PGY 412G: Principles of Human Physiology

Respiratory Physiology
Vander’s Human Physiology
Chapter 13
Francisco H. Andrade, Ph.D.
323-6045
Medical Sciences Building, MS509 paco.andrade@uky.edu Respiration
• Internal respiration – metabolic pathway to produce ATP
– Occurs in mitochondria
– Glucose (C6H12O6) + 6 O2 à 6 CO2 + 6 H2O + 36 ATP
• The oxidation of glucose to CO2 is coupled to the reduction of O2 to water
• ΔG = -2880 kJ per mole of glucose (ΔG of gasoline = -5470 kJ/mole)
• O2 is the final electron acceptor (meaning: O2 is REDUCED)

1

NOTE: Negative ΔG means the reaction may occur spontaneously

Respiration
(Krebs cycle)

Respiration
• Glucose + 6 O2 à 6 CO2 + 6 H2O + 36 ATP
• External respiration (necessary for large organisms)
– Ventilation (movement of air in and out of the lungs)
– Gas exchange (lung to blood)
– Gas transport (throughout the body)
– Gas exchange (blood to tissue)

2

Fig. 13.06

Ventilation
•

Mechanical process that moves air in and out of the lungs.

•

[O2] in air inside the lungs is higher than in the blood è O2 diffuses from air to the blood.

•

CO2 moves from the blood to the air by diffusing down its concentration gradient.

•

Gas exchange occurs entirely by diffusion:

Insert 16.1

– Diffusion follows concentration gradients
(passive).
– Diffusion is fast due to the large surface area and the short diffusion distance.

3

Acid/base balance
Also important for some GI and renal functions. Which?

Angiotensin II?

Fig. 13.01

4

Fig. 13.01

The larynx in action…

5

Numbers indicate the bronchopulmonary segments: 1, Apical; 2, posterior; 3, anterior; 4, lateral (superior);
5, medial (inferior); 6, superior; 7, medial basal; 8, anterior basal; 9, lateral basal; 10, posterior basal.

Airways form a complex network: Bronchogram

6

The airways and vasculature are close together

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Figure 12.2

7

Fig. 13.02

“Conducting” = plumbing
(No gas exchange here)

“Respiratory” = gas exchange

8

Cilia move particles out

9

The relaxation/contraction of circular smooth muscle lining these “airways” determines how easily airflow can occur: bronchodilation vs. bronchoconstriction

Comparison of a normal bronchiole with that in a patient with asthma. Note the accumulation of mucus in the bronchial lumen resulting from an increase in the number of mucus-secreting goblet cells in the mucosa and hypertrophy of submucosal mucous glands. In addition, there is intense chronic inflammation caused by recruitment of eosinophils, macrophages, and other inflammatory cells. Basement membrane underlying the mucosal epithelium is thickened, and there is hypertrophy and hyperplasia of smooth muscle cells.

10

A 37-year-old woman with a 25-year history of asthma that had been managed with inhaled budesonide and albuterol (salbutamol) as needed underwent high-resolution multislice helical computed tomographic scanning

Before

After

Tamura G and Suda Y. N Engl J Med 2005;352:e14

Conducting airways and terminal respiratory units of the lung. The relative size of the respiratory unit is greatly enlarged. Figures at the bottom indicate the approximate number of generations from trachea to alveoli, which may vary from as few as 10 to as many as 27.
(From Weibel ER: Morphometry of the human lung, Heidelberg, Germany, 1963, Springer-Verlag.)

11

Increase in surface area. Total cross section of the airways in the human lung by generation. Although each generation of airway is smaller than its parent, the total cross-sectional area of each generation is greater than the total area of the previous generation.
(From Weibel ER: Morphometry of the human lung, Heidelberg, Germany, 1963, Springer-Verlag.)

Figure 13-2

Most gas