32. Control of Ventilation Flashcards
Eupnoea
Normal breathing
Hypernoea
Increased ventilation (higher tidal volume)
Tachypnoea
Increased respiratory rate
Hyperventilation
Overventilation (low PCO2)
Hypocapnia
PCO2 is less than normal
Hypoxia
PO2 is less than normal
Hypoxaemia
Lower PO2 than normal in blood
Asphyxia
Lower PO2, high PCO2
Dyspnoea
Stressful breathing
Apnoea
Absence of breathing
What is the function of the dorsal respiratory group?
Causes inspiratory muscles to contract
What is the function of the ventral respiratory group?
Causes expiratory muscles to contract when breathing is elevated
What is the Pre-Botzinger complex?
Pace maker for breathing
What is the function of the apneustic center?
Drives inspiration by stimulating dorsal group
What is the function of the pneumotaxic center?
Inhibits apneustic center
What could damage to any respiratory control centre cause?
Hypoventilation
Hypoxaemia
What things might damage respiratory control centres?
Depressant drugs Spinal cord injury Motor nerve damage Muscle diseases Restriction and obstruction
What are stretch receptors?
Nerve endings in smooth muscle of airways
Stimulated when airways expand on inspiration
Impulses travel back in Vagus nerve
Inhibit respiratory centre: Hering-Breuer inflation reflex
What are irritant receptors?
Nerve endings near airway epithelial cells
Stimulated by noxious gases, cigarette smoke, dust, cold air
Impulse travels in Vagus
Causes bronchoconstriction and coughing
What are juxtacapillary receptors?
Near capillaries in alveoli
Stimulated by pulmonary decongestion and oedema
Vagus nerve
Reflex apnoea or rapid shallow breathing
Where are peripheral chemoreceptors found?
Aortic bodies on arch of aorta
Carotid bodies at bifurcation of carotid artery
What are peripheral chemoreceptors stimulated by?
Low PO2
High PCO2
H+
Where are central chemoreceptors located?
Medulla
Separate from respiratory centres
H+ can’t pass blood brain barrier so CO2 passes through and breaks down to form H+, stimulating the inspiratory response
What are the 4 types of hypoxia?
Hypoxic: PO2 is less than normal
Anaemic: O2 content is less than normal
Stagnant: O2 delivery is reduced
Histotoxic: Tissues can’t use O2 due to metabolic poisoning