CHAPTER 17

What are the primary functions of the respiratory system?

1. Gas exchange 2. pH regulation 3. Vocalization 4. Protection from inhaled substances

What is the difference between lung compliance and elastance? Would each affect inspiration or expiration more?

Compliance is the expandability of the lungs and elastance is the ability to return to resting volume when stretching force is released; they are opposite of each other.

Explain what happens during inspiration.

Is an active process in quiet breathing. Steps of inspiration: 1. Phrenic nerve signals the contraction of the diaphragm. 2. Diaphragm moves downward which expands the thoracic cavity. 3. External intercostals and scalene muscles contract pulling the ribs upward and out. This increases size of the thoracic cavity even more. 4. Increase in lung volume causes a decrease in intra-alveolar pressure according to Boyle's law. 5. Atmospheric pressure is slightly higher that intra-alveolar pressure. Air moves from high pressure to low pressure. 6. Air moves into the lungs.

What are the main gases in the air?

Nitrogen (78%) Oxygen (21%) Argon (1%) Carbon dioxide (0.04%)

How does the respiratory system control pH?

The lungs can alter body pH by selectively retaining or excreting carbon dioxide; the respiratory system helps control the acidity of the blood by regulating the elimination of carbon dioxide and water.

What are the two types of alveolar cells? What do they do?

Type I Cell - forms simple squamous epithelium-gases diffuse across the cell. Type II Cell - surfactant producing cell. Surfactant is a liproprotein that reduces the attractive force tension that tends to collapse alveolus. Macrophage - these are phagocytic cells. The alveoli contain some collagen and elastic fibers. The elastic fibers allow the alveoli to stretch as they are filled with air during inhalation. They then spring back during exhalation in order to expel the carbon dioxide-rich air; alveolus is surrounded by an extensive network of capillaries for gas exchange..

Why are there so many branches of airway?

We have to have many of these air sacs in order to have enough surface area to exchange carbon dioxide and oxygen; it increases the surface area of your lungs

What are the alveoli? What happens here?

a series of interconnected sacs and their associated pulmonary capillaries. These structures form the exchange surface, where oxygen moves from inhaled air to the blood and carbon dioxide moves from the blood to the air that is about to be exhaled; primary function is the exchange of gases between themselves and blood.

Explain what happens during expiration.

is a passive process in quiet breathing. Steps of expiration: 1. Diaphragm and other inspiratory muscles relax. 2. Stretched elastic tissue of the lungs and thoracic cage recoil. 3. Surface tension is another factor that collapses alveolar walls. 4. Lung volume decreases while intra-alveolar pressure increases according to Boyle's law. 5. Intra-alveolar pressure is slightly elevated above atmospheric pressure. Air flows from high pressure to low pressure. 6. Air moves out of the lungs.

What is a pneumothorax? What causes this? How does this relate to intrapleural pressure?

is air in the intrapleural space; lung collapse due to a wound that admits air into the pleural cavity. . Pneumothorax is caused by the puncturing the pleural membrane causes air to rush in since it is under lower pressure. This breaks the cohesive bonds between the two membranes. This is pneumothorax. *chest expands outward *lungs deflate If intrapleural pressure was equal to atmospheric pressure, the lungs would collapse.

What is surface tension? What is surfactant? How do these play a role in breathing?

is an important force of resistance; it occurs because of the cohesion of water molecules on the inner surfaces of the alveoli; the hydrogen bonds between water molecules that make it difficult to separate water molecules. chemical that decreases the surface tension of water; molecules that disrupt cohesive forces between water molecules by substituting themselves for water at the surface.

What is asthma?

is an inflammatory condition; associated with an allergic response to allergens that is characterized by bronchoconstriction and airway edema.

What is partial pressure? How does this influence movement of air molecules?

is the pressure of one gas in a mixture of gases. Partial pressure differential is the main driving force for oxygen movement in the lung. Since there is little interaction with the molecules in the lung fluids or tissue, until the oxygen molecule is within the red cell, its movement is dictated by partial pressure differences. The oxygen passes from the air to the fluid within the alveoli, into the cell of the alvioli and through the epithelium of the blood vessel and into the plasma, and then into the red cell.. Each is driven by a partial pressure difference. There are no oxygen binding molecules to facilitate transfer. (No "oxygen pumps") Carbon dioxide is totally different due to its much higher water solubility and it conversion to carbonate.

Why is pulmonary blood pressure so low?

it can be attributed to the shorter total length of pulmonary blood vessels and to the distensibility and large total cross-sectional area of pulmonary arteries

What is intrapleural pressure? Pleural fluid? Pleural cavity?

pressure within the fluid between the pleural membrane; it is normally subatmospheric. fills the pleural cavity. *Lubricant for sliding membranes *Holds lungs tightly against thoracic wall *causes parietal and visceral pleura to stick together located between the two membranes. Pleura are the serous membranes associated with the lungs: Parietal pleura - lines the thoracic wall Visceral pleura - lines the lungs

What is ventilation?

the movement of air between the atmosphere and the lungs/alveoli; breathing