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Know the structure and function of the respiratorysystem.

The primary function of the respiratory system is to supply the

blood with oxygen in order for the blood to deliver oxygen to allparts of the body. The respiratory system does this throughbreathing. When we breathe, we inhale oxygen and exhale carbondioxide. This exchange of gases is the respiratory system's meansof getting oxygen to the blood. ( www.fi.edu )

The pathway of the respiratory system process;

Air enters the nostrils passes through the nasopharynx, the oral pharynx through the glottis into the trachea into the right and left bronchi, which branches and rebranches

into bronchioles, each of which terminates in a cluster of

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alveoli (Only in the alveoli does actual gas exchange takesplace. There are some 300 million alveoli in two adult lungs.)

(www.users.rcn.com )

There are two types of respiration; Internal known as activerespiration and External known as passive, and respiration isachieved through the Mouth; Nose; Lungs; Trachea and diaphragm.

MouthAir can also be taken in through the mouth. These two openingsof the airway (the nasal cavity and the mouth) meet at thepharynx, or throat, at the back of the nose and mouth.

Nose

At the top of the respiratory system, the nostrils (also callednares) act as the air intake, bringing air into the nose, where it'swarmed and humidified. Tiny hairs called cilia protect the nasalpassageways and other parts of the respiratory tract, filtering outdust and other particles that enter the nose through the breathedair. ( www.kidshealth.org )

LungsThe paired right and left lungs smaller than the right lung)occupy most of the thoracic cavity and extend down to thediaphragm. They hang suspended in the right and left pleuralcavities straddling the heart. (BTEC Sport level 3)

Trachea

The trachea, or windpipe, extends downward from the base of thelarynx. It lies partly in the neck and partly in the chest cavity. The

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walls of the trachea are strengthened by stiff rings of cartilage tokeep it open and is very flexible.

DaphragmThe diaphragm separates the chest from the abdomen and is themost important muscle involved when breathing. It is a sheet of muscle that extends across the bottom of the rib cage.

The diaphragm's job is to help pump the carbon dioxide out of thelungs and pull the oxygen into the lungs. The diaphragm is a sheetof muscles that lies across the bottom of the chest cavity. As thediaphragm contracts and relaxes, breathing takes place. When thediaphragm contracts, oxygen is pulled into the lungs. When thediaphragm relaxes, carbon dioxide is pumped out of the lungs.(www.fi.edu/learn/heart )

Internal Respiration (The Process);

The intercostal muscles contract which causes the ribcage toexpand and pushes the sternum out.The diaphragm will contract and change shape from concaveor dome shape to a flattened shape.The pressure inside the chest cavity will be reduced, allowingair to be sucked into lungs.The air we breathe in is high in oxygen and Nitrogen but lowin Carbon dioxide.

External Respiration (The process);The intercostals muscles relax which causes the ribcage tolower and sternum pushed in.The diaphragm relaxes so a decrease in volume of chest andair is forced out.The air we breathe out it high in Nitrogen and Carbon Dioxide,and lower in Oxygen.

Diffusion & Gaseous Exchange

Diffusion occurs when molecules from an area of high concentrationto a region of low concentration. This occurs during gaseousexchange as the blood in the capillaries surrounding the alveoli hasa lower oxygen concentration of Oxygen than the air in the alveoliwhich has just been inhaled. (teachpe.com) both alveoli andcapillaries have walls which are only one cell thick and allow gasesto diffuse across them.

Gas Inhale Exhale

Oxygen 21% 17%Carbon Dioxide 0.04% 3%

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Gas exchange occurs in the alveolus when external respirationoccurs, therefore in the muscle cells when internal respirationoccurs. Gaseous exchange relies on a process known as diffusion,which is the movement of gases from a region of high concentrationto a region of low concentration, and the difference in high and lowpressure is called a diffusion gradient. (class notes) During exercisethe more intense you work, the steeper the diffusion gradient.Blood enters the lungs low in oxygen and high in carbon dioxide.The carbon dioxide diffuses from the blood to the alveolus, wherecarbon dioxide levels are low. Oxygen diffuses from the alveolus,where oxygen levels are high, into the blood where the level is low,so blood leaves the lungs high in oxygen and low in carbon dioxide. (www.talktalk.co.uk )

The

amount of pressure exerted by a gas in a mixture is known aspartial pressure, and the greater the concentration of gas thegreater the overall partial pressure. In the alveoli where externalrespiration occurs, the Oxygen concentration being high and CarbonDioxide being low. However, in internal respiration, in the capillaryfor example the Carbon dioxide concentration would be high, andthe Oxygen low. During exercise there is a greater diffusion gradientso faster diffusion will occur, resulting in haemoglobin being able topick up Carbon dioxide more easily when Oxygen isreleased.During internal respiration haemoglobin has lots of Oxygen and little Carbon Dioxide. Haemoglobin then reaches themuscles and Oxygen diffuses from the muscles into the myoglobin,

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which is then used to produce energy, and at the same timemyoglobin gives haemoglobin its Carbon Dioxide. (Class notes)

Lung volumes

Tidal volume (TV)

Amount of air inspired/expired per breathResting value: 500ml/breathDuring exercise: increases up to 3/4litres per breath

Minute ventilation (VE)

Amount of air inspired/expired in 1 minuteResting value: 6.5-7litres/minDuring exercise: increases 120-180litres/min

Breathing rate (BR)

Number of breaths/minuteResting value: 12-15 breathsDuring exercise: increases up to 40-60 breaths (due to ahigher demand of oxygen to the muscles.)

BIBLIOGRAPHY

www.fi.edu

www.users.rcn.com

www.kidshealth.org

BTEC Sport level 3: Mark Adams, Ray Barker, Adam Gledhill, ChrisLydon, Chris Mulligan, Pam Phillippo, Louise Sutton. Essex 2010.

www.fi.edu/learn/heart

teachpe.com

Class notes

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www.talktalk.co.uk

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