Respiratory System: Control of respiration, hypoxia, and applying physiological principles to athletic performance Flashcards
Rhythmical breathing is controlled by which skeletal muscles?
diaphragm and intercostal muscles
___ requires action potentials in ___ neurons and ___ is due to cessation of motor neuron activity and lung ___.
Inspiration; motor; expiration; recoil
What type of neurons control rhythmic contraction?
pacemaker neurons
The ___ stretch receptors are another ___ signal for inspiration and are activated by a large lung ___.
pulmonary; cutoff; inflation
T/F. Action potentials from the afferent nerve fibers from stretch receptors travel to the brain and inhibit the activity of the medullary inspiratory neurons. This is called the Hering-Breuer reflex.
True, feedback from the lungs helps to terminate inspiration by inhibiting inspiratory nerves in the DRG.
___ inspiratory neurons are quite sensitive to inhibition by drugs, such as ___ and ___. Death from overdose of these drugs is often due directly to a cessation of ___.
Medullary; barbiturates; ;morphine; breathing
T/F. Inspiratory motor neurons are driven primarily by the VRG while expiratory motor neurons (active mostly during forced expiration and strenuous exercise) are driven primarily by the DRG.
False, Inspiratory motor neurons are driven primarily by the DRG while expiratory motor neurons (active mostly during forced expiration and strenuous exercise) are driven primarily by the VRG.
Peripheral chemoreceptors include what two bodies? What is the role of these receptors?
- carotid
- aortic
to respond to changes in the arterial blood.
How are peripheral chemoreceptors stimulated?
- significantly decreased PO2 (hypoxia)
- increased H+ concentration (metabolic acidosis)
- Increased PCO2 (respiratory acidosis)
These changes will cause in ↑ in ventilation rate
Central chemoreceptors are located in the ___ ___ and respond to ___ in the H+ concentration of the ___ extracellular fluid.
medulla oblongata; increases; brain
T/F. Little increase in ventilation is observed until the oxygen concentration of the inspired air is reduced enough to lower arterial PO2 to 45mmHg.
False, Little increase in ventilation is observed until the oxygen concentration of the inspired air is reduced enough to lower arterial PO2 to 60 mmHg.
At PO2 = ___ mmHg, ___ is 90% saturated, so ventilation rate begins to ___ before blood is depleted of O2.
60; hemoglobin; increased
Complete with the correct arrow (↑↓):
- ↓ inspired PO2
- ___ alveolar PO2
- ___ arterial PO2
- Peripheral chemoreceptors ____ firing
- Respiratory muscles ___ contractions
- ___ ventilation
- Return of alveolar and arterial PO2 toward normal.
- ↓
- ↓
- ↑
- ↑
- ↑
T/F. Ventilation rate is more sensitive to PCO2 than to PO2.
True.
What value to PCO2 causes the rate to increase?
40 mmHg
Increased ___ increases the brain extracellular ___ concentration, which stimulates ___ chemoreceptors to stimulate the ___ inspiratory neurons to increase ventilation.
PCO2; H+ (decrease in brain pH); central; medullary
T/F. Increases in arterial PCO2 cause both peripheral and central chemoreceptors to be stimulated.
True.
T/F. Peripheral chemoreceptors are stimulated by an increase in H+ concentration AND a decrease in PO2.
True.
T/F. Ventilation rate can be modified by non-respiratory sources of H+.
True, by metabolic acidosis and alkalosis
With metabolic acidosis the H+ concentration is ___ and with metabolic alkalosis it is ___.
increased; decreased
In the case of metabolic ___ due to excess lactic acid, the excess ___ is detected by ___ chemoreceptors, which eliminate additional ___, but the lactic acid stays.
acidosis; H+; peripheral; CO2
In the case of metabolic ___ due to severe vomiting, ___ is removed from the body and the vomit acid must be replaced. Therefore, it is pulled from the ___ causing alkalosis. The body will increase ___ to increase the acid in the blood because it can’t correct the loss of ___.
alkalosis; H+; blood; CO2; H+
Why does anemia not change ventilation?
The Hb content is reduced but the PO2 is normal.
The total O2 is ↓ but the partial pressure of dissolved PO2 is unchanged. Chemoreceptors only detect the levels of dissolved PO2 not the amount of Hb.
Why does carbon monoxide poisoning not change ventilation?
HbO2 is reduced but PO2 is normal.
CO ↑ affinity and displaces O2 but PO2 is normal. Chemoreceptors only detect the levels of dissolved PO2 not the amount of Hb.
During ventilation, alveolar ventilation can increase by ___ fold.
20
Arterial ___ remains unchanged until exercise becomes ___. Then venous PCO2 increases but no change in arterial values. Why is there no change?
PCO2; strenuous
Chemoreceptors (peripheral) only detect PCO2 in the blood
Ventilation increases in exact proportion to venous ___ production and with severe exercise. Arterial PCO2 decreases due to ___.
PCO2; hyperventilation
If there is decreased PO2 during exercise, how does this control ventilation?
as with CO2, venous O2 decreases, but not arterial
increase in ventilation is proportional to O2 use
T/F. During exercise, increased H+ requires intense exercise due to lactic acid accumulation.
True.
Multiple factors provide input to the respiratory center and contribute to increasing ventilation during exercise. What are they and what do they do?
- temperature - trigger body to cool off
- proprioceptors - signal tells lungs to ↑ ventilation rate to supply more O2 b/c muscles are working
- ↑ epinephrine and ↑ K+ - Epi acts on respiratory neuron and K+ from exercising muscles depolarize so muscles are slightly more sensitive to contraction
- conditioned responses - ↑ output of motor neurons in muscle and stimulates respiratory center to ↑ ventilation
___ = a deficiency of O2 at the level of the tissues.
Hypoxia
Match the following
- Hypoxic hypoxia or hypoxemia
- Anemic hypoxia
- Ischemic hypoxia
- Histotoxic hypoxia
A. normal arterial PO2; decreased Hb and O2 content of blood
B. blood flow to tissues is low
C. cells unable to utilize O2
D. decreased arterial PO2
1 - D
2 - A
3 - B
4 - C
Cyanide poisoning is an example of ___ hypoxia. It competes with O2 for the ___ ___ ___ preventing O2 from becoming the final electron acceptor. This causes a ↓ in ___.
histotoxic; electron transport chain; ATP
What conditions can cause hypoxia?
- hypoventilation - increases in arterial PCO2 (also causes hypercapnia - excess PCO2)
- diffusion impairment (within lung) - thickened alveoli-blood interface or fluid in lung. This ↓ the rate of O2 diffusion from air alveoli
- vascular shunt - blood bypasses alveoli and there is mixing of blood from the right to the left side of the heart (blood ↓ O2) or unventilated alveoli due to bronchiole blockage.
- ventilation-perfusion inequality - can occur as a consequence of COPD (can also cause hypercapnia). Air in lungs has ↓ O2 or lungs cant expand to make use of O2
Because Patm decreases as altitude ___, PO2 ___ (even though O2 is still ___%).
increases; decrease; 21
Sea Level
Patm = ___ mmHg
Alveolar PO2 = ___ mmHg
Mt. Everest
Patm = ___ mmHg
Alveolar PO2 = ___ mmHg
Sea Level
Patm = 760 mmHg
Alveolar PO2 = 105 mmHg
Mt. Everest
Patm = 253 mmHg
Alveolar PO2 = 43 mmHg
What are the immediate responses to high altitude?
- stimulate ventilation - ↓ PO2 in arterial stimulate peripheral chemoreceptors causing hyperventilation
- increased dependence on anaerobic glycolysis - ↓ ATP and ↑ lactic acid
T/F. Acclimatization to high altitude depends on delayed responses that take 1 - 2 days.
False, Acclimatization to high altitude depends on delayed responses that take DAYS TO WEEKS.
At high altitudes, increased ___ which results in ___, stimulated by ___, a hormone from the kidneys
erythropoiesis; polycytothemia; EPO
At high altitudes, ___ increase , ___ synthesis which will shift the Hb-O2 curve to the ___.
RBCs; 2,3 DPG; right
This unloads O2 at higher PO2 and more O2 is available to the tissues. But Hb does not pick up O2 as readily in the lung b/c ↑ PO2 at which Hb is saturated.
At high altitudes, there is increased synthesis of other components of O2 delivery and consumption. What are these delayed responses that take place at a cellular level?
- ↑ capillary density - ↑delivery of blood to tissues
- ↑ mitochondria - ↑ ATP production
- ↑ myoglobin - respiratory pigment with heme group found in skeletal muscles is a nonvascular source of O2.
How can acclimatization to high altitude be accomplished at sea level?
by sleeping in a hypobaric atmosphere. This trains the body at low/ normal altitude and conditions the body to utilize increased O2 availability
One can also train at high altitude to stimulate EPO production in response to low arterial PO2
What is the old school vs the modern way to get EPO for blood doping?
old - RBC packing or use recombinant human EPO
new - gene therapy to increase endogenous EPO
What are the dangerous side effects of EPO use when blood doping?
increased blood viscosity
increased risk of stroke due to clot formation
high BP
autoimmune anemia
