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Ch. 22 The Respiratory System
Hoehn - Marieb Human Anatomy & Physiology, 12th edition
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732Not the one you use?Change textbook
All textbooksHoehn, Haynes, Abbott 12th EditionCh. 22 The Respiratory SystemProblem 10
Chapter 22, Problem 10

Which of the following has the greatest stimulating effect on the respiratory centers in the brain?
a. Oxygen
b. Carbon dioxide
c. Calcium
d. Willpower

Verified step by step guidance
1
Step 1: Understand the role of the respiratory centers in the brain. The medulla oblongata and pons are responsible for regulating breathing by responding to changes in blood gas levels, particularly carbon dioxide (CO2) and oxygen (O2).
Step 2: Recognize the primary stimulus for the respiratory centers. Carbon dioxide levels in the blood are the most significant factor affecting respiratory rate and depth. High CO2 levels lead to increased acidity (lower pH) in the blood, which stimulates the respiratory centers to increase breathing rate to expel CO2.
Step 3: Compare the effects of oxygen and carbon dioxide. While oxygen levels (hypoxia) can influence breathing, the respiratory centers are more sensitive to changes in CO2 levels than oxygen levels under normal conditions.
Step 4: Eliminate calcium and willpower as options. Calcium does not directly affect the respiratory centers, and willpower is not a physiological factor influencing breathing regulation.
Step 5: Conclude that carbon dioxide has the greatest stimulating effect on the respiratory centers in the brain due to its role in maintaining blood pH and homeostasis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Respiratory Centers

The respiratory centers are clusters of neurons located in the brainstem, specifically in the medulla oblongata and pons, that regulate the rate and depth of breathing. They respond to various chemical signals in the blood, primarily levels of carbon dioxide (CO2) and oxygen (O2), to maintain homeostasis and ensure adequate gas exchange.
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Role of Carbon Dioxide

Carbon dioxide plays a critical role in stimulating the respiratory centers. An increase in CO2 levels in the blood leads to a decrease in pH, which is detected by chemoreceptors. This triggers an increase in the rate and depth of breathing to expel excess CO2 and restore normal levels, making it a primary driver of respiratory drive.
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Chemoreceptors

Chemoreceptors are specialized sensory receptors that detect changes in chemical composition in the blood, particularly levels of oxygen, carbon dioxide, and pH. Central chemoreceptors in the brain respond mainly to CO2 levels, while peripheral chemoreceptors in the carotid and aortic bodies respond to both O2 and CO2, influencing respiratory patterns accordingly.
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Related Practice
Textbook Question

In mouth-to-mouth artificial respiration, the rescuer blows air from his or her own respiratory system into that of the victim. Which of the following statements are correct?

(1) Expansion of the victim's lungs is brought about by blowing air in at higher than atmospheric pressure (positive-pressure breathing).

(2) During inflation of the lungs, the intrapleural pressure increases.

(3) This technique will not work if the victim has a hole in the chest wall, even if the lungs are intact.

(4) Expiration during this procedure depends on the elasticity of the alveolar and thoracic walls.

a. All of these

b. 1, 2, 4

c. 1, 2, 3

d. 1, 4

Textbook Question

The bulk of carbon dioxide is carried:

a. Chemically combined with the amino acids of hemoglobin as carbaminohemoglobin in the red blood cells

b. As the ion HCO₃⁻ in the plasma after first entering the red blood cell

c. As carbonic acid in the plasma

d. Chemically combined with the heme portion of Hb

Textbook Question

Oxygen and carbon dioxide are exchanged in the lungs and through all cell membranes by:

a. Active transport

b. Diffusion

c. Filtration

d. Osmosis

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Textbook Question

The nutrient blood supply of the lungs is provided by:

a. The pulmonary arteries

b. The aorta

c. The pulmonary veins

d. The bronchial arteries

Textbook Question

A baby holding its breath will:

a. Have brain cells damaged because of low blood oxygen levels

b. Automatically start to breathe again when the carbon dioxide levels in the blood reach a high enough value

c. Suffer heart damage because of increased pressure in the carotid sinus and aortic arch areas

d. Be called a 'blue baby'

Textbook Question

Most oxygen carried in the blood is:

a. In solution in the plasma

b. Combined with plasma proteins

c. Chemically combined with the heme in red blood cells

d. In solution in the red blood cells