The respiratory system has several functions including breathing, gas exchange, sound production, and smelling. It consists of the upper respiratory tract including the nose, sinuses, pharynx and larynx, and the lower respiratory tract within the thorax including the trachea, bronchi, and lungs. The lungs contain alveoli which are the sites of gas exchange between the bloodstream and body tissues.

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Anatomy of Respiratory System
Salah Nazar Abdulwahhab M.Sc. Nursing

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The Respiratory System
The major functions of the respiratory system are:
1. Inhalation and exhalation (breathing). It is supplying oxygen O2 to the cells and
removing their gaseous waste product (carbon dioxide) CO2.
2. External respiration exchanges gases between the lungs and the bloodstream
3. Internal respiration exchanges gases between the bloodstream and body tissues
4. Air vibrating to create sound from the vocal cords
5. Olfaction (smelling)

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The Respiratory System Organs
1 Upper respiratory tract (outside thorax)
Nose and nasal cavity
Paranasal sinuses
Pharynx
Larynx
2 Lower respiratory tract (within thorax)
Trachea
Bronchi and their smaller branches
Lungs, which contain the terminal air sacs (alveoli)
The Nose
The nose is the only visible part of the respiratory system jutting external portion
is supported by bone and cartilage. Internal nasal cavity is divided by midline
(nasal septum) and lined with mucosa. The openings in the nose called the nostrils.
The nose located between the roof of the mouth and the cranium.
Roof of nasal cavity contains olfactory epithelium (Receptors for sense of smell)
The nasal cavity produces mucus; filters, warms, and moistens incoming air;
resonance chamber for speech

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Paranasal Sinuses
• They are air filled spaces lined by mucous membrane present around and
communicate with the nasal cavity.
• These are pairs of maxillary, ethmoidal, frontal, sphenoidal sinuses.
Same functions of nasal cavity; also lighten skull
The Pharynx
Passageway connecting nasal cavity to the larynx and oral cavity to esophagus
containing of three parts:
1. Nasopharynx cavity
2. Oropharynx cavity
3. Laryngopharynx cavity
Containing tonsils (lymphoid tissue masses involved in protection against
pathogens.

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The Larynx
An air passageway connects pharynx to trachea, has framework of cartilage and
connective tissue. Opening (glottis) can be closed by epiglottis to prevents food
from entering lower respiratory tract and containing vocal cords responsible of
voice production.
The Trachea (Windpipe)
It is flexible tube running from larynx at the level of C6 and dividing inferiorly
into two main bronchi right and left at the lower border of T6.
Walls of trachea contain C-shaped rings cartilages that are incomplete posteriorly
where connected by tracheal muscles.
The trachea is air passageway; cleans, warms, and moistens incoming air
The Bronchial tree
Consists of right and left main bronchi, which subdivide within the lungs to form
bronchi and bronchioles, bronchiolar walls lack cartilage but contain complete
layer of smooth muscle. Constriction of this muscle impedes breathing.
Considered Air passageways connecting trachea with alveoli; cleans, warms, and
moistens incoming air
The Alveoli
Microscopic chambers at termini of bronchial tree. Walls of simple squamous
epithelium are underlain by thin basement membrane. External surfaces are
intimately associated with pulmonary capillaries. Alveoli considered the main sites
of gas exchange.

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The Lungs
The lungs are pyramid-shaped of spongy air-filled organs that are connected to the
trachea by the right and left bronchi, the lungs are bordered by the diaphragm. The
diaphragm is the flat, dome-shaped muscle located at the base of the lungs and
thoracic cavity the lungs are enclosed by the pleurae.
Each lung is composed of smaller units called lobes. Fissures separate these lobes
from each other. The right lung consists of three lobes: the superior, middle, and
inferior lobes. The left lung consists of two lobes: the superior and inferior lobes.
Pleura of the Lungs
It is Serous membranes, Parietal pleura lines thoracic cavity and visceral pleura
covers external lung surfaces. Produce lubricating fluid acts as a lubricant allowing
the lungs to slip smoothly as they expand and contract with each breath