S3_L6: Control of Respiration Flashcards
The basic rhythm of breathing is controlled by respiratory centers located in the ___.
brainstem
The expiratory center (VRG) in the ___ appears to
function during forced expiration (labored, difficulty in breathing), stimulating the internal intercostal and abdominal muscles.
medulla oblongata
Located at the superior border of pons, it controls the switch off point of the dorsal respiratory group (DRG). It tells when the train of impulses stop.
Pneumotaxic center
The basic rhythm of breathing is modified by input
from the central and peripheral ____. They respond to changes in the PCO2, pH, and PO2 of arterial blood, the most important factors altering ventilation.
Chemoreceptors
Determine the corresponding descriptions of hyper- and hypoventilation
- High PCO2, Low pH of the blood results
- To counteract, ↑ in PCO2 ↓ in pH (alkaline blood) will stimulate peripheral chemoreceptors to activate the respiratory centers to decrease the activity of pneumotaxic center
- Low PO2 results
- Breathing rate and depth is too low to maintain normal blood gas levels
- Low PCO2, High pH of the blood results
A. Hyperventilation
B. Hypoventilation
- B
- A
- B
- B
- A
The basic rhythm of breathing is set by the ___, located in the medulla. Other respiratory centers, located in the medulla and pons, also control breathing.
inspiratory center
____ monitor the PCO2, pH, and PO2 of arterial blood and alter the basic rhythm of breathing
Chemoreceptors
____, reflected by changes in pH, is the most important stimulus controlling ventilation (rate
and depth of breathing)
Carbon dioxide / CO2
What has an acute response to an increase in CO2?
Central chemoreceptors
Found in the aortic bodies (aortic arch) and carotid bodies (bifurcation of carotids)
Peripheral Chemoreceptors
Efferent information from the peripheral chemoreceptors travels to the respiratory centers via what two nerves?
vagus and glossopharyngeal nerves / CN IX & CN X
Found in the CNS, specifically the medulla. It monitors the pH associated with CO2 levels in the CSF in the floor of 4th ventricle.
Central Chemoreceptors
Found outside the CNS and monitors the PCO2, pH, and PO2 of arterial blood
Peripheral Chemoreceptors
The ultrafiltrate of blood which protects brain from
traumatic injury and is rich in nutrients and O2.
Cerebrospinal fluid
The ___ sets the basic rhythm of breathing by automatically initiating inspiration
inspiratory center (dorsal respiratory group)
Which respiratory center has both I and E neurons; for inspiration and expiration which will be called upon
during labored breathing?
Ventral respiratory group
The normal resting breathing rate is between ___
breaths per minute
12-15
Contains I neurons for inspiration. Located at the medulla, bilaterally. Its function is for normal tidal inspiration
inspiratory center (dorsal respiratory group)
The inspiratory center sends a train of impulses that will travel through the phrenic nerve, going to which two muscles?
diaphragm and external intercostal muscles
For inspiration, the inspiratory center sends nerve impulses for (1)___ seconds, causing the diaphragm and external intercostal muscles to (2)___.
- 2
- contract
For expiration, the inspiratory center stops sending nerve impulses for (1)___ seconds, causing the diaphragm and external intercostal muscles to relax, allowing for (2)___.
- 3
- elastic recoil
What sends tetanic impulses for the respiratory muscles to fire and contract fully, allowing us to inspire completely?
Dorsal respiratory group
TRUE OR FALSE: Voluntary control can influence ventilation by sending signals from the cerebral cortex to respiratory muscles, so we can voluntarily change our breathing rate and depth when holding our breath, speaking, or singing. However, chemoreceptors input to the respiratory centers will eventually override conscious control and
force you to breathe.
True
What reflex is described wherein stretch receptors in the visceral pleura and large airways send inhibitory signals to the inspiratory center during very deep inspirations, protecting against excessive stretching of the lungs?
Hering-Breuer (Inflation) reflex
This reflex prevents superinflation and bursting of the alveolus
Hering-Breuer (inflation) reflex
Pain and strong emotions, such as fear and anxiety, can also influence ventilation. They act by way of the ____ to stimulate or inhibit
the respiratory centers.
hypothalamus
What two protective reflexes can remove pulmonary irritants from the airways, such as dust, smoke, noxious fumes, and excessive mucus?
- Coughing
- Sneezing
TRUE OR FALSE: Ventilation increases during strenuous exercise, with depth increasing more than the rate.
True
During exercise, ___ in moving muscles and joints stimulate
the respiratory centers, as does an increase in body temperature. As muscles and joints move, the brain responds by giving a motor outflow, as a result of an anticipatory response.
Proprioceptors
Other factors which increase ventilation during exercise are circulating epinephrine and norepinephrine secreted by the (1)___ stimulate the respiratory centers, as well as (2)___ produced by exercising muscles, which activate the peripheral chemoreceptors.
- adrenal medulla
- lactic acid
TRUE OR FALSE: Ventilation increases within seconds of the beginning of the exercise, probably in anticipation of exercise, a learned response. It also increases because the motor areas of the cerebral cortex which stimulate the muscles also stimulate the respiratory centers.
True
The peripheral chemoreceptors also monitor arterial PO2. However, the arterial PO2 must drop below ___ before chemoreceptors respond
60 mmHg
Additional: 60 mmHg is 90% O2 saturation
At very high altitudes, the alveolar PO2 may fall to ___ and increased ventilation will make a dramatic difference in the amount of O2 loaded into the blood. The decreased PO2 will activate the peripheral chemoreceptors, DRG, VRG, and ventilation muscles to normalize the gas.
40 mmHg
Carotid and aortic bodies are always exposed to
(1)___ blood; thus, any deviation of the blood
gases will immediately stimulate peripheral receptors to adjust respiration. (2)___ hemoglobin saturation will activate the peripheral chemoreceptors.
- oxygenated
- 75%
The peripheral chemoreceptors are sensitive to blood pH and the ___ that is in plasma, which is produced during strenuous exercise.
lactic acid
When there is an imbalance of the gas concentrations in the blood, the peripheral chemoreceptors increase ___ that will be exhaled to normalize
Carbon dioxide / CO2
When there is increased PCO2 in fourth ventricle, there is an increased (1)___ and decreased (2)___ in fourth ventricle.
- Hydrogen
- pH
TRUE OR FALSE: H+ ions cannot penetrate blood brain barrier formed by fibrous astrocytes
True
CO2 diffuses and combines with water results to carbonic acid. However, carbonic acid is unstable and will dissociate to (1)__ and (2)__.
1-2. Hydrogen & bicarbonate
Through hydrogen’s dissociation from carbonic acid, H+ will (1)___ stimulate the chemosensitive area. It depolarizes the nerve fibers, so more hydrogen means more action potentials. This results in the increased activity of (2)___ to increase the rate and depth of ventilation.
- directly
- phrenic nerve
