Breathing Flashcards
What is breathing controlled by?
centers in the brainstem
What are the 4 components that control breathing
1) chemoreceptors for O2 and CO2
2) mechanoreceptors in the lungs and joints
3) control centers for breathing in the brainstem
4) respiratory muscles
Breathing is an involuntary process that is controlled by the _____ and _____ of the brainstem.
medulla
pons
What are the 3 brain stem centers that control the frequency of normal, involuntary breathing?
- medullary respiratory center
- apneustic center
- pneumotaxic center
What are the 2 groups of neurons that compose the medullary respiratory center?
- inspiratory center
- expiratory center
Afferent (sensory) information reaches the medullary inspiratory center via what 3 things?
- central chemoreceptors
- peripheral chemoreceptors
- mechanoreceptors (in the lungs, muscles, and joints)
Efferent (motor) information is sent from the medullary inspiratory center to which nerve?
To the phrenic nerve, which innervates the diaphragm
What is apneusis?
An abnormal breathing pattern with prolonged inspiratory gasps, followed by brief expiratory movement
Stimulation of the apneustic center _____ the inspiratory center in the medulla. What does this result in?
excites
Results in prolonging the period of APs in the phrenic nerve, and thereby prolonging the contraction of the diaphragm
The pneumotaxic center turns inspiration ___.
off
What structures are the most important for the minute-to-minute control of breathing?
the central chemoreceptors in the brainstem
Increases in arterial PCO2 produces _____ in PCO2 in the brain and the CSF, which _____ pH of the CSF. Central chemoreceptors detect this decrease in pH and signal the inspiratory center to _____ the breathing rate
increases
decreases
increase
Other than chemoreceptors, what other types of receptors are involved in the control of breathing?
- Lung stretch receptors
- Joint and muscle receptors
- Irritant receptors
- J receptors
Lung stretch receptors instruct the inspiratory center to _____ the breathing rate.
decrease
Joint and muscle receptors instruct the inspiratory center to _____ the breathing rate.
increase
Irritant receptors instruct the inspiratory center to _____ the breathing rate.
increase
J receptors instruct the inspiratory center to _____ the breathing rate.
increase
What 6 things increase in response to exercise?
- O2 consumption
- CO2 production
- ventilation
- CO
- pulmonary blood flow
- venous PCO2
What 2 things decrease in response to exercise?
- pH (sometimes)
- physiologic dead space
What 3 things are unaffected in response to exercise?
- Arterial PO2
- Arterial PCO2
- pH (sometimes)
What happens to V/Q in response to exercise?
It increases in the lungs
In response to exercise the O2-hemoglobin dissociation curve shifts to the ____. Which means P50 _____ and the affinity for O2 _____.
right
increases
decreases
What 4 things increase in response to high altitude?
- ventilation rate
- pH
- pulmonary resistance
- pulmonary artery pressure
What 2 things decrease in response to high altitude?
- alveolar PO2
- arterial PO2
In response to high altitude the O2-hemoglobin dissociation curve shifts to the ____. Which means P50 _____ and the affinity for O2 _____.
right
increases
decreases
Define hypoxemia
a decrease in arterial PO2
What are 5 examples in which arterial PO2 decreases, which causes hypoxemia?
- high altitude
- hypoventilation
- diffusion defect (fibrosis)
- V/Q defect
- right-to-left shunt
What is a useful tool for comparing causes of hypoxemia?
the A-a gradient
What is the A-a gradient?
the difference between the PO2 of alveolar gas and the PO2 of systemic arterial blood
A-a gradient = PAO2 - PaO2
In some cases of hypoxemia, the A-a gradient is _____. What does this signify?
increased, signifying a defect in O2 equilibrium
Define hypoxia
a decrease in O2 delivery to, or utilization by, the tissues
What are the 5 causes of hypoxia?
- decreased cardiac output
- hypoxemia
- anemia
- carbon monoxide poisoning
- cyanide poisoning
