Lecture # 11 Regulation of Respiration Flashcards
(41 cards)
______ and _____ are specific areas of the brain stem that make up the respiratory center of the brain.
Medulla Oblongata and Pons
The 3 major groups of neurons located in the brain stem (medulla obglongata and Pons) that control respiration are:
- Dorsal Respiratory Group (DRG)
- Ventral Respiratory Group (VRG)
- Pneumotaxic center
Which of the 3 major groups of neurons in the brain stem plays the most fundamental role in control of breathing?
DRG (Dorsal Respiratory Group)
Dorsal Respiratory Group:
Does the DRG controls inspiration, expiration or both?
Inspiration. (remember, expiration is passive at rest)
Dorsal Respiratory Group:
Does the DRG control respiratory rate, rhythm, or depth? or all?
Rhythm.
Dorsal Respiratory Group:
Which 2 cranial nerves deliver sensory information to the DRG?
Glossopharyngeal (IX) and Vagus (X) nerves.
Dorsal Respiratory Group:
The Dorsal Respiratory Group (DRG) recieves peripheral sensory information through the Glossolpharyngeal and vagus nerves. There 3 peripheral sensory sources for this information, what are they?
- Peripheral Chemoreceptors
- Baroreceptors
- Lung receptors.
Dorsal Respiratory Group:
What is the Inspiratory “Ramp” Signal?
- The DRG neurons emit repetitive bursts of inspiratory action potentials in a rhythmic fashion to the diaphragm.
- The motor signals are NOT transmitted in an instantaneous action potential burst, but begins weakly and increases steadily in a “ramp-like” manner for 2 seconds to cause contraction of the diaphragm (inspiration).
- the excitatory signal abruptly stops for the next 3 seconds to allow relaxation of diaphragm (passive expiration)
- The advantage of the ramp signal is that it causes a steady increase in inspiratory volume, rather than a quick twitch of the diaphragm, which would not allow full inflation of lungs.
Dorsal Respiratory Group:
The DRG is responsible for control of respiration during rest or exercise?
Rest.
Ventral Respiratory Group:
The VRG controls Inspiration, Expiration or both?
- The VRG is active only with stress or exercise and inactive during normal quiet breathing.
- It controls BOTH inspiration and expiration during high levels of pulmonary ventilation. (exercise of stress).
- the VRG stimulates the abdominal muscles to assist in forced exhalation.
- VRG contributes to respiratory drive to increase pulmonary ventilation and does not appear to participate in basic rhythmic oscillation which controls respiration.
Pneumotaxic Center:
What are the major functions of the Pneumotaxic Center.
- Functions to limit inspiration phase of breathing cycle and secondarily to increase rate of breathing.
- Controls the “switch-off” point of the inspiratory point and shortens entire respiratory cycle.
Pneumotaxic Center:
Strength of inhibitory signal determines the filling phase and rate of breathing cycle. Therefore, a strong pneumotaxic signal will _____ the inspiration phase and _____ the respiratory rate.
- A strong pneumotaxic signal will SHORTEN the inspiration phase and INCREASE the respiratory rate.
- A weak pneumotaxic signal will LENGTHEN the inspiration phase and REDUCE respiratory rate.
The Apneustic Center works with which respiratory group of neurons?
It works with the ______ (answered above) to control the _______ of inspiration.
Pneumotaxic Center.
Pneumotaxic Center; INTENSITY
T/F: The Hering-Breuer Reflex is responsible for the involuntary gasp one makes when surprised.
False: I just made that up.
- The Hering-Breuer Reflex is a protective feed-back reflex which limits the over-inflation of the lungs.
- Stretch receptors in the muscular portions of the bronchi an bronchioles transmit signals via the VAGUS nerve to the DRG when lung is overstretched (Tidal volume >1.5L)
- Feedback response switches off the inspiratory ramp and stops further inflation.
- This reflex also increases the rate of respiration.
T/F: Much like preload and cardiac output in the CV system, respiratory system control is increased or decreased to match the ventilatory needs of the body.
TRUE
Chemical Control of the Respiration:
T/F: Both O2 and CO2 have direct effects on the respiratory centers on the brain.
FALSE
Excess CO2 or H ions in the blood act DIRECTLY on the respiratory center to increase strength of both inspiratory & expiratory motor signals.
Chemical Control of the Respiration:
Oxygen does NOT have a direct effect on respiratory centers but acts on peripheral chemoreceptors in the _____ and ______.
Carotid and Aortic Bodies.
_______ is the area of the brain stem that is highly responsive and sensitive to changes in blood pCO2 or H ion concentrations.
The ventral medulla surface.
Place in order by which has the most direct stimulus on the respiratory center.
pO2, pH (or H ions), pCO2
PCO2 = most direct stimulus pH= less direct stimulus pO2= least and is stimulated peripherally
T/F: CO2 is highly permeable to the blood-brain barrier so blood and brain concentrations of CO2 are equal.
Girl you know it’s TRUE!
T/F: [H] ions cross the blood brain barrier easily.
Nope! they do not!
Excitation of respiratory center is great in the first few house of carbon dioxide increase. After 1-2 days of carbon dioxide exposure the stimulatory response declines. Why?
- The decline results for renal adjustment of of hydrogen back to normal or close to normal levels (COPD).
- The effect decreases to about 1/5th of the initial response.
Why do patient’s with COPD have a blunted response to increased CO2?
Changes in blood CO2 concentration has a potent ACUTE effect on controlling respiratory drive but a weak CHRONIC effect after a few days (or years) of adaptation.
T/F: Changes in Oxygen have virtually NO effect on respiratory center to alter respiratory drive.
True!!!!!!!!!!!!!!!
-changes in O2 concentration acts indirectly by peripheral receptors to alter respiratory drive.
