Lungs, Gas Exchange and Respiration Flashcards
Are the lungs symmettrical?
No, left and right hiliums are not symmetrical due to cardiac notch in left (only one oblique fissure)
What are the lobes of the lungs?
Superior, middle and inferior
What are the roles of the oral and nasal cavity in the lung structure?
Moisturise air coming in, important to prevent damage to lungs as alveoli are single celled and will deteriorate if they get dry
Once oxygen has entered the blood via the lungs what happens?
Taken up by haemoglobin in red blood cells going through the alveolus, so the RBCs become fully oxygenated
Where are RBCs oxygenated?
In capillaries adjacent to the alveolus (CO2 out, O2 in)
What are the features of a RBC?
Biconcave disc = larger surface area
2.5 micrometres thick
7.5 micrometres wide
Haemoglobin
What does a haemoglobin molecule consist of?
4 units, each one has an iron/porphyrin complex
How many oxygen molecules can each haemoglobin molecule carry?
4
What is cooperativity?
When O2 binds to an oxygen carrying area, the other free areas become bigger allowing more O2 molecules to attach more easily. Altering protein structure, so affinity for O2 binding site increases as more O2 bind enabling O2 to attach to Hb until all 4 sites are full. This is COOPERATIVITY
Why is cooperativity important?
Allows us even in low O2 state, (emphysema, damaged lungs, COPD etc) to still fully oxygenate haemoglobin, so there is redundancy in system allowing us to cope in these circumstances.
How many lobes does the right lung have? Is this different to the left?
Right has superior, middle and inferior lobes while left has superior and inferior lobes
Why is the right bronchus more prone to having objects going down it?
Right bronchus is wider and more vertically orientated than the left
if a patient is choking on something, which lung is most likely to be affected?
Right lung, because right bronchus is wider, shorter and steeper, so will find object in right inferior lobe
What are the two types of pneumocytes and what makes them different from each other?
Type 1 and type 2 pneumocytes, type 1 are structural cells for gaseous exchange while type 2 reduce surface tension by secreting surfactant, prevent alveolar collapse and increase compliance (lungs inflate more easily)
What are the two zones in the tracheobroncial tree?
Conducting zone (areas of lung that conduct gas) and Respiratory zone (where gas exchange occurs)
What anatomical structures are in the conducting zone?
Trachea, bronchi, terminal bronchioles
What anatomical structures are in the respiratory zone?
Respiratory bronchioles, alevolar ducts, alveolar sacs
Describe the passage of blood through the alveoli and what gases are exchanged in this process
Blood enters through pulmonary arterioles (O2 depleted blood from cells where O2 has been utilised) and exits through pulmonary venule
Between them is capillary network covering alveolus surface, facilitates O2 and CO2 exchange- CO2 leaves blood and goes to alveoli for excretion, O2 leaves alveoli and into blood to be transported to heart and rest of body
How would an infection disrupt good gas exchange?
By blocking O2 in lungs, eg via mucus. This could affect O2 delivery into body and CO2 excretion. Unable to get inhaled gas down into alveoli for gas exchange, blockages of alveoli preventing adequate ventilation
How would a blood clot affect gas exchange?
A blood clot in a pulmonary vessel could prevent blood flowing through lungs, so while O2 is arriving at alveoli, without blood coming through arterioles or venules then the gas cannot get into the circulation, so inadequate perfusion
What are the two ways that gas exchange can be affected?
Inadeuqate ventilation (oxygen content of blood) Inadequate perfusion (blood flow)
What does the oxygen content of blood depend on?
O2 carried by Hb (majority)
O2 in solution (minority)
What are the key cells in the lungs?
Type 1 and type 2 pneumocytes
TYPE 1: structural cells for gas exchange (squamous epithelial)
TYPE 2: reduce surface tension, prevent alveolar collapse and increase lung compliance (cuboidal)
What is the role of Type 2 pneumocytes?
Reduce alveolar surface tension by secreting pulmonary surfactant, this prevents alveolar collapse. Also increase lung compliance (inflate more easily)
What is the difference between parietal and visceral pleura?
Visceral pleura INNER: nerve supply is pulmonary plexus, senses are stretch only via Vagas nerve, and arterial supply is bronchial arteries
Parietal pleura OUTER: nerve supply is phrenic and intercostal nerves, sensitive to pressure, pain and temeperature, and arterial supply is intercostal arteries
Pleural cavity between both parietal and visceral
Parietal pleura is sensitive to what 3 sensations?
Pain, touch and temperature
What are the 3 fissures of the lungs and what lobes do they separate?
Horizontal fissure (seperates superior and middle lobes on right lung) Oblique fissure (seperates middle and inferior lobes on right lung) Oblique fissure (seperates superior and inferior lobes on left lung)
How does gaseous exchange occur in the lungs?
Oxygen diffuses into the capillaries proximal to the alveolar walls (and CO2 diffuses out)
In carbon dioxide transport, what 4 ways is CO2 carried in?
- CO2 dissolved in plasma
- CO2 combines with water (H2O) in plasma in a SLOW reaction to produce bicarbonate (HCO3-) and H+ (carried in blood)
- CO2 and H2O in RBCs is a FAST reaction via enzyme carbonic anhydrase to produce bicarbonate (HCO3-) and H+
- Some CO2 combines with Hb -> HbCO2
What 3 compounds is CO2 transported as?
70% bicarbonate in the plasma (HCO3 - )
20% carbaminohaemoglobin in RBCs (HbCO2 )
10% carbon dioxide dissolved in plasma (CO2 )
What enzyme rapidly converts CO2 into unstable carbonic acid (H2CO3)?
Carbonic anhydrase (CAH)
How does carbonic anhydrase (CAH) convert CO2 into carbonic acid?
Breaks down into HCO3 - and H+
Haemoglobin binds to H+ to maintain the pH “buffers”
Chloride shift regulates the electric charge within the RBC
