Chapter 23: Respiratory system

respiratory system

consists of the nose, nasal cavity, pharynx (throat), larynx (voice box), trachea (windpipe), bronchi, and lungs

2 Structural Parts of the Respiratory System

(1) upper respiratory system
(2) lower respiratory system

upper respiratory system

includes nose, nasal cavity, pharynx, and associated structures

lower respiratory system

includes larynx, trachea, bronchi, and lungs

pulmonary ventilation, external respiration, and internal respiration

Three basic steps

Pulmonary ventilation

* inhalation and exhalation of air
* Exxhange of air between the **atmoshpere and the pulmonary alveoli of the lungs**
* Inhalation permits O2 to enter the lungs and exhalation permits CO2 to leave the lungs

External respiration

* exchange of gases between the **pulmonary alveoli of the lungs and the blood in pulmonary capillaries** across the respiratory membrane
* pulmonary capillary blood gains O2 and loses CO2.

Internal respiration

* exchange of gases between **blood in systemic capillaries and tissue cells**
* blood loses O2 and gains CO2

conducting zone, respiratory zone

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2 Functional Parts of the Respiratory System

conducting zone

consists of a series of interconnecting cavities and tubes both outside and within the lungs
*Structures:*
- nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles

respiratory zone

consists of tubes and tissues within the lungs where *gas exchange occurs*
*Structures:*
- respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

\---\> the main site of gas exchange between air and blood

otorhinolaryngology

The branch of medicine that deals with the diagnosis and treatment of diseases of the ears, nose, and throat (ENT)

Pulmonologist

person that specializes in studying diseases, diagnosis, treatment associated with lungs/respiratory system

nose

a special organ at the entrance to the respiratory system
*Divided into:*
- external nose
(visible external portion)
- nasal cavity
(internal portion within skull)

external nose

the skin and muscle-covered portion of the nose visible on the face


1. consists of a supporting framework of bone and hyaline cartilage covered with muscle and skin and lined by a mucous membrane.
2. two entryways (nostrils)

frontal bone, nasal bones, and maxillae

Form the bony framework of the external nose

nasal septal cartilage

forms the anterior portion of the nasal septum

nasal septum

a partition that divides the external nose into left and right chambers

bony nasal septum

perpendicular plate of ETHMOID and VOMER
- connect to the septal nasal cartilage to form nasal septum

lateral nasal cartilages (paired)

form the sides o the mid-portion of the external nose

major alar cartilages (paired)

form the sides of the inferior portion of the external nose
- form lateral and medial borders of the nostrils

minor alar cartilages

three or four small pieces of cartilage posterior to the major alar cartilages

What are the structures of the cartilaginous framework of the external nose?

- lateral nasal cartilages
- septal nasal cartilage
- major alar cartilages
- minor alar cartilages

\---\> These structures help keep nasal vestibules and nasal cavity open and unobstructed

What type of cartilage makes up the cartilaginous framework of the external nose?

hyaline cartilage

external nares (nostrils)

opening into the external nose which lead into cavities (nasal vestibules)

nasal vestibules

space formed between external nares and nasal conchae

- lower half: skin, hair, sebaceous, sweat glands
- upper half: mucous membrane (continues deeper into cavity)

nasal cavity (internal nose)

deeper region *beyond the nasal vestibules*

* a large space that forms the majority of the nose
* lined by mucous membrane and muscle

internal nares (choanae)

two openings that connect the nasal cavity to the nasopharynx

What ducts open into the nasal cavity?

- ducts from the paranasal sinuses (frontal, maxillary, sphenoidal, and ethmoidal)
- nasolacrimal ducts (from lacrimal glands of eyes)

paranasal sinuses

* drain mucus
* cavities in cranial cavity and facieal bones lined with mucous membrane that are continuous with the lining of the nasal cavity
* Serves as a resonating chambers for sound as we speak or sing

Nasolacrimal ducts

drain tears

2 Regions of the Nasal Cavity

(1) respiratory region
(2) olfactory region

* nasal vestibules
* the nasal cavity

What structures does the nasal septum divide into halves?

nasal vestibule

When air enters the nostrils, it passes first through

deviated spetum

cartilage can become displaced to one side during healing; makes breathing more difficult on narrower side of nose

nasal conchae

three projections that extend from lateral walls into the nasal cavity
- formed from superior, middle, and inferior nasal conchae

nasal meatuses (superior, middle, inferior)

subdivisions of the nasal cavity created by the nasal conchae
- superior, middle, and inferior nasal meatuses

Tonsillectomy

surgical removal of the tonsils

What are the functions of the nasal conchae and nasal meatuses?

- Increases surface area in the nasal cavity
- Traps water during exhalation, preventing dehydration of mucous membrane

olfactory epithelium

thin membrane lining the superior nasal conchae
- contains olfactory receptor cells, supporting cells, and basal cells
- contains cilia but NO goblet cells

respiratory epithelium

pseudostratified ciliated columnar epithelium
- contains cilia and goblet cells

3 Functions of the Interior Structures of the Nose

(1) warm, moisten, and filter incoming air
(2) detect olfactory stimuli
(3) modify speech vibration as they pass through the resonating chambers

pharynx (throat)

5 in. tube that starts at the internal nares and extends to the level of the cricoid cartilage (most inferior cartilage of the larynx)
- composed of skeletal muscle (voluntary)
- lined with mucous membrane

Function of the Pharynx

- passageway for food and air
- resonating chamber for speech and sounds
- houses tonsils (immune response)

3 Anatomical Divisions of Pharynx

(1) nasopharynx
(2) oropharynx
(3) laryngopharynx

nasopharynx

lies posterior to nasal cavity and extends to the plane of soft palate
-ciliated pseudostratified columnar epithelium

\---\> ONLY respiratory function

soft palate

forms the posterior portion of the roof of the mouth,

* arch-shaped muscular partition between the nasopharynx and oropharynx that is lined by mucous membrane

5 Opening of the Nasopharynx

(2) internal nares
(2) openings of the auditory tube
(1) opening into oropharynx

pharyngeal tonsil (adenoid)

posterior wall of the nasopharynx

oropharynx

intermediate portion of the pharynx posterior to oral cavity
- extends from soft palate to the level of the hyoid bone
- nonkeratinized stratified squamous epithelium

\---\> BOTH respiratory and digestive function

fauces (oropharynx)

* opening to pharynx from mouth
* has both respirator and digestive functions

2 Pairs of Tonsils of the Oropharynx

(1) palatine tonsils
(2) lingual tonsils

laryngopharynx

inferior portion of the pharynx beginning at the hyoid bone
- opens into the esophagus (posteriorly) and the larynx (anteriorly)
- nonkeratinized stratified squamous epithelium

\---\> BOTH respiratory and digestive function

larynx

a short passageway that connects the laryngopharynx with the trachea

9 Cartilages of the Larynx

*Single:*
- epiglottis
- thyroid cartilage
- cricoid cartilage
*Paired:*
- cuneiform cartilages
- corniculate cartilages
- arytenoid cartilage

arytenoid cartilages
(paired)

most important cartilage because it influence the positions and tensions of the vocal folds (true vocal cords)

laryngeal cavity

the space that extends from the laryngeal entrance to the inferior border of cricoid cartilage

2 Divisions of the Cavity of the Larynx

(1) laryngeal vestibule
(2) infraglottic cavity

laryngeal vestibule

space in the larynx above the vestibular folds (false vocal cords)

infraglottic cavity

portion of the cavity of the larynx below the vocal folds (true vocal cords)

thyroid cartilage

consists of two fused plates of hyaline cartilage that form the upper anterior and lateral walls of the larynx
- largest cartilage of the larynx
- forms the Adam's apple

thyrohyoid membrane

ligament that connects the thyroid cartilage to the hyoid bone

epiglottis

large leaf-shaped *elastic cartilage* covered with epithelium
- attaches to anterior rim of thyroid cartilage
- closes off larynx during swallowing

glottis

narrowed passageway through the larynx
*Consists of:*
- folds of mucous membrane
- vocal folds of the larynx
- rima glottidis

rima glottidis

space between the vocal folds (true vocal cords)

cricoid cartilage

a ring of hyaline cartilage that forms the inferior wall of the larynx

cricotracheal ligament

attaches the trachea (first ring of cartilage) to the larynx (cricoid cartilage)

cricothyroid ligament

* connects cricoid cartilage to thyroid cartilage
* landmark for making an emergency airway (tracheotomy)

arytenoid cartilages

* triangular pieces of mostly hyaline cartilage located at the posterior, superior border of the cricoid cartilage
* form synovial joints with the cricoid cartilage and have a wide range of mobility.

corniculate cartilages

horn-shaped *elastic cartilage* located at the apex of each arytenoid cartilage

cuneiform cartilages

club-shaped elastic cartilages anterior to the corniculate cartilages

* support the vocal folds and lateral aspects of the epiglottis

Epithelium of the Larynx

*Superior to vocal folds:*
- nonkeratinized stratified squamous epithelium
*Inferior to vocal folds:*
- ciliated pseudostratified columnar epithelium

Where does mucus of the respiratory tract go?

- Cilia pushes mucus towards the pharynx (to be swallowed).

Vestibular folds and Vocal folda

Two pairs of folds formed by the mucous membrane of larynx

vestibular folds

false vocal cords
- superior to vocal folds
- NO part in voice production
- help to hold breath against pressure of thoracic cavity (e.g. heavy lifting)

vocal folds

true vocal cords

* principal structures of voice production
*Epithelium of mucous membrane:*
* nonkeratinized stratified squamous epithelium

\---> High muscle tension = high pitch; Low muscle tension = low pitch

rima vestibuli

space between vestibular folds (false vocal cords)

laryngeal ventricle

lateral expansion of the middle portion of the laryngeal cavity inferior to the vestibular folds and superior to the vocal folds

Resonating Chambers for Speech

pharynx, mouth, nasal cavity, and paranasal sinuses

- sound vibrations originate from vocal folds

Whsipering

accomplished by closing all but the posterior portion of the rima glottidis

trachea

a tubular passageway for air anterior to the esophagus
- extends from larynx to T5 vertebra where into divides into main bronchi

Laryngitis

inflammation of the larynx that is most often caused by a respiratory infection or irritants

Cancer of the larynx

characterized by hoarseness, pain on swallowing, or pain radiating to an ear

trachea

tubular passageway for air located anterior to the esophagus

4 Layers of the Tracheal Wall

Innermost to outermost layer:
(1) mucosa
(2) submucosa
(3) fibromusculocartilaginous layer
(4) adventitia

mucosa (trachea)

(1) Epithelial layer:
- *ciliated pseudostratified columnar epithelium* w/ goblet cells
(2) Underlying lamina propria layer:
- elastic and reticular layer

submucosa (trachea)

*areolar connective tissue*
- contains seromucous glands and their ducts

fibromusculocartilaginous layer (trachea)

16-20 incomplete "C"-shaped horizontal rings of *hyaline cartilage* joined together by dense connective tissue
- prevents collapse of trachea

fibromuscular membrane

spans the open part of each C-shaped cartilage ring of the trachea
- contains trachealis muscle

trachealis muscle

transverse smooth muscle fibers that allows diameter of trachea to change

adventitia

*areolar connective tissue* that joins the trachea to surrounding tissues

2 Divisions of the Trachea

(1) right main bronchus
(2) left main bronchus

\---\> lined w/ ciliated pseudostratified columnar epithelium

right main bronchus

shorter, wider, and more vertical than the left main bronchus
- aspirated objects more likely to be lodged here

left main bronchus

slightly narrower and more horizontal than the right main bronchus

carina

internal ridge at the point where the trachea bifurcates into main bronchi
- sensitive mucous membrane;
triggers cough reflex

carcinoma

Widening and distortion of carina can lead to _____

secondary (lobar) bronchi

upon entering lungs, the main bronchi divide
- one secondary bronchus for each lobe of the lung (3 right, 2 left)
- *5 total*

How many lobes are in each lung?

- 3 lobes in right lung
- 2 lobes in left lung

tertiary (segmental) bronchi

supply the specific bronchopulmonary segments within the lobes of the lungs
- divisions of secondary bronchi
- *20 total*

terminal bronchioles

- smallest bronchioles
- end of conducting zone