Respiration Regulation
Sudden infant death syndrome (SIDS / crib death)
2-4 month old suddenly stops breathing, turns blue and dies. Possible that pace maker cells are not developed or connected properly or the reflexive respiratory pattern is disrupted.
Hypocapnia
Abnormally low Pco2 levels
Hypoventilation
Abnormally low respiratory rate that cannot meet oxygen demand and CO2 removal
Alveolar ventilation
Airflow in the alveoli
Hypercapnia homeostasis respons
CO2 rapidly diffuses into CSF lowering pH, activates chemoreceptors, Respiration is increased and deepened, alveoli CO2 levels drop, CO2 homeostasis is restored as CO2 diffuses out of the aveoli capillaries
Respiratory reflexes
Control the moto neurons in the spinal cord
Changes during the heroic breath
Foramen ovale (interatrial connection) and ductus arteriosus (fetal connection between the pulmonary trunk and aorta) are closed
Ventral respiratory group (VRG)
Functions during forced breathing only, innervates accessory motor neurons, inspiration center is involved in maximal inhalation
Hypercapnia
Increased Pco2 of arterial blood, CO2 rapidly diffuses into CSF lowering pH, respiration increases and deepens,
Pneumotaxic center of pons
Inhibits the apneustic center and promotes either passive or active exhalation
Deflation reflex
Inhibits the inhibitory centers and stimulates the inhibitory centers during exhalation. The greater the deflation the strong the response (hering-bruer reflex)
Protective reflexes
Located in epithelium of respiratory tract, can invoke sneezing, coughing laryngeal spasm operate when a hazardous exposure occurs
Goal of respiratory activity
Maintain oxygen and CO2 levels
Damage to the vagus nerves
May result in the Pneumotaxic center of the pons being cut off from signalling for the exhalation. Sensory innervation is cut off and the person is forced to maximally inhale for 20-30 seconds with very brief exhalation.
Inflation reflex
Prevents overexpansion of the lungs during forced breathing (hering-bueur reflex)
Hyperventilation
Rate and depth of respiration is to high
Chemoreceptor reflexes
Respond to Po2 and Pco2 levels in the blood and to the pH.
Apneustic center of pons
Stimulates the DRG for inhalation
Respiratory centers
Three pairs of nuclei in the reticular formation of the medulla oblongata and pons
Dorsal respiratory group (DRG)
Used in every respiratory cycle, inspiratory centers control the external intercostal muscles and the diaphragm
Respiratory reflexes
chemoreceptors, baroreceptors, stretch receptors, irritating stimuli, other sensations (includes pain, heath etc)
apnea
period when inhalation is suspended
Lung perfusion
Blood flow to the alveoli
