Respiratory System

AP2

Objectives


Describe the primary functions of the respiratory system



Identify the organs of the respiratory system and describe their functions



Define and compare the process of external respiration and internal respiration



Trace the path of air through the respiratory system

The need for the respiratory system

•Cells produce energy

•For maintenance, growth, defense, and division

•Through mechanisms that use oxygen and produce carbon dioxide

O2-CO2 exchange

Oxygen

Is obtained from the air by diffusion across delicate exchange surfaces of lungs

Is used in metabolic reactions


Carbon Dioxide

Is a by product of metabolic reactions and must be limited. It is carried by the cardiovascular system to the lungs

Five Functions of the Respiratory System

1.Provides extensive gas exchange surface area between air and circulating blood

2.Moves air to and from exchange surfaces of lungs

3.Protects respiratory surfaces from outside environment

4.Produces sounds

5.Participates in olfactory sense

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Where the air flows..

•Nose

•Nasal sinuses

•Pharynx (nasopharynx, oropharynx, laryngopharynx)

•Trachea

•Primary bronchioles

•Secondary bronchioles

•Tertiary bronchioles

•Terminal bronchioles

•Aveolar duct

•Aveoli

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Organization of the Respiratory System

The respiratory system is divided into:

Upper respiratory system – above the larynx

Lower respiratory system – below the larynx

Another way of dividing the Respiratory Tract

Conducting portion

From nasal cavity to terminal bronchioles


Respiratory portion

The respiratory bronchioles and alveoli

Alveoli: air-filled pockets within the lungs

Where all gas exchange takes place

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Airflow through the upper respiratory tract in detail

The Nose

Air enters the respiratory system through nostrils or external nares into nasal vestibule

Nasal hairs are in nasal vestibule and are the first particle filtration system

The Nasal Cavity

The nasal septum divides nasal cavity into left and right

Superior portion of nasal cavity is the olfactory region (olfactory epithelium)

Provides sense of smell

Mucous secretions from paranasal sinus and tears clean and moisten the nasal cavity

Internal nares

Through superior, middle, and inferior meatuses


Meatuses are constricted passageways that produce air turbulence

Warm and humidify incoming air trap particles

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The Palates

Hard palate

Forms floor of nasal cavity

Separates nasal and oral cavities


Soft palate

Extends posterior to hard palate

Divides superior nasopharynx from lower pharynx

Nasal cavity opens into nasopharynx through internal nares


The Nasal Mucosa

Warms and humidifies inhaled air for arrival at lower respiratory organs


Breathing through mouth bypasses this important step

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Pharynx


The Nasopharynx

Superior portion of pharynx

Contains pharyngeal tonsils and openings to left and right auditory tubes


The Oropharynx

Middle portion of pharynx

Communicates with oral cavity


The Laryngopharynx

Inferior portion of pharynx

Extends from hyoid bone to entrance of larynx and esophagus

Cartilages of the Larynx


Three large, unpaired cartilages form the larynx

Thyroid cartilage

Cricoid cartilage

Epiglottis

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The Thyroid Cartilage

Consists of hyaline cartilage

Forms anterior and lateral walls of larynx

Anterior surface called laryngeal prominence, or Adam’s apple

Ligaments attach to hyoid bone, epiglottis, and laryngeal cartilages

The Cricoid Cartilage

Is hyaline cartilage

Forms posterior portion of larynx

Articulates with arytenoid cartilages

Ligaments attach to first tracheal cartilage

The Epiglottis

Composed of elastic cartilage

Ligaments attach to thyroid cartilage and hyoid bone

Cartilage Functions

Thyroid and cricoid cartilages support and protect the glottis (the entrance to trachea)



During swallowing:

The larynx is elevated

The epiglottis folds back over glottis

Prevents entry of food and liquids into respiratory tract

The Larynx Contains Three Pairs of Smaller Hyaline Cartilages

1. Arytenoid cartilages

2. Corniculate cartilages

3. Cuneiform cartilages

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Cartilage Functions

Corniculate and arytenoid cartilages function in:

Opening and closing of glottis

Production of sound

Histological Components

The Respiratory Mucosa

Consists of:

An epithelial layer (pseudostratified ciliated columnar epithelia)

An areolar layer called the lamina propria

Lines the conducting portion of respiratory system
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Structure of Respiratory Epithelium

Pseudostratified ciliated columnar epithelium with numerous mucous cells

Nasal cavity and superior portion of the pharynx


Stratified squamous epithelium in the inferior portions of the pharynx


Pseudostratified ciliated columnar epithelium in the superior portion of the lower respiratory system


Cuboidal epithelium with scattered cilia in the smaller bronchioles

Alveolar Epithelium

Is a very delicate, simple squamous epithelium that contains scattered and specialized cells

Lines exchange surfaces of alveoli

The Respiratory Epithelium

For gases to exchange efficiently:

Alveoli walls must be very thin (<1 µm)

Surface area must be very great (about 35 times the surface area of the body)

The Lamina Propria

Underlying layer of areolar tissue that supports the respiratory epithelium

In the upper respiratory system, trachea, and bronchi

It contains mucous glands that secrete onto epithelial surface

In the conducting portion of lower respiratory system

It contains smooth muscle cells that encircle lumen of bronchioles