The Respiratory System

Chapter 15

Human Anatomy, 3rd editionPrentice Hall, © 2001

Introduction• Responsible for the exchange of gases between the

body and the external environment.– Cells need a supply of O2 and to eliminate CO2

– 3 basic processes• Breathing• External respiration

• Internal respiration

• Two systems supply O2 & eliminate CO2

– Respiratory system

– Cardiovascular system

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Respiratory Tract

• Passageways through which air will move

• Terminate in the alveoli

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Respiratory Tract

• Upper respiratory system– Superior to the

larynx– Functions – intake,

moistening, filtering, sensing

• Lower respiratory system– Larynx and below– Functions – sound

production, transport of air, gas exchange

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Respiratory Epithelium

• Lines the upper respiratory system

• Pseudostratified ciliated columnar epithelium with goblet cells – Entraps & removes

dust – Moistens incoming air– Olfactory sensation

• Capillaries warm incoming air

• The common cold

Human Anatomy, 3rd editionPrentice Hall, © 2001

Surface View of the Epithelium

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Nose

• Primary entrance to the respiratory system– Bone & cartilage

– External nares

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Nasal Cavity• Nasal septum

– Divides into left and right sides

• Hard & soft palate form the floor

• Nasal conchae cause turbulence through nasal cavity

• Internal nares lead to the pharynx

Human Anatomy, 3rd editionPrentice Hall, © 2001

Paranasal Sinuses

• Cavities in cranial bones

• Functions– Lighten skull bones

– Produce mucus

– Resonate during sound production

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Pharynx

• Area from the internal nares to the larynx

• Shared between the respiratory and digestive systems

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Larynx• Connects the pharynx

to the trachea• Lined by mucus-

producing columnar epithelium

• Functions– Produces sound

• Vocal folds

– Keeps food from entering the airways

• Vestibular folds• Epiglottis

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Larynx

• Formed by 9 cartilages– Thyroid cartilage

• Adam’s apple

– Epiglottis• Closes glottis

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Larynx

Voice Production• Ligaments lie under

mucous membrane• Muscles attached to

the cartilages– Control vocal

ligament tension

• Sound production– Air flowing over

vocal folds (through the glottis) produces sound waves

• Resonating chambershttp://www.entdocsonline.com/images/larynx.jpg

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Trachea• Extends from larynx

to primary bronchi• The “windpipe”• Structure

– Incomplete cartilaginous rings

• Lined by mucus-producing epithelium

• Function – passageway for air

Human Anatomy, 3rd editionPrentice Hall, © 2001

Bronchi, Bronchioles, & Alveoli• Trachea divides into

• Primary bronchii divide into

• Secondary bronchi divide into

• Tertiary bronchi divide into

• Bronchioles divide into• Terminal bronchioles

divide into

• Respiratory bronchioles divide into

• Alveolar ducts end in • Alveoli

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Respiratory Tree

Human Anatomy, 3rd editionPrentice Hall, © 2001

Changes as the Respiratory Tree Branches

• As branching of bronchi becomes more extensive– Rings of cartilage

become plates– Smooth muscle

increases– Columnar epithelium

becomes cuboidal, then squamous (in alveoli)

• Asthma

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Alveoli

• Site of gas exchange with the blood

• Closely associated with capillaries

• Wall of the alveolus + wall of capillary– Respiratory

membrane

• Gas exchange occurs by diffusion

Human Anatomy, 3rd editionPrentice Hall, © 2001

Alveoli

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Alveoli• Alveolar epithelium

contains:– Alveolar Type 1 cells

• Gas exchange • Emphysema

– Alveolar Type 2 cells• Secrete surfactant • Respiratory

Distress Syndrome

• Macrophages

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Lungs

• Soft, spongy, cone-shaped

• Right lung– 3 lobes

• Left lung– 2 lobes

Human Anatomy, 3rd editionPrentice Hall, © 2001

Blood Supply to the Lungs

– Pulmonary arteries, pulmonary veins

Human Anatomy, 3rd editionPrentice Hall, © 2001

Breathing• Lungs are prevented from collapsing

– Pressure in the pleural cavity is always slightly lower than the pressure in lungs

Human Anatomy, 3rd editionPrentice Hall, © 2001

Inhaling is Active Work

• Diaphragm• Intercostals contract• Other muscles in

thorax contract• Thoracic cage expands• Lung volume

increases• Pressure in lungs

drops below atmospheric pressure

• Air rushes in

Human Anatomy, 3rd editionPrentice Hall, © 2001

Exhaling is Passive

• Diaphragm relaxes• Intercostal muscles

relax• Thoracic cage drops• Lung volume

decreases• Pressure in lungs

increases above atmospheric pressure

• Air rushes out