10/13 Breathing

Question 1

• Describe respiratory and non-respiratory air movements

Answer 1

o Respiratory: apnea (temporary cessation of breathing)
o Dyspnea—labored, gasping
o Eupnea-normal, relaxed breathing
o Hyperpnea—increased rate and depth
o Hyperventilation—increased pulmonary ventilation
o Hypoventilation—reduced ventilation
o Orthopnea—dyspnea when lying down
o Respiratory arrest—permanent cessation of breathing
o Tachypnea—accelerated respiration
o Non-respiratory: coughing, hiccupping, sneezing, laughing, crying etc.

Question 2

• Brainstem respiratory control centers

Answer 2

o Chemoreceptors, lungs, and other receptors (sensors) send signals to central controller (pons, medulla) which sends output to effectors which are muscles in upper airway, inspiratory, and expiratory.
o The medullary respiratory center includes dorsal and ventral group which send projections to hypoglossal and phrenic nerves. It is the origin of respiratory rhythm Pre-botzinger and botzinger complexes are necessary. The DRG mainly fire during inspiration during resting breathing.
o Pontine control center modulates respiratory rhythm. Apneustic and pneumotaxic centers. Apneustic (lower pons)—facilitates inspiration by stimulating medullary neurons. Pneumotaxic (upper) inhibits inspiration so heavy breathing does not continue too long.

Question 3

• Factors affecting respiration: chemical and mechanical sensory inputs

Answer 3

o Chemical: Activated by decrease in pao2 or ph and increase in paco2. Includes n or solitary tract. Glossopharyngeal cells taste blood, o2. Aortic body (vagus) senses o2 and acidity. Locus ceruleus senses co2. Will increase ventilation to account for acidity.
o Mechanical: pulmonary stretch receptors. Slowly adapting (SARs), endings in airway smooth muscle (bronchi, trachea). Activated by lung stretch and bronchoconstriction. Slows breathing, terminates inspiration, regulates hering breur reflex (timing of inspiration/expiration). Rapidly adapting (RARs) are located between airway epithelial cells from larynx to bronchi. Sensitive to rapid deformation and minipulations of mucosa. Chemical and irritants. Increase ventilation and trigger bronchoconstriction.
o Higher center feedback: cerebral cotrex, hpc, limbic system.