Respiration in humans.pdf

Respiration in humans 7.1 LOs: 1. Define aerobic respiration in human cells and state the equation in words and symbols Definition: The release of energy by the breakdown of glucose in the presence of oxygen. - CO2 and water are waste products - Aerobic respiration generates a large am...

Respiration in humans 7.1 LOs: 1. Define aerobic respiration in human cells and state the equation in words and symbols Definition: The release of energy by the breakdown of glucose in the presence of oxygen. - CO2 and water are waste products - Aerobic respiration generates a large amount of energy in the form of ATP - Location of process: mitochondria 2. Define anaerobic respiration in human cells and state the equation in words and symbols Definition: The release of energy by the breakdown of glucose in the absence of oxygen Equation: glucose —> lactic acid - Generates relatively small amount of energy - Occurs in muscle cells during vigorous activity 3. Explain why cells respire anaerobically during vigorous exercise resulting in an oxygen debt that is removed by rapid, deep breathing after exercise During vigorous activity: - Aerobic respiration in muscle cells is increased —> increased breathing to obtain oxygen + increased heart rate to supply oxygen When continuous muscle contractions occurs: - Aerobic respiration alone is not fast enough to supply the increase in energy demand - Anaerobic respiration takes place to meet the increased energy demand After vigorous activity has stopped, we need to address oxygen debt (the amount of oxygen needed to remove lactic acid): - Continued heart rate - To transport lactic acid to liver via blood for removal - To transport oxygen to liver - Continued deeper and faster breathing - To obtain oxygen for supply to liver 4. Describe the effect of lactic acid in muscles during exercise a) The accumulation of lactic acid in muscles leads to a decrease in pH, making the environment more acidic. This acidity can interfere with enzyme activity and disrupt the normal functioning of muscle fibers, contributing to the feeling of muscle fatigue. b) The buildup of lactic acid in muscles during intense exercise can cause a burning sensation. This is a natural response that signals the body to slow down or stop the activity to prevent muscle damage. Respiration in humans 7.2 LOs: 1. Identify the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries and state their functions in human gaseous exchange Parts Functions Larynx Air passes into larynx and then into trachea through an opening Trachea (windpipe) - Supported by C-shaped rings of cartilage - Cartilage keeps the lumen (cavity) of the trachea open - Membrane next to the lumen is the epithelium - Epithelium consists of 2 types of cells: - Gland cells: secrete mucus to trap dust particles and  bacteria - Ciliated cells: have hair-like structures called cilia on their surfaces which sweep the dust-trapped mucus up the trachea (towards larynx) Bronchi - Trachea divides into 2 tubes called bronchi - Singular: Bronchus - Each Bronchus carries air into the lung and branches repeatedly, giving rise to numerous bronchioles - The bronchi are similar in structure to the trachea Bronchioles - Very fine tubes - Each bronchiole ends in a cluster of air sacs or alveoli Alveoli (Air sacs) - Gaseous exchange takes place through the walls of the alveoli - Numerous alveoli are found in the lungs, providing a very large surface area for gaseous exchange Alveolar walls - Thin, moist and well-supplied with blood capillaries - Gas exchange between the alveoli and the blood capillaries takes place through this wall  2. Explain how the structure of an alveolus is related to its function of gaseous exchange, including describing the role of the cilia Structure of alveolus (singular of alveoli) Adaptation Function Numerous alveoli - Provide large surface area for increased gas exchange to take place between the alveoli and the blood capillaries through the wall of the alveoli Wall of alveolus is only one - Provides short diffusion distance for gases cell thick - Ensures a higher rate of diffusion Thin film of moisture covers - Allows oxygen to diffuse in it the inner wall of the alveolus Walls of alveoli are richly - The flow of blood maintains the concentration supplied with blood capillaries gradient of gases Gaseous exchange in alveoli (through diffusion) a) Blood entering the lungs has a lower concentration of oxygen and a higher concentration of carbon dioxide than the atmospheric air entering the alveoli in the lungs b) A concentration gradient is set up between blood and alveolar air c) Oxygen dissolves into the thin film of moisture on the wall of the alveolus d) Dissolved oxygen then diffuses through the wall of the alveolus and the wall of the blood capillary into the red blood cells e) The oxygen combines with haemoglobin to form oxyhaemoglobin f) Carbon dioxide diffuses from the blood into the alveolar air Maintenance of concentration gradient through - Continuous flow of blood through blood capillaries - Continuous breathing, which causes air in the lungs to be constantly refreshed 3. Describe how the rate of diffusion depends on the surface area of the respiratory surface, the concentration gradient and the length of the diffusion path - Increase in surface area of the respiratory surface, high concentration gradient and shorter length of diffusion path all increases the rate of diffusion Respiration in humans 7.3 LOs: 1. Describe the process of breathing and the role of diaphragm, ribs and internal and external intercostal muscles - Breathing includes inspiration (inhalation) and expiration (exhalation) Inspiration (Inhalation) Expiration (Exhalation) - Diaphragm muscle contracts - Diaphragm muscle relaxes - Diaphragm flattens - Diaphragm arches upwards  - External intercostal muscles contract - External intercostal muscles relax - Internal intercostal muscles relax - Internal intercostal muscles contract - Ribs and sternum move upwards and - Ribs move downwards and inwards outwards - Sternum moves down to its original position - Volume of thoracic cavity increases - Volume of thoracic cavity decreases - Lungs expand - Lungs are compressed - Air pressure inside them decreases as - Air pressure inside them increases as volume increases volume decreases - Atmospheric pressure is higher than - Pressure within lungs is now higher the pressure within lungs than atmospheric pressure - Air moves into the lungs - Air is forced out of lungs to the external environment - The 2 intercostal muscles are antagonistic 2. State and account for the difference between inspired and expired air Component Inspired air Expired air Oxygen Higher (21%) Lower (16.4%) - Oxygen has been absorbed into the bloodstream but carbon dioxide is released from the blood in the lungs Carbon dioxide Lower (0.03%) Higher (4%) Nitrogen (inert) About the same (78%) About the same (78%) Water vapour Variable (rarely saturated) Saturated - Some water evaporates from the surfaces of the alveoli Dust particles Variable but usually present Little, if any Temperature Variable About body temperature (37 degree Celsius) - Some heat escapes from the blood into the alveolar air 3. State that the breathing rate is determined by the level of carbon dioxide in the blood - Normally, an increased concentration of carbon dioxide is the strongest stimulus to breathe more deeply and more frequently - Conversely, when the carbon dioxide concentration in the blood is low, the brain decreases the frequency and depth of breaths 4. Describe the removal of carbon dioxide from lungs, including the carbonic anhydrase enzyme a) Tissue cells produce. A large amount of CO2 as a result of aerobic respiration b) As blood passes through these tissues (via blood capillaries), CO2 diffuses into the blood and enters the red blood cells c) CO2 reacts with water in red blood cells to form carbonic acid - catalysed by carbonic anhydrase in red blood cells d) Carbonic acid is converted to bicarbonate ions which diffuse out of red blood cells. Most CO2 is carried as bicarbonate ions in blood plasma with a small amount of dissolveed CO2 carried in the red blood cells e) In the lungs, bicarbonate ions diffuse back into red blood cells where they are reconverted to carbonic acid, and then into water and CO2 f) CO2 then diffuses out of blood capillaries into alveoli, where it is expelled during exhalation Respiration in humans 7.4 LOs: 1. State the major toxic components of tobacco smoke — nicotine, tar and carbon monoxide, describe their effects on health Nicotine Carbon monoxide Tar - Increases heartbeat - Reduces the ability of - Increase risk of rate and blood blood to transport cancer in the lungs as pressure oxygen as carbon tar can cause monoxide binds uncontrolled cell - Increases the risk of permanently with division blood clots in the haemoglobin. There arteries, leading to will be less - Increases risks of increased risk of haemoglobin available chronic bronchitis and coronary heart to transport oxygen. emphysema by disease paralysis the cilia - In a pregnant mother, lining air passages so - Increases the risk of less oxygen reaches dust particles trapped arteries to narrow the fetus through the in the mucus lining placenta which may cannot be removed affect fetal development - Increases risk of coronary heart disease Chronic Bronchitis 1. Prolonged exposure of lungs to irritants 2. Inflamed linings of bronchus secrete excessive mucus 3. Cilia on cells of linings become paralysed (Cilia cannot sweep) 4. Dust-trapped mucus cannot be removed 5. Blocked airways 6. Pesistent coughing 7. Lung infections Emphysema 1. Breakdown of walls of alveoli 2. Reduced surface area for gaseous exchange 3. Reduced elasticity of lungs 4. Lungs becomes inflated 5. Wheezing and severe breathlessness (Breathing is difficult) *When someone has both chronic bronchitis and emphysema, they are said to suffer from chronic obstructive lung disease Lung cancer - Lumpy tissue due to uncontrolled growth of cells - Tobacco smoking increases the risk of lung cancer When running, anaerobic respiration occurs to release the additional energy required to meet the increased energy demand. Aerobic respiration is not able to fully meet the energy demand. This is because the rate at which aerobic respiration occurs is limited by the body’s breathing rate and heart rate. During anaerobic respiration, lactic acid is produced and transported via the bloodstream to the liver to be converted back to glucose. This process requires oxygen. Our breathing rate and heart rate remain high for some time after exercise to repay the body’s oxygen debt.