Initiation of Breathing

Volume of air with normal breath - 500ml

What is Tidal Volume?

Extra air inspired beyond normal - 3000ml

What is Inspiratory Reserve Volume?

Max air expired after normal breath - 1100ml

What is Expiratory Reserve Volume?

Air remaining after max expiration - 1200ml

What is Residual Volume?

Tidal Volume + Inspiratory reserve volume = 3500ml

What is Inspiratory Capacity?

Expiratory reserve volume + Residual Volume = 2300ml

What is Functional Residual Capacity?

Inspiratory reserve volume + Tidal volume + Expiratory Reserve volume = 4600ml

What is Vital Capacity?

Vital capacity + Residual Volume = 5800ml

What is Total Lung Capacity?

Dorsal Respiratory Group (DRG)

Medullary rhythmicity, active during inspiration.

Vagal and Glossopharyngeal nerves
Through the Nucleus Tractus Solitaritus (NTS)

What nerves input to the DRG and through what nucleus?

Ventral Respiratory Group (VRG)

Becomes active during forced exhalation and modifies inspiration and expiration with exercise or stress. Contains Pre-Bötzinger Complex.

Diaphragm
External intercostal muscles

What does the Nucleus retroambigus control?

Laryngeal and Pharyngeal muscles

What does the Nucleus para-ambigus control?

Phrenic → Diaphragm muscles

Intercostal → Intercostal muscles + abdominal muscles

Cranial → Upper airway dilator muscles

Efferent Pathway from Respiratory Centers

Apneustic Center Function

Promotes long, deep breaths and integrates incoming signals. Involved in prolonging ramp action to increase tidal volume.

Pneumotaxic Center Function

Controls the ramp duration of the DRG inspiratory signal to regulate respiratory rhythm and rate. Inhibitory to the Apneustic Center. Decreases TV.

Eupnea

Normal breathing cycle.

Tachypnea

Rapid, shallow breathing indicative of respiratory distress.

Bradypnea

Slow breathing, below normal (less than 12 bpm).

Apnea

Temporary halt in breathing, often associated with neurological damage.

Dyspnea

Subjective feeling of shortness of breath.

Spontaneous Breathing

What does the Pre-Botzinger Complex Control?