Ch. 42 Regulation of respiration

Which of the following play a part in the increase in ventilation with moderate exercise? A. Reflexes from moving limbs B. Decrease in body temperature C. Fall in arterial pO2 D. Rise in arterial pCO2

A. Reflexes from moving limbs

Tachypnea

Accelerated shallow breathing

Five hours after an uneventful knee surgery, a conscious 50-year-old woman has minor heart pains and a decrease in systolic blood pressure from 110 to 90 mmHg. Arterial blood gas analysis on her breathing room air shows: pH 7.30 pCO2 52 mmHg pO2 58 mmHg Which of the following is the most likely cause of these findings? A. Alveolar hypoventilation B. Cardiac failure C. Hypoxia due to anesthetic gases D. Pulmonary hypertension

Alveolar hypoventilation

Hyperventilation will result from:

An increase in alveolar pCO2

Peripheral and central chemoreceptors may both contribute to the increased ventilation that occurs as a result of:

An increase in arterial carbon dioxide tension

Chemosensitive area

Lies within the medulla and detects the *changes in the CO2 and H+ concentration* that in turn active other respiratory centers.

Emphysema:

Loss of the lung alveolar tissue by chronic infections or toxins

How long is inspiration vs. expiration? (Hint: Autorhythmic cells are active for 2 seconds then become inactive)

Autorhymthic cells become active to trigger inspiration (active) for 2 seconds, Autorhythmic cells are inactive and expiration (passive) for 3 seconds

Dyspnea (Hint: Air hunger)

Mental anguish due to inability to obtain enough ventilation

Why does CO2 have a more potent effect on the chemosensitive neurons than H+?

Bc CO2 is more permeable than H+ to cross the blood-brain barrier

Hyperventilation will result from: A. A decrease in arterial pCO2 to less than 30 mmHg B. Direct stimulation of the medulla chemosensitive area caused by an increase in pH C. An increase in alveolar pCO2 D. An increase in alveolar pO2

C. An increase in alveolar pCO2

Which of the following conditions would be expected to stimulate the arterial chemoreceptors? A. Mild anemia B. Normal breathing C. Hypoxia due to ascent to high altitude D. Hyperventilation E. Exposure to carbon monoxide

C. Hypoxia due to ascent to high altitude

A 9-year-old boy decided to find out how long he could breathe into and out of a paper bag. After ~2 minutes his friends noticed that he was breathing very rapidly and forced him to stop. Which of the following was the most potent stimulus for the boy's hyperventilation? A. Decreased arterial PO2 B. Increased arterial PO2 C. Increased arterial PCO2 D. Decreased arterial PCO2 E. Increased pH

C. Increased arterial PCO2

What artery goes to the left brain and allows us to detect changes in CO2 as well?

Carotid artery

Central Sleep apnea

Caused by cessation of the central nervous system ventilatory drive during sleep due to respiratory centers damage

Obstructive Sleep Apnea

Caused by nasal, pharyngeal or oral blockage of the airways during sleep

Which of the following would result in a decrease in nerve activity from the peripheral chemoreceptors? A. A decrease in arterial oxygen content B. A decrease in blood pH C. A decrease in arterial blood pressure D. An increase in arterial pO2

D. An increase in arterial pO2

What mainly controls inspiration? (Hint: Controls the basic rhythm of respiration)

Dorsal Respiratory Group

What is responsible for inspiratory neuronal action potentials? (Hint: One set of neurons excites a second set, which in turn inhibits the first. This same mechanism will repeat itself)

Dorsal respiratory group

What does expiration result from?

Elastic recoil of the lungs and the thoracic cage

How does hypercapnia affect breathing?

Excites the chemosensitive area in the medulla oblongata plus the peripheral chemoreceptors in carotid and aortic bodies to increase breathing rate

What is the fxn of the respiratory center?

Fxn of pneumotaxic center is to limit inspiration, which has a secondary effect of increasing the rate of breathing bc the limitation of inspiration also shortens expiration and the entire period of each respiration. TAKE MORE BREATHS PER MINUTE if the pneomtaxic signal is strong.

What nerve carries the afferent signal from the carotid body to the dorsal respiratory area?

Glossopharyngeal nerve

Voluntary apnea (breath-holding) for 60 seconds will:

Increase alveolar pCO2

Pneumonia:

Inflammatory condition of the lungs in which the alveoli are filled with fluid and blood cells

Where are most of the neurons for the dorsal respiratory group?

Nucleus of the tractus solitarius

What mainly controls the rate and depth of breathing?

Pneumotaxic center

What transmits the signals to the inspiratory area to switch-off to control the duration of the filling phase of the lung cycle?

Pneumotaxic center

Cheyne-Stokes Breathing

Slowly waxing and waning respiration cycle

Asthma:

Spasmodic contractions of the smooth muscles in the lungs bronchioles

Apnea

Temporary cessation of breathing

What is the name of the reflex initiated when the lungs over-inflate, thus causing the stretch receptors in the bronchi and bronchioles become activated to inhibit the dorsal respiratory group and apneustic center to avoid damage to the lungs by decreasing the respiratory rate?

The Hering-Breuer Inflation Reflex

Where are the partial pressures of oxygen sensed when they are below 70 to increase breathing rate? (Hint: Oxygen does not directly act on the respiratory center)

The peripheral chemoreceptors located in the carotid and aortic bodies. (Most sensitive when they are btwn 30-60)

The main reason that respiratory compensation occurs in metabolic acidosis is due to stimulation of:

The central chemoreceptors by CO2

How do the kidney's readjust to the H+ concentration to normal ?

The kidneys increase their absorption of HCO3-, which then bind with the H+ in the blood to reduce their concentrations Also the HCO3- combine with the H+ adjacent to the respiratory neurons

T/F Carbon monoxide does not affect alveolar pO2+pCO2 or the peripheral chemoreceptor activity

True

T/F Moderate aerobic exercise increases arterial pO2

True

T/F PCO2 is a more potent regulator of respiration than H+

True

T/F The ventral respiratory group is inactive during most quiet breathing, and only active during forced expiration as an overdrive mechanism

True

T/F XS CO2 or XS H+ ions in the blood mainly act directly on the respiratory center causing a great increase in inspiration and expiration.

True

T/F A weak inhibitory signal from the pneumotaxic center allows the lungs to fill more

True.

T/F Oxygen, in contrast, does not have a significant DIRECT effect on the respiratory center.

True. The brain does not detect the partial pressures of oxygen as well as CO2 Chemoreceptors mostly in the carotid bodies, and to some extent the aortic bodies detect the low levels of O2.

T/F The chemoreceptors are exposed at all time to only arterial blood

True. Their PO2 are equal to PaO2

What nerve carries the afferent signal from the aortic body to the dorsal respiratory area?

Vagus nerve

What mainly controls expiration? (Hint: Stimulate the abdominal muscles during heavy expiration)

Ventral respiratory group

Where is the respiratory center located?

medulla and pons