Gas ExchangeGas Exchange Regulation of RespirationRegulation of Respiration

Dr.Khaled Helmy

Gas ExchangeGas Exchange

Gas crosses the respiratory membrane by Oxygen enters the blood Carbon dioxide enters the alveoli

Conducting ZoneConducting Zone

Slide 13.16Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structures Primary bronchi Secondary bronchi Tertiary bronchi

Conduits to and from respiratory zone, no gas exchange occurs

Respiratory ZoneRespiratory Zone

Structures Respiratory bronchioles Alveolar duct Alveoli

Site of gas exchange

Respiratory Membrane Respiratory Membrane

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• Gas Exchange Gas Exchange

Pulmonary gas exchange - in lungsPulmonary gas exchange - in lungs • Oxygen (O2) moves into blood Oxygen (O2) moves into blood blood PO2 < alveolar PO2blood PO2 < alveolar PO2 • Carbon dioxide (CO2) moves out of blood Carbon dioxide (CO2) moves out of blood blood Pco2 > alveolar Pco2blood Pco2 > alveolar Pco2 • Ventilation/perfusion matching (V/Q) Ventilation/perfusion matching (V/Q) Perfusion (blood flow) is matched to ventilation (air Perfusion (blood flow) is matched to ventilation (air

flow) in each group of alveoliflow) in each group of alveoli

External RespirationExternal Respiration

The alveoli always has more oxygen than the blood Oxygen moves by diffusion towards the area of lower

concentration Pulmonary capillary blood gains oxygen (moves from

lung/alveoli to blood)

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External Respiration (cont’d)External Respiration (cont’d)

Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli

Pulmonary capillary blood gives up carbon dioxide Blood leaving the lungs (pulmonary vein) is oxygen-

rich and carbon dioxide-poor (coming in via pulmonary artery is opposite)

Oxygen Transport in the BloodOxygen Transport in the Blood

Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2])

A small amount is carried dissolved in the plasma

Internal RespirationInternal Respiration

Slide 13.34a

An opposite reaction to what occurs in the lungs Carbon dioxide diffuses out of tissue to blood

(concentration gradient) In RBC’s quickly forms carbonic acid by

combining with water Carbonic acid breaks down via carbonic

anhydrase creating bicarbonate ions Oxygen diffuses from blood into tissue

(concentration gradient)

External and Internal RespirationExternal and Internal Respiration

Slide 13.34bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 13.11

External Respiration, External Respiration, Gas Transport, and Gas Transport, and Internal Respiration Internal Respiration SummarySummary

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 13.10

Neural Regulation of RespirationNeural Regulation of Respiration

Respiratory Disorders: Respiratory Disorders:

Slide 13.40a

Bronchial asthma

Chronic bronchitis and emphysema

Lung fibrosis

Lung Cancer

Aging EffectsAging Effects

Slide 13.48Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Elasticity of lungs decreases Vital capacity decreases (decreased

ability to inflate the lungs) Blood oxygen levels decrease Stimulating effects of carbon dioxide

decreases (sleep apnea d/t hypoxia) More risks of respiratory tract infection

(decreased cilia and dust cell function)

Respiratory Rate Changes Respiratory Rate Changes Throughout LifeThroughout Life

Slide 13.49Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Newborns – 40 to 80 respirations per minute

Infants – 30 respirations per minute Age 5 – 25 respirations per minute Adults – 12 to 18 respirations per

minute Rate often increases somewhat with old

age