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Body Systems > Lecture 20 - Control of breathing > Flashcards

Lecture 20 - Control of breathing Flashcards

1
Q

What are the two mechanisms used to achieve balance in breathing?

A

Local and Central

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2
Q

What does the local mechanism detect?

A

Changes in blood flow and oxygen delivery

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3
Q

What does the central mechanism detect?

A

Changes in depth and rate of respiration

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4
Q

How does the local mechanism use PO2 and PCO2 in active tissue to control gas transport?

A

A decrease in PO2 increases O2 delivery
An increase in PCO2 will increase PCO2 removal and causes vasodilation to increase blood flow

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5
Q

How does the local mechanism use lung perfusion to control gas transport?

A

A decrease in PO2 causes vasoconstriction and decrease blood flow
This allows blood to be directed to areas of higher PO2

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6
Q

How does the local mechanism use alveolar ventilation to control gas transport?

A

An increase in PCO2 causes bronchodilation which increases airflow
Airflow is directed to areas of higher PCO2

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7
Q

What is the overall process of the central mechanism?

A

Sensors in the body detect a change
The sensors activate the central controller
The central controller activates the effectors

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8
Q

What are the two types of receptors used in the central mechanism?

A

Chemoreceptors and Mechanoreceptors

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9
Q

What are the two types of chemoreceptor?

A

Central and peripheral

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10
Q

What and where are central chemoreceptors?

A

Underneath ventral surface of medulla
Close to entry of VIII and XI cranial nerves
They are stimulated by acidic or high PXO2 in the cerebrospinal fluid

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11
Q

What is the process of central chemoreceptors?

A

Increased PCO2 is detected
Central mechanism decreases pH
This increases ventilation
This then decreases PCO2

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12
Q

What and where are peripheral chemoreceptors?

A

They detect changes in PO2 PCO2 and pH
They are outside of the brain
Have a carotid body which is innervated by carotid sinus nerve
Have aortic bodies which are innervated by vagus

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13
Q

What occurs if CO2 increases?

A

Equation shifts right
There is increased H+ which decreases pH
This means its more acidic, causing respiratory acidosis

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14
Q

What happens if PCO2 decreases?

A

The equation shifts left
This decreases H+ which increases pH
It becomes more alkaline which causes respiratory alkalosis

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15
Q

What happens if PO2 increases?

A

It generates free radicals which leads to coma and death

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16
Q

What happens if PO2 decreases?

A

Central chemoreceptors switch off
Peripheral chemoreceptors increase breathing rate

17
Q

What are the three types of mechanoreceptors?

A

Slowly adapting
Rapidly adapting
C-fibre endings

18
Q

What are slowly adapting mechanoreceptors?

A

Also called bronchopulmonary stretch receptors
They are stretch receptors in the visceral pleura, bronchioles and alveoli

19
Q

What is the Hering-Breuer reflex, the reflex that slowly adapting mechanoreceptors use?

A

There is overinflation
This increases discharge
This inhibits respiratory centres

20
Q

What are rapidly adapting mechanoreceptors?

A

Irritant receptors
They are in airway epithelia close to the mucosa
Shape ventilatory pattern and protect airway
At first fire rapidly then decrease firing rate

21
Q

What is bronchoconstriction, the reflex done by rapidly adapting mechanoreceptors?

A

There is a stimuli, eg noxious gases, smoke or cold air
This increases discharge
This causes bronchoconstriction, ie coughing

22
Q

What are c-fibres receptors?

A

They initiate bronchoconstriction
In alveoli wall and conducting airways

23
Q

What is bronchoconstriction as a reflex used by c-fibres receptors?

A

Theres mechanical or chemical stimuli
This increases discharge
This causes bronchoconstriction

24
Q

What are the locations of the respiratory centres in the brain?

A

Medulla
Pons

25
Q

What is the respiratory centre in the medulla?

A

The rhythmicity centre

26
Q

What is the role of the rhythmicity centre in the medulla?

A

To control automatic breathing
To set pace for respiratory movements

27
Q

What are the two respiratory groups in the rhythmicity centre?

A

Dorsal, which contains I neurons for inspiratory centre
Ventral, which contains E and I for expiratory centre

28
Q

What are I neurons in the rhythmicity centre?

A

Regulate activity of phrenic nerve
Set rhythm and stimulate muscles of quiet inspiration

29
Q

What are E neurons in the rhythmicity centre?

A

Passive process
Activity inhibits I neurons

30
Q

What are the respiratory centres in the pons?

A

Pneumotaxic centre
Apneustic centre

31
Q

What is the apneustic centre?

A

It promotes inspiration and stimulates I neurons
Increases intensity of exhalation

32
Q

What is the pneumotaxic centre?

A

Inhibits apneustic centre
Stops inhalation and promotes exhalation

33
Q

How do central neurons determine ventilation rate?

A

They regulate tidal volume and respiratory rate
VR = TV x f

Body Systems (22 decks)

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