Human respiratory system Flashcards
List the structures air passes through to reach the alveoli
Nostrils
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
Features of the larynx
Contains vocal cords
What are the trachea and bronchi lined with
Gland cells: Secrete mucus that traps dust and bacteria
Ciliated cells: Have hair-like structures called cilia that sweep dust-filled mucus to the pharynx to be expelled
Features of the trachea
Supported by C-shaped rings of cartilage that prevent the collapse of the tube
What allows for breathing to occur
Movement of ribs and diaphragm to change the volume of chest cavity
Which muscles are antagonistic
Internal intercostal muscles
External intercostal muscles
What happens during inhalation
- Diaphragm contracts and flattens
- External intercostal muscles contract
- Internal intercostal muscles relax
- Ribcage moves upwards and outwards
- Lung volume increases
- Lung pressure decreases
- Air enters from higher atmospheric pressure to lower lung pressure
What happens during exhalation
- Diaphragm relaxes and arches upwards
- External intercostal muscles relax
- Internal intercostal muscles contract
- Ribcage moves downwards and inwards
- Lung volume decreases
- Lung pressure increases
- Air expelled out from higher lung pressure to lower atmospheric pressure
Explain adaptations of alveoli
1) One cell thick alveolar walls
- Provides shorter distance for faster rate of diffusion of gases
2) Thin film of moisture on inner alveolar walls
- Allows gases to dissolve in the moisture for faster rate of diffusion
3) Surrounded by numerous blood capillaries
- Continuous transport of gases maintains steep concentration gradient
4) Present in large quantities
- Provides larger SA:V for faster rate of diffusion
Describe oxygen transport from lungs
- Alveolar air contains higher oxygen concentration than blood
- Oxygen dissolves in thin film of moisture on inner alveolar walls
- Dissolved oxygen diffuses through alveolar walls and through blood capillaries into the blood
- Oxygen diffuses into red blood cells
- Oxygen binds with haemoglobin to form oxyhaemoglobin
- Reaction is reversible and direction of reaction depends on oxygen concentration
- Oxyhaemoglobin releases oxygen when blood passes through oxygen-poor tissue
Describe carbon dioxide transport from body cells
- Carbon dioxide diffuses into blood from tissue
- Most carbon dioxide enters red blood cells
- Some carbon dioxide is carried in plasma as dissolved carbon dioxide
- Carbon dioxide reacts with water in cytoplasm of red blood cell to form carbonic acid, and this reaction is catalysed by carbonic anhydrase
- Carbonic dissociates to form hydrogen and hydrogencarbonate ions
- Hydrogen ions remain in red blood cell
- Hydrogencarbonate ions diffuse out of red blood cell to be carried in plasma
Describe carbon dioxide transport at lungs
- Hydrogencarbonate ions diffuse back into red blood cells
- Hydrogen and hydrogencarbonate ions combine to form carbonic acid
- Carbonic anhydrase catalyses conversion of carbonic acid to carbon dioxide and water
- Carbon dioxide diffuses out of red blood cell, into blood, through blood capillaries and alveolar walls
What is the stimulus for breathing
Stimulus for breathing is a high concentration of carbon dioxide in blood or alveolar air
Describe components of inhaled air
- 21% O2
- 0.03% CO2
- 78% N2
Describe components of exhaled air
- 16% O2
- 4% CO2
- 78% N2
- High water vapour concentration
- Around 37 degrees Celsius
What are some harmful components of tobacco smoke
- Nicotine
- Carbon monoxide
- Tar
- Irritant chemicals
What are the properties and effects of nicotine
- Addictive stimulant drug that causes release of adrenaline
- Makes blood clot easily
- Increases heart rate and blood pressure
- Increases risk of blood clots in arteries that can lead to coronary heart disease
What are the properties and effects of carbon monoxide
- Combines permanently with haemoglobin to form carboxyhaemoglobin
- Reduces ability of blood to carry oxygen
What are the properties and effects of tar
- Carcinogenic
- Paralyses cilia lining air passages
- Increases risk of lung cancer
- Dust trapped in mucus along air passages cannot be removed due to paralysed cilia, increasing risk of chronic bronchitis and emphysema
What are the properties and effects of irritant chemicals
- Causes gland cells to secrete more mucus
- Paralyses cilia lining air passages
- Dust trapped in mucus along air passages cannot be removed, increasing risk of chronic bronchitis and emphysema
Explain chronic bronchitis
- Prolonged exposure to irritant particles can cause chronic bronchitis
- Epithelium lining of airways becomes inflamed
- Epithelium produces excessive mucus
- Cilia lining air passages become paralysed, unable to remove mucus
- Airflow becomes blocked, making breathing difficult
- Efficiency of gaseous exchange decreases
- Persistent coughing occurs to clear airways
Explain emphysema
- Persistent and violent coughing from chronic bronchitis may lead to emphysema
- Alveolar walls break down, decreasing surface area for gaseous exchange
- Lungs lose elasticity and ability to expel air
- Build up of carbon dioxide in lungs occurs
- Severe breathlessness experienced
What is it called when someone suffers from both chronic bronchitis and emphysema
Chronic obstructive lung disease
