Respiratory 2 Flashcards
Describe pulmonary ventilation.
-process of exchanging gas in the airways & alveoli w gas from environment
>function: increase O2 & decrease CO2
>O2 needs of metabolism
Describe normoventilation.
-normal ventilation
-PaCO2 = 40mmHg
Describe hyperventilation.
-alveolar ventilation increased beyond metabolic needs
-PaCO2 = below 40 mmHg
Describe hypoventilation.
-alveolar ventilation decreased below metabolic needs
-PaCO2 = above 40mmHg
-acute hypoventilation = respiratory acidosis
Describe lung volumes.
-amount of air at any time or amount associated with a breath
1. Total ventilation
2. Tidal volume (VT)
3. Minute ventilation or minute respiratory volume (VE)
Describe total ventilation.
-volume of gas moved in or out of airways & alveoli over a period of time
Describe tidal volume. (VT)
-amount of air breathed in or out = during respiratory cycle
-increase or decrease from normal depending on ventilation requirements
Describe minute ventilation (VE) or minute respiratory volume.
-total volume of air breathed per min
-determined by tidal volume & number of breaths per min (respiratory freq - f)
[VE = VT x f]
an increase in O2 by increase VT or f or both
Describe what the tidal volume is used for.
-to ventilate not only the alveoli, but also the airways leading to the alveoli
-little/no diffusion of oxygen & CO2 through the membrane of most airways = anatomic dead space
-no exchange of gas in nonperfused alveoli = alveolar dead space (not present in normal conditions)
minute ventilation (VE) = sum of alveolar ventilation & dead space ventilation
Describe dead space ventilation.
-tempering & humidifying inhaled air
-helps cool body
>panting = increased respiratory freq & decreased tidal volume = alveolar ventilation is constant
>heat stress ventilation = respiratory alkalosis
What is the importance of pulmonary ventilation?
-continuous renewal of air in the gas exchange areas of the lung
>rate of which new air reaches these areas = alveolar ventilation (VA)
>depends on respiratory rate & amount of new air that enters respiratory areas with each breath
[VA = f(VT-VD)]
VD = dead space volume
What is airflow opposed by?
-frictional resistance in airways
>resistance determined by radius & length of airways
-as lung inflates = airways dilate passively & airway resistance decreases
>resistance is greater during expiration
-contraction of bronchial sm muscle = determines airway caliber
Describe the effect of change in lung volume on airway resistance.
as lung volume increases during inspiration, airways dilate & reduce resistance
RV = residual volume
FRC = functional residual capacity (air volume)
TLC = total lung capacity
Describe the resting animal nasal cavity.
-pharynx & larynx = 60% of airway resistance
>areas that humidify & warm the air
>nasal resistance can be decreased during exercise by dilation of external & by vasoconstriction of vascular tissue (mucosal thickness decrease)
-breathe through mouth = bypass high resistance
horses only breath through nose
Describe how the velocity of airway flow diminishes.
-from the trachea toward bronchioles due to the branching pattern
-total cross sectional area increases toward the periphery of lungs
-high velocity air in the trachea & bronchi = lung sounds
Describe hypoxic vasoconstriction.
-induces heart failure
-beneficial when there is a localized alveolar hypoxia
-generalized hypoxia = vasoconstriction has serious consequences
