types of phases of respiration

8/7/2019 Types of Phases of Respiration

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Many factors affect respiratory capacity forexample, a persons size, sex, age, and

physical

condition.

The normal quit breathing movesapproximately

500 ml of air into and out of the lungs witheach breath. This respiratory volume isreferred to as the tidal volume (TV)


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A person can inhale much more than istaken during a normal, or tidal breath . Theamount of air that can be taken in forciblyover the tidal volume is the inspiratoryreserve volume (IRV)

After a normal expiration, more air can beexhaled. The amount of air that can be

forcibly exhaled after a tidal expiration, theexpiratory reserve volume (ERV)isapproximately 1200 ml.


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Even after the most strenuous expiration,

about 1200 ml of air still remains in the

lungs, and it cannot be voluntarily expelled.

This is the residual volume.

Residual volume is important because it

allows gas exchange to go on continuously

even between breaths and helps keep the

alveoli open. (inflated)


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The total amount of exchangeable air is

typically around 4800 ml in healthy young

males, and this respiratory capacity is the

vital capacity

Much of the air that enters the respiratory

tracts remains in the conducting zone

passageways and never reaches the alveoli.This is called the dead space volume


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Lung Volume

The average total lung capacity of an adulthuman male is about 6 litres of air, but onlya small amount of this capacity is used

during normal

Lung volumes and lungcapacities refer to the volume of air

associated with different phases of therespiratory cycle. Lung volumes are directlymeasured. Lung capacities are inferredfrom lung volumes.


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Control of Respiration

Control of ventilation (control of

respiration) refers to

the physiological mechanisms involved

in the control of physiologic ventilation.

Gas exchange primarily controls the rate

of respiration.

Ventilation is normally controlled bythe autonomic nervous system, with only

limited voluntary override


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The activity of the respiratory muscles, thediaphragm and the external intercostals, is

regulated by nerve impulses transmitted to

them from the brain by the phrenic and

intercostal nerves.The neural centers that control the

respiratory rhythm and depth are located in

the medulla and pons.


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The medulla, which sets the basic rhythm

of breathing, contains a self-exciting

respiratory centers, as well as other

respiratory centers.The pons centers appear to smooth out

the basic rythym of inspiration and expiration

set by the medulla.


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Abnormal Reflexes

Asthma

common chronic inflammatorydisease of

the airways characterized by variable

and recurring symptoms, reversible

airflow obstruction,

and bronchospasm. Symptoms

include wheezing, coughing, chesttightness, and shortness of breath


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Bronchospasm

- bronchial spasm is a suddenconstriction of the muscles in the

walls of the bronchioles

- causes difficulty in breathing which `

can be very mild to severe


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Apnea

- is a term for suspension ofexternal breathing

- there is no movement of

the muscles of respiration and thevolume of the lungs initially remains

unchanged


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Hypercapnia

- known as hypercarbia, is a conditionwhere there is too much carbon

dioxide (CO2) in the blood. Carbon

dioxide is a gaseous product of

the body's metabolism and is normally

expelled through the lungs.

- normally triggers a reflex which

increases breathing and access tooxygen, such as arousal and turning the

head during sleep


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types of phases of respiration

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