(ppt) UNIT 8 The Pulmonary System Flashcards
How does the neuro system help us breathe?
sets auto rate via brainstem neurons that respond to peripheral chemoreceptors in carotid, aortic, and lungs, then sends impulses to intercostal muscles.
central chemoreceptors
are located below the blood/brain barrier in the near the Medulla Oblongata in the brain
Central Chemoreceptors sense changes in pH of CSF (reflects CO2 concentration because CO2 diffuses across the blood/brain barrier.
peripheral chemoreceptors
When arterial hypoxemia occurs, peripheral chemoreceptors in the aortic bodies, aortic arch, and carotid arteries sense the change in arterial blood PO2 and stimulate an increased ventilatory rate. (most sensitive to PO2)
lung receptors (J-receptors, SNS, PSN)
J receptors found near capillaries of alveolar septa and sense increased pulmonary capillary pressure, then initiate rapid, shallow breathing, hypotension, and bradycardia
Sympathetic autonomic nerves promote airway dilation when relaxed
Parasympathetic promote constriction when needed and in response to irritants
chemoreceptors
monitor PO2, PCO2, and pH of arterial blood –both central and peripheral receptors
alveolar surface tension
Surfactant
Reduces surface tension in alveoli
The elastic recoil of the lungs helps…
them to return to the resting state after inspiration and allows the lungs to remain passive during expiration.
Because of the elastic recoil property of the lungs there is no need for the major muscles to be involved with the action of expiration.
Airway resistance is normally…
- decreased…
- increased…
Normally low
Decreased (bronchodilation) with stimulation of Beta-2 adrenergic receptors
Increased by obstruction
- Edema of airway
- Mucous plugging
- bronchospasm
work of breathing is normally…
Muscular effort required to breath, normally low
Vt
Tidal Volume (Vt) = amount of air inhaled and exhaled with each breath (500 ml)
IRV
Inspiratory Reserve Volume (IRV) = amount of air that can be forcefully inhaled after a normal tidal volume (3000-3300 ml)
ERV
Expiratory Reserve Volume (ERV) = amount of air that can be forcefully exhaled after a normal tidal volume (100-1200)
RV
Residual Volume (RV) = amount of air left in the lungs after forced exhalation (1200)
TLC
Total Lung Capacity (TLC) = maximum amount of air that can be contained in the lungs after max inspiratory effort (TLC=VC+RV)– (5700-6200ml)
VC
Vital capacity (VC) = maximum amount of air that can be exhaled after a max inspiration (80%of TLC)= (4500-5000ml)
Inspiratory Capacity
Inspiratory Capacity = maximum amount of air that can be inspired after a normal expiration
FRP
Forced Residual Capacity (FRP) = volume of air remaining in lungs after a normal tidal volume exhalation
physiologic dead space
Physiologic Dead Space = volume of inspired air that does not exchange gases with pulmonary blood
Define V
Ventilation (V)
Gas distribution
Define Q
Perfusion (Q)
Blood distribution
Normal V/Q ratio is …
0.8 (V=80% of Q)
Net result: ventilation and perfusion are greatest in…
the lower lobes.
**Blood flow through pulmonary capillary bed increases in …
regular increments from the apex to the base.
**Perfusion is greater than ventilation in …
the bases and ventilation exceeds perfusion in the apices of the lung (expressed as the ventilation-perfusion ration (V/! = 0.8)