Flashcards in Respiratory system (262-271) Deck (35):
Alveolar ventilation = ?
Respiratory rate x (tidal volume - dead space)
Alveolar ventilation is a good criterion to determine what?
Effectiveness of breathing
Where does the exchange of oxygen and carbon dioxide between the lungs and blood occur?
T or F, When the lungs are in the resting position, the pressure inside them is less than the atmospheric pressure
False, Equal to atmospheric pressure
T or F, under normal circumstances, intrapulmonary pressure is ALWAYS greater than intracellular pressure
Pulmonary ventilation is influenced by what three things?
Arterial PO2, arterial PCO2 and arterial pH
What are the receptors that influence pulmonary ventilation
1. Central (medullary) chemoreceptors - located in the medulla; stimuli that increase breathing rate are decrease pH and increase PCO2
2. Peripheral chemoreceptors - located in the carotid and aortic bodies; stimuli that increase breathing rate are PO2, increase in PCO2 and decrease in pH
If there is a very low PO2 in arterial blood what happens to the pulmonary ventilation
If there is elevated arterial PCO2, what happens to pulmonary ventilation?
If there is a high arterial pH, what happens to pulmonary ventilation?
What is the major stimulus for the respiratory centers?
What is the Hering-Breuer Reflex?
It prevents overinflation of the lungs. It is mainly a protective mechanism that prevents the lungs from overfilling during inspiration. It is initiated by distention in lung stretch receptors.
3 major types of sensory receptors located in the tracheobronchial tree that control breathing?
1. J receptors (juxta-alveolar)
2. Irritant receptors
3. Joint and muscle receptors
Where are the J receptors located and what do they do?
located in alveolar walls; when stimulated J receptors cause rapid, shallow breathing
Where are the irritant receptors located and what do they do?
Located between airway epithelial cells; are stimulated by noxious substances
What activates the joint and muscle receptors?
activated during exercise to stimulate breathing
An increased PCO2 does what to respiration by stimulating what receptors?
- by stimulating the central H+ chemoreceptors
What term is the greatest amount of air that one can exchange in a forced respiration?
Vital capacity (VC)
- VC = TV+IRV+ERV
What term is the amount of air inspired or expired with each breath?
Tidal volume (TV)
- normal RR is about 12 times per minutes
What term is the volume of air inspired in a full inhalation, after an normal expiration?
- IC = IRV + TV
What is the amount of air remaining in the lungs at the end of normal expiration?
Functional residual capacity (FRC)
- provides air to alveoli that will aerate the blood evenly between breaths
- FRC = ERV + RV
What is the extra volume of air that can be inspired over and above the normal tidal volume (by taking a deep breath)
Inspiratory Reserve (IRV)
What is the extra volume of air that could still be expired past the normal expiration of tidal volume
Expiratory Reserve (ERV)
What is the volume of air moved into the respiratory passageways in one minute?
Minute respiratory volume (MRV)
- MRV=TV x RR
What is the maximum volume that the lungs can be expanded with the greatest possible inspiratory effrot?
Total lung capacity
What is the volume of air remaining in the lungs at the end of a forced maximal expiration?
Residual volume (RV)
4 factors that will determine how fast gas will pass (Diffuse) through the respiratory membrane
1. Thickness of Membrane - rate is inversely proportional
2. Surface area of membrane - rate is directly proportional
3. Gas solubility and MW - increasing pressure, more molecule dissolve in liquid
4. Pressure difference between the two sides of the membrane - net diffusion from high to low pressure regions
What is Apnea
Transient cessation or absence of breathing
What is Hyperapnea
Abnormally deep and rapid breathing
What is Dyspnea
Unpleasant sensation of difficulty in breathing
What is Hypercapnea
Excess CO2 in arterial blood
What is Hypocapnea
Below normal CO2 in arterial blood
What is Respiratory arrest
permanent cessation of breathing
Most important test for hypoventilation
Arterial CO2 tension