Gas Exchange and Respiratory Control Flashcards
What 3 cell types make up alveoli?
- Type 1 pneumocytes (majority)
- Type 2 pneumocytes (septal cells)
- Alveolar macrophages (dust cells)
what is the purpose of type 1 and type 2 pneumocytes?
type 1 - thin so gas exchange occurs through them Type 2 (septal) - secrete pulmonary surfactant to line the alveoli preventing lungs from collapsing and alveoli sticking together
What is the job of dust cells?
To remove any dust particles, and to clean the lungs
List a few important properties of an alveolus:
- surrounded by elastic fibres to recoil
- have continuous blood supply via extensive capillary network
- thin walls made of type 1 pneumocytes
- large surface area
- surfactant
what category of cells are type 1 pneumocytes?
- simple squamos
What is Henry’s law?
As pressure increases by a constant, the solubility of the gas also increases by the same constant so linear
What 5 factors cause efficient gas exchange?
1 - Large difference in partial pressures across membrane 2 - short distance for gas exchange 3 - Large surface area 4 - O2 and CO2 are lipid soluble 5 - Coordinated blood flow and air flow
What is the difference between external and internal respiration?
- External is everything where air is in contact with the external environment and the pulmonary circuit
- Internal is the systemic circuit and when O2 is taken up by body cells
How does the majority of our O2 get transported?
- In RBC’s bound to haemoglobin
- a little is just diffused into blood plasma
What factors affect the binding of O2 to Haemoglobin?
- Temperature
- blood PH
- Pp O2
- Other metabolic activities
RBCs generate ATP by glycolysis and what 2 other biproducts?
- Lactic Acid
- BPG (2,3 Bisphosphoglycerate)
What does BPG do?
- BPG lowers haemoglobins affinity for O2 causing it to release it
What causes a rise in BPG levels?
- when blood pH increase
- when stimulated by hormones
How does temperature affect haemoglobins affinity for O2? and why?
- a higher temp lowers haemoglobins affinity for O2
- so when blood reaches tissues generating lots of heat, and demand more O2, the higher temp causes O2 to unload from the haemoglobin
- Curve shifts right
How does pH affect haemoglobins affinity for O2? and what is this called?
- Bohr affect
- As blood becomes more acidic (pH lowers), the curve shifts right
- More acidic blood has a lower affinity for oxygen
what is the catalyst and the product of CO2 dissolving in the blood?
- CO2 dissolves into the water of the blood
- forming Carbonic acid
- catalysed by carbonic anhydrase
What are the 3 methods of CO2 transport on the blood?
- Dissolve in plasma
- Bind to haemoglobin
- Convert to carbonic acid
what are the 2 respiratory centres of the brain?
- The Pontine Respiratory centre
- The Medullary respiratory centres
what is the job of the pontine respiratory centre?
- interacts with the medulla to smooth out respiration
What makes up the Medullary respiratory centres?
- Ventral and dorsal group
what is the job of the pontine respiratory centre?
to interact with the medulla to smooth out respiration
what makes up the brainstem?
- the pontine respiratory centre
- the medullary respiratory centre (dorsal and ventral)
what are peripheral chemo receptors and where are they found?
- found in the carotid and aortic bodies of the heart
- detect chemical changes in the blood
describe the chain of events that take place when the aortic body detects a change in blood pH
- peripheral chemoreceptors are stimulated
- which stimulates or suppresses the pontine respiratory centre
- this goes on to stimulate the dorsal then ventral group of the medullary respiratory centre
