Respiratory System Flashcards
Functions of nostrils
Entrance to respiratory tract
Functions of nasal cavity
To clean, moisten and warm the incoming air
Hair on walls of nostrils filters dust and bacteria from inhaled air
Mucus-secreting cells: mucus traps bacteria and dust
Blood capillaries are close to surface of cavity, warms the inhaled air
Functions of larynx
Contains vocal chords
Feature of trachea
Supported by C-shaped rings of cartilage which prevent the trachea from collapsing during breathing due to change in air pressure
Feature of bronchus, bronchioles, alveoli
Trachea divides into two tubes, bronchi. Each bronchus divides into numerous fine tubes, bronchioles. Each bronchiole ends in a cluster of alveoli
What is the function of cilia in breathing (along respiratory tract)
Inner wall(made up of epithelium) of trachea and bronchi are lined with ciliated cells and gland cells. Gland cells secrete mucus that traps dust particles and bacteria
Ciliated cells have hair-like structures called cilia on their surface. They sweep dust-trapped mucus up bronchi and trachea away from lungs into pharynx, where they can be swallowed or expelled
What is the diaphragm
A sheet of muscular and elastic tissue which separates thorax from abdomen
Describe inhalation
Diaphragm contracts and flattens, external intercostal muscles contract. Ribcage moves outwards and upwards. Lung expands, as volume of lung increases, air pressure within the lung decreases. Air is drawn into lungs as air move from higher atmospheric pressure to lower air pressure in the lungs
Describe exhalation
Diaphragm relaxes and arches upwards to form dome shape and external intercostal muscles relax. Rib cage moves downwards and inwards. Lungs are compressed and as volume of lung decreases, air pressure within lung increases. Air is expelled out of lungs as air moves from higher pressure in lungs to lower atmospheric pressure
Why are alveolar walls one-cell thick
Provides shorter distance for faster rate of diffusion of gases into the blood
Why is each alveolus covered with thin film of moisture
Enables gases to dissolve, which increases rate of diffusion
Why is each alveolus surrounded by numerous blood capillaries
Blood capillaries transport diffused oxygen away from lungs and carbon dioxide from bloodstream to the lungs for removal. The continuous transport of gases maintains the concentration gradient of the gases for faster rate of diffusion
Why are alveoli present in large quantities
Provides large surface area to volume ratio to increase rate of diffusion of gases
Describe transportation of oxygen from lungs
Alveolar air contains a higher concentration of oxygen than the blood. Oxygen dissolves in the thin film of moisture of surface of alveoli. Oxygen then diffuses through the walls of alveoli and blood capillaries into blood, where it diffuses into the red blood cell. Oxygen binds with haemoglobin in red blood cells to form oxyhaemoglobin. Reaction is reversible and direction in which this takes place is dependent on concentration of oxygen in surroundings. When blood passes through oxygen-poor tissues, oxyhaemoglobin releases oxygen which diffuses through wall of capillaries into tissue cells
Describe carbon dioxide transport from the body cells
Tissue cells produce large amount of carbon dioxide as result of aerobic respiration. As blood passes these tissues, carbon dioxide diffuses into blood. Most carbon dioxide enters red blood cells, a small amount is carried in plasma as dissolved carbon dioxide. Carbon dioxide reacts with water in cytoplasm of red blood cells to from carbonic acid, catalysed by carbonic anhydrase. Carbonic acid dissociates to form hydrogen ions and hydrocarbonate ions (HCO(3)-. Hydrogen ions remain in red blood cells and hydrocarbonate 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 cell and combine with hydrogen ions to form carbonic acid. Carbonic anhydrase catalyses conversion of carbonic acid to carbon dioxide and water. Carbon dioxide diffuses out of red blood cell, through the capillaries and alveolar wall to be removed to environment during exhalation
Describe difference in proportion of dust, carbon dioxide, water vapour and temperature between inhaled air and exhaled air
Carbon dioxide: 0.03% –> 4%
Water vapour: variable(rarely saturated) –> saturated
Temperature: variable –> about 37C
Dust: Variable(usually present) –> little, if any
What is the stimulus for breathing
High concentration of carbon dioxide in blood or alveolar air. When there is too little carbon dioxide in lungs, breathing movements do not occur
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, if blood clots in coronary artery this results in coronary heart disease
Properties and effects of carbon monoxide
Combines permanently with haemoglobin to form carboxyhaemoglobin
Reduces ability of blood to carry oxygen
Properties and effects of tar
Carcinogenic, paralyses cilia lining air passage
Increases risk of cancer in lungs. Dust particles trapped in mucus lining the air passages cannot be removed, increasing risks of chronic bronchitis and emphysema
Effects of irritant chemicals
Causes cells in lining bronchi and bronchioles to increase production of mucus. Paralyses cilia lining air passages, dust particles trapped in mucus lining air passages cannot be removed, increases risk of chronic bronchitis and emphysema
Describe chronic bronchitis
Prolonged exposure to irritants particles that are found in tobacco smoke may cause this. Epithelium lining of airways becomes inflamed. Excessive production of mucus by epithelium. Cilia of epithelium become paralysed, unable to remove mucus and foreign particles. Airflow becomes blocked, makes breathing difficult. Decreases efficiency of gaseous exchange process, persistent coughing to clear air passages in order to breathe
Describe emphysema
Persistent and violent coughing due to bronchitis may lead to emphysema. Walls of alveoli break down due to persistent and violent coughing. This decreases surface area for gaseous exchange. Lungs lose elasticity and lungs lose ability to effectively expel air, causing build up of carbon dioxide. Oxygen uptake and carbon dioxide removal is impaired, severe breathlessness is experienced
