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Fisiologia

Respiratória

Table 36-1. Stimuli affecting the respiratory center.

Chemical control

CO2 (via CSF and brain interstitial fluid H+ concentration)

O2

H+

⎫⎬⎭

(via carotid and aortic bodies)

Nonchemical control

Vagal afferents from receptors in the airways and lungs

Afferents from the pons, hypothalamus, and limbic system

Afferents from proprioceptors

Afferents from baroreceptors: arterial, atrial, ventricular, pulmonary

Table 36-2. Airway and lung receptors.1

Vagal

Innervation Type

Location in

Interstitium Stimulus Response

Myelinated Slowly adapting Among airway

smooth muscle

cells(?)

Lung inflation Inspiratory time shortening

Hering-Breuer inflation and

deflation reflexes

Bronchodilation

Tachycardia

Rapidly adapting Among airway

epithelial cells

Lung hyperinflation

Exogenous and endogenous

substances (eg, histamine,

prostaglandins)

Hyperpnea

Cough

Bronchoconstriction

Mucus secretion

Unmyelinated

C fibers

Pulmonary C fibers

Bronchial C fibers

Close to blood

vessels

Lung hyperinflation

Exogenous and endogenous

substances (eg, capsaicin,

bradykinin, serotonin)

Apnea followed by rapid

breathing

Bronchoconstriction

Bradycardia

Hypotension

Mucus secretion1 Modified and reproduced, with permission, from Berger AJ, Hornbein TF: Control of respiration. In: Textbook of

Physiology, 21st ed. Vol. 2. Patton HD et al (editors). Saunders, 1989.

Figure 36-1. Respiratory neurons in the brain stem. Dorsal view of brain stem; cerebellum removed. The

effects of various lesions and brain stem transections are also shown. The spirometer tracings at the right

indicate the depth and rate of breathing. DRG, dorsal group of respiratory neurons; VRG, ventral group of

respiratory neurons; NPBL, nucleus parabrachialis (pneumotaxic center); 4th vent, fourth ventricle; IC,

inferior colliculus; CP, middle cerebellar peduncle. The roman numerals identify cranial nerves.

(Modified and reproduced, with permission, from Mitchell RA, Berger A: State of the art: Review of

neural regulation of respiration. Am Rev Respir Dis 1975;111:206.)

Figure 36-7. Rostral (R) and caudal (C) chemosensitive areas on

the ventral surface of the medulla

Figure 36-5. Organization of the carotid body. Type I (glomus) cells contain catecholamines. When exposed to hypoxia,

they release their catecholamines, which stimulate the cup-like endings of the carotid sinus nerve fibers in the

glossopharyngeal nerve. The glia-like type II cells surround the type I cells and probably have a sustentacular function.