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