Respiratory System

This document provides an in-depth overview of the respiratory system, including its anatomy, functions, and microscopic anatomy. It explains how oxygen is delivered to the body and carbon dioxide is eliminated. The document also explores the upper and lower respiratory zones, as well as the tracheobronchial tree and deep lung airways.

Running Head: RESPIRATORY SYSTEM
Respiratory System
Name
Institution

RESPIRATORY SYSTEM 2
Respiratory System
Table of Contents
Introduction......................................................................................................................................3
Anatomy and Functions of the Respiratory System........................................................................4
Nose and Paranasal Sinuses.........................................................................................................4
Pharynx........................................................................................................................................6
Larynx..........................................................................................................................................7
Tracheobronchial Tree and Deep Lung Airways.........................................................................8
Trachea.....................................................................................................................................8
Bronchus...................................................................................................................................9
Microscopic Anatomy of Respiratory System...............................................................................10
Non-ventilatory Functions.............................................................................................................11
Conclusions....................................................................................................................................12
References......................................................................................................................................14

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Introduction
The chief role of the respiratory system is to deliver oxygen (O2) to the body and
eliminate carbon dioxide (CO2). Oxygen (needed by cells to work) from the outside surroundings
is moved into the blood whilst CO2 is excluded into the external environment or external air
(Ionescu, 2013). The billions of tissues in the respiratory system are far away from the drawn in
air to exchange gases straight, and rather the blood moves the O2 in the body cells. Thus, this will
happen each inhalation one takes in which the oxygen initially enters the mouth or nose during
the time of inhalation. This air (oxygen) will pass through the larynx, as well as trachea where
then it splits into two bronchi. The several tubes create a huge amount of passageways in the
lung and ending at the stop with a link to minute sacs referred to as alveoli (Tu, Intavong &
Ahmadi, 2013). Thus, the exchange of gases primarily occurs at the alveoli, in which oxygen
circulates into the capillaries of the lungs in exchange of carbon dioxide. The exhalation starts
following the process of gas exchange where the air that contains carbon dioxide returns via the
bronchial passageways in addition to to the external environment via the mouth or nose
(Mazengenya & Bhikha, 2017). The secondary roles of the respiratory system include warming,
filtering, as well as humidifying the inhaled air.
In terms of anatomy, the respiratory system may be splitted into upper along with the
lower respiratory zone. Thus, the upper respiratory zone contains the organs situated external of
the thorax region (nose, pharynx, and larynx), while the lower respiratory zone contains organs
situated nearly wholly in it (trachea, bronchi, alveolar duct, and alveoli) (Meraz, Nazeran,
Ramos, Nava, Diong & Goldman, 2011).

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Anatomy and Functions of the Respiratory System
The human respiratory system comprises the nose, nasal cavity, plus paranasal sinuses;
the pharynx, larynx, the trachea; the bronchi plus their tiny branches; plus the lungs that have air
sacs or alveoli. In terms of function, the respiratory system contains two zones: the respiratory
and conducting zones as shown in figure 1.0. The respiratory zone is the actual region where gas
exchange occurs that has respiratory bronchioles, alveolar ducts, alveoli and all the microscopic
structures (Schachner, Sedlmayr, Schott, Lyson, Sanders & Lambertz, 2017). On the other side,
conducting zone comprises of other respiratory pathways that offer fairly rigid channels for air to
reach the gas exchange regions. The conducting zone has also the role of cleansing, humidify
and warm the air entering the system. Consequently, the air reaching the lungs of the body has
fewer contaminants or irritations (bacteria, dust) as compared to air that entered the system (Tu
et al., 2013).

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Figure 1.0: Respiratory and Conducting Zone
Nose and Paranasal Sinuses
The human nose is the single externally observable component of the respiratory system
that protrudes from the face, as well as lying in between the forehead and the higher lip. The
nose is composed of the skeletal part and a cartel part. The skeletal part of the nose is situated in
the higher half in addition to has a pair of nasal bones that sits jointly side by side, which is
divided in the center besides combined posteriorly by the medial plates of the cheeck bones
(Maina, 2015). The cartilaginous part is situated in the lesser half that comprises of stretchy
cartilages in the anterior, caudal part of the nose as shown in figure q below. The cartilages are
linked to each other plus to the bones through a sturdy membrane. Consequently, the base of the
nose has two opening referred to as nostrils (anterior nases, naris) and are estranged by nasal
septum cartilage.
Figure 1.1: Lateral view of the external nose (Tu et al., 2013)

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The sphenoid sinuses lie in the human body in the sphenoid bone, cavernous in the face
at the back the nose and ethmoid sinuses are a set of miniature air spaces situated in the bridge of
the nose. These sinuses are shown in figure 1.2 below:
Figure 1.2: Frontal view of human face showing paranasal sinuses
Pharynx
The pharynx (throat) is in the shape of a tube about 1.25 cm long, which connects the
posterior nasal besides oral cavities to the larynx together with the esophagus. The pharynx
extends from the bottom of the skull to the degree of the 6th cervical vertebrae (Lambertz, Böhme
& Perry, 2010). In terms of structure, the pharynx may be divided into three anatomical regions
as shown in figure 1.3 that are nasopharynx (posterior to the nasal chambers), the oropharynx, as
well as the larynpharynx (Korenbaum, D’yachenko, Nuzhdenko, Lopatkin, Tagil’tsev & Kostiv,
2011)..

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Figure 1:3: The pharynx and its subdivisions (Tu et al., 2013).
The nasopharynx is situated between the internal nares, as well as the supple palate plus
lies higher to the oral opening. The bottom of the nasopharynx ate the soft palate along with the
uvula. It wall has the aural (Eustachian) tubes linked to the middle ear. Accordingly, the
oropharynx is situated subsequent to the mouth, lower from the supple palate, plus superior to
the plane of the hyoid bone. In this specific position, the mouth directs into the oropharynx and
both the food in addition to inhaled oxygen pass via the oropharynx. The palatine tonsils are
located in the sideways walls of fauces. On the other hand, the laryngopharynx widens from the
hyoid bone to the esophagus. Thus, it is lower to the epiglottis plus higher to the intersection in
which the air splits amid the larynx, as well as the esophagus. In addition, the lingual tonsils are
situated in the posterior bottom of the tongue that is adjacent to the aperture of the oral cavity
(Ibe, Salami & Onyeanusi, 2011).
Larynx
The larynx is universally called the voice box because it accommodates the vocal folds,
which functions as sound producers. Larynx functions as a sphincter in passing on air from the
oropharynx towards the trachea and too in forming sound for speech purposes. The larynx is
located in the anterior of the neck, linking the hypopharynx together with the trachea that
expands perpendicularly from the incline of the epiglottis to the inferior boundary of the cricoids

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cartilage as shown in figure 1.4. Therefore, the laryngeal bones composes of 9 cartilages, 3 sole
(cricoids, thyroid, and epiglottis), as well as 3 paired (cuneiform, comiculate and arytenoids) that
are linked by ligaments and membranes. The hyoid bone is linked to the larynx; however, not
reflected as component of the larynx.
Figure 1.4: Anterior, mid-saggital (cut-away) and posterior views of the larynx
Tracheobronchial Tree and Deep Lung Airways
So, the tracheobronchial tree is a formation from the trachea, bronchi plus bronchioles,
which forms the upper region of the lung air passages. It is in the form of a tree since the trachea
splits into the right, as well as left main bronchi that more bifurcates into more increasingly
smaller air passages.
Trachea

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The trachea goes down from the larynx via the neck into the mediastinum. Trachea ends
by splitting into two main bronchi at the middle of the thorax. As a result, the trachea is around
10-12 cm long in humans and 2 cm in thickness and very elastic.
Bronchus
The trachea divides into primary bronchi at the carina with the right bronchus that is
broader, shorter and more vertical as compared to the left bronchus. Thus, this result in
enhanced probability of breathed in particles depositing in the right bronchus of the system. The
alveolar ducts are short tubes, which are propped by a dense matrix of elastic, as well as collagen
fibers. The alveoli are the lapses end of all the air passages in the respiratory system. Since the
exchange of air occurs in the acinus, the zone is enclosed by a dense system of capillaries as
shown in figure 1.5 (Stoliński, Plicner, Fijorek, Grudzień, Kruszec, Andres & Kapelak, 2017).
Figure 1.5: Acinus region showing the alveolar ducts, and a cutaway of the alveolar (Tu et
al., 2013).

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Microscopic Anatomy of Respiratory System
The internal nasal hollow lies in addition to posterior to the outside nose. In the process
of breathing, the air enters the nasal cavity via the nostrils or nares. The mucous and serous
glands secrete around liter mucus that contains lysozyme (antibacterial enzyme) where sticky
mucus traps enthused dust, bacterial elements plus other debris whilst the lysozyme attacks, as
well as obliterates the bacteria using chemicals. Hence, the epithelial cells of the respiratory
system mucosa also secrete defensins that are innate antibiotics, which aid eliminate the
attacking microbes (Smodlaka, Henry & Reed, 2009).
The wall of the trachea has many layers, which are widespread to several tubular body
organs and a layer of hyaline cartilage (Davies & Moores, 2014). The mucosa that is similar to
the goblet cell-containing pseudo-stratified epithelium, which occurs in nearly all parts of the
respiratory region. It contains cilia that constantly push debris-loaded mucus to the pharynx. The
elastic feature of trachea allows it to be elastic enough to extend and shift inferiorly in inspiration
in addition to recoil in expiration; however, the cartilage rings stop it from collapsing and keep
the airway patent in spite the changes in pressure that happens during breathing.
The epithelium of the bronchus system is pseudostratified columnar ciliated epithelium
with multiple goblet cells. The epithelium transitions initially into a simple columnar ciliated
epithelium and then proceeds into a cuboidal epithelium as it carries on to create smaller
bronchioles. In the end, the cartilage support is lost at the bronchiolar level (0.5-10 nm
thickness). Then, the muscle layer becomes the prevailing structure that has both the smooth and
elastic fibers. At this point, the mucosa can be highly folded due to the loss of supporting
structure. The terminal bronchioles are taken as the respiratory zone of the lungs (zone in which

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exchange of gases takes place). The bronchioles will divide into respiratory bronchioles that go
down to the alveolar ducts, which are totally coated with alveoli plus alveolar sacs. In the human
lung, there are more than 300 million alveoli covered by dense network of capillaries (branches
form the pulmonary capillaries) (Maina, 2015).
Furthermore, the epithelium of the respirator bronchiole is mainly cuboidal in shape and
can be cilitated, but the goblet cells are lacking. The supporting thin layer is created by the
collagenous, as well as smooth muscle. The alveolar wall is very thin (around 25 nm) and created
by squamous epithelium coated by a thin film of surfactant fluid that has hydrophilic
phospholipid generated by type II cells or septal cells. The role of the surfactant fluid is to keep
the alveoli open; thus, lowering the surface tension of the interface between conflicting alveolar
surfaces that mirrors into lowered inspiratory function. The respiratory epithelium is primarily
composed of type I cells and type II cells (septal cells) ((Stoliński et al., 2017). Thus, the basal
laimina has the role of initiating contact with the capillaries from the pulmonary vascular system,
which promotes the transfer of O2 to the red blood cells (RBCs), as well as to discharge CO2 to
the alveolar airway.
Non-ventilatory Functions
The key task of the respiratory system is the gas exchange, but also it serves non-
ventilatory functions. The system filters out particulate matter, like fibrin clumps, clots along
with other endogenous in addition to exogenous substances from entering the respiratory system.
Thus, the system functions as a substantial obstacle to different blood-borne materials; however,
it is totally effective in safeguarding the systemic exchange of air. Pulmonary capillaries have a

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thickness of around 7μm. However; it has been demonstrated in animal researches that glass
beads of up to 500μm may move through the perfused lungs (Patwa & Shah, 2015).
Chemical filtration is another function of the respiratory system. Pulmonary capillaries
too generate substances, which break blood clots. The pulmonary endothelium is an affluent
supply of fibrinolysin activator that changes plasminogen that is present in plasma to fibrinolysin
that consequently breaks fibrin-to-fibrin degradation outcomes. The respiratory system through
the lungs has an effective fibrinolytic structure that lyses coagulate in the pulmonary exchange
(Jurdziak, Gać, Martynowicz & Poręba, 2015). Additionally, the lung is the main supply of
heparin material (that stops coagulation), as well as thromboplastin (that through changing
prothrombin enhances coagulation). Thus, the lung will play a leading function in the general
coagulation process of the blood to support delayed coagulation. In addition, the non-ventilatory
function is a defense against inhaled particles. The ciliated columnar epithelium lines the higher
air passage from the posterior two-thirds of the human nose to the bronchioles of the respiratory
system. The mucus will provide defense against the inhaled physical substances (Lalley, 2013).
Conclusions
The principal role of the respiratory system is to deliver the body with sufficient O2 plus
expel CO2. In the process of inspiration, the outside air is inspired into the body that enters
through the mouth or nose to the lungs (Kamada, Kaneko & Tomioka, 2017). The air circulation
process in respiration occurs in the alveoli within the capillaries. Every alveolus is maximized
for gas exchange by possessing a thin humid surface, as well as a very huge total surface area in
whole. The O2 is moved from the alveoli to the adjacent capillaries, which has oxygen to

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depressed; CO2 rich blood is passed from the heart (Beom, Jisoo & Min, 2017). Gas exchange
occurs in which the O2 is dissolved in the water coating of the alveoli sooner than diffusing into
the bloodstream, whereby it leaves the body during the process of exhalation.

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