Organisms Exchange Substances with their Environment: Gas Exchange - Humans (Lung Disease) Flashcards
What is tidal volume?
- Tidal volume is the volume of air in each breath
- Usually between 0.4dm^3 and 0.5dm^3 for adults
What is ventilation rate?
- Ventilation rate is the number of breaths per minute
- For a healthy person it’s about 15 breaths
What is forced expiratory volume1 (FEV1)?
- FEV1 is the maximum volume of air that can be breathed out in 1 second
What is forced vital capacity (FVC)?
- FVC is the maximum volume of air it is possible to breathe forcefully out of the lungs after a really deep breath in
How does asthma affect the lungs?
- Asthma is when airways become inflamed and irritated
- Smooth muscle lining the bronchioles constrict airways
- Excess mucus also constrict airways
How does asthma affect the efficiency of gas exchange?
- Inflamed linings of airways and mucus decrease SA
- Asthma reduces ventilation and reduces the maintenance of a steep concentration gradient
How does asthma result in symptoms?
• Difficulty breathing
- Constriction of bronchioles and inflamed linings - smaller SA
- Excess mucus
• Wheezing
- When air passes through constricted bronchi(oles) - smaller SA
• Tight feeling in chest
- Constricted bronchi(oles) reduce ventilation
- Concentration gradient not maintained
• Coughing
- Reflex response to obstructed bronchi(oles) to clear them
How does emphysema affect the lungs?
- Emphysema is caused by smoking or long-term exposure to air pollution
- Foreign particles get trapped in alveoli
- This causes inflammation and attracts phagocytes
- Phagocytes produce enzyme that breaks down elastin
- Also leads to destruction of alveoli walls
How does emphysema affect the efficiency of gas exchange?
• Loss of elastin
- Makes recoil harder during expiration
- Alveoli not emptied so had to inhale new air
• Destruction of alveoli walls
- Reduces SA of alveoli, so rate of diffusion decreases
How does emphysema lead to symptoms?
• Shortness of breath
- Loss of elastin makes it hard to exhale
- Small SA of alveoli means less oxygen transported to blood - person may breathe more rapidly
• Chronic cough
- Cilia have been destroyed
- Body’s effort to remove damaged mucus and tissue
How does fibrosis affect the lungs?
- Fibrosis the formation of scar tissue in the lungs
- Scar tissue is thicker and less elastic than normal lung tissue
- Lungs are less able to expand and can’t hold as much air as normal
How does fibrosis affect the efficiency of gas exchange?
• Thicker and less elastic scar tissue
- Increases diffusion pathway
- Less elasticity means less ventilation and reduced maintenance of concentration gradient
• Faster ventilation rate
- To compensate for lower amount of air that lungs can hold
How does fibrosis lead to symptoms?
• Shortness of breath
- Volume of air decreased
- Less elasticity means less ventilation and reduced maintenance of concentration gradient
• Dry cough
- Fibrous tissue obstructs air ways
- Reflex response is to cough
- Tissue doesn’t move so is classed as dry cough
• Chest pain
- Result of pressure and damage from fibrous tissue
- Coughing causes further damage
• Fatigue
- Less oxygen taken in
- Less energy released by respiration
How does tuberculosis affect the lungs?
- Pulmonary tuberculosis (TB) is caused by bacteria
- Immune system cells build a wall around bacteria
- This forms small, hard lumps called tubercles
How does tuberculosis affect the efficiency of gas exchange?
• Tubercles
- Infected tissue within tubercles dies
- Gaseous exchange surface is damaged
- Reduces tidal volume
• Increased ventilation rate
- Due to lower tidal volume
- Means less air can be inhaled with each breath
