Respiratory System Overview

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Questions and Answers

What is the primary function of the respiratory system?

To provide oxygen to the blood (correct)

To regulate body temperature

Sound production

To filter out pollutants from the air

What is the purpose of the conchae in the nasal cavities?

To create turbulence in inspired air (correct)

To filter out dust particles

To warm the air

To detect odors

What type of epithelium lines the deeper areas of the nasal cavities?

Cuboidal epithelium

Simple columnar epithelium

Stratified squamous epithelium

Pseudostratified ciliated columnar epithelium (correct)

What is the function of the goblet cells in the respiratory epithelium?

To secrete mucus Signup and view all the answers

What is the purpose of the seromucous glands in the nasal cavities?

To humidify the air Signup and view all the answers

Which type of epithelium covers the roof and part of the superior concha?

Olfactory epithelium Signup and view all the answers

What is the primary function of the vocalis muscles in the larynx?

To produce sounds by vibrating the vocal folds Signup and view all the answers

What type of cartilage supports the trachea?

Hyaline cartilage Signup and view all the answers

What is the function of the smooth trachealis muscles in the posterior opening of the tracheal rings?

To facilitate the movement of air through the trachea Signup and view all the answers

What is the characteristic of the respiratory mucosa lining the bronchi and their branches?

It has a prominent spiraling band of smooth muscle Signup and view all the answers

What is the characteristic of bronchioles?

They are lined by simple columnar or cuboidal ciliated cells Signup and view all the answers

What type of cells line the terminal bronchioles?

Simple cuboidal epithelial cells Signup and view all the answers

What is the function of Clara cells in the terminal bronchioles?

To have innate immune and surfactant secretory functions Signup and view all the answers

What is the primary function of the cells lining the alveolar sac?

Surfactant secretion Signup and view all the answers

What type of fibers are found in the interalveolar septa?

Reticular and elastic fibers Signup and view all the answers

What is the purpose of the surfactant material secreted by Clara cells and type II alveolar cells?

To form a film and lower surface tension in alveoli Signup and view all the answers

What is the characteristic of the wall of each alveolus?

It consists of two cell types and a dense capillary network Signup and view all the answers

What is the structure formed by the fused basal laminae of the type I alveolar cells and the capillary endothelial cells?

Blood-air barrier Signup and view all the answers

What is the purpose of the visceral pleura?

To cover the lungs and line the pleural cavity Signup and view all the answers

What is the characteristic of the alveolar duct?

It is lined by a continuous series of alveoli and ends in a cluster of alveoli called the alveolar sac Signup and view all the answers

What is the ultrastructural characteristic of type II alveolar cells?

They have large granules with closely stacked layers of membrane Signup and view all the answers

What is the function of the lamellar bodies in type II alveolar cells?

Surfactant synthesis Signup and view all the answers

Study Notes

Functions of the Respiratory System

Provides oxygen to the blood
Has a secondary function of sound production in the larynx

Structure of the Respiratory System

Consists of an air conducting region and a respiratory region with alveoli
Air conducting region includes the upper respiratory tract, larynx, trachea, bronchi, and most bronchioles

Nasal Cavities

Left and right nasal cavities have vestibules where air enters
Vestibules have three projections called conchae that create turbulence in inspired air
Moist vibrissae in the vestibular openings filter some material from inspired air
Deeper areas of the nasal cavities are lined by respiratory epithelium

Respiratory Epithelium

Pseudostratified ciliated columnar epithelium
Includes goblet cells that secrete mucus
Includes ciliated columnar cells that sweep mucus along the surface
Includes chemosensory brush cells
Includes scattered endocrine cells
Includes basal stem cells

Olfactory Epithelium

Found on the roof and part of the superior concha in each nasal cavity
Pseudostratified epithelium containing bipolar olfactory neurons, support cells, and stem cells

Additional Features of the Nasal Cavities

Mucosa of the nasal cavities and nasopharynx contains a rich vasculature
Mucosa contains many seromucous glands that help warm, humidify, and clean inspired air

Larynx

Bilateral vocal folds (or cords) within the lumen of the larynx can be placed under variable tension by the underlying vocalis muscles.
Expelled air causes the vocal folds to vibrate, producing sounds.

Trachea

The trachea is completely lined by respiratory epithelium.
C-shaped rings of hyaline cartilage in the mucosa support the trachea.
Smooth trachealis muscles are located in the posterior opening of the rings.

Bronchial Tree

Left and right primary bronchi enter the two lungs and bifurcate repeatedly as secondary, tertiary, and smaller segmental bronchi.
The bronchial tree is lined by respiratory mucosa, with prominent spiraling bands of smooth muscle and increasingly smaller pieces of hyaline cartilage.
Bronchioles are branches of the bronchial tree with diameters of 1 mm or less.
Bronchioles are lined by simple columnar or cuboidal ciliated cells, with circular smooth muscle but no cartilage.

Terminal Bronchioles

Terminal bronchioles are the last branches to lack alveoli.
They are lined by simple cuboidal epithelium consisting mainly of Clara cells.
Clara cells have innate immune and surfactant secretory functions.

Respiratory Region

Terminal bronchioles subdivide into 2-3 respiratory bronchioles lined by simple cuboidal epithelium and Clara cells, with scattered squamous evaginations called alveoli, where gas exchange occurs.
Respiratory bronchioles lead to alveolar ducts, lined by continuous series of alveoli, ending in clusters of alveoli called alveolar sacs.

Alveoli Structure

Alveoli are surrounded by sparse connective tissue in interalveolar septa, composed primarily of elastic and reticular fibers and a dense capillary network.
Alveolar walls consist of two cell types: extremely thin type I alveolar cells (pneumocytes) and cuboidal type II alveolar cells with surfactant secreting and innate immune properties.

Type II Alveolar Cells

Type II alveolar cells are characterized by unique cytoplasmic lamellar bodies, large granules with closely stacked layers of membrane involved in surfactant synthesis.

Blood-Air Barrier

The blood-air barrier, allowing gas exchange at each alveolus, consists of thin type I alveolar cells, thin capillary endothelial cells, and fused basal laminae of these two cells.

Surfactant Production

Surfactant material, secreted by Clara cells and type II alveolar cells, is an oily mixture of phospholipids and surfactant proteins, forming a film that lowers surface tension in alveoli.

Pleural Layers

Each lung is covered by visceral pleura, a layer of thin connective tissue and mesothelium.
Visceral pleura is continuous with parietal pleura, a similar tissue layer lining the pleural cavity.

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Description

Learn about the functions and components of the respiratory system, including the air conducting region and respiratory region with alveoli.