Body Systems L21 Notes Flashcards

1
Q

What are the two types of breathing control?

A

Subconscious

Conscious

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2
Q

Give an example of when subconscious breathing occurs

A
  • Subconscious
    » Until something goes wrong
    -> Dyspnea Eg. High altitude
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3
Q

Give an example of when conscious breathing occurs

A
  • Conscious

|&raquo_space; Scuba diving, partners -> Snorers.

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4
Q

What are the tasks of breathing control?

A
  • Establish automatic rhythm
  • Adjust rhythm -> Accommodate
  • > Metabolic
  • > Mechanical
  • > Episodic Non-Ventilatory Behaviours
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5
Q
Give examples of 
-> Metabolic
-> Mechanical 
-> Episodic Non-Ventilatory Behaviours
changes which need to be accommodated by breathing control
A
 Metabolic 
  >> Arterial Blood gases & pH
 Mechanical 
  >> Postural changes
 Episodic Non-ventilatory Behaviours
  >> Speaking, sniffing, eating etc.
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6
Q

Describe the normal rates of O2 absorption as a result of breathing control

A
  • Rates:
     O2:
    &raquo_space; Rate -> absorption matched to delivery
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7
Q

Describe the normal rates of CO2 absorption as a result of breathing control

A

 CO2:

|&raquo_space; Rate -> generation matched to removal.

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8
Q

Describe the two conditions involved in maintenance of balance in regards to breathing control

A
  • Maintenance -> Balance:
     Local:
    » Changes -> Blood flow & oxygen delivery
     Central:
    » Changes -> Depth & rate of respiration
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9
Q

What are local factors involved in maintenance of balance of breathing control?

A

 Local:

|&raquo_space; Changes -> Blood flow & oxygen delivery

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10
Q

What are central factors involved in maintenance of balance of breathing control?

A

 Central:

|&raquo_space; Changes -> Depth & rate of respiration

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11
Q

What are the two complexities regarding the control of breathing?

A
  • Complexities:
     No single pacemaker generating basic breathing rhythm
     No single muscle devoted -> pumping of air
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12
Q

What three locations are involved in local control of gas transport?

A

Active tissue
Lung perfusion
Alveolar ventilation

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13
Q

Describe local control of gas transport in active tissue

A
  1. P(O2) & P(CO2) -> Active Tissue
    - Incr. P(CO2)
     Vasodilation
    &raquo_space;Incr. Blood Flow
    i) Decr. P(O2)
    &raquo_space; Incr. Delivery -> O2
    ii) Incr. Removal -> CO2
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14
Q

Describe local control of gas transport in lung perfusion

A
  1. Lung Perfusion:
    - Decr. P(O2)
     Vasoconstriction
    &raquo_space; Decr. Blood Flow
     Directs blood -> Areas of higher P(O2)
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15
Q

Describe local control of gas transport in alveolar ventilation

A
  1. Alveolar Ventilation:
    - Incr. P(O2)
     Bronchodilation
    &raquo_space; Incr. Air Flow
     Directs airflow -> Areas of higher P(CO2)
    &raquo_space; Improves efficiency -> Gas transport
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16
Q

What are the aims of the central control of ventilation?

A

 Aims -> Maintenance of arterial P(CO2) & P(O2)

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17
Q

Describe the process of central control of ventilation

A
•	Central Control -> Ventilation:
	Aims -> Maintenance of arterial P(CO2) & P(O2) 
1.	 -> Detection 
>> Change -> arterial P(CO2) & P(O2)
 Central & Peripheral Chemoreceptors 
 Mechanoreceptors
2.	Send impulses / signals ->  Central Controller
 Respiratory Centres 
    >> Pons
    >> Medulla 
3.	Send impulses / signals -> Effectors
>>  Muscles of Ventilation 
 Initiate change
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18
Q

Name the major types of receptors involved in control of breathing

A

Central Chemoreceptors
Peripheral Chemoreceptors
Mechanoreceptors

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19
Q

Describe the effects of the central chemoreceptors

A
1.	Central chemoreceptors 
>> Medulla
 Change -> pH
 Hypercapnia
 No effect of hypoxia
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20
Q

Where are the central chemoreceptors located?

A
  • Central Chemoreceptors:
     Location:
     Just beneath ventral surface of medulla
    &raquo_space; Close -> Entry of VIII & XI cranial nerves
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21
Q

What are the central chemoreceptors stimulated by?

A

 Stimulated

 Acidic pH / High P(CO2) -> within CSF

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22
Q

Describe the response of the central chemoreceptors to incr. P(CO2)

A

 Incr. P(CO2)
 Decr. pH
» Incr. ventilation
> Decr, P(CO2)

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23
Q

Describe the response of the central chemoreceptors to CO2 passing the blood-brain barrier

A

 CO2 crosses blood-brain barrier
» Lipid soluble
 Decr. pH -> CSF
( CSF weakly buffered )

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24
Q

Describe the response of the central chemoreceptors to decr. O2

A

 Decr. O2

|&raquo_space; No effect -> Central chemoreceptors

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25
Q

Describe the effects of the peripheral chemoreceptors

A
2.	Peripheral chemoreceptors 
>> Aortic & carotid body 
 Hypoxia
 Hypercapnia
 Change -> pH
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26
Q

Where are the peripheral chemoreceptors located?

A

 Location:

 Outside Brain

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27
Q

Name the components of the peripheral chemoreceptors

A

Carotid body

Aortic bodies

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28
Q

Describe the location of the carotid body of the peripheral chemoreceptors

A

 Bifurcation of carotid arteries

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29
Q

Describe the location of the aortic bodies of the peripheral chemoreceptors

A

 Above & Below aortic arch

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30
Q

How is the carotid body of the peripheral chemoreceptors innervated?

A

> > Innervated -> Carotid Sinus Nerve -> Glossopharyngeal

31
Q

How is the aortic bodies of the peripheral chemoreceptors innervated?

A

> > Innervated -> Vagus

32
Q

What are the peripheral chemoreceptors stimulated by?

A

 Stimulated:
» Decr. P(O2)
Incr. P(CO2)
Decr. pH -> Arterial Blood

33
Q

Why are the peripheral chemoreceptors vital to the response of decr. P(O2)?

A

 Vital -> Response to Decr. P(O2)

|&raquo_space; No effect -> Central Chemoreceptors

34
Q

Describe the characteristics of the Mechanoreceptors controlled in breathing

A
Mechanoreceptors
>> Lung receptors
     ->> Respond -> Stretch
>> Characterised -> Response to lung inflation 
>> Innervated -> Fibres of Vagus Nerve
35
Q

Name the types of mechanoreceptors involved in control of breathing

A

Rapidly growing receptors
 Slowly adapting receptors
 C-fibres receptors

36
Q

Describe the slowly-adapting mechanoreceptors involved in control of breathing

A
  1. Slowly adapting
    » Hering Breuer Reflex
     Bronchopulmonary Stretch receptors
    &raquo_space; Visceral Pleura, Bronchioles & Alveoli
     Over-inflation -> Incr. Discharge
    &raquo_space; Inhibition -> Respiratory Centres
37
Q

Describe the rapidly-adapting mechanoreceptors involved in control of breathing

A
  1. Rapidly adapting
    » Cough Reflex
     Irritant Receptors
    &raquo_space; Airway epithelia -> Close to mucosa
     Shape ventilatory pattern & protect airways
     Initially fire rapidly
    &raquo_space; Decr. within short period
     Noxious Gases (Smoke / Dust) / Cold -> Incr. Discharge
    &raquo_space; Bronchoconstriction (Coughing reflex)
38
Q

Describe the c-fibre ending mechanoreceptors involved in control of breathing

A
3.	C-Fibre Endings
>> Defence mechanism 
 J receptors
	Chemical / mechanical stimuli -> Incr. Discharge
>> Bronchoconstriction 
      -> Rapid shallow breathing 
      -> Mucus secretion
39
Q

Describe the J-receptors of the c-fibre endings of mechanoreceptors involved in control of breathing

A

 J receptors
&raquo_space; Alveoli walls -> Close to capillaries
&raquo_space; Conducting airways -> Bronchial mucosa

40
Q

Give an example of mechanical response fo c-fibre endings in response to left heart failure

A

E.g Mechanical
&raquo_space; Left heart failure -> Engorgement of pulmonary capillaries
-> Innervate C-fibres
&raquo_space; Rapid shallow breathing

41
Q

What are the most important factors influencing gas exchange & breathing?

A

CO2 & H+

42
Q

Write the equation connecting CO2 , H2CO3 & HCO3-

A

 CO2 + H2O H2CO3 H+ + HCO3-

43
Q

Describe the response to incr. P(CO2) in terms of the equation connecting CO2 , H2CO3 & HCO3-, Give an example of a situation in which this would occur & the associated P(CO2)

A
-	Incr. P(CO2)
 Eg. Limited gas exchange -> Emphysema 
        -> Incr. P(CO2) -> ( > 43mmHg )
	CO2 + H2O   H2CO3   H+ + HCO3- 
	 Eqn pushed   -->
  Incr. H+ -> Decr. pH 
                             >> (Incr. Acidity)
                                  Respiratory Acidosis -> (pH < 7.35)
44
Q

Describe the response to decr. P(CO2) in terms of the equation connecting CO2 , H2CO3 & HCO3-, Give an example of a situation in which this would occur & the associated P(CO2)

A
  • Decr. P(CO2)
    Eg. Hyperventilation
    -> Decr. P(CO2) -> ( <37mmHg )
     CO2 + H2O  H2CO3  H+ + HCO3-
     Eqn pushed Incr. pH
    &raquo_space; (Incr. Alkalinity)
    Respiratory Alkalosis (pH > 7.45)
45
Q

Describe hyperventilation

A

[ Excessive ventilation of the lungs, beyond what is required. Rate or tidal volume of breathing eliminates more carbon dioxide than the body can produce.
Little effect on arterial pO2 and almost no effect on oxygen saturation which is nearly 100%
under normal circumstances. Its main effect is to lower pCO2 and produce a respiratory
alkalosis. ]

46
Q

Describe the affect of incr. P(O2) on breathing & generation of radicals

A
-	Changes -> P(O2)
	Incr. P(O2) 
Eg. Breathing -> O2 rich gas mixtures
>>  Generates free radicals 
    > Coma &amp; Death
47
Q

Describe the affect of decr. P(O2) on breathing & generation of radicals

A

 Decr. P(O2)
» Arterial P(O2) must drop below 60mmHg before ventilation incr.
» Central chemoreceptors switch off
» Peripheral chemoreceptors incr. breathing rate

48
Q

What are the factors influencing rate & depth of breathing?

A
•	Factors influencing Rate &amp; Depth -> Breathing:
-	Variation -> Bodily Demands 
Eg, Exercise
-	Altitude -> Acute mountain sickness
-	Disease
-	Changing conc. gases -> Arterial Blood
>> CO2
>> H+
>> O2
                    Only a problem when P(O2) -> Alveolar gas &amp; arterial blood below 60mmHg.
49
Q

At what partial pressure of oxygen do problems start to occur regarding factors affecting rate & depth of breathing?

A

 Only a problem when P(O2) -> Alveolar gas & arterial blood below 60mmHg.

50
Q

What are the components of the central controller responsible for control of breathing?

A
Rhythmicity Centre (Medulla) 
Pneumotaxic &amp; Apneaustic respiratory centre (Pons)
51
Q

What are the functions of the Rhythmicity Centre (Medulla)?

A

 Controls Automatic Breathing

 Sets pace -> respiratory movements

52
Q

Describe how the rhythmicity centre sets the pace of respiratory movements

A

 Sets pace -> respiratory movements

 Interacting neurons -> Fire during diff. stages.

53
Q

What are the two components of the rhythmicity centre responsible for setting the pace of respiratory movements?

A

Dorsal Respiratory Group

Ventral Respiratory Group

54
Q

What centres of respiration does the Dorsal Respiratory Group contain?

A

 Dorsal Respiratory Group (DRG)

-> I Neuron Inspiratory Centre

55
Q

What centres of respiration does the Ventral Respiratory Group contain?

A

Ventral Respiratory Group

-> E & I Neuron Expiratory Centre

56
Q

What is the function of the I Neurons of the I Neuron Respiratory Centre?

A

-> I Neuron Inspiratory Centre
o I Neurons -> DRG
» Regulate activity -> Phrenic Nerve
» Set rhythm & stimulate muscles -> Quiet respiriation

57
Q

What is the function of the E Neurons of the E & I Neuron Respiratory Centre?

A

-> E & I Neuron Expiratory Centre
o E Neurons -> VRG
» Passive process
» Activity inhibits I neurons.

58
Q

What are the functions of the Pneumotaxic & Apneustic centres (Pons)?

A
  • Pneumotaxic & Apneustic Centres (Pons)
     Modify firing patterns -> Medullary Centres.
     Adjust output -> Rhythmicity Centres
     Regulate respiratory rate & depth of respiration
59
Q

What is the function of the Apneustic Centre of the Pons?

A

 Apneustic Centre
» Promotes inspiration
–> Stimulates I Neurons
» Incr. intensity -> Inhalation -> Respiratory Cycle

60
Q

What are the functions of the Pneumotaxic Centre of the Pons?

A

 Pneumotaxic Centre
» Inhibits Apneustic Centre
» Stops inhalation & promotes exhalation

61
Q

When is the Pneumotaxic & Apneustic centres (Pons) not required?

A

 Not necessary -> Normal respiratory Output.

62
Q

How do central neurons determine Ventilation rate?

A
  • Central Neurons determine Ventilation Rate (VR) by regulation -> Tidal Volume (TV) & Respiratory Rate (f)
63
Q

What is the equation for calculation of ventilation rate?

A

> > VR = TV x f

64
Q

Describe the role of the central chemoreceptors in control of ventilation rate

A
  • Central Chemoreceptors:
     Steep incr. -> Ventilation Rate –
    » Incr. P(CO2)
65
Q

Describe the role of the peripheral chemoreceptors in control of ventilation rate

A
  • Peripheral Chemoreceptors:
     Incr. Ventilation Rate -> Incr. Sensitivity
    » Decr. P(O2)
66
Q

Describe the oxygen sensitivity curve

A
-	Oxygen Sensitivity Curve:
	Little change -> Ventilation Rate 
>> Until P(O2)  < 60mmHg
  ->> Response -> Peripheral receptors
	Incr. P(CO2) -> Incr. slope 
>> Central Chemoreceptors
67
Q

What locations are responsible for control of breathing by use of neurond?

A
•	Breathing controlled -> neurons 
>> Pons 
>> Medulla 
-	Central controller 
>> Rhythmicity Centre
>> Pneumotaxic &amp; apneustic centre
68
Q

What do the central chemoreceptors detect?

A

• Central Chemoreceptors

- Detect changes -> CO2

69
Q

What do the peripheral chemoreceptors detect?

A

• Peripheral Chemoreceptors

- Detect changes -> O2

70
Q

Where are the mechanoreceptors located?

A

• Mechanoreceptors -> Lungs

71
Q

What affect does incr. CO2 have on ventilation rate & depth?

A

• Ventilation rate & depth incr. with incr. CO2

72
Q

What affect does decr. CO2 have on ventilation rate & depth?

A

• Ventilation rate & depth decr. when CO2 decr.

73
Q

What are the overall functions of the Central Controller responsible for control of breathing?

A

 Controls Automatic Breathing
 Sets pace -> respiratory movements
 Modify firing patterns -> Medullary Centres.
 Adjust output -> Rhythmicity Centres
 Regulate respiratory rate & depth of respiration