Respiratory physiology 3. - u-szeged.hu. 1 Respiratory physiology 3. Control Prof. Gyula Sáry 1 normoventilation hypoventilation hyperventilation eupnoe bradypnoe tachypnoe orthopnoe

2017.10.17.

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Respiratory physiology 3.

Control

Prof. Gyula Sáry

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normoventilation

hypoventilation

hyperventilation

eupnoe

bradypnoe

tachypnoe

orthopnoe

dyspnoe

asphyxia

What do these terms mean?

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1.

2.

3.

Reflexes and negative feedback

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Rhytm generator

Respiratory muscles

Arterial blood, CSF

Chemoreceptors +

mechanoreceptors

in lung, muscle, joints

Alveolar

ventilation

Reference

value of

Changes in

metabolism,

inspired air,

circulation,

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Respiratory drive

• A „simple” question: if metabolism in the body

produces CO2 (has to be removed) and

needs O2 (has to be supplied)

which one is more important in driving respiration?

– What experiment would you design?

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A simple view

Chemoreceptors,

mechanoreceptors

-prolonged inspiration

-turns off inspiration

Cerebral cortex

(voluntary hyperventilation

and hypoventilation)

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Respiratory centers in the brainstem

Central pattern generation(pre-Bötzinger)

Dorsal respiratory group (I)

Ventral respiratory group (I & E)

Chemoreceptors in arteries

& lung mechanoceptors

Pontine Respiratory Group :

Parabrachial nucleus & Kölliger- Fuse

(modulates, inhibits)

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Ventilatory volumes and efferent nerve activity

inspiration

expiration

C3-C5

T1-T11

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Respiratory rhytm

Neurogenic rhytm

Inspiration Expiration

Lung volume

Phrenic nerve (inspiratory)

Diaphragm constriction

Intercostal nerve (expiratory)

3 phases

I= inspiratory phase

PI= postinspiratory phase

E2= expiratory phase

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Responses of the ventilation to:

arterial PO2;

arterial PCO2;

and blood pH.

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Central chemoreceptors

Dorsal respiratory

group

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Negative feedback in CO2 control

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Arterial (peripheral) chemoreceptors

N. IX.

action pot.

Dopamin

receptor

Ca++ flowoutflow

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Carotid body chemoreceptor responses

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Carotid body chemoreceptor responses

PaO2 and PaCO2 have synergistic effect

pHa and PaCO2 effects

on carotid body receptors

pH acts only on the carotid body receptors!!

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Test: re-breathing method

Effects originate from the

central receptors

Ventilatory responses to PACO2

(hypercapnic respiratory response)

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CO2 narcose (CO2 in the air)

CO2 content in atmospheric air is very low (0.04%)

1% --> inreased respiratory rate

5% --> dyspnea

10% --> restlessness, dyzziness, headache

15% --> consciousness lost

20-30% --> CO2 narcose

cellar accidents at harvest time

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Ventilatory responses to pHa

Only the

carotid bodies

react!(Kussmaul type)

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Ventilatory response to PaO2

(hypoxic ventilatory response)

non-linear response

CO2 rulez!

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Adaptation to CO2

• Long term increases in arterial PaCO2

• Sleeping pill poisoning

drive for respiration: O2 receptors

consequences of extra O2

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Pulmonary (airway) reflexes

sneezing

sniffing, swallowing

expiratory relex, coughing

Hering-Breuer reflex

coughing, mucus,

bronchial constriction

rapid breathing, mucus

tachypnea, (embolism, edema)21

Cutting the vagal nerve...

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Pathological resporatory patterns

acidosis (respiration compensates)

medullar and pontin lesion

severe disturbance, agony

sleep, high altitude, opiates

brainstem lesion, meningitis Biot

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Explanation for the Cheyne-Stokes breathing

apnoe

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Basic respiratory rhythm; a summary

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Don’t hyperventillate before diving!

CO2 receptors stimulated too late

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