THE HUMAN RESPIRATORY SYSTEM

● A system, consisting of tubes and is responsible for the exchange of

gases in humans by filtering incoming air and transporting it into the
microscopic alveoli where gases are exchanged.

RESPIRATORY SYSTEM: OXYGEN DELIVERY SYSTEM

The respiratory system is the set of organs that allows a person to breathe and
exchange oxygen and carbon dioxide throughout the body.

The integrated system of organs involved in the intake and exchange of oxygen and
carbon dioxide between the body and the environment and including the nasal
passages, larynx, trachea, bronchial tubes, and lungs.

The respiratory system performs TWO MAJOR TASK:

● Exchanging air between the body and the outside environment known as
external respiration.
● Bringing oxygen to the cells and removing carbon dioxide from them
referred to as internal respiration.

FUNCTION OF RESPIRATORY SYSTEM

1. Supplies the body with oxygen and disposes of carbon dioxide
2. Filters inspired air
3. Produces sound
4. Contains receptors for smell
5. Helps regulate blood pH

Breathing
● Breathing (pulmonary ventilation). consists of two cyclic phases:
- Inhalation, also called inspiration - draws gases into the lungs.
- Exhalation, also called expiration - forces gases out of the lungs.

The organs of the “Respiratory Tract” can be divided into two groups
“STRUCTURALLY”

The Upper Respiratory Tract Lower Respiratory Tract

● Nose - Larynx
● Nasal cavity - Trachea
● Sinuses - Bronchial Tree
● Pharynx - Lungs

Upper Respiratory Tract Functions

● Passageway for respiration
● Receptors for smell
● Filters incoming air to filter larger foreign material
● Moistens and warms incoming air
● Resonating chambers for voice
Lower Respiratory Tract Functions:
● Larynx: maintains an open airway, routes food and air appropriately, assists
in sound production
● Trachea: transports air to and from the lungs
● Bronchi: branch into lungs
● Lungs: transport air to alveoli for gas exchange

The organs of the “Respiratory Tract” can be divided into two groups
“FUNCTIONALLY”
1. Conducting Portion
2. Respiratory Portion

The Conducting Portion- a system of interconnecting cavities and tubes that

conduct air into the lungs
● Nose
● Pharynx
● Larynx
● Trachea
● Bronchi

The Respiratory Portion- system where the exchange of respiratory gases

occurs
● Respiratory bronchioles
● Alveolar Ducts
● Alveoli

THE HUMAN RESPIRATORY SYSTEM

I. N O S E
A. N a s a l C a v i t y
B. P a r a n a s a l S i n u s e s
II. P H A R Y N X
III. L A R Y N X
A. E p I g i o t t i s
B. V o c a l C o r d s
IV. T R A C H E A
V. B R O N C H I
A. B r o n c h i a l T r e e
VI. L U N G S
A. L o b e s o f t h e L u n g s
B. P l e u r a l C a v i t i e s
C. A l v e o l i

NOSE
● Divided into two halves by the nasal septum.
● Contains the paranasal sinuses where air is warmed.
● Contains cilia which are responsible for filtering out foreign bodies.
NOSE AND NASAL CAVITIES
● Internal nares – opening to the pharynx
● External nares - opening to the exterior
● Nasal conchae - folds in the mucous membrane that increase air turbulence
and ensure that most air contacts the mucous membranes
Provide an airway for respiration
● Moistens and warm entering air
● Filters and cleans inspired air
● Resonating chamber for speech
- detects odors in the air stream

Nasal Cavity
● Lies in and posterior to the external nose
● Is divided by a midline nasal septum
● Opens posteriorly into the nasal pharynx via internal nares
● The ethmoid and sphenoid bones form the roof
● The floor is formed by the hard and soft palates

Vestibule – nasal cavity superior to the nares

Vibrissae – hairs that filter coarse particles from inspired air

Olfactory mucosa
● Lines the superior nasal cavity
● Contains smell receptors

PARANASAL SINUSES
* Sinuses are air-filled spaces
within the maxillary, frontal, ethmoid,
and sphenoid bones of the skull.

* These spaces open to the nasal cavity

and are lined with a mucus membrane
that is continuous with that lining the nasal cavity.

* The sinuses reduce the weight of the skull

and serve as a resonant chamber to affect
the quality of the voice.

Pharynx
● Common space used by both the respiratory and digestive systems.
● Commonly called the throat.
● Originates posterior to the nasal and oral cavities and extends inferiorly near
the level of the bifurcation of the larynx and esophagus.
● A common pathway for both air and food.

Three Sections of the Pharynx

● Nasopharynx
 contains the pharyngeal tonsils (adenoids) which aid in the body’s
immune defense.

● Oropharynx
the back portion of the mouth that contains the palatine tonsils which
aid in the body’s immune defense.

● Laryngopharynx
bottom section of the pharynx where the respiratory tract divides
into the esophagus and the larynx.

Larynx
● Voicebox is a short, somewhat cylindrical airway that ends in the trachea.
● Prevents swallowed materials from entering the lower respiratory tract.
● Conducts air into the lower respiratory tract.
● Produces sounds.
● Supported by a framework of nine pieces of cartilage (three individual
pieces and three cartilage pairs) that are held in place by ligaments and
muscles.

The Epiglottis
● It is a large leaf-shaped piece of cartilage.
● A flap of cartilage that prevents food from entering the trachea (or
windpipe).
● During swallowing, there is the elevation of the larynx

The Vocal Cords

● Inside the larynx, 2 pairs of folds of muscle and connective tissues
covered with mucous membrane make up the vocal cords.
a. The upper pair is the false vocal cords.
b. The lower pair is the true vocal cords.
c. Changing tension on the vocal cords controls pitch, while
increasing the loudness depends upon increasing the force of air
vibrating the vocal cords.

The Vocal Cords

● During normal breathing,
-the vocal cords are relaxed and the glottis is a triangular slit.
● During swallowing,
-the false vocal cords and epiglottis close off the glottis.

Trachea
● A flexible tube is also called a windpipe.
● Extends through the mediastinum and lies anterior to the esophagus and
inferior to the larynx.
● Cartilage rings reinforce and provide rigidity to the tracheal wall to ensure
that the trachea remains open at all times.
 ● At the level of the sternal angle, the trachea bifurcates into two smaller
tubes, called the right and left primary bronchi.
● Each primary bronchus projects laterally toward each lung.

THE TRACHEA
● The inner wall of the trachea is lined with a ciliated mucous membrane
with many goblet cells that serve to trap incoming particles.
● * The tracheal wall is supported by 20 incomplete cartilaginous rings.

BRONCHI
● The Bronchi are the two main air passages into the lungs.
● They are composed of the:
“Right Primary Bronchus”
- leading to the right lung.
“Left Primary Bronchus”
- leading to the left lung.

THE BRONCHIAL TREE

● The bronchial tree consists of branched tubes leading from the trachea to
the alveoli.
● The bronchial tree begins with the two primary bronchi, each leading to a
lung.
● The branches of the bronchial tree from the trachea are right and left
primary bronchi; these further subdivide until bronchioles give rise to
alveolar ducts which terminate in alveoli.
● It is through the thin epithelial cells of the alveoli that gas exchange
between the blood and air occurs.

LUNGS

● Each lung has a conical shape. Its wide, concave base rests upon the
muscular diaphragm.
● Its superior region called the apex projects superiorly to a point that is
slightly superior and posterior to the clavicle.
● Both lungs are bordered by the thoracic wall anteriorly, laterally, and
posteriorly, and supported by the rib cage.
● Toward the midline, the lungs are separated from each other by the
mediastinum.
● The relatively broad, rounded surface in contact with the thoracic wall is
called the costal surface of the lung.

Left lung
● divided into 2 lobes by an oblique fissure
● smaller than the right lung
● cardiac notch accommodates the heart

Right lung
● divided into 3 lobes by oblique and horizontal fissure
 ● located more superiorly in the body due to the liver on the right side

Pleura
● The outer surface of each lung and the adjacent internal thoracic wall are
lined by a serous membrane called pleura.
● The outer surface of each lung is tightly covered by the visceral pleura.
● while the internal thoracic walls, the lateral surfaces of the mediastinum,
and the superior surface of the diaphragm are lined by the parietal
pleura.
● The parietal and visceral pleural layers are continuous at the hilus of each
lung

Pleural Cavities

● The potential space between the serous membrane layers is a pleural

cavity.
- The pleural membranes produce a thin, serous pleural fluid that
circulates in the pleural cavity and acts as a lubricant, ensuring
minimal friction during breathing.
- Pleural effusion – pleuritis with too much fluid

Lobes of the Lungs

● The right lung has three lobes.
● The left lung has two lobes.
● Each lobe is composed of lobules that contain air passages, alveoli,
nerves, blood vessels, lymphatic vessels, and connective tissues.

The Alveoli

● They are cup-shaped out pouching lined by epithelium and supported by

a thin elastic basement membrane.
● With that, you can imagine having a bunch of grapes with each grape
indicating an alveolus.
● Alveolar sacs are 2 or more alveoli that share a common opening.
● This is where the primary exchange of gases occurs.

STRUCTURE FUNCTION

nose / nasal cavity warms, moistens, & filters air as it is

inhaled

pharynx (throat) passageway for air, leads to the

trachea

larynx the voice box, where vocal chords are

located
trachea (windpipe) tube from the pharynx to the bronchi
rings of cartilage provide structure, and
keep the windpipe "open"
the trachea is lined with fine hairs called
cilia which filter air before it reaches the
lungs

bronchi two branches at the end of the trachea,

each leading to a lung

bronchioles a network of smaller branches leading

from the bronchi into the lung tissue &
ultimately to air sacs

alveoli the functional respiratory units in the

lung where gases (oxygen & carbon
dioxide) are exchanged (enter & exit the
bloodstream)

Malfunctions & Diseases of the Respiratory System

asthma severe allergic reaction characterized

by the constriction of bronchioles

bronchitis inflammation of the lining of the

bronchioles

emphysema condition in which the alveoli

deteriorate, causing the lungs to lose
their elasticity

pneumonia condition in which the alveoli become

filled with fluid, preventing the exchange
of gases

lung cancer irregular & uncontrolled growth of

tumors in the lung tissue