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
