of drawing air into the lungs. 14. Exhalation/Expiration – The process of expelling air out of the lungs. 15. Alveoli – Tiny air sacs in the lungs where gas exchange takes place. 16. Capillaries – Small blood vessels that surround the alveoli, facilitating the exchange of gases. 17. Diffusion – The movement of molecules from an area of higher concentration to an area of lower concentration. 18. Hemoglobin – A protein in red blood cells that binds to oxygen, allowing it to be transported in the blood. 19. Deoxygenated Blood – Blood that has released its oxygen to the tissues and contains a higher concentration of carbon dioxide. 20. Bicarbonate Ions – The form in which carbon dioxide is transported in the blood. 21. Interstitial Fluid – The fluid between cells, including between the alveolar walls and the capillaries, which aids in the diffusion of gases. 22. Ventilation – The process of moving air into and out of the lungs to facilitate gas exchange. 23. Pulmonary Artery – The blood vessel that carries deoxygenated blood from the heart to the lungs. 24. Pulmonary Veins – The blood vessels that carry oxygenated blood from the lungs back to the heart. 25. Emphysema: A chronic lung disease characterized by the destruction of lung tissue, particularly the alveoli, resulting in difficulty breathing. 26. Alveoli: Small air sacs in the lungs where gas exchange occurs. They provide a large surface area for oxygen to enter the blood and carbon dioxide to be expelled. 27. Carcinogen: A substance capable of causing cancer in living tissue. 28. Mutation: A change in the DNA of a cell, which can lead to abnormal cell growth and cancer. 29. Bronchitis: Inflammation of the bronchial tubes, causing coughing and difficulty breathing. 30. COPD: Chronic Obstructive Pulmonary Disease, a group of lung diseases that block airflow and make breathing difficult. 31. Hemoglobin: A protein in red blood cells that carries oxygen from the lungs to the rest of the body. 32. Oxyhemoglobin: The combination of oxygen and hemoglobin. 33. Carboxyhemoglobin: The combination of carbon monoxide and hemoglobin, preventing oxygen from being transported effectively. 34.