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P & A Notes Respiratory System

February 07, 2011


C6H12O6 + 6O2----> 6CO2 + 6H2O + energy

-What is the respiratory system’s role in this reaction?


-Delivers O2 to the blood stream

-Removes the waste CO2 from the blood.

-Produces sound

-Controls body temperature by the
elimination of H2O vapor.

This system can be divided into two parts: The upper and lower respiratory

The upper part serves primarily as the “Air Conditioner”

-It cleans and filters air

-It warms air

-It moistens the air

The opening into the respiratory tract is the nostrils. They are lined with hairs that filter out the larger dust particles that may enter with air. (pickuns!)

The hollow space just behind the nose is called the nasal cavity. This cavity is lined with a mucous membrane, containing a large network of blood vessels. When air moves over the membranes it is quickly warmed close to the body temperature. Water from the mucous membrane will evaporate helping to moisten the air. This membrane will also catch dust particles and the cilia on the cells sweep the mucous and particles back to the pharynx where it is swallowed.

Where is the pharynx? (cross road)

The larynx is the enlarged area that is located at the top of the trachea and below the pharynx. The opening in the larynx that leads into the trachea is called the glottis. When we swallow food or drink the glottis is covered by a flap called the epiglottis and prevents food from entering the air tube. The larynx also contains the vocal cords and is commonly called the voice box.

The trachea lies just in front of the the esophagus. It is about 5 inches long and contains many cartilage rings that keep it from collapsing and blocking the airway.

- Are the rings complete?

-What is the function of the soft tissue that completes the rings in the back?
The trachea branches into a right and left bronchi or bronchial tubes at its lower end. These tubes are the beginning of the bronchial tree. The bronchial tubes branch into smaller bronchioles, which branch into smaller tubes called alveolar ducts. At the ends of these ducts are the microscopic sacs called alveoli. The large numbers of alveoli provide a large surface area in which gas can be exchanged. (300 million alveoli)

-Lungs occupy a large portion of the thoracic cavity.

-Each lung is covered by a serous membrane, visceral pleura.

-The membrane that lines the thoracic cavity is called the parietal pleura.

-The space between these membranes is the pleural cavity.

-Both of the visceral and parietal pleura produce serous fluid which reduces friction when breathing.

Due to the surface tension of the fluid it allows for the expansion of the lungs during inspiration.

*Inspiration- Atmospheric Pressure is normally 760 mm.

-Diaphragm muscles contract, moving the diaphragm down. The intercostal muscles contract raising the ribs and elevating the sternum. This increases the size of the of the thoracic cavity, reducing the pressure to less than atmospheric pressure and air rushes in.

*Expiration- The muscles relax, the size of the thoracic cavity is decreased, pressure becomes higher than A.P. and air rushes out.

Tidal volume- normal expiration (500 cc)

Vital capacity- maximum amount of air (4600 cc)

You can exhale after a deep breath.

Residual volume- 1200 cc remains in lungs

Functions of: coughing, sneezing, laughing, crying, hiccuping, and yawning. (see text)



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