Airway and Lung Anatomy and Function Flashcards
What is cellular respiration?
Respiration which is carried out in all living cells
How do cells make energy?
Cells use oxygen (glucose catabolism) for the production of energy in the form of ATP
Electron transport chain
What happens to the protons and electrons produced?
2H+ + 2e- + ½O2 -> H2O (protons and electrons are mopped up by oxygen to produce water)
What is respiration?
Breathing
O2 is obtained from the air and CO2 is released back into the air (a toxic compound which can build up and cause problems)
How are cellular respiration and breathing respiration linked?
By the circulatory system
The circulatory system delivers oxygen to the respiring cells and removes CO2 which is then excreted by the lungs
What are the conducting airways? And what does the term refer to?
Airways which ‘conduct’ air into the body
Refers to the upper airways
Name the elements of the conducting airways in order.
Nose Mouth Pharynx (back of throat) Larynx (voice box) Trachea (windpipe) Bronchi Bronchioles Terminal bronchioles
Why part of the conducting airways is largest in diameter?
Trachea
Which parts of the conducting airways have cartilage in the walls?
Trachea and bronchi
Helps support airways and prevent collapse
What is anatomic ‘dead space’?
Areas where no gaseous exchange occurs
Which areas are referred to as ‘dead space’?
Conducting airways
Name the elements of the respiratory airways in order.
Respiratory bronchioles
Alveolar ducts
Alveolae (‘bunch of grapes’)
What can be found between adjacent alveolae?
Pores, these are important as they allow the movement of gases between alveolae via pores
Useful if for example one region is diseased, can make use of an adjacent alveolae
What is the function of alveolae?
Sites of gaseous exchange (between air and blood)
Oxygen moves into the body and carbon dioxide is released
How many alveolae are there in the human lungs?
Around 300 million
What do the conducting airways provide?
A low-resistance pathway for air flow which makes it easier for air to flow in and out
Describe the appearance of healthy airways.
Wide diameter, easy movement of air
Describe the appearance of the airways in COPD.
Airways are constricted, mucous membrane is inflamed, airway wall thickened, ‘floppy’ airway as muscle fibres lose elasticity, much more difficult for air to flow
What is the function of the larynx?
Houses the vocal cords and allows us to speak
How do the conducting airways effect gaseous exchange?
Warm and moisten the air which increases the efficiency of gaseous exchange, molecules are moving faster and better movement of oxygen in the blood
How do conducting airways act as a defence mechanism against infection?
Presence of macrophages, will engulf any inhaled bacteria
Cilia structures line the airways and ‘beat’ constantly in an upward fashion to help clear things
Epithelial cells lining the airways secrete mucus
Dust/bacteria get caught in this mucus and are constantly moved upwards by the cilia to the pharynx where it is swallowed (‘mucocilliary escalator’)
Which mechanism allows mucus to move freely within the airway?
Mucus escalator rides across a layer of watery fluid secreted by epithelial cells
The movement of Cl- ions is essential in this as they are associated with the movement of water
Despite their small size, chloride ions are charged and so have to pass through Cl- channels in the apical membrane
What is the Cl- channel in the apical membrane of airway epithelial cells called?
Cystic fibrosis transmembrane regulator (CFTR)
What is the pathophysiology of cystic fibrosis?
It is the CTFR structure which is defective in CF patients
Affects the secretion of fluid
The impact of this is that mucus builds up in the airways leaving patients more prone to infections as the mucus, containing the inhaled bacteria, cannot be cleared effectively
How does smoking predispose you to chest infections?
Smoking reduces the beating of the cilia, mucus isn’t cleared as effectively which can lead to chest infections
How is a respiratory cycle defined?
An inspiration (in) and an expiration (out)
What is the first stage in the respiratory cycle?
Ventilation - movement of air by bulk flow, flowing down through the airways into the lungs
What can be said about the resistance pathway of healthy individuals?
Healthy individuals have a low resistance pathway (larger diameter) = high air flow
How do we take in air?
The way we take in air is for the pressure within our lungs to drop
If you reduce the pressure in your lungs, air will then flow from a higher pressure to a lower pressure
At inspiration, alveolar pressure drops
This is done by increasing lung volume, alveolar pressure deep in the lungs drops and air rushes in
How would you describe the lungs, in terms of structure?
Passive elastic structures
This means that the lungs themselves do not have any musculature (floppy, cannot move independently)
What are our lungs surrounded by?
Pleural sacs (membranes) containing (intra)pleural fluid
How is the membrane surrounding the lung attached?
Pleural membrane is stuck to the surface of the lung
The inner side of the sac is attached to the lung by connective tissue
The outer surface of the sac is attached to the diaphragm muscle and the thoracic (chest) wall (spinal column, ribs, intercostal muscles)
What is connective tissue made up of?
Elastic fibres
Collagen
How do the constituents of connective tissue contribute to its properties?
Elastic fibres - allow expansion
Collagen - scaffolding protein, gives strength to the structure
What happens within the lung structures to change pressure?
Muscles (diaphragm and intercostal muscles) contract and increase the volume of the thoracic cage
This results in a drop in pressure which then allows for inspiration
What is transpulmonary pressure?
The pressure we put across our lungs
What is the equation for transpulmonary pressure?
TP = Palv – Pip
Between breaths…?
Patm = Palv = 0mmHg
What happens if the pleural sac is damaged?
If the pleural sac which covers the lungs is broken e.g. through trauma to the chest, puncture of the chest wall, the result is that air moves in through the puncture wound into the chest, the chest wall recoils and expands and the lungs recoil (pull away from the chest) and collapse
What is damage to the pleural sac resulting in lung collapse called?
A pneumothorax
How are our bodies adapted to prevent pneumothorax?
Each lung is isolated in its own plural cavity (sac), so that if you damage one sac and the lung collapses, the other lung remains intact
What is a spontaneous pneumothorax?
Occurs if disease damages the pleural sac e.g. pneumonia, emphysema
How can a pneumothorax be treated?
For a minor injury, a chest drain can be put in to remove the air and then stitch it up
If it is a major pneumothorax, then surgery would be needed to repair the puncture wound
At inspiration, Palv…
Is less than Patm
At expiration, Palv
Is greater than Patm
