ANHB1102 Study Guide - Final Guide: Cellular Respiration, Pulmonary Vein, Hypoventilation
3 Jun 2018
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TOPIC FIVE: The Respiratory System
Respiration:
Respiration can be defined as the exchange of gases between the atmosphere,
blood and the cells. It includes the movement of air from outside the body into
the lungs, the exchange of gases from the lungs to the blood and the exchange of
gases from the blood to the cells.
Function of the Respiratory System:
The main function of the respiratory system is to move air into and from the
body for oxygen and carbon dioxide exchange. However, it performs a number of
non-respiratory functions, including homeostasis of body fluids, vocal
communication, olfaction, and providing nonspecific defenses against pathogens.
Embryological Development of the Respiratory System:
Development of the respiratory system begins in week 4 of embryological
development, where buds off the foregut endoderm form the pleural cavity.
These buds continue to grow and branch. By week 8, the mesoderm has formed
cartilage, muscle and connective tissue supports, and the pleura is forming.
(owever as the alveoli haven’t developed, there is no breath yet. At week 24, the
alveoli have developed sufficiently for survival and between this point and week
28, the surfactant is beginning to be produced. This surfactant production
increases in the final 2 months in utero. The first gasp of breath after birth takes
supreme effort, and after this point the lungs are never completely empty until
death.
Structure of the Respiratory Tract:
Nasal Cavity
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The nasal cavity consists of nasal conchae and the sinuses. The nasal cavity is
covered in respiratory mucosa, which is made up of respiratory epithelium
(pseudostratified ciliated columnar with goblet cells that produce and secrete
mucus) and underlying connective tissue. The nasal cavity has numerous
functions, including warming, moistening and cleaning the air that enters the
respiratory tract. The nasal cavity plays an important role in olfaction.
Pharynx
The pharynx is split into three sections:
1. The nasopharynx, which is posterior to the nasal cavity,
2. The oropharynx, which is posterior to the oral cavity, and
3. The laryngopharynx, which is posterior to the larynx
A lot of muscle coordination is required for the muscles of the pharynx to
generate a swallow. These same muscles also help with phonation. At the end of
the pharynx is the epiglottis, which is a small fold of muscle that separates the
oseophagus from the larynx, keeping food and air in their respective tubes.
Larynx
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The larynx is comprised of cartilage, ligaments and muscles. Its main function is
to protect the airway (through the cough reflex) and to aid in phonation. The
vocal cords are also located in the larynx. When the 2 mucous membranes of the
vocal cords stretch against the larynx when air moves through, sound is
generated.
Trachea
The trachea leads from the larynx to the primary bronchi. It is lined with the
same respiratory epithelium found in the nasal cavity, however it also has C-
shaped cartilage to support it. The cartilage is opened at the back to make room
for the oseophagus (which is posterior)
Lungs
Each lung is comprised of individual lobes – with 3 lobes on the right and 2 on
the left. These lobes are completely independent from each other – they can be
removed and the remaining lobes will continue to function properly. The left
lung is smaller than the right to allow room for the heart. The right lung is
shorter than the left lung to allow room for the diaphragm to rise up during
expiration.
Pleura
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Document Summary
Respiration can be defined as the exchange of gases between the atmosphere, blood and the cells. It includes the movement of air from outside the body into the lungs, the exchange of gases from the lungs to the blood and the exchange of gases from the blood to the cells. The main function of the respiratory system is to move air into and from the body for oxygen and carbon dioxide exchange. However, it performs a number of non-respiratory functions, including homeostasis of body fluids, vocal communication, olfaction, and providing nonspecific defenses against pathogens. Development of the respiratory system begins in week 4 of embryological development, where buds off the foregut endoderm form the pleural cavity. By week 8, the mesoderm has formed cartilage, muscle and connective tissue supports, and the pleura is forming. (owever as the alveoli haven"t developed, there is no breath yet.
