Respiratory physiology 6 Flashcards
The Haldane effect states that in the presence of deoxygenated hemoglobin, the carbon dioxide dissociation curve shifts:
a. to the right
b. to the left
c. up
d. down
b. to the left
The Haldane effect describes
CO2 carriage
it says that oxygen causes the erythrocyte to release CO2
With the carbon dioxide dissociation curve right is ________ & left is ____________
release; love
The presence of oxygenated hemoglobin shifts, the CO2 dissociation curve to the
right
The presence of deoxygenated hemoglobin shifts the CO2 dissociation curve to the
left
What is the difference between the Haldane effect and the Bohr effect?
Bohr effect- describes oxygen carriage
Haldane effect- describes CO2 carriage
Where in the body is the CO2 dissociation curve right-shifted?
at the lungs (facilitates Co2 elimination)
Where in the body is the CO2 dissociation curve left-shifted?
at the systemic capillaries (facilitates CO2 loading and transport by Hgb)
Consequences of hypercapnia include: (select 2):
a. hypokalemia
b. increased myocardial oxygen demand
c. increased oxygen carrying capacity
d. hypoxemia
b. increased myocardial oxygen demand
d. hypoxemia
Hypercapnia is defined as
a PaCO2 greater than 45 mmHg
Etiologies of hypercapnia can be classified in 3 ways:
- increased CO2 production
- decreased CO2 elimination
- rebreathing
Causes of increased CO2 production include
sepsis, MH, thyroid storm, burns, overfeeding, prolonged seizure activity, & shivering
Causes of decreased CO2 elimination include
airway obstruction, ARDS, COPD, increased dead space, respiratory center depression, inadequate NMB reversal, increased Vd/Vt, and opioid overdose
Causes of rebreathing include
exhausted soda lime
faulty unidirectional valve in a circle system
inadequate FGF in a Mapleson circuit
Consequences of hypercarbia include
hypoxemia, acidosis, cardiac depression, hyperkalemia, increased pulmonary vascular resistance, increased Ca2+, SNS stimulation, & increased ICP
PaCO2 is equal to
CO2 production/ alveolar ventilation
During respiratory acidosis, the kidneys excrete
hydrogen and conserve bicarbonate to return to normal pH
may take several days for full compensation to occur
For every 10 mmHg increased above 40 mmHg in PaCO2 (acute), pH will
decrease by 0.08
For every 10 mmHg increase above 40 mmHg (chronic), pH will
decrease by 0.03 (due to bicarb retention by the kidneys)
Which conditions increase minute ventilation for a given PaCO2? (select 3)
a. surgical stimulation
b. salicylates
c. hypoxemia
d. sevoflurane
e. carotid endarterectomy
f. respiratory alkalosis
a. surgical stimulation
b. salicylates
c. hypoxemia
The carbon dioxide ventilatory response curve describes the relationship between
PaCO2 and minute ventilation
The __________________ is the primary monitor of PaCO2
central chemoreceptor in the medulla
The _____________________________________ play a secondary role in monitoring PaCO2
peripheral chemoreceptors in the carotid bodies and transverse aortic arch
Conditions that shift the CO2 response curve down and to the right include
volatile anesthetics
opioids
NMBs
metabolic alkalosis
carotid endarterectomy
Conditions that shift the CO2 response curve to the left include
hypoxemia
metabolic acidosis
surgical stimulation
intracranial hypertension
The apneic threshold is
the highest PaCO2 at which a person will not breathe; once the PaCO2 exceeds the apneic threshold, the patient will begin to breathe
The slope of the CO2 ventilatory response curve represents
the sensitivity of the entire respiratory apparatus to PaCO2
Minute ventilation _____________ with PaCO2 in a __
increases; linear fashion when PaCO2 is between 20-80 mmHg
CO2 is a respiratory depressant when PaCO2 exceeds
80-100 mmHg
MAC of CO2 is
200 mmHg
A left shift of the CO2 ventilatory response curve implies that the apneic threshold has
decreased
A right shift of the CO2 ventilatory response curve implies that the apneic threshold has
increased
What is the pacemaker for normal breathing?
a. pneumotaxic center
b. apneustic center
c. dorsal respiratory center
d. ventral respiratory center
c. dorsal respiratory center
The respiratory center is located in the
reticular activating system in the medulla & the pons
The respiratory center’s primary job is to
determine how fast and deep you breathe (this regulates PaCO2 & PaO2)
The respiratory center receives afferent input from
the central and peripheral chemoreceptors as well as stretch receptors in the lungs
The respiratory center integrates the incoming signals with its
intrinsic respiratory pattern and sends a coordinated response to the diaphragm, intercostals, & accessory muscles
The ___________________ can modify the respiratory center responses.
cerebral cortex
What are the medullary respiratory centers?
dorsal respiratory group
ventral respiratory group
What are the pontine respiratory centers?
pneumotaxic center
apneustic center
What does the dorsal respiratory group do?
active during inspiration
What is the role of the ventral respiratory group?
active during expiration
What is the role of the pneumotaxic center?
(upper pons): inhibits the DRG
What is the role of the apneustic center?
(lower pons): stimulates the DRG
The respiratory rate and pattern are determined by these 4 things:
- neural control in the respiratory center- medulla
- chemical control in the central chemoreceptors- medulla
- chemical control in the peripheral chemoreceptors- carotid bodies and aortic arch
- baroreceptors- lungs
Newer evidence says that the respiratory pacemaker function is performed by
the central pattern generator which includes the DRG, pre-Botzinger complex (in the VRG), and other medullary structures
