Human Respiratory System Overview

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Questions and Answers

What is one of the defense mechanisms of the lungs?

Secreting anticoagulants (correct)

Exchange of gases between blood and tissues

Regulation of body temperature

Synthesizing hormonal substances

During which process is water evaporated and lost from the body?

Expiration (correct)

Inspiration

Internal respiration

External respiration

What is the role of the lungs in maintaining acid-base balance?

Maintaining water balance

Synthesizing hormonal substances

Regulating carbon dioxide content in blood (correct)

Regulating oxygen content in blood

What is the function of endothelial cells in the pulmonary capillaries?

Converting angiotensin I to angiotensin II Signup and view all the answers

What is the primary function of external respiration?

Exchange of gases between lungs and blood Signup and view all the answers

What is the process by which the body loses heat?

Expiration Signup and view all the answers

What is the term for the exchange of gases between the atmosphere, lungs, blood, and tissues?

Respiration Signup and view all the answers

What is the stage of respiration during which air enters the lungs?

Inspiration Signup and view all the answers

What is the name of the enlarged structure that each alveolar duct enters?

Alveolar sac Signup and view all the answers

Which of the following is NOT part of the respiratory unit?

Bronchial tree Signup and view all the answers

What process occurs when the diaphragm contracts during inhalation?

Increased thoracic volume Signup and view all the answers

During passive exhalation, what happens to the external intercostal muscles?

They relax Signup and view all the answers

Which of the following statements about inhalation is true?

Rib cage moves upward and forward Signup and view all the answers

What is the role of the ribs in breathing?

To increase or decrease the anteroposterior diameter of the chest cavity Signup and view all the answers

What is the primary function of the respiratory system?

To provide a way for oxygen to enter and carbon dioxide to leave the body Signup and view all the answers

Which of the following is NOT part of the upper respiratory tract?

Trachea Signup and view all the answers

What is the role of olfactory receptors in the respiratory system?

To allow for the sense of smell Signup and view all the answers

What structures make up the conducting portion of the respiratory system?

Nose and terminal bronchioles Signup and view all the answers

How does the respiratory system prevent dust particles from reaching the lungs?

Through filtration by nasal hairs Signup and view all the answers

Which function of the respiratory system is associated with vocalization?

Speech production through the larynx Signup and view all the answers

In which part of the respiratory system does gas exchange primarily occur?

Respiratory bronchioles and alveoli Signup and view all the answers

Which component is part of the lower respiratory tract?

Alveolar ducts Signup and view all the answers

Study Notes

Respiratory System Overview

The respiratory system provides oxygen (O2) to the body and removes carbon dioxide (CO2), a waste product of cells.
The system consists of two parts: the upper respiratory tract and the lower respiratory tract.

Respiratory Tract Structure

The respiratory tract is the anatomical structure through which air moves in and out.
The organs of the respiratory tract can be divided into two groups: the upper tract (nose, nasal cavity, sinuses, pharynx, and larynx) and the lower tract (trachea, bronchial tree, and lungs).

Conducting and Respiratory Portions

The conducting portion is a system of interconnecting cavities and tubes that conduct air into the lungs.
The respiratory portion is where the exchange of respiratory gases occurs.

Non-Respiratory Functions

The respiratory tract is involved in several non-respiratory functions, including:
Olfaction (olfactory receptors in the mucous membrane of nostrils)
Vocalization (larynx forms the speech apparatus)
Prevention of dust particles (filtration action of hairs in nasal mucous membrane)
Defense mechanism (defenses and various cell types in the mucous membrane lining alveoli)
Maintenance of water balance (water loss through expiration)
Regulation of body temperature (heat loss during expiration)
Regulation of acid-base balance (lungs regulate carbon dioxide content in blood)
Anticoagulant function (mast cells in lungs secrete heparin)
Secretion of angiotensin converting enzyme (endothelial cells of pulmonary capillaries)
Synthesis of hormonal substances (lung tissues synthesize hormonal substances)

Respiration

Respiration is the movement of oxygen (O2) from the environment to cells within tissues and the transport of carbon dioxide (CO2) in the opposite direction.
It involves the exchange of gases between the atmosphere, lungs, blood, and tissues.
Respiration is classified into two types: external respiration (exchange of gases between lungs and blood) and internal respiration (exchange of gases between blood and tissues).

Stages of Respiration

Pulmonary ventilation: inhalation and exhalation of air, involving the exchange of air between the atmosphere and lungs alveoli.
External respiration: exchange of gases between lung alveoli and blood in pulmonary capillaries.
Transport of respiratory gases: O2 and CO2 transported to and from the lungs and tissue cells via the bloodstream.
Internal respiration: exchange of gases between blood and tissue cells.

Lung Structure and Function

Lungs are paired, soft, spongy, and cone-shaped organs separated medially and enclosed by the diaphragm and thoracic cage.
Each lung is enclosed by a bilayered serous membrane called pleura or pleural sac.
The respiratory unit includes respiratory bronchioles, alveolar ducts, alveolar sacs, antrum, and alveoli, where the exchange of gases occurs.

Lung Expansion and Contraction

Lungs can be expanded and contracted in two ways:
Downward and upward movement of the diaphragm to lengthen or shorten the chest cavity.
Elevation and depression of ribs to increase and decrease the anteroposterior diameter of the chest cavity.

Inhalation and Exhalation

Inhalation (active process) involves:
External intercostal muscle contraction and internal intercostal muscle relaxation, expanding the rib cage.
Rib cage moving upward and forward.
Diaphragm contraction and flattening, increasing thoracic volume vertically.
Decreased intrapulmonary pressure, allowing air to push in.
Exhalation (passive process) involves:
External intercostal muscle relaxation and internal intercostal muscle contraction, reducing the rib cage.
Rib cage moving downward and backward.
Diaphragm relaxation, decreasing thoracic volume vertically.
Increased intrapulmonary pressure, allowing air to move out.