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Bmsc 208 > Respiratory 8 > Flashcards

Respiratory 8 Flashcards

1
Q

What happens when O2 leaves Hb at the tissues

A

CO2 binds with free Hb at exposed amino groups (-NH2)
Forms carbaminohemoglobin

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2
Q

What happens to O2 on Hb when CO2 very high

A

Can cause o2 release and CO2 will bind

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3
Q

When CO2 bound to Hb or converted to bicarbonate what happens to partial pressure

A

Does not contribute to partial pressure so gradient continues

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4
Q

CO2 removal at the lungs

A
  1. Plasma CO2 to alveoli
  2. Cytosol co2 to plasma
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5
Q

What happens to CO2 and Hb during CO2 removal

A

CO2 unbinds from Hb and diffuses out of RBC

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6
Q

What happens to CO2 and HCO3 during CO2 removal in lungs

A

CO2 levels in RBC drop and equilibrium of CO2 and HCO3 is disturbed causing reverse reaction
- Hb releases H+ and joins HCO3 to become CA
- CA converts to H20 + CO2

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7
Q

What happens when HCO3 drops in plasma during CO2 removal

A

Cl-/HCO3- exchanger reverses

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8
Q

When O2 moves out of the alveoli how much stays in plasma and how much moves in RBC

A

<2% in plasma
>98% joins Hb in RBC

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9
Q

How much of CO2 that is picked up from cells diffuses in plasma and how much in RBC

A

7% co2 in plasma
93% in RBC

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10
Q

Breathing

A

Rhythmic process that occurs subconsciously
- mix of voluntary and involuntary

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11
Q

What happens during subconscious breathing

A

Involuntary contraction and relaxation of inspiratory muscles

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12
Q

What can skeletal muscles not do when controlling ventilation

A

Cannot contract spontaneously

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13
Q

What causes skeletal muscle contraction of the muscles that control ventilation

A
  • spontaneously firing networks of pacemaker neurons in the brainstem (medulla)
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14
Q

What is the network of pacemaker neurons influenced by

A

Sensory and chemoreceptors, and higher brain centres

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15
Q

What is neural control of ventilation considered

A

Blackbox

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16
Q

Where are the respiratory neurons that control inspiratory and expiratory muscles

A

Medulla

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17
Q

What do the neurons in the pons do to control respiration

A

Integrate sensory info and interact with medullary neurons to influence ventilation

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18
Q

Where does rhythmic pattern of breathing arise from

A

Neural network with spontaneously discharging neurons

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19
Q

What is ventilation continuously modulated by

A

Various chemoreceptors (primarily) and mechanoreceptor linked reflexes and higher brain centres (hypothalamus, cerebral cortex, limbic system)

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20
Q

What are the 3 bundles of neurons in the medulla control breathing

A
  1. Dorsal respiratory group
  2. Pontine respiratory group
  3. Ventral respiratory group
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21
Q

What contains the DRG

A

Nucleus tractus solitaris (NTS)

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22
Q

What does the DRG control during quiet breathing

A

Inspiratory muscles via phrenic nerve and intercostal nerve to influence inspiration

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23
Q

Where does the NTS receive input

A

The peripheral mechano and chemoreceptors

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24
Q

Where does pontine respiratory group (PRG) receive info from

A

Receives sensory info from DRG

25
What does the PRG do
Provides tonic input to DRG to help the medullary networks coordinate a smooth respiratory rhythm - does to create rhythm
26
What is PRG not necessary for
Not necessary for ventilation to occur but helps smooth it out
27
What are the areas of the ventral respiratory group
Pre-botzinger complex Outputs to control muscles Outputs that keep upper airways open
28
Pre-botzinger complex
Contain pacemaker neurons that may initiate respiration
29
What do the outputs to control muscles do
Control muscles of active inspiration and expiration, remain quiet otherwise
30
What do outputs that keep upper airways open sometimes do
Sometimes outputs slow down to munch while asleep (sleep apnea, snoring)
31
What causes the activity of inspiratory neurons to increase steadily
Positive feedback mechanism
32
What causes feedback loop to be shut off
End of inspiration - abruptly shuts off and expiration takes place
33
How does positive feedback loop work
Believed to be initiated by pacemaker - recruits more neurons “ramping” recruiting more outputs to inspiratory muscles
34
What do levels of CO2, O2, pH within blood influence
Ventilation
35
Where are peripheral chemoreceptors
Aortic arch and carotid bodies
36
What do peripheral chemoreceptors do
Sense changes in arterial PO2, PCO2, and pH and adjust ventilation accordingly
37
What region of carotid bodies sense changes in levels of O2, H+ and CO2
Type 1 (glomus) cell
38
What do afferent neurons of carotid bodies do
Synapse with glomus cells and provide input back to medulla
39
How do glomus cells respond to low PO2
1. ATP sensitive ATP channels close 2. Cell depolarizes 3. Voltage gated Ca channels open 4. Ca enters 5. Exocytosis of neurotransmitters signals AP 6. Signal to medulla increase ventilation
40
What type of drop in PO2 does it take to trigger peripheral chemoreceptors
Large drop
41
What can peripheral chemoreceptors respond to
- pO2 in plasma - increases in H+ - increases in CO2
42
Where are central chemoreceptors located and what do they do
Medulla - provide continuous input to respiratory control center - respond mainly to changes in PCO2
43
If PCO2 increases what happens to ventilation
Increase
44
If PCO2 decreases what happens to ventilation
Decreases
45
Where can central chemoreceptors respond to changes in CO2
PH changes in cerebrospinal fluid causes by CO2 but not in plasma pH (H+ cannot cross blood brain barrier)
46
What do neurons in the region of central chemoreceptors contain
H+ sensitive channels (ASIC)
47
What do the H+ sensitive channels do
Become activated and transmit APs to respiratory control center
48
What happens with decreased arterial o2 when it is peripheral chemoreceptor mediated
Peripheral chemoreceptors fire, reflex via medullary respiratory neurons, respiratory muscle contract, increase ventilation, return of alveolar and arterial O2 to normal
49
What happens when increased arterial H+ independent of CO2 increase Peripheral chemoreceptor mediated
Increase peripheral chemoreceptors firing, reflex via medullary respiratory neurons, respiratory muscle contract, increase ventilation, decrease arterial and alveolar PCO2, return of H+ to normal
50
What is is arterial CO2 mediated by
Central chemoreceptors (70%) Peripheral chemoreceptors (30%)
51
What are irritant receptors
In lungs and respond to inhaled particles of noxious gases
52
What do the irritant receptors do
Send sensory input into CNS, then parasympathetic outputs cause bronchoconstriction
53
What does the bronchoconstriction caused by irritant receptors cause
Rapid shallow breathing and turbulent airflow to deposit irritant in mucosa - reflexes can initiate coughing or sneezing
54
What do stretch receptors in lungs prevent
Over inflation of the lungs “hering-Breuer inflation reflex” - terminated inspiration in very active inspiration
55
What causes the feedforward component to the exercise ventilatory response
Proprioceptors in muscles and joints - arterial PCO2 or PO2 have not changed
56
Why does the feedforward response begin at onset of exercise
Initiates change in ventilation in anticipation that O2, CO2, and H+ levels will change
57
How much can minute ventilation increase during exercise
20-fold
58
Why is there large increase in minute ventilation during exercise
Compensates for O2 requirements because O2 demands remain constant until max exercise
59
What is limiting factor during moderate to strenuous exercise
CV system is limiting factor not ventilation

Bmsc 208 (33 decks)

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