(3)	Respiratory+system+structure

__Th Respiratory System__

Oxygen is very important to all living things. For us, humans, we can die in six minutes without oxygen. The Respiratory System is a group of organs in the body that play an important job of letting living things, such as humans and animals, inhale oxygen and exhale carbon dioxide. The Respiratory System includes many different organs, and each of the organs have a specific role in the system.



The nose consists of the visible external nose and the internal nasal cavity. The nasal septum is the part that divides the nasal cavity into two parts; right and left. Air enters through these two openings and passes into the vestibule and through meatuses. The concha, the walls of the meatuses, are formed by facial bones. From the meatuses, air goes into two internal nares. Hair, mucus, blood capillaries and cilia that line the nasal cavity filter and unwanted things such as dust.
 * Nose/Nasal Cavity: **

The pharynx, known as the throat, consists of three regions. The nasopharynx receives the incoming air from the two internal nares. The two auditory tubes that equalize air pressure in the middle ear also enters here. The second part is the oropharynx, which receives air from the nasopharynx and food from the oral cavity. The last part is the laryngopharynx which controls movement, such as food to the esophagus and air to the larynx.
 * Pharynx: **

Larnyx is another name for our voice box. Larynx receives air from the laryngopharynx. The larynx is consisted of several parts that are joined by membranes and ligaments. The epiglottis is the first piece of cartilage of the larynx. It is a flexible part that covers the glottis, the upper part of the larynx, during swallowing so it prevents food going the wrong way.
 * Larynx: **

The trachea is known as the windpipe, which is a flexible tube, 10cm to 12cm long and 2.5cm in diameter.
 * Trachea: **

Mucosa is the inner part of the trachea.
 * Mucosa: **

The mucosa is a layer of areolar connective tissue that warps around the mucosa
 * Sub mucosa: **

The hyaline cartilage forms several rings that warp around the sub mucosa. The rigid rings are used to prevent the trachea from collapsing during inspiration.
 * Hyaline cartilage: **

Adventitia is the most outer layer of the trachea.
 * The adventitia: **

**Bronchi:** Bronchi is two tubes that divide from the trachea to each lung. Inside the lungs, each bronchus divides repeatedly into smaller branches forming secondary bronchi and tertiary bronchi. The wall of the primary bronchi is constructed like the trachea but as the branches get smaller and thinner, cartilaginous rings and mucosa are replaced by smooth muscle. Alveolar ducts are the last branches and each alveolar duct has bubble like things called alveolus.

Alvioli are the ducts at the end of the bronchi. They are in charge of breathing and gas respiration, where oxygen comes in and exits to the blood stream through capillaries, and carbon dioxide de oxygenates the blood when exhaled.
 * Alvioli **



The respiratory membrane consists of the alveolar and capillary walls. Gas exchange occurs across this membrane. Type I cells are thin and oxygen diffusion occurs across these cells. Type II cells makes pulmonary surfactant to reduces surface tension which permits oxygen to diffuse more easily into the moisture. Alveolar macrophage cells move around the cells removing microorganisms.
 * Respiratory membrane: **

The diaphragm is a band of mus cle that is under the lungs which forms the base of breathing in and out. As we breathe, the diaphragm contracts and flattens to give the lungs room to fill up with air.
 * Diaphragm: **

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__Works Cited __

===="Anatomy & Physiology: Structure of the Respiratory System." Anatomy & Physiology: Structure of the Respiratory System. N.p., n.d. Web. 17 May 2012. []. ====