The Respiratory SystemThe Respiratory SystemCh 22Ch 22

Human AnatomyHuman AnatomySonya Schuh-Huerta, Ph.D.Sonya Schuh-Huerta, Ph.D.

Leonardo Da Vinci

The Upper Respiratory Tract

Sphenoid sinusFrontal sinus

Nasal meatuses(superior, middle,and inferior)

Nasopharynx

Uvula

Palatine tonsilIsthmus of thefauces

Posterior nasalaperture

Opening ofpharyngotympanictube

Pharyngeal tonsil

Oropharynx

Laryngopharynx

Vocal fold

Esophagus

Nasal conchae(superior, middle and inferior)

Nasal vestibuleNostril

Nasal cavity

Hard palate

Soft palate

Tongue

Lingual tonsil

Epiglottis

Hyoid boneLarynx

Thyroid cartilageVestibular fold

Cricoid cartilage

Thyroid gland

Trachea

Cribriform plateof ethmoid bone

Organs of the Respiratory System

Nasal cavity

Trachea

Carina of trachea

Left main (primary) bronchus

Right main (primary) bronchus

Right lung

Parietalpleura

Left lung

Alveoli

Bronchi

NostrilOral cavityPharynx

Larynx

Diaphragm

Bronchi in the Conducting Zone

TracheaSuperior lobe of right lung

Middle lobe of right lung

Inferior lobe of right lung

Superior lobe of left lung

Left main(primary) bronchusLobar(secondary)bronchus

Segmental(tertiary)bronchus

Inferior lobeof left lung

(a) The branching of the bronchial tree

Structures of the Respiratory Zone

Alveolar duct

Alveolar ductAlveoli

Alveolarsac

Respiratory bronchioles

Terminalbronchiole

(a)

Alveoli & the Respiratory Membrane

Elasticfibers

(a) Diagrammatic view of capillary-alveoli relationships

Smoothmuscle

Alveolus

Capillaries

Terminal bronchioleRespiratory bronchiole

Anatomy of Alveoli & the Respiratory Membrane

Alveolus

Capillary

Type II (surfactant-secreting) cell

Type I cell of alveolar wall

Endothelial cell nucleusMacrophage

Alveoli (gas-filledair spaces)

Red blood cellin capillary

Alveolar pores

Capillary endothelium

Fused basement membranes of the alveolar epitheliumand the capillary endothelium

Alveolar epitheliumRespiratorymembrane

Red blood cell

O2

Alveolus

CO2

Capillary

Nucleus of type I(squamousepithelial) cell

(c) Detailed anatomy of the respiratory membrane

The Respiratory System

• Basic functions of the respiratory system– Supplies body with oxygen– Disposes of carbon dioxide

• 4 processes involved in respiration:– Pulmonary ventilation– External respiration– Transport of respiratory gases– Internal respiration

Functional Anatomy of the Respiratory System

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

Organs of the Respiratory System

• Divided into– Conducting zone– Respiratory zone

The Nose

• Provides an airway for respiration

• Moistens & warms air (humidifies air)

• Filters inhaled air

• Resonating chamber for speech

• Houses olfactory receptors (olfaction)

The Nose

• Size variation due to differences in nasal cartilages

• Skin is thin contains many sebaceous glands

Frontal bone

Nasal bone

Septal cartilage

Maxillary bone(frontal process)

Lateral process ofseptal cartilage

Minor alar cartilages

Major alarcartilages

Dense fibrousconnective tissue

(b) External skeletal framework

Epicranius,frontal belly

Ala of nose

Root and bridgeof nose

Dorsum nasi

Apex of nose

Philtrum

Naris (nostril)

(a) Surface anatomy

The Nasal Cavity

• External nares nostrils

• Divided by nasal septum

• Continuous with nasopharynx

Nasal Cavity

• 2 types of mucous membrane:– Olfactory mucosa

• Near roof of nasal cavity• Houses olfactory receptors

– Respiratory mucosa• Lines nasal cavity• Pseudostratified ciliated columnar epithelium

The Upper Respiratory Tract

Sphenoid sinusFrontal sinus

Nasal meatuses(superior, middle,and inferior)

Nasopharynx

Uvula

Palatine tonsilIsthmus of thefauces

Posterior nasalaperture

Opening ofpharyngotympanictube

Pharyngeal tonsil

Oropharynx

Laryngopharynx

Vocal fold

Esophagus

Nasal conchae(superior, middle and inferior)

Nasal vestibuleNostril

Nasal cavity

Hard palate

Soft palate

Tongue

Lingual tonsil

Epiglottis

Hyoid boneLarynx

Thyroid cartilageVestibular fold

Cricoid cartilage

Thyroid gland

Trachea

Cribriform plateof ethmoid bone

Respiratory Mucosa

• Consists of:– Pseudostratified ciliated columnar epithelium– Goblet cells within epithelium – Underlying layer of lamina propria

• Cilia move contaminated mucus posteriorly

Nasal Conchae

• Superior & middle nasal conchae – Part of the ethmoid bone

• Inferior nasal conchae– Separate bone

• Project medially from the lateral wall of the nasal cavity

• Particulate matter: – Deflected to mucus-coated surfaces

The Pharynx

• Funnel-shaped passageway

• Connects nasal cavity & mouth

• Divided into 3 sections by location:– Nasopharynx– Oropharynx– Laryngopharynx

• 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• Pharyngeal tonsil (adenoids)

– Located on posterior wall– Destroys pathogens that enter

• Contains the opening to the pharyngotympanic tube (auditory or eustachian tube)– Tubal tonsil

• Provides some protection from infection

The Oropharynx

• Arch-like entrance-way fauces– Extends from soft palate to epiglottis

• Epithelium– Stratified squamous epithelium

• 2 types of tonsils in the oropharynx– Palatine tonsils in lateral walls of the fauces – Lingual tonsils covers the posterior surface

of the tongue

The Laryngopharynx

• Passageway for both food & air

• Epithelium– Stratified squamous epithelium

• Continuous with the esophagus & larynx

The Larynx

• 3 functions – Voice production– Provides an open airway– Routes air & food into the proper channels

• Superior opening (epiglotis) is:– Closed during swallowing– Open during breathing

9 Cartilages of the Larynx

• Thyroid cartilage– Shield-shaped, forms laryngeal prominence (=

Adam’s apple)

• 3 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)

• Function in sound production

– Vestibular folds (= false vocal cords)• No role in sound production

• Epithelium of the larynx:– Stratified squamous superior portion– Pseudostratified ciliated columnar inferior

portion

Anatomy of the Larynx

Body of hyoid bone

Cricoid cartilage

Laryngeal prominence(Adam’s apple)

Clavicle

Sternal headClavicular head

Sternocleidomastoid

Jugular notch

(a) Surface view

Body of hyoid bone

Epiglottis

Cricoid cartilage

Trachealcartilages

Thyroid cartilageLaryngeal prominence(Adam’s apple)

Cricothyroid ligament

Cricotracheal ligament

(b) Anterior view

Thyrohyoidmembrane

Anatomy of the LarynxHyoid bone

Thyroidcartilage

Glottis

(c) Photograph of cartilaginous framework of the larynx, posterior view

Epiglottis

Corniculate cartilage

Arytenoid cartilage

Cricoid cartilage

Tracheal cartilages

Thyrohyoidmembrane

Epiglottis

Body of hyoid bone

Thyrohyoid membrane

Vestibular fold(false vocal cord)

Vocal fold(true vocal cord)

Cricothyroid ligament

Cricotracheal ligament

Fatty pad

Thyroid cartilage

Cuneiform cartilage

Corniculate cartilageArytenoid cartilage

Cricoid cartilage

Tracheal cartilages

Arytenoid muscle

(d) Sagittal section (anterior on the right)

Thyrohyoidmembrane

Movements of the Vocal Cords

(a) Vocal folds in closed position; closed glottis (b) Vocal folds in open position; open glottis

Base of tongue

Epiglottis

Vestibular fold (false vocal cord)

Vocal fold (true vocal cord)

Glottis

Inner lining of trachea

Cuneiform cartilage

Corniculate cartilage

Thyroid cartilage

Cricoid cartilageVocal ligaments of vocal cords

Lateral cricoarytenoid muscle

Arytenoid cartilage

Posterior cricoarytenoid muscle

Anterior

Posterior

Glottis

Corniculate cartilage

The Larynx

• Voice production – Length of the vocal folds changes with pitch– Loudness depends on the force of air across

the vocal folds

• Sphincter function of the larynx– Valsalva’s maneuver straining

• Innervation of the larynx– Recurrent laryngeal nerves (branch of vagus)

The Trachea

• Descends into the mediastinum

• C-shaped cartilage rings keep airway open!

• Carina– Marks where trachea divides into 2 primary

bronchi– Epithelium

• Pseudostratified ciliated columnar epithelium

~remember this?

The Trachea

(a) Cross section of the trachea and esophagus

Hyaline cartilage

Submucosa

Mucosa

Seromucous glandin submucosa

Posterior

Lumen of trachea

Anterior

Esophagus

Trachealismuscle

Adventitia

(b) Photomicrograph of the tracheal wall (250)

Hyaline cartilage

Lamina propria(connective tissue)

Submucosa

Mucosa

Seromucous glandin submucosa

Pseudostratifiedciliated columnarepithelium

Bronchi in the Conducting Zone

• Bronchial tree– Extensively branching respiratory

passageways• Primary bronchi (main bronchi)

– Largest bronchi

• Right main primary bronchi– Wider & shorter than the left– Right lung also bigger than the left

Bronchi in the Conducting Zone

TracheaSuperior lobe of right lung

Middle lobe of right lung

Inferior lobe of right lung

Superior lobe of left lung

Left main(primary) bronchusLobar(secondary)bronchus

Segmental(tertiary)bronchus

Inferior lobeof left lung

(a) The branching of the bronchial tree

Bronchi in the Conducting Zone

• 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

Bronchi in the Conducting Zone

Mucosa Pseudostratified epithelium

Lamina propria

Fibromusculo-cartilaginous layer

Cartilage plate Smooth muscle

Lumen

(b) Photomicrograph of a bronchus (13)

Changes in Tissue Along Conducting Pathways

• Supportive connective tissues change– C-shaped rings replaced by cartilage plates

• Epithelium changes– First, pseudostratified ciliated columnar– Replaced by simple columnar, then simple

cuboidal epithelium• Smooth muscle becomes important:

– Airways widen with sympathetic stimulation– Airways constrict with parasympathetic stim.

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

Alveolar duct

Alveolar ductAlveoli

Alveolarsac

Respiratory bronchioles

Terminalbronchiole

(a)

Structures of the Respiratory Zone

Alveolarpores

Alveolarduct

Respiratorybronchiole

Alveoli

Alveolarsac

(b)

Structures of the Respiratory Zone

• Alveoli– ~300 million alveoli account for tremendous

surface area of the lungs!• Surface area of alveoli is ~140 square meters!!!• Why such a large surface area?

Structures of the Respiratory Zone

• Structure of alveoli– Type I cells single layer of simple

squamous epithelial cells• Surrounded by basal lamina

– Alveolar & capillary walls plus their basal lamina form

• The Respiratory membrane

Anatomy of Alveoli & the Respiratory Membrane

Elasticfibers

(a) Diagrammatic view of capillary-alveoli relationships

Smoothmuscle

Alveolus

Capillaries

Terminal bronchioleRespiratory bronchiole

Structures of the Respiratory Zone

• Structures of alveoli (cont.)– Type II cells scattered among type I cells

• Are cuboidal epithelial cells• Secrete surfactant (very important!)

– Detergent-like molecule, that reduces surface tension within alveoli (prevents them from collapsing)

– Alveolar macrophages also present

Anatomy of Alveoli & the Respiratory Membrane

Alveolus

Capillary

Type II (surfactant-secreting) cell

Type I cell of alveolar wall

Endothelial cell nucleusMacrophage

Alveoli (gas-filledair spaces)

Red blood cellin capillary

Alveolar pores

Capillary endothelium

Fused basement membranes of the alveolar epitheliumand the capillary endothelium

Alveolar epitheliumRespiratorymembrane

Red blood cell

O2

Alveolus

CO2

Capillary

Nucleus of type I(squamousepithelial) cell

(c) Detailed anatomy of the respiratory membrane

The Respiratory Zone

• Features of alveoli– Surrounded by elastic fibers– Interconnect by way of alveolar pores– Internal surfaces

• A site for free movement of alveolar macrophages

Gross Anatomy of the Lungs

• Major landmarks of the lungs– Apex, base, hilum, & root

• Left lung– Superior & inferior lobes

• Right lung– Superior, middle, & inferior lobes

Leftsuperior lobe

Obliquefissure

Left inferiorlobe

(b) Photograph of medial view of the left lung

Left mainbronchus

Pulmonaryvein

Impressionof heart

Obliquefissure

Lobules

Pulmonary artery

Apex of lung

Hilum

Aorticimpression

Gross Anatomy of the Lungs

Anterior View of Thoracic Structures

Trachea

Apex of lung

Thymus

Right superior lobe

Horizontal fissure

Right middle lobe

Oblique fissure

Right inferior lobeHeart(in mediastinum)

Diaphragm

Base of lung

Leftsuperior lobe

Cardiac notch

Obliquefissure

Left inferiorlobe

Lung Pleural cavityParietal pleura

Rib

Intercostal muscle

Visceral pleura

(a) Anterior view. The lungs flank mediastinal structures laterally.

Bronchial Tree

Rightsuperiorlobe (3segments)

Rightmiddlelobe (2segments)

Rightinferior lobe(5 segments)

Left superiorlobe(4 segments)

Left inferiorlobe(5 segments)

Right lung Left lung

Blood Supply & Innervation of the Lungs

• Pulmonary arteries– Deliver oxygen-poor blood to the lungs

• Pulmonary veins– Carry oxygenated blood to the heart

• Innervation– Sympathetic, parasympathetic, & visceral

sensory fibers• Parasympathetic constrict airways• Sympathetic dilate airways

Transverse Cut Through Lungs

(d) Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown.

Esophagus(in mediastinum)

Right lung

Parietal pleura

Visceral pleura

Pleural cavity

Pericardial membranes

Sternum

Anterior

PosteriorVertebra

Root of lungat hilum

Left lung

Thoracic wall

Pulmonary trunk

Heart (in mediastinum)

Anterior mediastinum

Left main bronchusLeft pulmonary arteryLeft pulmonary vein

The Pleurae (review)

• A double-layered sac surrounding each lung– Parietal pleura– Visceral pleura

• Pleural cavity – Potential space between the visceral &

parietal pleurae

• Pleurae help divide the thoracic cavity – Central mediastinum – 2 lateral pleural compartments

Diagram of the Pleurae & Pleural Cavities

Trachea

Apex of lung

Thymus

Right superior lobe

Horizontal fissure

Right middle lobe

Oblique fissure

Right inferior lobe

Heart(in mediastinum)

Diaphragm

Base of lung

Leftsuperior lobe

Cardiac notch

Obliquefissure

Left inferiorlobe

Lung Pleural cavityParietal pleura

Rib

Intercostal muscle

Visceral pleura

(a) Anterior view. The lungs flank mediastinal structures laterally.

The Mechanisms of Ventilation

• 2 phases of pulmonary ventilation– Inspiration inhalation – Expiration exhalation

Inspiration

• Volume of thoracic cavity increases– Decreases internal gas pressure– Action of the diaphragm

• Diaphragm flattens

– Action of intercostal muscles• Contraction raises the ribs

Inspiration

• Deep inspiration requires – Scalenes– Sternocleidomastoid– Pectoralis minor– Erector spinae extends the back

Expiration

• Quiet expiration chiefly a passive process!– Inspiratory muscles relax– Diaphragm moves superiorly– Volume of thoracic cavity decreases

• Forced expiration an active process– Produced by contraction of

• Internal & external oblique muscles• Transverse abdominis muscles

Changes in Thoracic Volume

Ribs areelevated and sternum flaresas externalintercostalscontract.

Diaphragm and intercostal musclescontract (diaphragm descends and

rib cage rises). Thoracic cavityvolume increases.

Diaphragm movesinferiorly duringcontraction.

Externalintercostalscontract.

Changes insuperior-inferior andanterior-posteriordimensions

Changesin lateraldimensions(superiorview)

(a) Inspiration

Inspiratory muscles relax (diaphragm rises andrib cage descends due to recoil of the costal

cartilages). Thoracic cavity volume decreases.

Ribs andsternum aredepressed asexternalintercostalsrelax.

Externalintercostalsrelax.

Diaphragm movessuperiorly as it relaxes.

(b) Expiration

At rest, no air movement: Air pressure in lungs is equal to atmospheric (air) pressure. Pressure in the pleural cavity is less than pressure in the lungs. This pressure difference keeps the lungs inflated.

Inspiration: Inspiratory muscles contract and increase the volume of the thoracic and pleural cavities. Pleural fluid in the pleural cavity holds the parietal and visceral pleura close together, causing the lungs to expand. As volume increases, pressure decreases and air flows into the lungs.

Expiration: Inspiratory muscles relax, reducing thoracic volume, and the lungs recoil. Simultaneously, volumes of the pleural cavity and the lungs decrease, causing pressure to increase in the lungs, and air flows out. Resting state is reestablished.

Trachea

Diaphragm

Lung

Lung

Air flows in

Air flowsout

VP

VP

VP

VP

Pleuralcavity

Thoracicwall

Air

Air

Main bronchiParietalpleura

Visceralpleura

Thoracic wallPleural cavity

At rest

Expanded

1

2

3

Changes in Thoracic Volume

Neural Control of Ventilation

• Respiratory center– Generates baseline respiration rate– In the reticular formation of the medulla

oblongata

• Chemoreceptors– Sensitive to rising & falling oxygen levels – Central chemoreceptors located in

medulla– Peripheral chemoreceptors

• Aortic bodies • Carotid bodies

Location of Peripheral Chemoreceptors

Brain

Sensory nerve fiber in cranial nerve IX (pharyngeal branch of glossopharyngeal)

External carotid artery

Internal carotid arteryCarotid body

Common carotid arteryCranial nerve X (vagus nerve)

Sensory nerve fiber in cranial nerve X

Aortic bodies in aortic arch

Aorta

Heart

Disorders of Lower Respiratory Structures

• Bronchial asthma – A type of allergic inflammation

• Hypersensitivity to irritants in the air or to stress

– Asthma attacks characterized by• Contraction of bronchiole smooth muscle • Secretion of mucus in airways

Disorders of Lower Respiratory Structures

• Cystic fibrosis (CF) inherited disease – Exocrine gland function is disrupted– Respiratory system affected by

• Oversecretion of viscous mucus

• Pneumonia infectious disease– Accumulation of fluid in alveoli– Interferes with gas exchange (drowning)

Disorders of Lower Respiratory Structures

• Chronic obstructive pulmonary disease (COPD)– Airflow into & out of the lungs is difficult

• Obstructive emphysema• Chronic bronchitis

– History of smoking usually associated

Disorders of Lower Respiratory Structures

Figure 22.18

Alveolar Changes in Emphysema

Figure 22.19

Lung Cancer

• Most common cause of cancer-related death!

– 1.3 million deaths/year worldwide– Treated by surgery, radiation, and/or

chemotherapy– Symptoms shortness of breath,

coughing (up blood), weight loss

– History of smoking or 2nd- hand smoke usually associated

– 14% survival rates

Aging of the Respiratory System

• The number of glands in nasal mucosa declines• Nose dries

– Produces thickened mucus

• Thoracic wall becomes more rigid• Lungs lose elasticity• Oxygen levels in the blood may fall

• Again…Exercise throughout life important for respiratory health!

Questions…?

What’s Next?Wed Lecture: Lecture Exam 4! Wed Lab: Start Digestive SystemMon Lecture: Digestive Sys. & class Potluck! ~We’ll eat while we learn about eating & digestion