Quiz 6 Flashcards
Motor signal from DRG to diaphram what type of signal?
Ramp type signal lasting 2 seconds
(Gives time to move air)
(then excitatory signal stops for next 3 seconds to allow relaxation of the diaphragm - expiration)
How VRG differs from DRG (4)
- Inactive during normal respiration
- No rhythmic oscillation help (Respiration)
- Contributes to increase pulm ventilation
- Stimulates abdominal muscles for forced expiration
What reflex inhibits over inflation of the lung? How transmitted? what does it also do?
Hering-Breuer Reflex
from stretch receptors in bronchioles/bronchi to DRG via Vagus nerve (X)
increases RR
what acts directly on the respiratory center to increase strength of both inspiratory and expiratory motor signals?
Excess CO2 or H+ ions
oxygen does not have a direct effect but acts on peripheral chemoreceptors
Why are CO2 levels in brain and blood equal?
CO2 is highly permeable to Blood-brain barrier
What equation to disassociate CO2 to get into brain? What stimulates Respiratory center activity?
- CO2 and H2O form Carbonic acid (H2CO3), which disassociates into H+ and HCO3 (bicarbonate)
- The release of H+ in brain
How do changes in CO2 blood levels affect respiration drive over time?
By how much?
Acute - potent affect
Chronic (after a few days) - weak effect
about 1/5th initial response
When are blood oxygen PO2 levels sensed by chemoreceptors?
< 70mmHg
where are chemoreceptors?
Carotid and Aortic bodies (they act on DRG)
high flow arterial blood supply areas
Carotid bodies what nerve?
CN IX (Glossopharyngeal)
Aortic bodies what nerve?
CN X (Vagus)
What increases alveolar ventilation drive?
- Increased PCO2
- Increased O2
- Acidosis
What causes a quicker reaction of increasing alveolar ventilation?
- Decreased PH
- Decreased PCO2
what does increased metabolism do to alveolar ventilation during exercise?
Increases linearly with alveolar ventilation
what causes increase in ventilation during exercise? (4)
- Brain transmits to brainstem/VRG while transmitting motor impulses to contracting muscles
- joint and muscle proprioceptors transmit signal
- Hypoxia in muscles
- PCO2 and O2 changes
at the start of exercise PCO2 and alveolar ventilation do what?
PCO2 and A.V. drop then slowly increase with exercise
at the end of exercise PCO2 and alveolar ventilation do what?
PCO2 increases and A.V. drops
treatment of brain edema?
Hyperventilation and Hypertonic diuresis
2 conditions that allow Cheynes-Stokes breathing to occur?
- Long delay in transport of blood from lungs to brain (low CO)
- Increased negative feedback gain (brain damage) due to hypoxia or severe metabolic abnormality
physiologies of Cheynes-Stoke Breathing (2)
- Large amounts of dissolved and bound CO2 & O2 in blood and tissue
- Lungs cannot build-up enough CO2 or deplete O2 supply normally
What plays most fundamental role in control of breathing?
DRG
DRG receives signals from what three sources
- Peripheral Chemoreceptors
- Baroreceptors
- Lung receptors
What Controls the ‘switch-off’ point of the inspiratory point & shortens entire respiratory cycle?
Pneumotaxic center
Weak vs strong Pneumotaxic center?
Strong - shorter inspiratory phase (0.5 sec) and higher RR (30-40)
Weak - longer Inspiratory phase (5 sec) and lower RR (3-5)
DRG controls?
Inspiration and Rhythm
VRG controls?
expiration and inspiration, exercise
Signals the DRG to prevent or retard the ‘switch-off’ of inspiratory ramp stimuli
Apneustic center
controls the intensity of inspiration (2)
Pneumotaxis and Apneustic centers
