RESPIRATORY SYSTEM

The Respiratory System is the process through which man and animals take in oxygen and give off carbon dioxide and water as waste products, it is a group of organs that supply the body with oxygen.
There are many different organs involved in the respiratory process which have different functions.

The three functions of the respiratory system:
Transport air into the lungs
Facilitates the diffusion of oxygen into the blood stream
Helps remove carbon dioxide
The components of the respiratory system in order:
Mouth or Nose:
In take of oxygen and out take (excrete) of carbon dioxide
Pharynx:
Propells food when taken into eosophagus
Larynx:
A voice box which contains vocal chods.
Trachea:
Tube in which air passes down to the lung from nose.
Bronchi :
Air pathway to the lungs
Bronchioles:
Smaller ariways than bronchi to get air to wall of lungs.
Alveoli:
Supply oxygen towards de-oxygenated blood through gas exchange.
Diaphragm:
Muscle for breathing (main)

The respiratory system consists of two parts, divided into an upper and lower tract.
Upper Respiratory Tract
Mouth, nose and nasal cavity: Warm, filter and moisten incoming air
Pharynx: Where throat divides into trachea (wind pipe) and oesophagus (food pipe). There is a flap called the epiglottis which prevents food from entering the trachea.
Larynx: Voice box, where sound is generated
Lower Respiratory Tract
Trachea: Carries air from the throat to the lungs
Bronchi: 2 tubes, one enters the right and the other enters the left lung. Left bronchi is narrower, larger and more horizontal.
Bronchioles: Small bronchi within the lung
Alveoli: Individual hollow cavities containing alveolar sacs. Thin walls which allow exchange of gases (breathing). Surrounded by a network of capillaries. Approximately 3 million alveoli in an average adult lung.
Diaphragm: Muscle which sits underneath lungs, attached to lower ribs.


external image respiratory_system.jpg

Lower Respiratory Tract
Trachea: Carries air from the throat to the lungs
Bronchi: 2 tubes, one enters the right and the other enters the left lung. Left bronchi is narrower, larger and more horizontal.
Bronchioles: Small bronchi within the lung
Alveoli: Individual hollow cavities containing alveolar sacs. Thin walls which allow exchange of gases (breathing). Surrounded by a network of capillaries. Approximately 3 million alveoli in an average adult lung.
Diaphragm: Muscle which sits underneath lungs, attached to lower ribs.
external image alveoli.jpg

As an introduction, the reason that humans have to respire in the first place with a complicated system, is because humans cannot diffuse enough oxygen from the air though their cell membranes to meet the metabolic needs. From this, humans use their respiratory system, composed of the lungs, structures that lead from the lungs to the external environment, diaphragm, and the muscles in the thoracic/rib cage.
The nose and mouth is where air enters the body, with the nasal cavity behind the protruding nose. In the nostrils, the dense network of hairs filter particles in the air. The air then meets the walls of the nasal cavity, which is covered in a mucous membrane with a rich blood supply. Once air comes in contact with the mucous membrane, remaining air particles get stuck to it because the mucous membrane warms and moistens the air, allowing air to pass back and down, into the pharynx.
The rood of the mouth/buccal cavity is formed by a hard and soft palate, ending bear the top of the lips and at the sides of the muscles by the cheek; the tongue forms and fills the floor of the mouth. It is because of muscular soft palate that hangs at the back of the hard palate that separates the mouth and the pharynx - the soft palate moves backwards to block the nasal cavity so that food cannot enter and block the airway.
The pharynx is muscular tube that is lined with mucous that joins the nasal and buccal cavities, which then leads to the oesophagus and the larynx. The three parts of the pharynx are the nasopharynx, oropharynx, and the laryngopharynx, with the nasopharynx behind the nasal cavity, the oropharynx behind the buccal cavity, and the laryngopharynx behind the larynx.
The larynx can also be called the voice box, which is positioned in the neck behind the hyoid bone, connecting to the trachea. It specialises in voice production, and allows air into and out of the lungs. There are 5 cartilages that make it up: thyroid, cricoid, epiglottis, and 2 arytenoid cartilages. The largest, the thyroid cartilage, is commonly known as the Adam's apple, and protects the vocal chords.
The trachea is also called the wind pipe, and is composed of membranes and cartilages that allow air to pass from the pharynx to the lungs, through the principle bronchi. It starts below the cricoid cartilage of the larynx, and descends through the thorax, where it divides into the right and left principle bronchi, which begin the left and right lungs. The mucous membrane in the trachea contains cilia that pulse/beat upwards to transport molecules and any inhaled particles out of the lungs, where it could be swallowed and neutralized in the stomach.
The structure of the left and right principal bronchi is that it is similar to the trachea: incomplete rings of cartilage united by fibroblastic membrane. They travel in separate directions, enter the lung through the hilum, then divide into smaller lobar bronchi. The lobar bronchus branches then spread and divide into smaller segmental bronchi in each of the segments of the lungs. The combination of the divisions of the bronchi create the bronchial tree.
The "last branches" of the bronchial tree are called the bronchioles, and are composed completely of a fibroblastic membrane and smooth muscle. The smallest of these bronchioles branch to form multiple alveolar ducts.
The ducts lead into alveoli sacs, where the individual alveoli where gas exchange takes place. Hundred of millions of alveoli sacs make up the large surface area for the diffusion of gases. The alveoli, being only 1 cell wide, have very tiny and thin walls that surround the rich blood supply in the air sacs. There are capillaries that surround the alveoli, which means that the barrier for gasses to diffuse through is 2 cells thick, in order for it to get access to the blood stream. The inside of the alveoli wall is moist, which allows oxygen from the air we breath to dissolve on it, and because of the rich phospholipids and proteins, when we breath out, the alveoli don't collapse. Inside the alveoli, bacteria can be killed once it has entered the lungs and has been trapped on the moist walls.
Onto the lungs. The lungs are held inside the thoracic cavity (the rib cage and other smaller structures), and is suspended in place so that each lung is on one side of the heart. The lungs are organized into lobes, with the left one being slightly smaller (2 lobes) than the right (3 lobes) because of the positioning next to the heart. Pulmonary arteries supply the lungs with deoxygenated blood, and through a process, oxygenated blood leaves through the pulmonary veins. The lungs themselves get oxygenated blood from bronchial arteries, and remove deoxygenated blood through bronchial veins. On the lungs there are 2 thin membranous sheets called pleura. The membranes are like "skin" on lungs, and the 2 layers are called the visceral and parietal layers. The visceral pleural is the innermost layer and it sticks closely to the lungs; it almost fuses with the lung surface, and by doing so, can't be separated from the surface. The outer layer, parietal pleural, lines the thoracic wall, the diaphragm, and a few other structures. There is almost no space between the two layers of the membrane since they slide against one another with help from pleural fluid, but the space in between the layers is called the pleural cavity.
Works Cited:
Websites:
"THE RESPIRATORY SYSTEM." Anatomy T.V. N.p., n.d. Web. 22 Feb. 2012.
<http://www.anatomy.tv/StudyGuides/StudyGuide.aspx?guideid=26&nextID=17&maxID=0&customer=primal>.
View this animation to further understand the structure of the respiratory system

For more information in the Respiratory System you can go here

Diagram of the Respiratory System
The Respiratory System
The Respiratory System


Close Up of the Aveldi
Close Up of Alvedi
Close Up of Alvedi

Close Up of Larynx

Close Up of Larynx
Close Up of Larynx


Respiratory System Structure and Function


Respiratory System Structure and Function

YouTube. Dir. Slackerbiz. YouTube. YouTube, 03 Apr. 2008. Web. 03 Mar. 2012. <http://www.youtube.com/watch?v=kZzn_8ztPMA>.

Works Cited :

"Parts of the Respiratory System." Takdang Aralin. Web. 18 Feb. 2012. http://www.takdangaralin.com/science/life-science/respiratory-system/parts-of-the-respiratory-system/.

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=AP15104