Chapter 23: The Respiratory System

BIO 211 LabInstructor: Dr. Gollwitzer

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• Today in class we will discuss:– The structural divisions of the respiratory system

• Identify the components of the respiratory system– The respiratory tract

• Define the respiratory tract• Identify the functional divisions of the respiratory tract

– The respiratory mucosa• The respiratory mucosa and list its functions• The respiratory defense system and look at some of its

components– The upper respiratory system and its components

• Nose and nasal cavity• Pharynx • Paranasal sinuses

– The lower respiratory system and its components• Pharynx• Larynx 2

Structural Divisions

• Upper respiratory system– Above the larynx– Includes nose, nasal cavity, paranasal sinuses, pharynx– Filters, warms, and humidifies incoming air (“conditioning

process”)– Protects more delicate structures of lower respiratory system– Cools and dehumidifies outgoing air

• Lower respiratory system– From larynx down– Includes larynx (voice box), trachea (windpipe), bronchi,

bronchioles, alveoli

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Figure 23-1 The Components of the Respiratory System

Nasal cavity

Internal nares

Pharynx

Sphenoidal sinus

EsophagusClavicle

UPPERRESPIRATORYSYSTEM

LOWERRESPIRATORYSYSTEM

RIGHTLUNG

BronchiolesBronchus

TracheaLarynxHyoid bone

Tongue

NoseNasal conchae

Ribs Diaphragm

LEFTLUNG

RIGHTLUNG

Frontal sinus

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Respiratory Tract

• = Airways that carry air to/from exchange surfaces of lungs

• Functional divisions– Conducting portion• Nose to terminal bronchioles

– Respiratory portion• Respiratory bronchioles, alveolar ducts, and alveoli• Alveoli = air-filled pockets within lung where gas

exchange takes place

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Respiratory Mucosa• Mucous membrane– = Pseudostratified columnar epithelium + areolar tissue– Lines conducting portion of respiratory tract– Underlying mucous glands mucus

• Responsible for success of air conditioning process (prior to it reaching conducting respiratory portion)– Filters (traps dust and particles), warms, humidifies– When air reaches alveoli, most foreign particles and

pathogens removed and temperature and humidity at acceptable levels

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Figure 23-2bc The Respiratory Epithelium of the Nasal Cavity and Conducting System

Movementof mucus

to pharynx Ciliated columnarepithelial cell

Mucous cell

Stem cell

Mucus layer

Lamina propria

A diagrammatic view of therespiratory epithelium of the trachea, indicating the direction of mucus transport inferior to the pharynx.

The sectional appearance ofthe respiratory epithelium, apseudostratified ciliated columnar epithelium.

Stem cell

Basementmembrane

Mucous cell

Nucleus ofcolumnar

epithelial cell

Laminapropria

Cilia

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Respiratory Mucosa• Respiratory defense system– Goblet cells (single cell exocrine glands) and

mucous glands• Secrete sticky mucus that bathes exposed surfaces

– Cilia• Sweep mucous and trapped debris or microorganisms

toward pharynx (mucus escalator)

– Mucus is swallowed and exposed to acids/enzymes of the stomach

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Upper Respiratory System

• Nose and nasal cavity• Pharynx• Paranasal sinuses

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Figure 23-3c Structures of the Upper Respiratory System (Part 1 of 1)

Nasal cavity

Internal nares

Nasopharynx

Pharyngeal tonsil

Pharynx

Oropharynx

Laryngopharynx

Epiglottis

Entrance to auditory tube

GlottisVocal fold

Esophagus

The nasal cavity and pharynx, as seen in sagittalsection with the nasal septum removed

Thyroid gland

Trachea

Cricoid cartilage

Thyroid cartilage

Hyoid boneLingual tonsil

Mandible

Palatine tonsilSoft palate

Oral cavity

Tongue

Hard palateExternal nares

Nasal vestibule

Inferior

Middle

Superior

Nasal conchae

Frontal sinus

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Nose and Nasal Cavity• External naris (pl –es) = nostril opening• Nasal cavity (2) = space within nose– Nasal vestibule = space within flexible tissues of

the nose at the entrance to the nasal cavity– Coarse hairs prevent entry of foreign objects

• Nasal septum (that divides nasal cavity into two areas)– Bony portion fusion of parts of vomer and

ethmoid bones– Anterior portion formed from hyaline cartilage;

supports bridge and tip of nose

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Nose and Nasal Cavity• Superior, middle, inferior nasal conchae– Project from lateral walls of nasal cavity toward the nasal

septum– Air bounces off, churns; creates turbulence promotes

filtration, warms, and humidifies– Also creates eddy currents bring olfactory stimuli to

receptors– AKA: turbinates

• Superior, middle, inferior nasal meatuses (passages)– Narrow grooves through which air flows between adjacent

conchae

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Upper Respiratory System

Figure 23-3 13

Figure 17–1a

Nose and Nasal CavityOlfactory region• In superior nasal

cavity on either side of nasal septum

• Has olfactory epithelium– Specialized receptors

that provide sense of smell)

– Connected to olfactory bulb and tract (N I)

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Nose and Nasal Cavity• Hard palate

– Separates oral and nasal cavities– Forms floor of nasal cavity, roof of oral cavity– Formed by maxillary and palatine bones

• Soft palate– Fleshy extension posterior to hard palate– Marks boundary between nasopharynx and lower pharynx– Uvula = dangling process on posterior margin; helps prevent food

from entering pharynx prematurely

• Internal naris (pl –es)– Opening from nasal cavity into nasopharynx posterior to conchae

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Pharynx• Shared by respiratory and digestive systems• Extends from internal nares to entrances to

larynx and esophagus• Divided into:– Nasopharynx– Oropharynx– Laryngopharynx

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Pharynx• Nasopharynx– Superior portion of pharynx– Separated from oral cavity by soft palate– Contains pharyngeal tonsils, entrances to auditory (eustachian)

tubes

• Oropharynx– Middle part of pharynx (inferior to nasopharynx)– Posterior portion of oral cavity

• Laryngopharynx– Inferior part of pharynx– Between hyoid bone and entrance to larynx and esophagus

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Figure 23-3c Structures of the Upper Respiratory System (Part 1 of 1)

Nasal cavity

Internal nares

Nasopharynx

Pharyngeal tonsil

Pharynx

Oropharynx

Laryngopharynx

Epiglottis

Entrance to auditory tube

GlottisVocal fold

Esophagus

The nasal cavity and pharynx, as seen in sagittalsection with the nasal septum removed

Thyroid gland

Trachea

Cricoid cartilage

Thyroid cartilage

Hyoid boneLingual tonsil

Mandible

Palatine tonsilSoft palate

Oral cavity

Tongue

Hard palateExternal nares

Nasal vestibule

Inferior

Middle

Superior

Nasal conchae

Frontal sinus

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Paranasal Sinuses• Sinuses of the frontal, sphenoid, ethmoid and

paired maxillary and palatine bones– Spaces in the bones surrounding nasal passages

• Lighten skull weight• Lined with mucous membranes– Produce mucous secretions (plus tears through

nasolacrimal ducts)– Lubricate and clean nasal cavity surfaces

• Secretions increase in response to changes in:– Temperature and humidity– Viral or bacterial infection– Irritating vapors

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Lower Respiratory System

• Larynx (voice box)• Trachea (windpipe)• Bronchi• Bronchioles• Alveoli

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Larynx• Air leaves pharynx and enters larynx through

glottis (opening) • Comprised of incomplete cartilaginous walls

stabilized by ligaments and skeletal muscles• Cartilage surrounds and protects glottis• Walls formed by 9 cartilages– 3 Pairs of small cartilages– 3 Large, unpaired cartilages• Thryoid cartilage, cricoid cartilage, epiglottic cartilage

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Figure 23-4c 22

Larynx• Thyroid cartilage– Largest, anterior (hyaline) cartilage– Protects glottis and entrance to trachea– Forms anterior and lateral walls of larynx– Anterior laryngeal prominence (Adam’s apple)

• Cricoid cartilage– Inferior to thyroid cartilage– Ring-like hyaline cartilage– Also protects glottis and entrance to trachea

• Epiglotic cartilage (epiglottis)– Elastic cartilage– Forms lid over the glottis– Prevents entry of liquids or food into the larynx and rest of

respiratory tract23

Larynx• Laryngeal epithelial folds– Vestibular folds (false vocal cords)

• Superior folds in lateral walls• Help prevent foreign objects from entering glottis• Protect delicate vocal folds

– Vocal folds (true vocal cords)• Inferior folds in lateral walls• Also guard entrance to glottis• Involved in production of sounds

• Ventricle of larynx– Space between epithelial folds

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Figure 23-5 25

• Today in class we will continue our discussion of:– The lower respiratory system and its components• Pharynx• Larynx • Trachea• Bronchi

– Lungs– Bronchial tree

• Bronchioles– Alveolar ducts– Alveolar sac

• Alveoli of the lungs– Respiratory membrane

– The blood supply to and from the lungs– Muscles involved in respiration– Respiratory pathology and diseases 26

Trachea• Tough, flexible tube• Comprised of:– 15-20 C-shaped/tracheal cartilages (hyaline)– Tracheal ligaments bind cartilages together– Carina = internal ridge at end of trachea that

separates bronchi

• Branches to form R and L primary bronchi• Tracheostomy– Insertion of tube into trachea to bypass blocked

or damaged trachea27

Figure 23-6a 28

Lungs• In thoracic cavity (walls are ribcage, floor is diaphragm)• Lie within two pleural cavities separated by mediastinum

(central tissue mass)• Lined by pleura (serous membranes, like pericardium)

– Parietal pleura – covers inner surface of thoracic (chest) wall and extends over diaphragm and mediastinum

– Visceral pleura – covers outer surfaces of lungs, extending into fissures between lobes

• Pleurae secrete pleural fluid moist, slippery coating that lubricates, reducing friction between parietal and visceral surfaces as you breathe

• Pleurisy = normal pleural fluid coating unable to prevent friction pain and pleural inflammation, breathing becomes difficult

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Relationship between Lungs and Heart

Figure 23–8 30

Lungs• Hilus = where root (primary bonchus, blood vessels, nerves)

enters• Shape = blunt cone

– Superior apex – extends into base of neck superior to first rib– Inferior base – rests on superior surface of diaphragm

• Separated into lobes divided by fissures– Right lung

• Superior, middle, inferior lobes (N=3)• Horizontal and oblique fissures

– Left lung• Superior, inferior lobes (N=2)• Oblique fissure• Narrower than R lung (heart and great vessels project into left thoracic

cavity)• Longer than R lung (diaphragm rises on right side to accommodate liver

mass)• Cardiac notch accommodates heart

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Figure 23-7c, 7th edition 32

Figure 23-7b, 7th edition 33

Lungs• Pulmonary lobules– Formed by interlobular septa (finest partitions) – Each supplied by branches of pulmonary arteries,

veins, and respiratory passageways

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Bronchial Tree• Formed by primary bronchi and branches• Progresses from less cartilage to more smooth muscle• R and L primary bronchi (extrapulmonary bronchi)– Also have cartilaginous C-shaped supporting rings– Carina (ridge at base of trachea) separates two bronchi– R primary bronchus

• Larger in diameter than L• Steeper angle toward lung than L• Route of most foreign objects

• Each primary bronchus branches to form secondary bronchi

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Figure 23-9a, 7th edition 36

Bronchial Tree

• Intrapulmonary bronchi (inside lungs)– Secondary bronchi• One to each lobe (R = 3; L = 2)• In each lobe, secondary bronchi branch to form tertiary

bronchi

– Tertiary bronchi• Each supplies air to specific region of one lung =

bronchopulmonary segment (8-10/lung)• Branch to form bronchioles

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Bronchial Tree• Bronchioles– “Arterioles” of respiratory system– Walls dominated by smooth muscle– ANS controls diameter and airflow• Bronchodilation = enlargement of airway diameter

decreased resistance• Brochoconstriction = reduction of airway diameter

increased resistance. Also occurs in asthma and allergic reaction (e.g. anaphylaxis, in response to histamine release by basophils and mast cells)

– Each bronchiole 6,500 terminal bronchioles38

Bronchial Tree• Terminal bronchioles– Each one delivers air to a single pulmonary lobule

• Pulmonary lobule– Smallest compartments of lung; divided by interlobular

septa– Each one supplied by pulmonary arteries and veins

• Within lobule, each bronchiole branches to form several respiratory bronchioles

• Respiratory bronchioles– Thinnest, most delicate branches– Deliver air to gas exchange surfaces of lungs– Lined by simple cuboidal epithelium (also lines terminal

bronchioles) 39

Bronchial Tree• Summary– Primary bronchus (to lung) – Secondary bronchus (to lobe) – Tertiary bronchus – Bronchiole – Terminal bronchiole (to lobule) – Respiratory bronchioles – Alveolar ducts – Alveolar sac – Alveolus

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Alveolar Ducts and Alveoli• Respiratory bronchioles alveolar ducts

which end at alveolar sacs• Alveolar sacs = common chambers connected

to multiple individual alveoli• Alveoli (sing. = alveolus)– Blind pockets at end of respiratory tree– Sites of gas exchange with blood– 50 million alveoli per lung open, spongy

appearance

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Alveolar Ducts and Alveoli• Alveolar epithelium– Lines exchange surfaces of alveoli– Consists of simple squamous epithelium

• Very thin, delicate• aka Type 1 cells

• Contains septal cells (Type II cells)– Produce surfactant– Surfactant

• Oily secretion, mixture of phospholipids and proteins• Coats alveolar surface• Reduces surface tension so alveoli don’t collapse

• Alveolar macrophages (dust cells)– Patrol epithelial surfaces, phagocytosing particles

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Alveolar Ducts and Alveoli

• Pores of Kohn = small openings in wall between alveoli

• Each alveolus surrounded by:– Extensive capillary network• For gas exchange (O2 and CO2)

– Elastic fibers• Recoil during exhalation• Reduce size of alveolus and helps push air out of

lungs

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Figure 23-9b 44

Respiratory Membrane

• Site of gas exchange• 3-part structure– Squamous epithelial lining of alveolus– Endothelial cells lining adjacent capillary– Fused basement membranes that lie between

alveolar and endothelial cells• Diffusion very rapid– Distance is very small– Both O2 and CO2 are lipid soluble– Membranes do not pose barrier between

blood and alveolar air spaces45

Figure 23-11c 46

Figure 23-12 47

Blood Supply to/from Lungs• To/from respiratory exchange surfaces– Pulmonary artery enters lungs at hilus and branches

within bronchi• Each lobule receives a pulmonary arteriole (and venule)• Network of (pulmonary) capillaries surrounds each alveolus as

part of respiratory membrane– Blood from alveolar capillaries passes through

pulmonary venules (also 1/lobule) to pulmonary veins– Returns to L atrium

• To/from conducting passageways– Capillaries supplied by bronchial arteries

• Provide O2 and nutrients to tissues of respiratory tract– Venous blood flows into pulmonary veins– Returns to L atrium

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Respiratory Muscles

• Most important– Diaphragm– External intercostals (raise ribs)

• Accessory muscles– Kick in when breathing deeply/frequently – e.g.,• Internal intercostals• Pectoralis minor• Sternocleidomastoid• Serratus anterior

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Figure 23-16, 7th edition 50

Respiratory Pathology/Diseases• Cystic fibrosis (CF)

– Lethal inherited disease– Respiratory mucosa produces dense, viscous mucus that cannot be

transported by respiratory defense system– Mucus blocks smaller respiratory passageways, reduces diameter of

airways, makes breathing difficult– Inactivation of normal respiratory defenses leads to frequent bacterial

infections• Tuberculosis (TB)

– Results from bacterial infection of lungs (Mycobacterium tuberculosis)– May colonize respiratory passageways, interstitial spaces, alveoli, or

combination– Symptoms variable, but generally include coughing, chest pain, fever,

night sweats, fatigue, weight loss

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Respiratory Pathology/Diseases• Pneumonia

– Develops from pathogenic infection or anything else that causes inflammation of lung lobules

– As inflammation occurs, fluids leak into alveoli, respiratory bronchioles swell and constrict

– Respiratory function deteriorates– More likely when respiratory defenses compromised (e.g. epithelial

damage from smoking, breakdown of immune system with AIDS)• Pulmonary embolism

– Pulmonary system blood pressure low (< 30 mm Hg)– Pulmonary vessels can easily become blocked by small blood clots, fat

masses, air bubbles in pulmonary arteries– Stops blood flow to group of lobules or alveoli– Alveoli permanently collapse, pulmonary resistance increases, strains

heart, unable to maintain cardiac output CHF (congestive heart failure)

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