Main points 1

ventral , dorsal

Medullary respiratory centers are the ____ and ____ respiratory groups.

rhythmicity

The ventral respiratory group is responsible for the _____ of breathing.

pontine

The ____ respiratory centers influence the activity of the medullary respiratory centers.

CO2, H+, and O2.

Important chemical factors modifying baseline respiratory rate and depth are arterial levels of ___ , ___ , and ____.

powerful respiratory stimulant.

An increasing arterial PCO2 level (hypercapnia) is the most _____?

central chemoreceptors

An increasing arterial PCO2 level acts on _______ to cause a reflexive increase in the rate and depth of breathing.

decreased ventilation and, possibly, apnea.

Hypocapnia depresses respiration and results in _____?

peripheral chemoreceptors.

Arterial PO2 levels below 60 mm Hg strongly stimulate _____?

peripheral chemoreceptors

Decreased pH and a decline in blood PO2 act on ______ and enhance the response to CO2.

hypothalamic centers.

Emotions, pain, body temperature changes, and other stressors can alter respiration by acting through _____?

voluntarily

Respiration can also be controlled ______ for short periods.

pulmonary irritant reflexes.

Dust, mucus, fumes, and pollutants initiate ____?

overinflation , inspiration.

The inflation (Hering-Breuer) reflex is a protective reflex initiated by extreme _____ of the lungs; it acts to terminate _____.

increase , gradual increase.

As exercise begins, there is an abrupt ____ in ventilation (hyperpnea) followed by a more _____.

decrease , decline

When exercise stops, there is an abrupt _____ in ventilation followed by a gradual ____ to baseline values.

constant

PO2, PCO2, and blood pH remain quite _____ during exercise and hence do not appear to account for changes in ventilation.

fall

At high altitudes, arterial PO2 and hemoglobin saturation levels ____ because of the decrease in atmospheric pressure compared to sea level.

PO2

Increased ventilation helps restore ___ to physiological levels.

erythropoiesis.

Long-term acclimatization involves increased _____.

COPD , lung cancer , asthma.

Two major respiratory disorders are ____ and _____ ; smoking is a significant cause. A third major disorder is _____.

irreversible decrease

COPD is characterized by an _____ in the ability to force air out of the lungs.

enlarge permanently , elasticity

In emphysema, alveoli ______ and disintegrate. The lungs lose their ____, and expiration becomes an active process.

excessive mucus production , ventilation , gas exchange.

Chronic bronchitis is characterized by _______ in the lower respiratory passageways, which severely impairs ____ and ______.

wheeze , constrict

Asthma is a reversible obstructive condition caused by an immune response that causes its victims to ____ and gasp for air as their inflamed respiratory passages ____. It is marked by acute episodes and symptom-free periods.

airborne bacterium

Tuberculosis, an infectious disease caused by an ______, mainly affects the lungs.

free radicals , carcinogens

Lung cancer, promoted by _____ and other _____ in tobacco smoke, is extremely aggressive and metastasizes rapidly.

pharynx

Sleep apnea is usually caused by obstruction of the ____ during sleep.

invagination

The mucosa of the nasal cavity develops from the ____ of the ectodermal olfactory placodes.

endodermal foregut lining.

The mucosa of the pharynx and lower respiratory passageways develops from an outpocketing of the ________.

Mesoderm

_____ forms the walls of the respiratory conduits and the lung stroma.

CFTR protein , chloride

Cystic fibrosis (CF), the most common fatal hereditary disease in North America, results from an abnormal _____ that fails to form a _____ channel.

rigid , elastic , declines

With age, the thorax becomes more ___, the lungs become less ____, and vital capacity ____. In addition, sleep apnea becomes more common, and respiratory system protective mechanisms are less effective.