respiratory system

• The respiratory control centre, which includes the Medulla Oblongata and the Pons, is responsible for controlling breathing.
• The Medulla Oblongata and the Pons contain three groups of neurons: the Dorsal respiratory group (DRG) and the Ventral respiratory group (VRG).
• The Dorsal respiratory group (DRG) is responsible for initiating inspiration.
• The Ventral respiratory group (VRG) is responsible for initiating exhalation.
• Asthma is a reversible condition that is acute and episodic, affecting approximately 5% of the population.
• The aetiologies of asthma can be extrinsic, such as atopic, or intrinsic, which include immune, psychological, infectious, and endocrine factors.
• Asthma is asymptomatic between attacks.
• Asthma is characterized by spasm of bronchiole smooth muscle.
• Asthma results in hyper-responsive airways, which are inflammation of the bronchial mucosa.
• Asthma causes hypersecretion of tenacious mucous.
• Asthma leads to hyperplasia of smooth muscle.
• The Pontine respiratory group, further divided into pneumotaxic and apneustic centres, is responsible for the rate and pattern of breathing.
• Central and peripheral chemoreceptors receive information on the balance of Oxygen, Carbon dioxide and pH levels in the body and relay this to the respiratory control centre in the brain.
• Central Chemoreceptors, located in the brain stem, monitor CO2 and Ph levels and communicate with the respiratory centre via the Glossopharyngeal nerve (CN:9).
• Peripheral chemoreceptors, located in the aortic and carotid bodies, monitor O2 levels as well as CO2 and pH and communicate with the respiratory centre via the Vagus nerve (CN:10).
• Mechanoreceptors monitor and relay information regarding pressure, located in the nose, lungs, GI tract etc.
• In the lungs, these receptors register when the lungs are full, sending a message to the Resp centre that it's time to exhale.
• The Hypothalamus is responsible for anxiety, fear, pain etc, and respiratory changes due to emotion.
• The Cerebrum is responsible for voluntary breathing, such as singing, free diving, scaring your parents.
• CO2 is the main stimulus for breathing, and increased concentration of dissolved CO2 stimulates the central chemoreceptors in brain stem which are sensitive to CO2 and pH changes.
• Functional residual capacity is the amount of air still in your lungs after normal exhalation.
• Inspiratory capacity is the amount of air you can breathe in after normal exhalation.
• Inspiratory reserve volume is the amount of air you can still breathe in after normal inhalation.
• Expiratory reserve volume is the amount of air you can still breathe out after normal exhalation.
• Residual volume is the amount of air still in your lungs after you have forced out as much as you can.
• Ventilation (V) is the amount of air entering the lungs.
• Perfusion (Q) is the amount of blood passing through the lungs.
• For normal healthy functioning of the body, V/Q should be balanced.
• If V/Q becomes imbalanced (through disease or deformity), V/Q will be mismatched and hypoxia will result, leading to ill health.
• Common respiratory diseases include Asthma and COPD.
• Asthma is often triggered by an allergen or physical activity and can be managed with inhalers.
• COPD is a permanent and progressive disease managed with various medications and behavioural changes.
• Both Asthma and COPD are lung diseases, with COPD being more common in women and causing a greater lung cancer risk.
• Chronic Bronchitis is a symptomatic diagnosis characterized by a productive cough for 3 months for 2 successive years.
• Hypertrophy of mucous glands, hyper-secretion of mucous, and semi-solid plugging of distal airways are changes in Chronic Bronchitis.
• Chronic Bronchitis is often associated with COPD.
• Emphysema is characterized by damage of the acinus, enlargement of the distal air spaces, destruction of alveolar septa and walls, loss of elastin, and loss of surface area/ volume ratio.
• COPD has two types: Pink, with no cough and hyper-expanded 'barrel' chest, and Blue, with a productive cough and hyper-expansion on CXR.
• Notes: Do not use derogatory terms when speaking about COPD patients.
• Peripheral chemoreceptors in blood vessels, which are sensitive to O2 as well as pH and CO2, also relay information to the brain.