Respiratory System Flashcards
3major functions of respiratory?
Pulmonary ventilation
Gas exchange/transport
Regulation of respiration
Inspiration
Contraction of inspiratory muscles+diaphragm
Increase of chest cavity, lungs expanding
Decrease in pressure causes air to be sucked in
Active
Expiration
Relaxation of inspiratory muscles+diaphragm
Contraction of expiration muscles, depression of chest cavity
Positive pressure presses air out
Passive
Eupnea
Normal breathing
Hyperpnea
Greater range of motion
Polypnea
Increased frequency du to thermal regulation
Tachypnea
Increased frequency due to other reasons
Apnea
Respiratory arrest
Lung compliance
Distensibility=volume/pressure
Depends on elasticity and surface tension of alveoli
Tidal volume
Vet
Air in and out during normal breath
Inspiratory reserve volume
IRV
Amount of air able to force in after tidal volume
Forced inspiration
Expiratory reserve volume
ERV
Amount of air able to force out after tidal volume
Forced expiration
Residual volume
RV
Amount of air left in lungs after maximal expiration
Inspiratory capacity
IC
Amount of air that can be inspired after normal inspiration
IC=Vt+IRV
Functional residue capacity
FRC
Amounts of air left after normal respiration
FRC=ERV+RV
Vital capacity
VC
Amount of air in lungs after maximal inhalation
VC=Vt+IRV+ERV
Total lung capacity
TLC
amount of air in lungs after maximal inspiration
TLC=Vt+IRV+ERV+RV
Pulmonary ventilation
Amount of air into lungs per min
Vol/min=Vt*respiratory frequency
Alveolar ventilation
Amount of air reaching alveoli/min
Alveolar volume/min=(VT-dead space volume)*respiratory frequency
Gas exchange betw lungs and blood
Passive diffusion due to pressure gradients
Depend on pressure differentials, solubility of gas into fluid, temperature
Mechanisms of O2 transport
Dissolved in plasma
Together with hemoglobin
Oxyhemoglobin
Hb with O2
Deoxyhemoglobin
Hb without O2
Transport of CO2 in blood
Dissolved in plasma 10%
Carbamino hemoglobin 20%
Bicarbonate ions 70%
Voluntary respiratory regulation
Cerebral cortex
Involuntary respiratory regulation
Respiratory center in brain stem
- medulla oblongada
- pons
Rhythmicity center
In medulla oblongada
Dorsal respiratory group- inspiratory
Ventral respiratory group- expiratory
Accessory respiratory regions
In pons
Apneustic center-promotes inspiration
Pneumotaxic center-inhibits respiration
Modifies activities of rhytmicity center
Dorsal respiratory group
In medulla oblongada
Sets basic respiratory rate
Stimulates contraction of inspiratory muscles
Ventral respiratory center
In medulla oblongada
Inactive in normal quiet respiration
When increased inhalation=signals to dorsal
Stimulation of inspiratory and expiratory muscles
Pneumotaxic center
In pons
Inhibits inspiration
Continous inhibitory impulses to dorsal group to avoid excessive filling
Inhibits inspiration=increased rate of inspiration
Apneustic center
In pons
Promotes inspiration
Excitatory impulses to dorsal group=prolonged inspiration, delaying signals from pneumotaxic center
Factors affecting respiratory center
+higher centers of brain (speech, emotions, voluntary breath…)
+chemoreceptors in aortic+carotid body
+proprioreceptors in muscles/joints
+receptors for touch, temp, pain
-higher centers in brain
-Hering-Breuer reflex=stretch receptors in lung
Peripheral chemoreceptors
Aortic bodies- in aortic arch, sensitive to PO2 changes
Carotid bodies- bifurcation of carotid A, sensitive to changes of PO2
Central chemoreceptors
In medulla oblongada
Sensitive to changes in OO2 and pH
Chemoreceptors role
Modifies ventilation to maintain CO2, O2, pH levels
PO2 most important due to effects of blood pH
Hypocapnia
Low CO2 in blood
Caused by hyperventilation
Hypercapnea
High CO2 in blood
Caused by hypoventilation
