140401 pertukaran gas, transportasi gas dan pengendalian pernapasan

8/11/2019 140401 Pertukaran Gas, Transportasi Gas Dan Pengendalian Pernapasan

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4/8/20

FisiologiPernapasan:Pertukaran Gas, Transportasi Gas dan

Pengendalian Pernapasan

Ninuk Dian K

1

Tujuan instruksional, mahasiswadapat menjelaskan:• Proses pertukaran gas: pressure gradient, sistem kapiler,

ventilasi dan perfusi matching

• Transport gas: fungsi Hb, faktor yang mempengaruhi afinitas

Hb, BGA sebagai penanda status respirasi (keseimbangan

asam-basa respiratorik), proses pengikatan O2 dan CO2 dalam

darah, transport O2 dan CO2

• Pengendalian respirasi: batang otak, pengendalian secara

kimiawi oleh PO2, PCO2, H+

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http://www.docu-track.com/buy/





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Organ Respirasi

Zona konduksi• Saluran yang

membawa udara ketempat pertukarangas

• Menyaring,melembabkandanmenghangatkanudara

Zona respirasi• Tempat pertukaran

gas

• Terdiri dari• Bronkhioli

• Alveoli 3

• Ventilasi:

• Bernapas dengan paru dan otot

• Pertukaran gas:

• Antara udara dan kapiler paru

• Antara kapiler sistemik dengan jaringan

• Penggunaan 02 :

•Respirasi seluler di mitokondria

Respirasi

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PERTUKARAN:

DIFUSI &

TRANSPORT GAS

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Alveolus

tempat gas difusion & gas exchange

O2

CO2

• antara 2 kompartemen

alveolus & kapiler

• dibatasi oleh parenkim

• dipengaruhi oleh

1. gradient tekanan

2. luas permukaan

3. tebal membran

RD = k x A x P x 1/D 6






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P : Gradient tekanan

• P : beda tekanan parsial gas antara alveolus dengan kapiler

• Tekanan parsial gas : PO2, PCO2

• Semakin besar beda tekanan, semakin mudah difusi terjadi

• Arah difusi, dari tekanan

• PaO2,> PO2,O2,berdifusi ke dalam kapiler

• PaCO2, < PCO2 ,CO2 berdifusi ke alveolus

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Man a ya ng R D pa li ng be sa r ?

• alveolus yang lebih

besar memiliki area

difusi yang lebih luas

• makin besar alveolus,

makin mudah difusi gas

• restriksi, compliance ,alveolus kecil, RD kecil,

hipoksia8






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PERTUKARAN GAS DAN V/Q

MATCHING

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ec an sms o u monary

Ventilation

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Komponen sistem respirasi

• Zona konduksi.

• Zona Respirasi

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• All the structures air

passes through before

reaching the respiratory

zone.

• Function:

• Warms and humidifies

inspired air.

• Filters and cleans:

• Mucus secreted to

trap particles in theinspired air.

• Mucus moved by cilia

to be expectorated.

Insert fig. 16.5

Conducting Zone






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• Region of gasexchangebetween airand blood.

• Includesrespiratorybronchioles

and alveolarsacs.

Respiratory Zone

The Bronchi and Lobules of the

Lung

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Respiratory Membrane

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Respiratory Membrane

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Lung Perfusion and Ventilation

Matching

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Circulation Overview

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Ventilation and Perfusion

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Ventilation Perfusion Match in the Lungs

Local controls act on the smooth muscles of airways andarterioles to match airflow to blood flow

Accumulation of CO2 in alveoli as a result of increasedperfusion decreases airway resistance leading toincreased airflow

Increase in alveolar O2 concentration as a result of increased ventilation causes pulmonary vasodilation

which increases blood flow to match larger airflow

Area in which blood flow (perfusion)

is greater than airflow (ventilation)

Helps

balance

Helps

balanceLarge blood flow

Small airflow

CO2 in area

Relaxation of local-airway

smooth muscle

Dilation of local airways

Airway resistance

Airflow

O2 in area

Contraction of local pulmon-

ary arteriolar smooth muscle

Constriction of local blood vessels

Vascular resistance

Blood flow






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Area in which airflow (ventilation)

is greater than blood flow (perfusion)

Helps

balance

Helps

balanceLarge airflow

Small blood flow

CO2 in area

Contraction of local-airway

smooth muscle

Constriction of local airways

Airway resistance

Airflow

O2 in area

Relaxation of local pulmonary

arteriolar smooth muscle

Dilation of local blood vessels

Vascular resistance

Blood flow

Edema paru: swelling parenkim paru

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Transport Gas

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Transport Gas dalam darah

• Transport oksigen dalam darah

• Sebagian besar melalui hemoglobin (Hb)

• Sebagian kecil terlarut dalam plasma

• Jumlah Oksigen yang dibawa Hb dipengaruhi :

• PO2 plasma: ventilasi paru, komposisi gas, RD

• pH

• temperature

• DPG

• Kadar Hb

• Fetal hemoglobin has a higher O2 affinity than adult

hemoglobin

• % saturasi Hb = O2 max yang terikat x 100% 27

An Overview of Respiratory Processes and Partial Pressures in

Respiration

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Gas Exchange in the Lungs and

Tissues: Oxygen

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Gas Transport in the Blood:

Oxygen

• 2% in plasma

• 98% in hemoglobin (Hb)

• Blood holds O2 reserve

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Hemoglobin Transport of Oxygen

• 4 binding sites per Hb molecule

• 98% saturated in alveolar arteries

• Resting cell PO2 = 40 mmHg

• Working cell PO2 = 20 mmHg

• More unloaded with more need

• 75% in reserve at normal activity

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Forming Oxyhemoglobin

Figure 17.6a

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Dissociation of O2 from

Hemoglobin

Figure 17.6b

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Saturation of Hemoglobin with

O2

• Arterial blood

• Hemoglobin is 98.5% saturated

Figure 17.7a

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Saturation of Hemoglobin with

O2

• Venous blood

• Hemoglobin is 75% saturated

Figure 17.7b

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O2 and CO2 Movement

Figure 17.1

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Hemoglobin Saturation Curve

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• Temperature, pH, PCO2, and DPG• Increase of temperature, PCO2, and DPG and decrease of pH :

• Decrease hemoglobin’s affinity for oxygen

• Enhance oxygen unloading from the blood

• Decreases of temperature, PCO2, and DPG and the increase of pH act in theopposite manner

• These parameters are all high in systemic capillaries where oxygenunloading is the goal

Factors Influencing

Hemoglobin Saturation

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Figure 17.9

Effects of O2 Affinity Changes• Shift right

• Less loading of O2

• And less unloading

• Shift left

• More loading of O2

• And less unloading

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Temperature Effects: O2

Saturation• Higher temperature

• Active tissues

• Shift right

• More O2 unloading in tissues

• More O2 delivery to tissues

Figure 17.10a

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Figure 17.10b

pH Effects: O2 Saturation• Bohr effect

• Lower pH increases O2 unloading

• Active tissues

• Produce more acid pH decreases intissues

• Decreased pH causes shift right insaturation curve

• More O2 is unloaded to tissues

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A Functional Comparison of Fetal

and Adult Hemoglobin

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Carbon Monoxide• Hemoglobin has greater affinity for carbon monoxide (CO) than for

oxygen

• Prevents oxygen from binding to hemoglobin

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• 7% dissolved in plasma

• 70% carried as carbonic acid

• buffer system

• 23% bound to hemoglobin

• carbaminohemoglobin

• Plasma transport

Carbon dioxide transport

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Carbon Dioxide Transport in

Blood

45

CO2

+ H2

O H2

CO3

H+ + HCO3

-

CA

Carbonic Anhydrase

• Enzyme that converts carbon dioxide and water to

carbonic acid

• Law of Mass Action: An increase in CO2 causes an

increase in bicarbonate and hydrogen ions

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CO2 Exchange: Tissues

Figure 17.11a

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CO2 Exchange: Lungs

Figure 17.11b

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PO2 Effect on CO2 Transport

Figure 17.12

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Figure 17.13a

Tissues: CO2

Loading/O2

Unloading

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Figure 17.13b

Lungs: CO2 Loading/O2

Unloading

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• Driven by differences in partial pressure

• Oxygen enters blood at lungs and leaves at tissues

• Carbon dioxide enters at tissues and leaves at lungs

Summary of gas transport

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A Summary of the Primary Gas

Transport Mechanisms

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PCO2, sistem buffer & pH

darah

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Analisis gas darahpH darah = 7.3

pCO2 = 50 mmHg

[HCO3-] = 35 mM

Dx : asidosis respiratorik

Urine pH ~ 6.0

Blood pH = 7.35 - 7.45

Blood [HCO3-] = 24 mM

Blood PCO2 = 45 - 35 mmHg

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Respiratory compensation for metabolic acidosis

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BMJ Acute Medical Emergency

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Tissue Respiration

Oxygen release and CO2 pick up at the tissue level.

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Cellular Respiration

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Pengendalian Respirasi

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Kendali napas : ventilasi• Kendali napas mempengaruhi ventilasi

• Pusat kendali terdapat pada :

• Medulla oblongata : rhythmic of breathing

• Pons : frekuensi dan intensitas napas

• Pusat fungsi luhur : sistem limbik

• Input : perubahan mekanik, pH darah, PCO2, PO2, emosi

• Receptor : mechano & chemoreceptor

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Control centersin the brain

regulate

breathing

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Neural control

• Respiratorycenters

• In hindbrain

• - medullaoblongata

• - pons

• Automaticbreathing

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Pacemaker di Medulla• Dorsal respiratory group (DRG) : Rhythmic Inspiratory

neuron

• Diafragma + m.intercosatlis externa.

• Ventral respiratory group (VRG) : forced respiratory neuron

• E neuron : m.intercostalis interna dan otot abdomen

• I+ neuron m.sternocleidomastoideus.

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Neural control

• I neurons = inspiration

• E neurons = expiration

• I neurons -> spinal motorneurons -> respiratorymuscles.

• E neurons inhibit I neurons.

67

Neural control

• Also

• voluntary breathing controlled by the

cerebral cortex.

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Rhythmic of breathing

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Peripheral chemoreceptorsregulating respiration

• Aortic bodies*

• On aorta

• Send sensory info to medulla

through X (vagus n)

• Carotid bodies+• At fork of common carotid

artery• Send info mainly through IX

(glossopharyngeal n)

*

+






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Chemoreceptors

• Oxygen: large “reservoir” attached

to hemoglobin.

• So chemoreceptors are more

sensitive to changes in PC02(as

sensed through changes in pH).

• Ventilation is adjusted to maintain

arterial PC02 of 40 mm Hg.

•Chemoreceptors are locatedthroughout the body (in brain and

arteries).71

CO2, O2 DAN pH MEMPENGARUHI VENTILASI

• Chemoreceptor :

• Perifer : carotid dan aortic bodies

• Central : Ventral medulla

• Carotid dan aortic bodies peka thd :

• pH dan PCO2

• PO2 (< 60 mmHg)

• Central chemoreceptor peka thd PCO2 bukan [H+] dan pH

, mengapa …?

72






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• K channel pada membran sel

Glomus peka thd PO2

• PO2 sensor kanal K

permeabelitas ion K ion

K sulit keluar depolarisasi

memanjang

• Potensial aksi memanjang

neurotramisi inspirasi

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Mechanoreceptor• Input : iritan & hyperinflation

• Bahan iritan terhirup iritasi mukosa sensoris SSP

parasimpatik brochiolus konstriksi

• Hering–Breuer inflation reflex

Vol tidal > 1 lt stretch receptor brainstem inspirasi stop

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140401 pertukaran gas, transportasi gas dan pengendalian pernapasan

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