Ch 12 respiration

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Questions and Answers

What is one of the main functions of the respiratory system?

To regulate body temperature

To digest food in the stomach

To allow gas exchange to occur at the respiratory membrane (correct)

To filter waste from the blood

What is the path that air takes to reach the lungs?

External nares → nasal cavity → nasaopharynx → laryngopharynx → larynx → trachea → lungs (correct)

Mouth → pharynx → larynx → bronchi → lungs

Mouth → nasal cavity → esophagus → larynx → trachea → lungs

Nose → throat → stomach → lungs

What is the term for the sacs where gas exchange occurs in the lungs?

Trachea

Bronchioles

Bronchi

Alveoli (correct)

What is the fluid that fills the pleural cavity?

Pleural fluid Signup and view all the answers

What is the purpose of surfactant in the lungs?

To reduce surface tension in the lungs Signup and view all the answers

What is the membrane that lines the thoracic cavity?

Parietal pleura Signup and view all the answers

What is the term for the tube that divides into small branching tubes in the lungs?

Respiratory tree Signup and view all the answers

What happens to the intrapleural cavity pressure during inspiration?

It decreases Signup and view all the answers

What is the shape of the lungs?

Cone-shaped Signup and view all the answers

What is the primary muscle responsible for quiet breathing?

Diaphragm Signup and view all the answers

What is the average amount of gas that moves in and out of the lungs during quiet breathing?

6 liters per minute Signup and view all the answers

What is the maximum amount of gas that can move in and out of the lungs during maximal exercise?

100 liters per minute Signup and view all the answers

What is the average tidal volume (TV) in milliliters?

500 ml Signup and view all the answers

What is the formula to calculate inspiratory reserve volume (IRV)?

IRV = IC - TV Signup and view all the answers

What is the average vital capacity (VC) in milliliters?

5000 ml Signup and view all the answers

What is the term for the amount of air that is always left in the lungs after expiration?

Residual volume Signup and view all the answers

What is the relationship between pressure and volume according to Boyle's law?

Inversely proportional Signup and view all the answers

What is the primary cause of the contraction of the diaphragm and external intercostals muscles during inspiration?

Nerve impulses from the medulla oblongata Signup and view all the answers

What happens to the thoracic volume during inspiration?

It increases Signup and view all the answers

What is the change in intraalveolar pressure during inspiration compared to atmospheric pressure?

It falls below atmospheric pressure Signup and view all the answers

What is the primary cause of the recoil of the diaphragm and external intercostals muscles during expiration?

Elastic tissues of the lungs Signup and view all the answers

What happens to the intraalveolar pressure during expiration compared to atmospheric pressure?

It rises above atmospheric pressure Signup and view all the answers

What is the mechanism by which air is exchanged between the atmosphere and the alveoli?

Pulmonary ventilation Signup and view all the answers

What happens to the intrapleural cavity during inspiration?

It expands Signup and view all the answers

What is the average value of total lung capacity (TLC)?

6,000 ml Signup and view all the answers

What is the term for the amount of air that remains in the bronchial tree and is not involved in gas exchange?

Anatomic dead space Signup and view all the answers

What is the term for the total amount of air in the lungs that is not involved in gas exchange?

Physiologic dead space Signup and view all the answers

What is one of the major factors that affect normal breathing?

Stretching in the lungs and thoracic walls Signup and view all the answers

What stimulates normal breathing?

Relaxing of the lungs and thoracic walls Signup and view all the answers

What prevents overinflation of the lungs during forceful breathing?

Stretch of tissues Signup and view all the answers

What happens when blood PO2 is low?

Alveolar ventilation increases Signup and view all the answers

What happens when blood Pco2 is high?

Alveolar ventilation increases Signup and view all the answers

What is the effect of an increase in H+ ion concentration in CSF on breathing rate and alveolar ventilation?

Increase breathing rate and alveolar ventilation Signup and view all the answers

Which part of the brain stem is responsible for setting the basic rhythm of inspiration and expiration?

Medulla oblongata Signup and view all the answers

What is the effect of CO2 combining with water in the CSF?

Formation of carbonic acid Signup and view all the answers

What type of chemoreceptors are associated with the respiratory centers?

Central chemoreceptors Signup and view all the answers

What is the effect of a low O2 concentration on alveolar ventilation?

Increase alveolar ventilation Signup and view all the answers

What is the effect of increased blood CO2 on the pH of CSF?

Decrease pH of CSF Signup and view all the answers

What type of chemoreceptors are located in the carotid bodies and aortic bodies?

Peripheral chemoreceptors Signup and view all the answers

What is the effect of an increase in blood CO2 on the aortic and carotid bodies?

Increase stimulation of the aortic and carotid bodies Signup and view all the answers

Study Notes

Functions of the Respiratory System

The respiratory system allows gases from the environment to enter the bronchial tree through inspiration by expanding the thoracic volume.
It allows gas exchange to occur at the respiratory membrane, so that oxygen diffuses into the blood while carbon dioxide diffuses into the bronchial tree.
It permits gases in the lungs to be eliminated through expiration by decreasing the thoracic volume.

General Anatomy of the Respiratory System

The respiratory system consists of a tube that divides into small branching tubes in the lungs.
The pathway from the external nares to the alveoli is: external nares → nasal cavity → nasopharynx → laryngopharynx → larynx → trachea → primary bronchi → lungs (secondary bronchi → tertiary bronchi → bronchioles → alveolar sacs → alveoli).

Lungs

The lungs are cone-shaped organs located in the thoracic cavity.
The thoracic cavity is lined with a body membrane called parietal pleura, while the surface of the lungs is covered with visceral pleura.
The thin space between the two pleural membranes is called the pleural cavity, which is filled with a clear fluid called plural fluid to minimize friction between the tissues and to provide surface tension in the pleural cavity.
A chemical substance called surfactant secreted by the lungs also facilitates the surface tension.

Inspiration (Inhalation)

Inspiration is an active process where nerve impulses from the medulla oblongata cause the contraction of the diaphragm and external intercostals muscles.
As these muscles contract, thoracic volume increases, which decreases the pressure within the lung (intraalveolar pressure) due to Boyle's Law.
When intraalveolar pressure falls below atmospheric pressure, gases move from the environment into the lungs.

Expiration (Exhalation)

Expiration is a passive process where elastic tissues of the lungs and diaphragm recoil to their original position.
As the diaphragm and external intercostals muscles relax and recoil, thoracic volume decreases, which raises the intraalveolar pressure due to Boyle's Law.
When intraalveolar pressure rises above atmospheric pressure, gases move from the lungs into the environment.

Pulmonary Ventilation

Pulmonary ventilation is the mechanism by which air is exchanged between the atmosphere and the alveoli.
Air is exchanged due to the expansion and contraction of the lungs.
Contraction of the diaphragm pulls down, enlarging the intrapleural cavity, and elevation of the ribs also expands the intrapleural cavity.
These factors decrease the intrapleural cavity pressure, thus air flows into the lungs (inspiration).

Lung Capacities

Lung capacities can be measured by a spirometer, providing valuable information regarding the normal function of the respiratory system.

Control of Breathing

Four major factors affect normal breathing: stretching in the lungs and thoracic walls, O2 level in the blood, CO2 level in the blood, and H+ level in the blood.
Normal breathing is inhibited by stretching of the lungs and thoracic walls, a rise in O2 level, and a decrease in CO2 and H+ levels; while normal breathing is stimulated by relaxing of the lungs and thoracic walls, a decrease in O2 level, and a rise in CO2 and H+ levels.
Chemicals and emotional state also affect breathing.

Respiratory Centers

Normal breathing is a rhythmic, involuntary action regulated by the respiratory centers in the pons and medulla oblongata of the brain stem.
Rhythmicity area in the medulla oblongata sets the basic rhythm of inspiration and expiration, and is subdivided into the dorsal respiratory group and the ventral respiratory group.

Chemoreceptors

Central chemoreceptors are associated with the respiratory centers.
CO2 combines with water to form carbonic acid, which in turn, releases H+ ions in CSF.
Stimulation of these areas increases alveolar ventilation.
Peripheral chemoreceptors are in the carotid bodies and aortic bodies, sensing low O2 concentration, and when O2 concentration is low, alveolar ventilation increases.

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