The Respiratory System• Basic functions of the respiratory system

• Breathing (Pulmonary Ventilation) – movement of air in and out of the lungs• Inhalation (inspiration) draws gases into the lungs.• Exhalation (expiration) forces gases out of the lungs.

• Gas Conditioning – as gases pass through the nasal cavity and paransal sinuses, inhaled air becomes turbulent. The gases in the air are

• warmed to body temperature• humidified• cleaned of particulate matter

• Gas Exchange - respiration• Supplies body with oxygen• Disposes of carbon dioxide

• Produces Sounds

• Protects respiratory surfaces

• Site for olfactory sensation

Respiration

• Respiration – four distinct processes must happen• Pulmonary ventilation – moving air into and out of

the lungs• External respiration – gas exchange between the

lungs and the blood• Transport – transport of oxygen and carbon dioxide

between the lungs and tissues• Internal respiration – gas exchange between

systemic blood vessels and tissues

Functional Anatomy of the Respiratory System

• Respiratory organs• Nose, nasal cavity, and paranasal sinuses• Pharynx, larynx, and trachea• Bronchi and smaller branches• Lungs and alveoli

Organs of the Respiratory System

Figure 21.1

Respiratory System

• Consists of• Respiratory muscles – diaphragm and

other muscles that promote ventilation• Respiratory zone – site of external

respiration – respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

• Conducting zones• Provides rigid conduits for air to

reach the sites of gas exchange• Includes nose, nasal cavity,

pharynx, trachea• Air passages undergo 23 orders of

branching in the lungs

The Nose• Provides an airway for

respiration• Moistens and warms air• Filters inhaled air• Resonating chamber for

speech• Houses olfactory receptors• Skin is thin – contains

many sebaceous glands

The Nasal Cavity• External nares – nostrils• Divided by – nasal septum• Vestibule - anterior opening • Continuous with nasopharynx• Two types of mucous membrane

• Olfactory mucosa - Near roof of nasal cavity, houses olfactory (smell) receptors

• Respiratory mucosa - Lines nasal cavity

• Epithelium is pseudostratified ciliated columnar

• Goblet cells within epithelium • Underlying layer of lamina propria

has glands that contribute to the mucus layer and blood vessels that warm the air.

• Cilia move contaminated mucus posteriorly

Nasal Cavity

Nasal Conchae• 3 paired bony projections

along the lateral walls of the nasal cavity

• Superior and middle nasal conchae - part of the ethmoid bone

• Inferior nasal conchae - separate bone

• Function - Particulate matter deflected to mucus-coated surfaces

The Paranasal Sinuses

Figure 7.11a, b

The Pharynx• Funnel-shaped passageway• Connects nasal cavity and

mouth• Shared by the digestive and

respiratory systems• Divided into three sections by

location• Nasopharynx – superior

portion, • Oropharynx – continuous

with the oral cavity• Laryngopharynx – between

the hyoid bone and the esophagus

• Type of mucosal lining changes along its length

The Nasopharynx

• Superior to the point where food enters

• Only an air passageway• Closed off during

swallowing• Epithelium consists of

ciliated pseudostratified epithelium that moves mucus

The Oropharynx• Arch-like entranceway –

fauces• Extends from soft palate to

the epiglottis• Epithelium - stratified

squamous epithelium• Two types of tonsils in the

oropharynx• Palatine tonsils – in the

lateral walls of the fauces • Lingual tonsils – covers

the posterior surface of the tongue

The Laryngopharynx

• Passageway for both food and air

• Epithelium - stratified squamous epithelium

• Continuous with the esophagus and larynx

The Larynx• Prevent food and drink from entering the trachea• Passageway for air• Produces Sound• It connects the pharynx to the trachea• Epithelium of the larynx

• Stratified squamous – superior portion• Pseudostratified ciliated columnar – inferior portion

Nine Cartilages of the Larynx• Thyroid cartilage - shield-shaped, forms laryngeal prominence

(Adam’s apple)• Three pairs of small cartilages

• Arytenoid cartilages• Corniculate cartilages• Cuneiform cartilages

• Epiglottis - tips inferiorly during swallowing

The Larynx

• Vocal ligaments of the larynx• Vocal folds (true vocal

cords) - act in sound production

• Vestibular folds (false vocal cords) - no role in sound production

• Voice production • Length of the vocal folds

changes with pitch• Loudness depends on the

force of air across the vocal folds

The Trachea• Descends into the mediastinum• C-shaped cartilage rings keep airway open• Carina - marks where trachea divides into two primary

bronchi• Epithelium - pseudostratified ciliated columnar

The Trachea

Figure 21.7a, b

Bronchi in the Conducting Zone• Bronchial tree - extensively

branching respiratory passageways• Primary bronchi (main

bronchi)• Largest bronchi • Right main bronchi - wider

and shorter than the left• Secondary (lobar) bronchi

• Three on the right • Two on the left

• Tertiary (segmental) bronchi - branch into each lung segment

• Bronchioles - little bronchi, less than 1 mm in diameter

• Terminal bronchioles - less than 0.5 mm in diameter

Tissue Composition of Conducting Zone• Changes along pathway• Supportive connective tissues change

• C-shaped rings – trachea, primary bronchi• Replaced by cartilage plates, secondary & tertiary bronchi

• Epithelium changes• First, pseudostratified ciliated columnar – trachea• Replaced by simple columnar - bronchi• Then simple cuboidal epithelium - bronchioles and

terminal bronchioles • Smooth muscle becomes important at the bronchioles -

controlled by the ANS (bronchoconstriction and bronchodilation).

Lobes and Surfaces of the lungs• Right lung has three lobes• Left lung has two lobes• Concavity on medial surface = cardiac notch• Bronchi enter the lungs at the hilus

The Pleurae• A double-layered sac surrounding each lung

• Parietal pleura• Visceral pleura

• Pleural cavity - potential space between the visceral and parietal pleurae• Pleurae help divide the thoracic cavity

• Central mediastinum • Two lateral pleural compartments

Structures of the Respiratory Zone

• Consists of air-exchanging structures• Respiratory bronchioles – branch from terminal

bronchioles• Lead to alveolar ducts

• Lead to alveolar sacs

Structures of the Respiratory Zone

Figure 21.9b

Features Of Alveoli

Figure 21.10b

• Alveoli cell types• Type I cells site of gas exchangeand• Type II cells - secrete surfactant• Macrophages

• Surrounded by basal laminae and elastic fibers• Interconnect by way of alveolar pores• Internal surfaces - site for free movement of alveolar macrophages