Respiratory system Flashcards
What are the two kinds of respiration?
Internal- within the cell, CO2 produced from glycolysis and krebs cycle, O2 produced by oxidative phosphorylation
External- ventilation, exchange and transport of gases around the body
What are the two sections of the respiratory system?
Conducting zone- provide pathways to get air to and from the respiratory zone
Respiratory zone- where gas exchange takes places
What structures are in the conducting zone? What is their function?
Nose, nasopharynx, osopharynx, pharynx, larynx, trachea and bronchial tree
Conditions the incoming air by filtering, warming and humidifying
Structure of the bronchial wall
Reinforced with cartilage
Smooth muscle
Mucous glands
Elastic tissue
Structure of respiratory epithelium
Ciliated epithelia
Goblet cells
Sensory nerve endings
Structure of bronchioles
Lack of cartilage support
Lined by respiratory epithelium
Proportionately more smooth muscle
Structure of alveoli
Large surface area
Fed from terminal bronchiole
Thin walled
What is the air blood barrier?
Sandwich created by flattened cytoplasm of type I pneumocytes and the capillary wall
Large surface area for gas exchange to take place
How do pressure gradients aid inspiration and expiration?
Inspiration- atmospheric pressure > pressure in alveoli so air moves into the lungs
Expiration- atmospheric pressure < pressure in alveoli so air moves out of the lungs
Quiet inspiration
Uses primary muscles of inspiration- diaphragm and external intercostal muscles
Increases thoracic and lung volume
Air movement follows principles of Boyle’s law- increase in volume leads to decrease in pressure so air moves down pressure gradient
Forced inspiration
Primary muscles as well as accessory or secondary muscles used- scalenes, sternocleidomastoids, neck and back muscles, upper respiratory tract muscles
Quiet expiration
Passive process using elastic recoil, there are no primary muscles of expiration
Relaxation of external intercostal muscles and diaphragm
Elastic forces return the lungs to their usual size
Forced expiration
Uses accessory muscles- internal intercostal muscles, abdominal muscles, neck and back muscles
What is the pleura and it’s function?
Pleural cavity filled with secretions
Prevents lungs from sticking to the chest wall and enables free expansion and collapse of the lungs
What is lung compliance?
Measure of elasticity- the ease with which the lungs and thorax expand during pressure changes
Low compliance means more work is required to inspire and high compliance means more work is required to expire
How do disease states effect lung compliance?
Emphysema- high lung compliance
Fibrosis- low lung compliance
What are the two major components of the elastic recoil of the lungs?
Anatomical- elastic nature of cells and the extracellular matrix
Surface tension generated at the air-fluid interface
How does surface tension at the air-fluid interface impact the volume of alveoli?
There are many air sacs of different volumes and because of Laplace’s equation, the pressure in larger sacs is lower than smaller ones
This means air will flow from smaller alveoli to larger ones which means they will collapse
How is the problem of smaller alveoli collapsing solved?
Lung surfactant which is produced by type II pneumocytes
Reduces surface tension
Composed of a number of lipids and proteins
What is the only lung volume that cannot be measured with a spirometer?
Residual volume
What is anatomical dead space?
Volume of conducting airways, at rest 30% of inspired air volume