Control of respirationControl of respiration..

Prof. Omer Abdel Aziz MusaProf. Omer Abdel Aziz MusaFaculty of medicineFaculty of medicine,,

National Ribat UniversityNational Ribat University..

ObjectivesObjectives

Respiratory centerRespiratory centerChemical controlChemical controlNeural controlNeural controlExercise & altitudeExercise & altitude

ReviewReview

Mention three factors affecting gas Mention three factors affecting gas exchange at the alveoli?exchange at the alveoli?

What are the factors leading to increased What are the factors leading to increased P50 for oxygen?P50 for oxygen?

Mention three factors leading to increased Mention three factors leading to increased bronchial tone?bronchial tone?

What is the effect of the following on What is the effect of the following on surfactant: cortisol, smoking.surfactant: cortisol, smoking.

Neural & Chemical ControlNeural & Chemical Control::

Rythmic breathing is generated Rythmic breathing is generated in the brain stem (Respiratory in the brain stem (Respiratory centre).centre).

Chemoreceptors, Chemoreceptors, mechanoreceptors and higher mechanoreceptors and higher centers regulate breathing.centers regulate breathing.

Basically the control is neural Basically the control is neural through the resp. centre .through the resp. centre .

Respiratory centreRespiratory centre::

Pre-BÖttzinger complex in the Pre-BÖttzinger complex in the medulla.medulla.

Respiratory CentreRespiratory Centre::

Medullary centers:Medullary centers: 1. Dorsal respiratory group (DRG): 1. Dorsal respiratory group (DRG):

close to nucleus of tractus close to nucleus of tractus solitarius from which it receives solitarius from which it receives and integrates afferent information and integrates afferent information from resp. mechano- and from resp. mechano- and chemoreceptors.chemoreceptors.

Composed of inspiratory neurons (I -Composed of inspiratory neurons (I -neurons) and supply contralateral neurons) and supply contralateral phrenic nerve.phrenic nerve.

Medullary contMedullary cont..

2. Ventral respiratory group (VRG):2. Ventral respiratory group (VRG):Receives afferents from DRG and Receives afferents from DRG and

has both inspiratory and expiratory has both inspiratory and expiratory neurons (E-neurons)neurons (E-neurons)

Pontine influencesPontine influences::

1. Pneumotaxic centre: in upper 1. Pneumotaxic centre: in upper pons and contains both inspiratory pons and contains both inspiratory and expiratory cells. Normal and expiratory cells. Normal function is unknown but it may function is unknown but it may tune fine breathing pattern tune fine breathing pattern switching insp. to exp.switching insp. to exp.

2. Apneustic centre: in caudal pons. 2. Apneustic centre: in caudal pons. If damaged it will lead to arrest of If damaged it will lead to arrest of breathing in inspiration. It receives breathing in inspiration. It receives afferents from pneumotaxic centre afferents from pneumotaxic centre and vagus.and vagus.

QuizQuiz

Rythmicity center is most likely in :Rythmicity center is most likely in :1. Pre-Bottzinger complex1. Pre-Bottzinger complex2. DRG2. DRG3. VRG3. VRG4. Apneostic center4. Apneostic center5. Pneumotaxic center5. Pneumotaxic center

Regulation of the respiratory Regulation of the respiratory centrecentre

1.Chemical control:1.Chemical control: Chemoreceptors in carotid and aortic bodiesChemoreceptors in carotid and aortic bodies

and medulla are stimulated by:and medulla are stimulated by: a-Increased PaCO2 ( via CSF & brain a-Increased PaCO2 ( via CSF & brain

interstitial H).interstitial H). b- decreased pH ( carotid & aortic)b- decreased pH ( carotid & aortic) C- decreased PaO2 ( carotid & C- decreased PaO2 ( carotid &

aortic).aortic).

Regulation contRegulation cont..

2.Non-chemical (neural):2.Non-chemical (neural):a-vagal afferents.a-vagal afferents.b- afferents from pons, b- afferents from pons,

hypothalamus & limbic system.hypothalamus & limbic system.c-afferents from proprioceptors.c-afferents from proprioceptors.

d- afferents from pharynx, trachea d- afferents from pharynx, trachea & bronchi.& bronchi.

e- afferents from barroreceptors.e- afferents from barroreceptors.

Chemical controlChemical control: :

Chemoreceptors are stimulated by an Chemoreceptors are stimulated by an increased PaCO2 or [H] or a decline in increased PaCO2 or [H] or a decline in PaO2.PaO2.

11..Peripheral chemoreceptorsPeripheral chemoreceptors

Carotid chemoreceptors:Carotid chemoreceptors: Near carotid bifurcation. It has two Near carotid bifurcation. It has two

types of cells 1&11. Impulses carried by types of cells 1&11. Impulses carried by the glossopharyngeal nerve & carotid the glossopharyngeal nerve & carotid sinus to the medulla.sinus to the medulla.

More sensitive to drop of O2 by type 1 More sensitive to drop of O2 by type 1 cells.cells.

Type 1 cells contain dopamine which is Type 1 cells contain dopamine which is released in response to low O2.released in response to low O2.

They are stimulated by a drop in They are stimulated by a drop in dissolved oxygen, so they are not dissolved oxygen, so they are not stimulated in anemia and CO poisoning.stimulated in anemia and CO poisoning.

They can be stimulated by cyanide, They can be stimulated by cyanide, nicotine & increased K.nicotine & increased K.

Aortic bodies: are in the arch of the Aortic bodies: are in the arch of the aorta and more responsive to increased aorta and more responsive to increased PaCO2.Impulses carried by the vagus.PaCO2.Impulses carried by the vagus.

QQ

Carotid bodies chemoreceptors:Carotid bodies chemoreceptors: 1. Contain type 11 cells which secrete 1. Contain type 11 cells which secrete

surfactant.surfactant. 2. Are found at the beginning of the common 2. Are found at the beginning of the common

carotid a.carotid a. 3.Has type 1 cells which are sensitive to low 3.Has type 1 cells which are sensitive to low

PaO2.PaO2. 4. Has type 11 cells which contains dopamine.4. Has type 11 cells which contains dopamine. 5. are stimulated by barroreceptors.5. are stimulated by barroreceptors.

22..Chemo receptors in the brain Chemo receptors in the brain stemstem::

Located in the medulla oblongata nearLocated in the medulla oblongata near the respthe resp. . centre and responds mainly centre and responds mainly

to an increasedto an increased PCO2PCO2 and a drop in and a drop in PO2.PO2.

CO2 easily penetrate the blood brain CO2 easily penetrate the blood brain barrierbarrier combining with water to form combining with water to form H2CO3 whichH2CO3 which dissociate to give (H) and dissociate to give (H) and HCO3. Hydrogen ion stimulate HCO3. Hydrogen ion stimulate receptors sensitive to it,receptors sensitive to it, stimulating stimulating respiration, leading to loss of CO2 andrespiration, leading to loss of CO2 and consequently a drop in PaCO2.consequently a drop in PaCO2.

Sever drop in PaO2 (<60) stimulate Sever drop in PaO2 (<60) stimulate these receptors.these receptors.

QQ

Mention the components of the resp. Mention the components of the resp. center?center?

How do carotids chemoreceptors work?How do carotids chemoreceptors work?How are the medullary chemoreceptors How are the medullary chemoreceptors

stimulated by PCO2?stimulated by PCO2?

Pulmonary and myocardial Pulmonary and myocardial chemoreceptorchemoreceptor::

Non physiologic.Non physiologic.Injection of nicotine leads to Injection of nicotine leads to

apnea?apnea?

Hormonal effectsHormonal effects

During the luteal phase of the During the luteal phase of the menstrual cycle and in menstrual cycle and in pregnancy ventilation pregnancy ventilation increases. This could be due to increases. This could be due to activation of estrogen-activation of estrogen-dependent progesterone dependent progesterone receptors in the hypothalamus. receptors in the hypothalamus.

NNeuraleural control control

Afferents from higher centers:Afferents from higher centers: 1. Cerebral cortex: voluntary control of 1. Cerebral cortex: voluntary control of

respiration.( Ondine curse)respiration.( Ondine curse) 2.Cerebellum: coordination with2.Cerebellum: coordination with swallowing swallowing

and talkingand talking 3.Hypothalamus: increased resp3.Hypothalamus: increased resp, , with high with high

temp.temp. 44. . Limbic system: pain and emotional stimuli Limbic system: pain and emotional stimuli

affect resp.affect resp.

Reflex controlReflex control::

1. Pulmonary receptors:1. Pulmonary receptors: Inflation of the lungs will stimulate stretch Inflation of the lungs will stimulate stretch

receptors on smooth muscles & through the receptors on smooth muscles & through the vagus inhibits insp. Deflation of the lungs in vagus inhibits insp. Deflation of the lungs in expiration will stimulate pulmonary deflation expiration will stimulate pulmonary deflation receptors, triggering inflation ( Hering- receptors, triggering inflation ( Hering- Breuer reflex).Breuer reflex).

Reflex contReflex cont..

2. Lung irritant receptors:2. Lung irritant receptors:Mechanical and chemical irritants can Mechanical and chemical irritants can

stimulate lung irritant receptors, vagal stimulate lung irritant receptors, vagal nervenerve endings in epithelia of trachea endings in epithelia of trachea and large airways.and large airways.

Stimulation of trachea & extrapulm. Stimulation of trachea & extrapulm. bronchibronchi leads toleads to cough ( deep insp. cough ( deep insp. followed by forced exp. against a followed by forced exp. against a closed glottis).closed glottis).

Stimulation of irritant receptors inside Stimulation of irritant receptors inside the lung can lead to the lung can lead to bronchoconstriction ( histamine ).bronchoconstriction ( histamine ).

Stimulation of nerve ending of the Stimulation of nerve ending of the olfactory and trigeminal nerves in the olfactory and trigeminal nerves in the nose leads to sneezing.nose leads to sneezing.

Reflex contReflex cont..

3. J-receptors( juxtacapillary):3. J-receptors( juxtacapillary): Stimulated by hyperinflation and chemicals Stimulated by hyperinflation and chemicals

(pulmonary chemoreflex) (pulmonary chemoreflex) producing producing apnea followed by rapidapnea followed by rapid breathing,breathing, bradycardia and hypotention . They are bradycardia and hypotention . They are stimulated during pulmonary congestion, stimulated during pulmonary congestion, microembolism in pulmonary capillaries & microembolism in pulmonary capillaries & pneumonia.pneumonia.

4 Afferents from proprioceptors. : 4 Afferents from proprioceptors. : Exercise, passive or active movementsExercise, passive or active movements of of

joints, stimulate respjoints, stimulate resp..

Respiratory components of Respiratory components of visceral reflexesvisceral reflexes

Inhibition of respiration and closure of Inhibition of respiration and closure of glottis occur during vomiting and glottis occur during vomiting and swallowing.swallowing.

Hiccup is a spasmodic contraction of Hiccup is a spasmodic contraction of the diaphragm that produces insp. the diaphragm that produces insp. during which the glottis suddenly during which the glottis suddenly closes. It can be stopped by?closes. It can be stopped by?

Yawning? Sighing?Yawning? Sighing?

Baroreceptors stimulation inhibits resp. Baroreceptors stimulation inhibits resp. slightly.slightly.

Thermo-receptors: cold stimulates cold Thermo-receptors: cold stimulates cold receptors, which send impulses to the receptors, which send impulses to the brain which stimulates the resp. center brain which stimulates the resp. center to increase ventilation.to increase ventilation.

Reflex contReflex cont..

Heart & lung transplant:Heart & lung transplant: Lungs and heart nerves are cut up to carina.Lungs and heart nerves are cut up to carina. 1. Cough reflex due to trachea stimulation is 1. Cough reflex due to trachea stimulation is

normal but to bronchi is abscent.normal but to bronchi is abscent. 2. Bronchi dilated.2. Bronchi dilated. 3.Normal number of sighs and yawning.3.Normal number of sighs and yawning. 4. Lack of Hering-Breuer reflex.4. Lack of Hering-Breuer reflex. 5. Pattern of breathing at rest is normal.5. Pattern of breathing at rest is normal.

QQ

Respiration can increase in:Respiration can increase in:1. Luteal phase of menses.1. Luteal phase of menses.2. Hering Breuer reflex.2. Hering Breuer reflex.3. Swallowing.3. Swallowing.4. Baroreceptors stimulation.4. Baroreceptors stimulation.5. Proprioreceptors stimulation.5. Proprioreceptors stimulation.

High altitudeHigh altitude::

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم

{ �م ال س� إل ل ه� ص�د�ر� ح� ر� �ش� ي �ه� �ه�د ي ي ن� أ �ه� الل �ر د ي } ف�م�ن �م ال س� إل ل ه� ص�د�ر� ح� ر� �ش� ي �ه� �ه�د ي ي ن� أ �ه� الل �ر د ي ف�م�ن

#م�ا ن� �أ ك ' جا ح�ر� ' *قا ض�ي ه� ص�د�ر� �ج�ع�ل� ي #ه� �ض ل ي �ن أ �ر د� ي #م�ا و�م�ن ن� �أ ك ' جا ح�ر� ' *قا ض�ي ه� ص�د�ر� �ج�ع�ل� ي #ه� �ض ل ي �ن أ �ر د� ي و�م�ن

ع�ل�ى ج�س� الر* �ه� الل �ج�ع�ل� ي ك� �ذ�ل ك م�اء الس# ف ي �ص#ع#د� ع�ل�ى ي ج�س� الر* �ه� الل �ج�ع�ل� ي ك� �ذ�ل ك م�اء الس# ف ي �ص#ع#د� ياألنعام { �ون� �ؤ�م ن ي � ال #ذ ين� األنعام {ال �ون� �ؤ�م ن ي � ال #ذ ين� 125125ال

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم المسجد من ' ليال بعبده أسرى الذى المسجد سبحان من ' ليال بعبده أسرى الذى سبحان

حوله باركنا الذى االقصى المسجد إلى حوله الحرام باركنا الذى االقصى المسجد إلى الحرامالبصير السميع هو انه آياتنا من البصير لنريه السميع هو انه آياتنا من لنريه

(( 11االسراء) االسراء )

ExerciseExercise..

HypoxiaHypoxia::

Decreased O2 supply to the tissues Decreased O2 supply to the tissues produces hypoxia. Types:produces hypoxia. Types:

1. : decreased PaO2 as in pulmonary and 1. : decreased PaO2 as in pulmonary and cardiac diseases, high altitude.cardiac diseases, high altitude.

11 . .Hypoxic hypoxiaHypoxic hypoxia

Decreased oxygen supply to the blood Decreased oxygen supply to the blood leading to decreased PaO2leading to decreased PaO2

Causes of hypoxic hypoxiaCauses of hypoxic hypoxia

1.Low PO2 in inspired air: high altitude, 1.Low PO2 in inspired air: high altitude, breathing air from a closed space.breathing air from a closed space.

2. Respiratory disorders: obstructive lung 2. Respiratory disorders: obstructive lung diseases ) asthma, chronic bronchitis(, diseases ) asthma, chronic bronchitis(, poliomyelitis affecting respiratory muscles, poliomyelitis affecting respiratory muscles, brain tumors affecting the respiratory brain tumors affecting the respiratory center, pneumothorax, pleural effusion, center, pneumothorax, pleural effusion, haemothorax..haemothorax..

3. Cardiac disorders: congestive heart 3. Cardiac disorders: congestive heart failure, arterio-venous shuntsfailure, arterio-venous shunts

High altitudeHigh altitude::

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم

{ �م ال س� إل ل ه� ص�د�ر� ح� ر� �ش� ي �ه� �ه�د ي ي ن� أ �ه� الل �ر د ي } ف�م�ن �م ال س� إل ل ه� ص�د�ر� ح� ر� �ش� ي �ه� �ه�د ي ي ن� أ �ه� الل �ر د ي ف�م�ن

#م�ا ن� �أ ك ' جا ح�ر� ' *قا ض�ي ه� ص�د�ر� �ج�ع�ل� ي #ه� �ض ل ي �ن أ �ر د� ي #م�ا و�م�ن ن� �أ ك ' جا ح�ر� ' *قا ض�ي ه� ص�د�ر� �ج�ع�ل� ي #ه� �ض ل ي �ن أ �ر د� ي و�م�ن

ع�ل�ى ج�س� الر* �ه� الل �ج�ع�ل� ي ك� �ذ�ل ك م�اء الس# ف ي �ص#ع#د� ع�ل�ى ي ج�س� الر* �ه� الل �ج�ع�ل� ي ك� �ذ�ل ك م�اء الس# ف ي �ص#ع#د� ياألنعام { �ون� �ؤ�م ن ي � ال #ذ ين� األنعام {ال �ون� �ؤ�م ن ي � ال #ذ ين� 125125ال

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم المسجد من ' ليال بعبده أسرى الذى المسجد سبحان من ' ليال بعبده أسرى الذى سبحان

حوله باركنا الذى االقصى المسجد إلى حوله الحرام باركنا الذى االقصى المسجد إلى الحرامالبصير السميع هو انه آياتنا من البصير لنريه السميع هو انه آياتنا من لنريه

(( 11االسراء) االسراء )

ExerciseExercise..

22 . .Anaemic HyAnaemic Hypoxiapoxia

Causes:Causes:

- Anaemia- Anaemia

- CO poisoning- CO poisoning

- Methaemoglobin formation: poisoning - Methaemoglobin formation: poisoning with chlorates, nitrates, ferricyanidewith chlorates, nitrates, ferricyanide

33 . .Stagnant hypoxiaStagnant hypoxia

Due to decreased flow of bloodDue to decreased flow of bloodCausesCauses

- CHF- CHF

- Hemorrhage- Hemorrhage

- Shock- Shock

- Thrombosis & embolism- Thrombosis & embolism

- Vasospasm- Vasospasm

44 . .Histotoxic hypoxiaHistotoxic hypoxia

Prevention of oxygen utilization at tissues Prevention of oxygen utilization at tissues level eg cyanidelevel eg cyanide poisoning. poisoning.

Effects of hypoxiaEffects of hypoxia

1. Increased erythropoietin release which 1. Increased erythropoietin release which increase RBC.increase RBC.

2. Initially increase HR, force of 2. Initially increase HR, force of contraction, COP & BP, later they contraction, COP & BP, later they decrease.decrease.

3. Increase resp. rate but if continued will 3. Increase resp. rate but if continued will lead to resp. centers failure.lead to resp. centers failure.

4. Associated with loss of appetit, nausea 4. Associated with loss of appetit, nausea & vomitting with feeling of thirst.& vomitting with feeling of thirst.

5. Depression, apathy, ill tempered, lack of 5. Depression, apathy, ill tempered, lack of coordination, loss of consciousness and coordination, loss of consciousness and coma leading to death.coma leading to death.

6.Mountain sickness )delayed effect(: 6.Mountain sickness )delayed effect(: nausea, vomiting, depression, weakness nausea, vomiting, depression, weakness and fatigue.and fatigue.

Oxygen therapy in hypoxiaOxygen therapy in hypoxia

Oxygen therapy can help in hypoxic Oxygen therapy can help in hypoxic hypoxia & slightly in anemic and stagnant hypoxia & slightly in anemic and stagnant hypoxia but not in histotoxic hypoxia.hypoxia but not in histotoxic hypoxia.

Asphyxia: Decreased PaO2, increased Asphyxia: Decreased PaO2, increased PCO2.PCO2.

Hypercapnia: increased PCO2.Hypercapnia: increased PCO2.Hypocapnia: decreased PCO2.Hypocapnia: decreased PCO2.

CyanosisCyanosis

DefinitionDefinition: it is diffused bluish coloration of skin : it is diffused bluish coloration of skin and mucus membranes due to presence of large and mucus membranes due to presence of large amount of reduced Hb )5 g or more(.amount of reduced Hb )5 g or more(.

TypesTypes:: 1.Central: in heart failure, right to left shunts; 1.Central: in heart failure, right to left shunts;

cyanosis is general) tongue & extremities(cyanosis is general) tongue & extremities( 2. Peripheral: flow of blood is slowed in 2. Peripheral: flow of blood is slowed in

capillaries as in cold, venous obstruction & heart capillaries as in cold, venous obstruction & heart failure.failure.

SummarySummary

Respiratory center.Respiratory center.Chemical controlChemical controlNeural control.Neural control.HypoxiaHypoxiaCyanosis.Cyanosis.

ThanksThanks ThanksThanks

It has a rostral group in nucleus It has a rostral group in nucleus ambiguus which supplies the ambiguus which supplies the

ipsilateral accessory muscles; and ipsilateral accessory muscles; and a caudal group in nucleus a caudal group in nucleus

retroambigualisretroambigualis..

الدعاء صالح من تنسونا الدعاء ال صالح من تنسونا ال