22D

Which brain stem structure is primarily responsible for generating the basic respiratory rhythm?

A. Cerebellum
B. Ventral respiratory group (VRG)
C. Hypothalamus
D. Carotid body

Ventral respiratory group (VRG)

The dorsal respiratory group (DRG) mainly functions to:

A. Generate forced expiration
B. Control voluntary breathing
C. Integrate sensory input and send signals to VRG (Ventral respiratory group)
D. Detect oxygen levels in blood

Integrate sensory input and send signals to VRG (Ventral respiratory group)

Which brain region smooths transitions between inhalation and expiration?

A. Medulla only
B. Cerebellum
C. Pons
D. Thalamus

Pons

The strongest chemical stimulus for increasing ventilation is:

A. Decreased oxygen
B. Increased carbon dioxide
C. Increased blood glucose
D. Decreased nitrogen

Increased carbon dioxide

When CO₂ levels rise in the blood, ventilation increases mainly because:

A. Oxygen binds more strongly to hemoglobin
B. Carbonic acid forms and lowers pH
C. Blood pressure increases
D. Hemoglobin breaks down

Carbonic acid forms and lowers pH

Central chemoreceptors are located in the:

A. Aortic arch
B. Carotid arteries
C. Medulla/brain stem
D. Alveoli

Medulla/brain stem

Peripheral chemoreceptors are found in the:

A. Brain stem only
B. Carotid and aortic bodies
C. Alveoli
D. Bronchioles

Carotid and aortic bodies

Oxygen becomes a major driver of ventilation when arterial O₂ drops to about:

A. 90 mmHg
B. 75 mmHg
C. 60 mmHg or less
D. 120 mmHg

60 mmHg or less

Hyperventilation causes:

A. Increased CO₂ in blood
B. Decreased blood pH
C. Decreased CO₂ in blood
D. Increased oxygen binding to hemoglobin only

Decreased CO₂ in blood

Rebreathing into a paper bag helps treat hyperventilation because it:

A. Increases oxygen levels
B. Increases CO₂ levels
C. Decreases hemoglobin
D. Stops alveolar diffusion

Increases CO₂ levels

During exercise, the initial increase in breathing is mainly caused by:

A. Increased CO₂ levels
B. Increased oxygen demand only
C. Neural input from brain and muscles
D. Decreased blood pressure

Neural input from brain and muscles

Hyperpnea is best defined as:

A. Breathing caused by low oxygen only
B. Increased breathing due to metabolic demand
C. Complete cessation of breathing
D. Breathing caused by lung disease

Increased breathing due to metabolic demand

At high altitude, ventilation increases mainly because:

A. CO₂ decreases
B. Oxygen partial pressure decreases
C. Nitrogen increases
D. Blood glucose drops

Oxygen partial pressure decreases

Acclimatization to high altitude includes:

A. Decreased RBC production
B. Increased EPO production
C. Decreased breathing rate permanently
D. Increased CO₂ retention only

Increased EPO production

The inflation reflex (Hering-Breuer reflex) is triggered by:

A. CO₂ increase in blood
B. Lung stretch receptors
C. Oxygen drop in tissues
D. Brain glucose levels

Lung stretch receptors

Coughing and sneezing are examples of:

A. Voluntary breathing control
B. Pulmonary irritant reflexes
C. Chemical control of breathing
D. Oxygen transport mechanisms

Pulmonary irritant reflexes

Which condition most directly causes apnea during sleep?

A. Asthma
B. Sleep apnea
C. Emphysema
D. Tuberculosis

Sleep apnea

Which brain structure allows voluntary control of breathing?

A. Cerebral cortex
B. Medulla only
C. Pons
D. Carotid body

Cerebral cortex

During breath-holding, breathing eventually resumes because:

A. Oxygen rises sharply
B. CO₂ builds up and stimulates chemoreceptors
C. Nitrogen increases
D. Blood pressure drops

CO₂ builds up and stimulates chemoreceptors

The most important factor controlling normal resting ventilation is:

A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Blood glucose

Carbon dioxide