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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
Q

What does the PRG do

A

Provides tonic input to DRG to help the medullary networks coordinate a smooth respiratory rhythm
- does to create rhythm

26
Q

What is PRG not necessary for

A

Not necessary for ventilation to occur but helps smooth it out

27
Q

What are the areas of the ventral respiratory group

A

Pre-botzinger complex
Outputs to control muscles
Outputs that keep upper airways open

28
Q

Pre-botzinger complex

A

Contain pacemaker neurons that may initiate respiration

29
Q

What do the outputs to control muscles do

A

Control muscles of active inspiration and expiration, remain quiet otherwise

30
Q

What do outputs that keep upper airways open sometimes do

A

Sometimes outputs slow down to munch while asleep (sleep apnea, snoring)

31
Q

What causes the activity of inspiratory neurons to increase steadily

A

Positive feedback mechanism

32
Q

What causes feedback loop to be shut off

A

End of inspiration
- abruptly shuts off and expiration takes place

33
Q

How does positive feedback loop work

A

Believed to be initiated by pacemaker
- recruits more neurons “ramping” recruiting more outputs to inspiratory muscles

34
Q

What do levels of CO2, O2, pH within blood influence

A

Ventilation

35
Q

Where are peripheral chemoreceptors

A

Aortic arch and carotid bodies

36
Q

What do peripheral chemoreceptors do

A

Sense changes in arterial PO2, PCO2, and pH and adjust ventilation accordingly

37
Q

What region of carotid bodies sense changes in levels of O2, H+ and CO2

A

Type 1 (glomus) cell

38
Q

What do afferent neurons of carotid bodies do

A

Synapse with glomus cells and provide input back to medulla

39
Q

How do glomus cells respond to low PO2

A
  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
Q

What type of drop in PO2 does it take to trigger peripheral chemoreceptors

A

Large drop

41
Q

What can peripheral chemoreceptors respond to

A
  • pO2 in plasma
  • increases in H+
  • increases in CO2
42
Q

Where are central chemoreceptors located and what do they do

A

Medulla
- provide continuous input to respiratory control center
- respond mainly to changes in PCO2

43
Q

If PCO2 increases what happens to ventilation

A

Increase

44
Q

If PCO2 decreases what happens to ventilation

A

Decreases

45
Q

Where can central chemoreceptors respond to changes in CO2

A

PH changes in cerebrospinal fluid causes by CO2 but not in plasma pH
(H+ cannot cross blood brain barrier)

46
Q

What do neurons in the region of central chemoreceptors contain

A

H+ sensitive channels (ASIC)

47
Q

What do the H+ sensitive channels do

A

Become activated and transmit APs to respiratory control center

48
Q

What happens with decreased arterial o2 when it is peripheral chemoreceptor mediated

A

Peripheral chemoreceptors fire, reflex via medullary respiratory neurons, respiratory muscle contract, increase ventilation, return of alveolar and arterial O2 to normal

49
Q

What happens when increased arterial H+ independent of CO2 increase
Peripheral chemoreceptor mediated

A

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
Q

What is is arterial CO2 mediated by

A

Central chemoreceptors (70%)
Peripheral chemoreceptors (30%)

51
Q

What are irritant receptors

A

In lungs and respond to inhaled particles of noxious gases

52
Q

What do the irritant receptors do

A

Send sensory input into CNS, then parasympathetic outputs cause bronchoconstriction

53
Q

What does the bronchoconstriction caused by irritant receptors cause

A

Rapid shallow breathing and turbulent airflow to deposit irritant in mucosa
- reflexes can initiate coughing or sneezing

54
Q

What do stretch receptors in lungs prevent

A

Over inflation of the lungs “hering-Breuer inflation reflex”
- terminated inspiration in very active inspiration

55
Q

What causes the feedforward component to the exercise ventilatory response

A

Proprioceptors in muscles and joints
- arterial PCO2 or PO2 have not changed

56
Q

Why does the feedforward response begin at onset of exercise

A

Initiates change in ventilation in anticipation that O2, CO2, and H+ levels will change

57
Q

How much can minute ventilation increase during exercise

A

20-fold

58
Q

Why is there large increase in minute ventilation during exercise

A

Compensates for O2 requirements because O2 demands remain constant until max exercise

59
Q

What is limiting factor during moderate to strenuous exercise

A

CV system is limiting factor not ventilation

Bmsc 208 (33 decks)

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