Respiratory system: Regulation of Respiration Flashcards
Eupnea
normal respiratory rate & rhythm
apneustic breathing
prolonged inspirations
- gasping!
apnea
cessation of breathing
hyperpnea
increase in ventilation
ex. after exercise
What are the 3 respiratory centers ? where are they located?
- dorsal respiratory group - medulla
- Pneumotaxic center - pons
- ventral respiratory group - medulla
What does the dorsal respiratory group control?
Inspiration
Where does the DRG get its sensory info from?
afferent from vagus and glossopharyngeal N.
- peripheral chemoreceptors
- baroreceptors
- receptors in lungs
What is the basic rhythm of respiration controlled by the DRG?
- action potentials from DRG ramp up and signal inspiratory mm (diaphragm)
- signals stop suddenly for 3 sec which stops stimulating the diaphragm to contract –> passive recoil
- process repeats
what are the 2 points of control of the respiratory Ramp?
- rate of increase of the ramp signal.
- can occur quickly when needed for rapid breathing - End of ramping
- usual method for controlling rate of respiration
What does the pneumotaxic center do?
signals DRG, determines the “TURN OFF” point of inspiratory ramp –> limits inspiration
What will a strong pneumotaxic signal equal?
short lung filling time (inhibits DRG)
What will a weak pneaumotaxic signal do?
longer lung filling time.
what does limiting the ramp time do?
shortens inspiratory time (and therefore, expiratory time) –> overall increase in breathing rate
What does the VRG- ventral respiratory group do? When is it active?
with increased need for ventilation, VRG contributes to inspiration and expiration (diaphragm& abdominals)
-normally inactive during quiet breathing
What is the Hering Breuer reflex? How does it work?
- Stretch receptors
- in walls of bronchi and bronchioles
- send signals to DRG when overstretched –> turns OFF ramp
- increases respiratory rate
- similar to pneumotaxic center
What is the goal of matching ventilation needs of the body?
What are control mechanisms responsive to?
maintain appropriate 02, C02, H+
- control mechanisms are responsive to these molecules.
Central chemoreceptors respond to acute increased what? Where are they?
C02 & H+
Medulla
_____ is the primary stimulus, but presents across the blood brain barrier as a direct effect of _______
H+
CO2
H cannot cross the blood brain barrier, but CO2 can. This means that the main driver is CO2
what is the process of the chemoreceptors?
increase in blood C02 –> gets into CSF –> reacts with H20 –> forms H+ –> H+ ions stimulate rate and depth of breathing
how long does the increased level of C02 last? What is this due to?
1-2 days
- due to renal readjustment
Change in blood C02 has a ________ acute effect on controlling respiratory drive, but ________ chronic effect after a few days of adaptation
strong
weak
What effect does 02 have on CNS respiratory centers?
no direct effect
How does peripheral chemoreceptor system work? Does it have a rapid or slow response?
What will happen to blood Hgb?
responds to changes in blood 02
- sends signals to DRG
- rapid response to low arterial P02. (especially if P02 falls between 30-60)
- blood Hgb will decrease in this range.
what effect do C02 and H+ have on peripheral receptor response?
much less powerful influence.
- However, peripheral effects of C02 occur 5x faster than central effects. This may be important at onset of exercise.
what is acclimatization?
Adapting to high altitude
-respiratory center in brainstem loses 4/5 of sensitivity to changes in PC02 & H+ over 2-3 days
how does exercise affect ventilation?
brain may initially stimulate respiratory center in brainstem when sending motor impulses to working mm –> anticipatory stimulation
what are some other influences on ventilation?
pain pulmonary irritant receptors proprioceptors brain edema anesthesia
How does hyperventilation work?
increase in rate and depth of breathing, exceeds need to remove CO2
- get rid of C02 too fast –> urge to breathe decreases
- low blood C02 (hupocapnia) causes cerebral vasoconstriction
How does pulmonary disease work ?
retention of C02 can occur (emphysema)
- PC02 chronically elevated - chemoreceptors adapt
- reduced P02 acts on peripheral chemoreceptors & provides main stimulus for respiration = hypoxic drive
What would be the result of giving pure oxygen to a pt. with emphysema?
No hypoxic drive –> no C02 to get rid of –> stop breathing.
