Respiratory Physiology Flashcards
Outline the basic anatomy of the lungs
- Trachea (windpipe)
- Pleura (lung lining)
- Pleural effusion (fluid between pleural space)
- Diaphragm
- Cardiac impression - small indentation of left lung
- Weights around 1kg
Describe the bronchi, bronchioles and alveoli
- Bronchi - seperate branches of the trachea and provide air supply to each lung
- Bronchioles - subdivisions of the bronchi and conduct air towards alveoli
- Alveoli - elastic, thin walled sacs that are a crucial surface for a gas exchange
How do the inspiratory and expiratory muscles assist breathing?
By moving the ribcage and therefore altering thoracic cavity
What are the 3 main steps of respiration/gas exchange?
- Pulmonary ventilation - includes inhalation and exhalation of air between the atmosphere and lungs
- External (pulmonary) respiration - gas exchange between alveoli and capillaries in the lungs, pulmonary capillary blood gains oxygen and loses carbon dioxide
- Internal (tissue) respiration - gas exchange between blood in the syystemic capillaries and tissue cells, blood loses oxygen and gains carbon dioxide (synthesis of ATP)
Define minute ventilation, and the equation
- Total amount of air per unit of time (usually 1 min)
- Breathing frequency (number of breathing cycles per min) x Tidal volume (volume of air per breath that is being moved)
- Units L/min
Describe Boyle’s Law and how is relates to ventilation
- Pressure of gas is inversely proportional related to the volume (constant temp)
- Pressure altered in the lungs by altering the size of the thoracic cavity, and volume of lungs as a result
- This is done by contraction and relaxation of respiratory muscles
Describe the process of inhalation
- Diaphragm lowers and flattens
- External intercostal muscles assist ribcage expansion
- Leads to increased thoracic cavity and lung volume, and decreased lung pressure
How is expiration assisted during exercise?
By contraction of abdominals and intercostal muscles
Define vital capacity
- Maximum amount of air moved in one breath
What is FEV1?
- Forced expiratory volume in one second
- Measures capability of airways
- FEV1/VC of under 0.7 is used as a marker for obstruction diagnosis
What is the difference between concentration and pressure?
- Concentration - amount of gas in a given volume of air
- Pressure - force exerted by gas molecules
Describe Dalton’s Law
- Pressure of a mixture of gases is equal to the sum of individual gas pressures
- Each of these gases exert their own partial pressure
- Partial pressure = gas concentration x total pressure of gas mixture
Describe gas exchange at the lungs and tissue
- Lungs - carbon dioxide diffuses from capillaries to alveoli, oxygen alveoli to capillaries
- Tissue - co2 from inside tissue to outside tissue, o2 from outside tissue to inside tissue
What are the 2 main mechanisms of oxygen transport?
- Physical solution - dissolved into the fluid portion of blood (plasma)
- Bound to Hb - iron compound in RBC (majority of o2 transported in this way)
Describe the oxyHb dissociation curve
- Relationship between partial pressure of o2 with Hb saturation with o2
- Alveoli - high PO2 leads to an almost full saturation of Hb with oxygen
- Muscle tissue at rest - lower PO2, therefpre Hb does not hold onto as much o2, leading to unloading of oxygen into the tissue
- Muscle tissue during exercise - much lower PO2 therefore Hb does not hold onto as much oxygen, facilitating greater release of oxygen into tissue
Describe the Bohr effect
- Hb and o2 binding affected by acidity and temperature
- During exercise, temperature and acidity increase, reducing the affinity of oxygen and causing Hb to let go of oxygen
Describe the impact of high altitudes
- Oxygen pp is lower (concentration is always the same, but o2 is thinner)
- More difficult for diffusion to occur at alveoli
- Results in a lower o2 saturation
What are the 3 ways carbon dioxide can be transported to the lungs?
- Physical solution - dissolved directly into blood plasma (7-10% of co2 transport)
- Carbamino compunds/Hb binding - when Hb releases o2, it picks up co2 (20%)
- Bicarbonate ions - co2 forms carbonic acid which dissociates into hydrogen and bicarbonate (70%)
Where is the primary respiratory centre?
Medulla oblongata
