Chapter 13 Respiratory Physiology Respiratory physiology

(1) Internal (cellular) (2) External (pulmonary) physiology

Utilization of oxygen in the metabolism The exchange of oxygen and carbon dioxide of organic molecules by cells between an organism and the external environment Organization of the

Respiratory cycle: (1) Inspiration () (2) Expiration ()

Upper airways

Lower airways

(skeletal muscle) Airway branching

Contain rings of cartilage

Without cartilage

216

219

222

Alveolus, alveoli 223 Relationship between blood vessels and airways

Blood Air 5 L/min 4 L/min

Thorax Functions of the conducting zone of the airways Cross section through an area of the respiratory zone

Surfactant

(thick)

0.2 m

(flat) Relationship of , pleura, and thoracic wall

Completely separate and no communication

(few ml)

壁胸膜

內臟胸膜 The steps of respiration Relationships require for ventilation

Patm: atmospheric pressure Palv: alveolar pressure

F: flow P P: pressure difference F = R: resistance R Palv: the gas pressure in the alveoli Patm: the gas pressure at the mouth and nose

(1) The difference in pressure between the inside & outside of the  transpulmonary pressure (2) How stretchable the lungs are Boyle’s law

The pressure exerted by a constant number of gas molecules (at a constant temperature) is inversely proportional to the volume of the container. Pressure differences involved in ventilation

P : transpulmonary pressure tp The driving pressure gradient for airflow in and out of the lungs Pip: Pcw: trans-chest-wall pressure Patm: atmospheric pressure Palv: alveolar pressure

經肺壓力 跨胸壁壓 = Palv -Pip = Pip -Patm  A determinant of lung size  The transmural pressure across the chest wall Alveolar (Palv), intrapleural (Pip), transpulmonary (Ptp), and trans-chest-wall (Pcw) pressures (mmHg) at the end of an unforced expiration Two important transmural pressures of the respiratory system Pneumothorax

Chest wall elastic recoil

Lung elastic recoil Sequence of events during respiration

Phrenic nerves Intercostal nerves 膈神經 肋間神經

2

1 Summary of (Palv), intrapleural (Pip), and transpulmonary (Ptp) pressure changes and airflow during a typical respiratory cycle

efflux influx X-ray of chest at full respiration Sequence of events during expiration

2

1 A graphic representation of The greater the lung compliance, the easier it is to expand the lungs at any changes in transpulmonary pressure. 可塑性，應變性

(emphysema)

(the lung is stiffer)

(1) The stretchability of the lung tissues (elastic connective tissues) (2) The surface tension at the air-water interfaces within the alveoli (surfactant secreted by type II alveolar cells  surface tension  lung compliance ) Some important facts about

Infant respiratory distress syndrome (IRDS) Stabilizing effect of surfactant

P: pressure inside the alveoli T: surface tension r: the radius of the alveolus

Law of Laplace Surfactant stabilizes alveolar size

T: surface tension

P = 2T / r P: pressure T: surface tension r: bubble radius Asthma Asthma is a disease characterized by intermittent attacks in which airway smooth muscle contracts strongly, markedly increasing . The basic defect is chronic inflammation of the airways (allergy, viral infections, and sensitivity to environmental factors).

Exercise (especially in cold, dry air), cigarette smoke, environmental pollutants, viruses, allergens, normally released bronchoconstrictor chemicals) (1) anti-inflammatory drugs; (2) drugs Emphysema

Emphysema is a chronic obstructive pulmonary disease (COPD) that causes increased airway resistance as a result of destruction and collapse of the smaller airways. Chronic bronchitis

Chronic bronchitis is another chronic obstructive pulmonary disease that is characterized by excessive production in the bronchi and chronic inflammatory changes in the small airways. The cause of obstruction is an accumulation of mucus in the airways and thickening of the inflamed airways. and capacities recorded on a spirometer 肺活量計

潮氣容積 吸氣儲備量 呼氣儲備量 剩餘體積

肺活量

吸氣能力 功能肺餘量 肺總容量 Effects of anatomical on alveolar ventilation

Tidal volume (Vt) – Anatomical dead space (VD) = Fresh air entering alveoli in one respiration (VA) Alveolar ventilation

Physiological dead pace = Anatomical dead space + Alveolar dead space Effect of patterns on alveolar ventilation

Minute ventilation is not equal to alveolar ventilation

Rapidly Shallowly Normal Slowly Deeply Summary of typical oxygen and carbon dioxide exchanges between atmosphere, lungs, blood, and tissues during 1 min (rest individual)

4000 x 21% 呼吸商 (RQ)

 The ratio of CO2 producted to O2 consumed

1 for carbohydrate 0.7 for fat 0.8 for protein Partial pressures of carbon dioxide and oxygen in inspired air at sea level and in various places in the body Henry’s law: The amount of gas dissolved will be directly proportional to the partial pressure of the gas with which the liquid is in equilibrium. 亨利定律(Henry's law)氣體在溶液中之溶解性質與氣體的分壓有關

= 760 x 0.21

(1) The PO2 of atmospheric air (2) The rate of alveolar ventilation (3) The rate of total-body oxygen consumption Effects of various conditions on alveolar gas pressures Effects of increasing or decreasing alveolar ventilation on alveolar partial pressures in a person having a constant metabolic rate Normal gas pressure Equilibration of blood PO2, with an alveolus with a PO2 of 105 mmHg along the length of a pulmonary capillary

(1) Pulmonary edema (2) Diffuse interstitial fibrosis Local - matching Oxygen content of systemic arterial blood at sea level

in plasma & erythrocyte cytosol O2 carrying by hemoglobin Heme in hemoglobin

Deoxyhemoglobin

O2 + Hb HbO2

Oxyhemoglobin

Percent of Hb saturation (oxygen-carrying capacity) =

O bound to Hb 2 x 100% Maximal capacity of Hb to bind O2 Oxygen-hemoglobin dissociation curve Oxygen content Oxygen Effect of added hemoglobin on oxygen distribution between two compartments containing a fixed number of oxygen molecules and separated by a semipermeable membrane Oxygen movement in the lungs and tissues

Cells can obtain more oxygen whenever they increase their activity

O2 < 40 mmHg 105 mmHg

40 mmHg (75% hemoglobin saturation) 40 mmHg O2 < 5 mmHg

CO with extremely high affinity (210 times that of oxygen) for the oxygen-binding sites in hemoglobin Effect of DPG concentration, temperature, and acidity

on the relationship between PO2 and hemoglobin saturation

DPG (2, 3-diphosphoglycerate; bisphosphoglycerate) = BPG (bisphosphoglycerate) DPG is produced during glycolysis, reversibly binds with hemoglobin, allosterically causing it to have a lower affinity for oxygen.

At tissue’s capillaries: P  CO2 DPG  Hemoglobin affinity  O release  Temperature   for oxygen  2 [H]+  Summary of CO2 movement

200 mL/min 10%

25-30%

Carbonic anhydrase 60-65%

carbonic anhydrase In the erythrocytes - + but not in the plasma CO2 + H2O H2CO3 HCO3 + H carbonic bicarbonate acid Binding of H+ by hemoglobin as blood flows through tissue capillaries

Arterial blood: pH=7.40 Venous blood: pH=7.36

Hypoventilation  P , [H+] , pH respiratory acidosis CO2 Hyperventilation  P , [H+] , pH respiratory alkalosis CO2 Effects of various factors on hemoglobin Brainstem respiratory control cneters

Fine-tunes (medullary , also the cardiovascular control centers) (+)

(-)

Phrenic nerve Diaphragm intercostal nerve Hering-Breuer reflex

+ O2, CO2, [H ] Location of the carotid and aortic bodies

To monitor O2 supply to the brain 頸動脈體

P  O2 (+) [H+] Peripheral P  CO2

主動脈體

P  (+) CO2 (medulla) [H+] Major stimuli for the central and peripheral chemoreceptors The effect on ventilation of breathing different oxygen mixture

We are insensitive to smaller reductions of arterial P O2 Sequence of events by which a low arterial P cause O2 hyperventilation Effect on respiration of increasing arterial PCO2 achieved by adding CO2 to inspired air

We are sensitive to smaller elevations of arterial P CO2 Pathways by which increased arterial PCO2 stimulated ventilation Changes in ventilation in response to an elevation of plasma H+ concentration produced by the administration of lactic acid

We are sensitive to smaller elevations of plasma [H+] Reflexively induced hyperventilation minimizes the changes in arterial H+ concentration when acids are produced in excess

A change in arterial H+ concentration is due to some cause other than a primary change in P CO2 [H+] → Metabolic acidosis  Hyperventilation [H+] → Metabolic alkalosis  Hypoventilation Summary of the major chemical inputs that stimulate ventilation The effect of exercise on ventilation, arterial gas pressure, and H+ concentration

Moderate exercise Ventilation changes during exercise Summary of factors that stimulate ventilation during exercise 低氧性缺氧

Causes of a decreased arterial PO2 (Hypoxic ) in disease Acclimatization to the hypoxia of high altitude Functions of the respiratory system Pathogenesis of obstructive sleep apnea 阻塞性睡眠呼吸暫停 The pathophysiology and a standard treatment of obstructive sleep apnea

Continuous Positive Airway Pressure (CPAP) Respiratory acidosis & Respiratory alkalosis