The respiratory system Flashcards
(35 cards)
Explain the anatomy of the respiratory system
Lungs: location; 3 lobes right and 2 left
Upper airways: air passage in the head and neck: nasal cavity and oral cavity, pharynx - a muscular tube for booth food and air
Respiratory tract - larynx (vocal cords), Glottis, Epiglottis
Conducting zone
Respiratory zone
Thoracic cavity
Explain the function of the conducting zone
Provides a passageway for air to enter the respiratory zone
Adjusts air temperature
Humidify air
Explain the structure of the respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveoli (alveolus)
Alveolar sac (in cluster)
Explain the function of the respiratory zone
Gas exchange between air and blood
Location - respiratory membrane
Mechanism - by simple diffusion
Explain the structure and function of alveolus
300 million alveoli in the lungs
The rich supply of capillaries, which form sheet over alveoli
Alveolar pores
Type I cells: a single layer of epithelial cells overlaying a basement membrane (alveolar wall)
Type II cells: secrete surfactants
Alveolar macrophages
Explain the structure and function of the respiratory membrane
Where gas exchange occurs
Three layers:
Alveolar epithelium
Fused basement membrane
Capillary endothelium
Thickness: 0.2 um
What facilitates gas exchange?
Thin respiratory membrane
Large surface area for diffusion
Lipid solubility of gases (O2 and CO2)
Partial pressure gradient between alveoli and capillary created by ventilation
Explain the structure of the thoracic cavity
Chest wall:
Bones (rib cage, sternum, thoracic vertebrate)
Muscles (internal and external intercostal muscles)
The pleural sac surrounds each lung
Pleura: a membrane composed of a layer of epithelial cells
What are the 2 functions of the thoracic cavity?
Protects the lungs
Facillitates ventiliation
Explain the structure and function of the pleural sac
Pleural sac:
Three layers:
Visceral pleura - attached to the lung tissue
Interpleural space - filled intraplural fluid
Parietal pleura: attached to the chest wall
Functions:
Ensures the lung tissues and the chest wall are stuck together
With certain flexibility
Lubricated
Explain the muscle involved in inspiration
Inspiratory muscles:
The diaphragm (contraction - move downwards)
The external intercostal muscles (contraction - ribs pivot upwards and outwards)
Explain the muscles involved in expiration
Expiration muscles:
The internal intercostal muscles
The abdominal muscles
Normal expiration is passive (relaxation of inspiratory muscles), only forceful expiration involves contraction of expiratory muscles (active expiration)
Explain what Boyle’s law states about the mechanism of breathing and give the equation used
Boyle’s Law: for a given quantity of gas in a container, the pressure is inversely related to the volume
P = C/V
P = nRT/V
What 2 things is intra-alveolar pressure dependent on?
Quantity of air (moles)
Volume of air
Explain the mechanism of inspiration
inspiratory muscle contract
Lung volume increases
pressure within the lungs decreases
P alveoli is greater than the pressure of the atmosphere
Air flows into the lungs
The quantity of air in the lungs increases
Explain what lung compliance is and what it depends on
The change in lung volume that results from a given transpulmonary pressure
It depends on:
The elasticity of the lungs (elastic fibers)
The surface tension lining the alveoli (the work required to increase surface area)
Explain the effect of surfactants on respiration
Secreted by type II alveolar cells
To decrease the surface tension
To prevent alveoli from collapsing
Explain how airway resistance is regulated
Regulated by:
Smooth muscle in the walls of the bronchioles
Extrinsic (neural, hormonal)
Intrinsic (O2 and CO2)
Explain the effects of airway resistance
Airway resistance increases asthma - same change in volume and bigger change in pressure or same chance in pressure and smaller change in volume
When does airway resistance become increased?
With diseases:
Asthma
COPD (chronic obstructive pulmonary disease)
Explain what tidal volume, inspiratory reserve volume, expiratory reverse volume, and residual volume are
Tidal volume - The volume of air that moves into and out of the lungs during a single, unforced breath - about 500ml
Inspiratory reserve volume - The maximum volume of air that can be inspired from the end of a normal inspiration - about 3000ml
Expiratory reserve volume - The maximum volume of air that can be expired from the end of a normal expiration - about 1000ml
Residual volume - the volume of air remaining in the lungs after a maximum expiration - about 1200ml
Explain what inspiratory capacity, vital capacity, functional residual capacity, and total lung capacity are
Inspiratory capacity - the maximum volume of air that can be inspired at the end of a resting expiration
Vital capacity - the maximum volume of air that can be expired following a maximum inspiration
Functional residual capacity - the volume of air remaining in the lungs at the end of a tidal expiration
Total lung capacity - the volume of air in the lungs at the end of a maximum inspiration
How to calculate Functional residual capacity
Expiratory Reserve Volume + Residual Volume
How to Calculate Vital Capacity
Tidal Volume + Inspiratory reserve volume + Expiratory Reserve Volume
