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17 Cards in this Set
- Front
- Back
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What is inspiration?
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Breathing in - inhalation
active process Muscular involvement of Diaphragm and IC muscles |
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What is expiration?
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Breathing out - exhalation
Passive rprocess Caused by elastic recoil of diaphragm Relaxation of IC muscles |
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What is the fundamental principle of how we take in air?
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We must decrease the pressure within ourselves in order to assist in movement of air from an area of high concentration to low concentration
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How do we decrease the pressure in the respiratory tract?
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-Expand thorax
--By contraction of the diaphragm (flatten out) --External IC muscles raise the ribs ---both work by either lowering or increasing the borders of the thorax to elongate the the thorax NB Pec minor and sternocleidomastoid help on deep inspiration |
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Describe the pleural membranes of the lungs
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Visceral pleura-coats lung tissue surface
Pleural cavity with serous fluid Parietal pleura - Coats thoracic body wall |
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How do pleural membranes assist is lung expansion
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When the thorax expands the parietal and visceral pleura are pulled together and therefore the lungs are expanded alongside.
This is because of the surface tension between the two layers behaves like glue. |
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How are the alveoli not affected by this?
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Surfactant - type 2 pneumocytes
decreases surface tension - alveolus retains shape and does not buckle |
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Explain expiration
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Abdo Pressure>thorax pressure
-Diaphragm is elastically recoiled -IC Muscle stimulation is shut off internal intercostal muscles Internal/external obliques rectus abdominus all the above contribute to forced expiration (when talking, blowing etc) |
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Why can we not use all 500ml of our tidal volume?
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Because 30% is dedicated to the anatomic dead space
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What is the anatomic dead space?
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The parts of the respiratory tract where no gas exchange occurs.
It is necessary to remain there to prevent a vacuum forming. A vacuum would cause the lung to buckle onto itself |
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Neural regulation of breathing
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Dorsal inhibitory centres cause contraction inspiratory musculature
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When does the ventral respiratory group come into effect?
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During more active breathing
-Forced expiration requires the ventral respiratory group |
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Describe the pneumotaxic area
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Pons - determines how much air we take in
As the dorsal RC fires constant and rhytmic they can not alone account for the change of breathing we experience The Pneumotaxic area adjust the firing patternof the DRG Faster=hyperventilation Prolonging of bursts = Deeper breaths |
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How is breathing dynamically controlled?
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Central chemoreceptors
Peripheral chemoreceptors Inflation reflex |
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Outline the central chemoreceptor reflex
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In the brainstem and detect changes in the CO2 levels.
High CO2=inc breathing rate In CSF no globin to take H+ away from CO2 in fluid The chemorecpetors detect changing H+ levels so indirectly detects levels CO3-. |
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Outline the peripheral chemoreceptors role in breathing
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Only really detect very low O2 levels, only play a part in life threatening levels
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Inflation reflex - go
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Negative feedback
Detect lung stretching (sensory neurons that detect stretch) The more they are active, the more info that is fed into the pneumotaxic area and tell our lungs to end inspiration no alveolus bursting |
