The respiratory

System

Prepared by Mickelder Kercy, MD - Instructor

Upper Respiratory Tract : Nose, Paranasal

Sinuses, Pharynx(throat), Larynx(voice box)

and Trachea(Windpipe)

Lower Respiratory Tract : Bronchi, Bronchioles,

Alveolar Ducts, Alveolar Sacs

Organs of the Respiratory System

Divided into the 2 nares/nostrils by the septum

Septum has on each lateral wall a superior,

middle and inferior concha

The mucous membrane lines the conchae

The Nose

Drains fluid from the frontal sinuses, ethmoidal sinuses, sphenoidal sinuses and the maxillary sinuses

Drains fluid from the eyes through the nasolacrimal duct

Serves as a passageway for air (nares)

Warms and moistens inhaled air (conchae)

Traps dust, pollen and other foreign matter with hair-like projections (cilia) and mucous (mucous membrane)

Functions of the Nose

Air-filled spaces located within the bones of the

skull and face

Four sets of paired sinuses exist: Frontal,

Ethmoid, Sphenoid and Maxillary

Paranasal Sinuses

Lightens the weight of the head

Humidifies and heats inhaled air

Assist in the making of sounds for speaking and

singing by increasing resonance

Serves as a crumple zone to protect vital

structures in the event of facial trauma

Functions of the Paranasal Sinuses

Lacrimal System

Lacrimal gland (secretes the tears)

Excretory ducts (drain the tears to the surface of

the eye)

Lacrimal canaliculi, the lacrimal sac, and the

nasolacrimal duct (drain the tears to the nares)

Connects the base of the skull to the trachea and

esophagus

Divided into the Nasopharynx, oropharynx and

laryngopharynx

Contains the pharyngeal, palatine & lingual

tonsils/adenoids and the uvula

Pharynx

Carries air from the nose and mouth toward the larynx

Pushes food toward the esophagus by swallowing reflex

Helps form sounds with the larynx, tongue and soft

palate

Enables equilibration of pressure differences between

the throat and the middle ear during quick changes of

altitude, diving or in disorders of the middle ear through

the Eustachian tubes

Prevents some microbes and foreign particles to enter

the lungs by the tonsils/adenoids catching them

Functions of the Pharynx

Consists of the thyroid cartilage (adam’s apple), the epiglottic cartilage (epiglottis), cricoid cartilage, three paired cartilages (arytenoid, corniculate, and cuneiform) besides the muscles and ligaments etc..

Contains the false vocal cords (minimal role in phonation) located above the true vocal cords (major role in phonation)

Larynx

Prevents food from entering the glottis (opening

between the vocal cords) when pulled upwards

while the epiglottis closes up the glottis

Production of vocal sounds when air passes

through the vocal cords

Functions of the Larynx

Links the larynx to the right and left bronchi

Passageway for the air entering the lungs

Trachea

Two main branches of the trachea that extend

into the lungs

Right bronchus is wider, shorter, and more

vertical

Left bronchus is longer with a smaller caliber

They each divide into many small bronchi that

subdivide into the smaller bronchioles

Bronchi & Bronchioles

The bronchi conduct the air into the bronchioles

The bronchioles conduct the air into the alveolar

ducts

Functions of the Bronchi & Bronchioles

Mucus is a thin layer of sputum (phlegm) lining

the inside of the breathing tubes (trachea,

bronchi and bronchioles) to prevent irritants

from getting into the lungs

Cilia are little hairs lining the breathing tubes

moving the mucus from the lungs upward

toward the throat to the epiglottis that opens up

before the mucus is swallowed into the

esophagus

Cilia and Mucus

Composed of microscopic alveoli/alveolar sacs

(subdivision of the alveolar ducts)

Right lung has an upper, middle and lower lobe

Left lung has an upper and lower lobe

Covered by the visceral (internal) and parietal

(external) pleurae (pleural membranes)

Lungs

Gas exchange by bringing oxygen (O2) into the

body and removing carbon dioxide (CO2) from

the body

Functions of the Lungs

Produce serous fluid that cause the pleurae to

adhere closely to one another, holding the lungs

to the thoracic wall and allowing the pleural

membranes to move easily against each other

during breathing

Functions of the Pleurae

Ventilation is a process of inhalation (air moving down to the alveoli) and exhalation (air moving out of the alveoli)

- During inhalation the diaphragm contracts

and flattens → elevation of the ribs → ↑ size of the thorax

(- pressure) as the air moves down to the alveoli

- During exhalation the diaphragm relaxes →

thorax returns to its resting size and shape (+ pressure) as

the air moves out of the alveoli

- During forceful expiration the internal and

external intercostal and abdominal muscles are involved

Mechanism of Breathing

Tidal Volume : Volume of air entering or leaving

the lungs during a single breath

Inspiratory Reserve Volume : Volume of air that

can be inhaled after a forceful inspiration

Expiratory Reserve Volume : Volume of air that

can be expelled after a forceful expiration

Residual Volume : Volume of air remaining in

the lungs after a maximal/forceful expiration

Respiratory Volumes and Capacity

Asphyxia : Suffocation resulting from the lack

of oxygen. ABG is a test used to detect the level

of oxygen and carbon dioxide in the blood

Asthma : Chronic inflammatory disease of the

bronchi caused by allergens or other irritating

substances.

Common Disorders associated with the Respiratory System

COPD : - Chronic Bronchitis (Chronic inflammation of the mucous membrane in the bronchial passages causing the membrane and the mucus to thicken making it hard to breathe (SOB) because the air cannot pass through easily. It leads to SOB). Acute (lasting less than 6 weeks). Chronic (recurring for more than a year). Mostly viral. Tobacco, Coal miners, grain handlers, metal holders, dust etc…

- Emphysema (Destruction of the lung tissue around the bronchioles causing these airways to collapse preventing the air to come out during exhalation. The chest wall muscles have to work harder to expel the air. There is also damage of the walls between many of the air sacs. As a result, the air sacs lose their shape and become floppy causing a reduction in the amount of gas exchange in the lungs. Tobacco, alpha-1 antitrypsin, air pollution, heredity etc..

Pulse Oxymeter

Spirometer

Common Cold : Viral infection of the upper respiratory tract. Rhinovirus. Spread by droplets through sneezing, coughing, and contacts and fomites

Hay Fever : Seasonal allergic rhinitis or pollinosis. Mucous membrane of the nose and the eyes become inflamed

Influenza : Flu caused by viruses

Legionnaire’s Disease : Pneumonia caused by the Legionella bacteria

Lung Cancer : Leading cause of deaths in both

women and men in the USA. Smoking

Pertussis : Whooping cough (Persistent and

severe cough) caused by the bacteria Bordetella

Pertussis

Pleurisy: Pleuritis or inflammation of the

pleurae

Pneumonia : Inflammation of the lungs caused

by bacteria/viruses/chemical irritants

Pneumothorax : Air accumulation in the pleurae

compressing the lungs (collapsing)

Pulmonary Embolism : Blood clot in the lungs

coming from smaller vessels in the legs, pelvis

arm or heart. The clot obstructs partially or

completely the blood flow to a section of the

lung causing a pulmonary infarct

Severe Acute Respiratory syndrome : Mild to

moderate respiratory illness caused by

coronavirus

Sinusitis : Inflammation of mucous membranes

of the sinuses

Pulmonary Tuberculosis : Pneumonia caused by

the bacteria Mycobacterium tuberculosis

Pleural Effusion : Excessive liquid accumulating

in the space between the visceral and parietal

pleural membranes. CHF, Pneumonia, RF,

Cancer etc…

The End