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PowerLecture:

Chapter 9

The Respiratory System

Learning Objectives

Understand how the human respiratory system functions and how it works in coordination with other systems of the body.

Explain the controls over the breathing processes.

List some of the things that can go wrong with the respiratory system.

The Respiratory System – Built for Gas Exchange

Airways are pathways for oxygen and carbon dioxide.  The respiratory system brings in oxygen that each body cell requires and takes away carbon dioxide that every cell generates.  Through the nasal cavities of the nose, air enters and leaves the respiratory system; the nasal cavities are separated by a septum of cartilage and bone.

The Respiratory System – Built for Gas Exchange

• (^) Hair and ciliated epithelium filter dust and particles

from the air.

• (^) Blood vessels warm the air and mucus moistens it.
• (^) The paranasal sinuses lie just above the cavities

and are linked to them by channels.

Nasal Cavity Pharynx (throat) Epiglottis Larynx (voice box) Trachea (windpipe) Lung (one of a pair) Bronchial Tree Pleural Membrane Oral Cavity (mouth) Intercostal Muscles Diaphragm Fig. 11.1, p. 196 bronchiole alveolar duct alveoli alveolar sac (sectioned) alveolar sac pulmonary capillary

© 2007 Thomson Higher Education Fig. 10. vocal cords glottis (closed) epiglottis tongue’s base glottis (open)

The Respiratory System – Built for Gas Exchange

Lungs are elastic and provide a large surface area for gas exchange.  Human lungs are a pair of organs housed in the rib cage above the diaphragm ; the two lungs are separated by the heart.  Each lung is enclosed by a pair of thin membranes called pleurae (singular: pleura); the pleural membrane is folded in a manner that forms a pleural sac leaving an intrapleural space filled with a lubricating intrapleural fluid.

2 pleural membranes: line thoracic cavity and are the outside of lung, lubrication for inhalation / exhalation.  (^) Note: inhaling is not due to lungs contracting (they are not muscles)

Lungs

bronchiole alveolar duct alveoli alveolar sac (sectioned) alveolar sac pulmonary capillary Fig. 10.

The Respiratory System –

Built for Gas Exchange

Gases are exchanged between alveoli and capillaries only

Exchanging carbon dioxide and oxygen: Oxygen inhaled alveoli in lungs  capillaries in lungs capillaries of body  cells of body  mitochondria in cells (carbon dioxide diffuses in the opposite direction).

Section 2

Respiration = Gas

Exchange

Respiration = Gas Exchange

Respiration is the overall exchange of inhaled oxygen from the outside air for exhaled carbon dioxide waste.

This exchange occurs in the alveoli; afterward, the cardiovascular system is responsible for moving gases in the body.

Fig. 10.

RESPIRATORY

SYSTEM

food, water intake elimination of carbon dioxide elimination of excess water, salts, wastes water, solutes carbon dioxide oxygen nutrients, water, salts elimination of food residues rapid transport to and from all living cells oxygen intake DIGESTIVE SYSTEM CARDIOVASCULAR SYSTEM

URINARY

SYSTEM

The “Rules” of Gas Exchange

Respiratory systems rely on the diffusion of gases down pressure gradients.  Air is 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, and 0.96% other gases.

• (^) Partial pressures for each gas in the atmosphere

can be calculated; for example, oxygen’s is 160 mm

Hg and carbon dioxide is 0.3 mm Hg.

• (^) Oxygen and carbon dioxide diffuse down pressure

gradients from areas of high partial pressure to areas

of low partial pressure.