Sugeng Hadisaputra, M.Kep, Sp.Kep.An

The Student ObjectiveAfter attending the discussion of respiratory physiology, students will be able to explain the normal function of

respiratory system, rightly

THE SUBTOPICS

1. Structure of the Respiratory System

2. The Pulmonary Ventilation

3. Lung Volume and Capacity

4. The O2 – CO2 Exchange

5. The Transport of O2 and CO2

6. The Control of Respiration

7. Exercise and The Respiratory System

8. Aging and Respiratory System

Structures of The Respiratory System

Upper Respiratory System•Nose•Pharynx•Associated structures

Lower Respiratory System•Larynx•Trachea•Bronchi•Lung

The respiratory Tract

Alveolus

The Muscles of Breathing

Inspiratory muscles• Diaphragm• External

Intercostalis• Sternocleido-

mastodeus• Scalenus

Expiratory muscles• Internal

Intercostalis• Abdominal

Muscles

PULMONAL VENTILATION(BREATHING)

1. Inspiration

2. Expiration

* The movement of air into and out of the lung depends on pressure change (Boyle’s law)

INSPIRATION

Active

Boyle law

EXPIRATION

Passive•Muscle relaxation

•Elastic recoil

Active•Labor

BREATHING PATTERN

Eupnea = Normal quiet breathing

Apnea = A temporary cessation of breathing

Dyspnea = A painful or labored breathing + tachypnea

Costal breathing = Shallow (chest) breathing

Diaphragmatic breathing = Deep (abdominal) breathing

ALVEOLAR SURFACE TENSION

•Alveolar fluid surrounds air in alveoli exerts tension (surface tension)

•Lowered by Surfactant

•Great surface tension tend to collapse the lung

COMPLIANCE

•The ease of lung + thoracic wall to expand

•The higher the compliance the easer to expand

•The higher the surface tension the lower the compliance

•The lesser the elasticity the lower the compliance

•The Compliance decrease in:

Scar lung

Pulmonary edema

Surfactant deficiency

Muscle paralysis , emphysema

AIRWAY RESISTANCE

•The narrower the airway diameter the higher the resistance

•The broader the airway diameter the lower the resistance

MODIFIED RESPIRATORY MOVEMENT

•Laughing, Sighing, Sobbing

•Sneezing, Coughing

•Talking, Singing

LUNG VOLUME AND CAPACITY

6000 ml

5000 ml

4000 ml

3000 ml

2000 ml

1000 ml

LUNG VOLUMES LUNG CAPACITIES

O2 – CO2 EXCHANGE

Changes In Partial Pressure During External and Internal

Respiration

(Dalton & Henry’s laws)

TRANSPORT OF O2 AND CO2

IN THE BLOOD

O2:

1. 1.5% Dissolved in plasma

2. 98.5% as Oxyhemoglobin

CO2:

1. 7% Dissolved in plasma

2. 23% as Carbaminohemoglobin

3. 70% as Bicarbonate ions

O2 – Hb dissociation curve at normal body temperature

As pO2 increase, more O2 combines with hemoglobin

HEMOGLOBIN AND OXYGEN PARTIAL PRESSURE

HEMOGLOBIN AND OTHER FACTORS

The effect pH on affinity of hemoglobin for oxygen

As pH decrease , the affinity of hemoglobin for O2 is less, so less O2 combines with hemoglobin and

more is available to tissue

The effect pCO2 on affinity of hemoglobin

for oxygen

As pCO2 increase , the affinity of hemoglobin for O2 decreases

The effect body temperature on affinity of hemoglobin

for oxygen

As temperature increase , the affinity of hemoglobin for O2 decreases

FETAL HEMOGLOBIN

Oxygen – hemoglobin dissociation curve

comparing fetal and maternal hemoglobin

Fetal Hb has a higher affinity for O2 than does adult Hb

HYPOXIA

1. Hypoxic hypoxia Low pO2 in arterial blood: high altitude, airways obstruction,

fluid in lung

2. Anemic hypoxia Low Hb: hemorrhage, anemia, CO poisoning

3. Stagnant (ischemic) hypoxia Low tissue blood flow

4. Histotoxic hypoxia Tissue unable uses O2 properly

CARBON DIOXIDE TRANSPORT

1. Dissolved CO2: 7 % dissolved in plasma

2. Carbaminohemoglobin

Hb + CO2 Hb.CO2

3. Bicarbonate ions

CO2 + H2O H2CO3 H+ + HCO3-

Summary of Gas Exchange and Transport in Lung and Tissue

CONTROL OF RESPIRATION

Respiratory center

1. Medullary Rhythmicity Area

2. Pneumotaxic Area

3. Apneustic Area

REGULATION OF THE RESPIRAORY CENTER

1. Cortical influences Voluntary, protective

2. Chemical regulation Central Chemoreceptors: located in Medulla Oblongata

Peripheral Chemoreceptors: Aortic & carotid bodies

3. Neural changes due to movement

4. Inflation reflex Baroreceptors = Stretch receptors

5. Other influences Blood pressure, Limbic system, Temperature, Pain, Stretching the anal

sphincter muscle, Irritation of airways

Proposed role of the medullary rhythmicity area in controlling the basic rhythm of respiration

Return to homeostasis

Stimulus (stress)

Increase arterial blood pCO2

Central & peripheral chemo-receptor

Inspiratory area control center (in MO)

Respiratory muscle: hyperventilation

Decrease arterial blood pCO2; increase pO2

NEGATIVE FEEDBACK

Positive feedback further lowers pO2 so hypoxia

worsens

Stimulus (stress)

Decrease arterial blood pO2 (severe hypoxia)

Central chemo-receptor suffer hypoxia

Inspiratory area suffer hypoxia (in MO)

Respiratory muscle: hypoventilation

Decrease arterial blood pO2

POSITIVE FEEDBACK

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1. Voluntary hyperventilation controlled by cerebral cortex

2. Anticipation of activity via stimulation of the limbic system

VENTILATION RATE AND DEPTH INCREASE WITH:

5. Decrease in blood pressure detected by baroreceptors

7. Prolonged pain

4. Increase in sensory impulses from proprioceptors in muscles and joints and increase in motor impulses from the motor cortex

6. Increase in body temperature

8. Stretching anal sphincter

3. Increase in arterial blood H+ level or pCO2 above 40 mm Hg and decrease in arterial blood pO2 from 100 to 50 mm Hg, detected by central and peripheral chemoreceptor

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AND DEPTH DECREASE WITH:

9. Irritation of pharynx or larynx by touch or chemicals causes apnea followed by coughing or sneezing

10. Severe pain causes apnea

11. Decrease in body temperature (sudden cold stimulus) causes apnea

14. Decrease in arterial blood H+ level or pCO2

below 40 mm Hg and decrease in arterial blood pO2 below 50 mm Hg, detected by central and peripheral chereceptors

15. Voluntary hypoventilation controlled by cerebral cortex (limited by buildup of CO2 and H+)

12. Increase in blood pressure detected by baroreceptors

13. Decrease in sensory impulses from proprioceptors in muscles and joints and decrease in motor impulses from the motor cortex

EXERCISE AND THE RESPIRATORY SYSTEM

Exercise

Raises pulmonary perfusion

Raises the O2 diffusion capacity

Pulmonary ventilation

1. Anticipation of the activity, which stimulates the limbic system

2. Sensory impulses from proprioceptors in muscles and joints

3. Motor impulses from the primary motor cortex (precentral gyrus)

a. Decreased pO2, due to increased O2 consumption

b. Increased pCO2, due to increased CO2 production by contracting muscle fibersc. Increased temperature due to liberation of more heat as more O2 utilized

AGING AND THE RESPIRATORY SYSTEM

Aging

The airways and tissue become more rigid

Decreases1. Vital capacity, as much as 35%2. Blood level of O2

3. Alveolar macrophage activity4. Ciliary action

More susceptible to: pneumonia, bronchitis, emphysema, and other pulmonary disorders