weeeeeeeeeeeeeeeeeeeeeeeeeeeow-
what 2 areas of neurons in the medulla oblongata are crucial to respiration?
ventral respiratory group
dorsal respiratory group
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what is the role of the VRG?
rhythm generating and integrative center in the ventral brain stem
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what nerve travels to the diaphragm?
phrenic nerve
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what nerves excite the external intercostal muscles?
phrenic
intercostal nerves
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what happens when the VRG's expiratory neurons fire?
VRG expiratory neuron impulses cause output to stop and expiration occurs as inspiratory muscles relax and lungs recoil
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what is the usual respiratory rate?
12-16 breaths per minute
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what is the term that refers to the usual respiratory rate and rhythm
Tidal Volume
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what is the role of the pontine respiratory centers
transmits impulses to VRG of medulla from higher brain centers and various sensory receptors to smooth out inspiration and expiration rhythms
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can we fully explain the origin of the respiratory rhythm?
no, we know its rhythmic but we don't know why
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what is one hypothesis that explains the origin of the respiratory rhythm?
pacemaker VRG neurons that have intrinsic rhythmicity
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what determines respiratory depth?
how actively the respiratory centers stimulate the motor neurons serving the muscles
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what determines respiratory rate?
how long the inspiratory center is active or how quickly it is switched off
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what are central chemoreceptors?
receptors located in brain stem that respond to chemical fluctuations regarding CO2, O2, and H+
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what are peripheral chemoreceptors
found in aortic arch and carotid arteries and respond to chemical fluctuations regarding CO2, O2, and H+
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What happens to the rate and depth of breathing under the following circumstance
↑ CO2
why?
respiratory rate increases
respiratory depth increases
most powerful respiratory stimulant is liberated H+ from CO2 that acts directly on central chemoreceptors
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What happens to the rate and depth of breathing under the following circumstance
↓ CO2
respiratory rate decreases
respiratory depth decreases
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What happens to the rate and depth of breathing under the following circumstance
↓ O2
arterial PO2 must drop to ____________
respiratory rate increases
respiratory depth increases
60mm Hg
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What happens to the rate and depth of breathing under the following circumstance
↓ pH
why?
respiratory rate increases
respiratory depth increases
hydrogen does not cross blood brain barrier but changes in arterial pH due to CO2 retention or metabolic factors act on peripheral receptors
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What happens to the rate and depth of breathing under the following circumstance
↑ pH
__________ does not cross ______ _______ _________ but changes in ______ __ due to ____ _________ or ________ ______ act on __________ ___________
respiratory rate decreases
respiratory depth decreases
hydrogen
blood brain barrier
arterial pH
CO2 retention
metabolic factors
peripheral receptors
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what are metabolic factors that affect arterial pH?
lactic acid accumulation
fatty acid metabolites
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what is hyperventilation?
increase in the rate and depth of breathing that exceeds the body's need to remove CO2
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why might a person experiencing an anxiety attack faint?
person with an anxiety attack may hyperventilate involuntarily causing hypocapnia which constricts cerebral blood vessels leading to dizziness or fainting
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what is hypocapnia
low CO2 levels in blood
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why is breathing in a paper bag helpful during ventilation?
air being inspired contains more CO2 preventing hypocapnia
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If a patient retains CO2 due to pulmonary disease, should they be given copious amounts of excess O2 during respiratory distress?
WHY?
what should be done instead?
copious amounts of O2 for patients with COPD can increase blood PCO2 and lower blood pH to life-threatening levels
use the minimum concentration of oxygen that relieves the patients hypoxia
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what is the impact of the hypothalamus on respiration?
strong emotions, pain, and changes in temperature send signals to medullary respiratory centers to modify respiratory rate and depth
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what happens when mucus, dust, or fumes are inhaled
pulmonary irritant reflexes
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what is the first step of pulmonary irritant reflexes?
receptors in lungs respond to irritants via vagus nerve afferents
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what is the second step of pulmonary irritant reflexes?
___________________________________________
_______________________________
_______________________________
in ________ or _________ same irritants trigger a cough
stimulation in _____ _______ triggers ______
irritants stimulate receptors in bronchioles that promote reflexive constriction of air passages
trachea
bronchi
cough
nasal cavity
sneeze
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What is the role of stretch receptors in the visceral pleurae and conducting passages of the lungs?
initiation reflex
protective response to prevent lungs from being overstretched
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initiation reflex when lungs inflate 1/2
1. _______________ and ______________ __________ contain numerous _______ ___________
2. ____________ when lungs are __________
visceral pleurae
conducting passages
stretch receptors
stimulated
inflated
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initiation reflex when lungs inflate 2/2
3. _________ signal the _________ ___________ _________ via ______ ______ afferents
4. sends __________ _________ that end ____________ and allow ___________ to occur
receptors
medullary respiratory centers
vagus nerve
inhibitory efferents
inspiration
expiration
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Initiation reflex when lungs recoil and relax
1. _______ __________ become quiet
2.___________ is initiated again
stretch receptors
inspiration
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why are there respiratory adjustments during exercise?
working muscles consume O2 and produce large amounts of CO2 causing ventilation to increase 10x to 20x the normal amount
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increased ventilation in response to metabolic needs is called what?
does it alter blood and CO2 levels significantly?
hyperpnea
no
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what 3 factors account for increased ventilation at the beginning of exercise?
1. _____________________________________________
2. simultaneous cortical motor activation of skeletal muscles and respiratory centers
3. excitatory input reaching respiratory centers from proprioceptors in active muscles, tendons, and joints
psychological stimuli from the conscious anticipation of exercise
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what 3 factors account for increased ventilation at the beginning of exercise?
1. psychological stimuli from the conscious anticipation of exercise
2. ___________________________________________________
3. excitatory input reaching respiratory centers from proprioceptors in active muscles, tendons, and joints
simultaneous cortical motor activation of skeletal muscles and respiratory centers
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what 3 factors account for increased ventilation at the beginning of exercise?
1. psychological stimuli from the conscious anticipation of exercise
2. simultaneous cortical motor activation of skeletal muscles and respiratory centers
3. ________________________________________________________
excitatory input reaching respiratory centers from proprioceptors in active muscles, tendons, and joints
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high altitude causes __ __________ for __ to _____ due to increase in _____ levels
HB affinity
O2
drop
BPG
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Altitude AMS occurs
moving ________ from ___ ______ ~2400 m (8000 feet) to elevations _____ _____ __ where ____________ __________ and ___ are lower
quickly
sea level
above 8000 ft
atmospheric pressure
PO2
