A & P II, Chapter 21.4

higher pressure

A gas follows a pressure gradient and moves from an area of __________ __________ to an area of lower pressure. The greater the pressure difference, the more rapidly the gas diffuses.

oxygenated blood

After pulmonary gas exchange, __________ __________ is then delivered via the pulmonary veins to the left side of the heart to be distributed to all the tissues of the body.

atmospheric pressure

Air is a mixture of gases, made up of about 78% nitrogen and 21% oxygen, with the remaining 1% composed of carbon dioxide, argon, and other gases. The total __________ __________ is equal to the partial pressures of all of these gases.

ventilation-perfusion matching

Another factor that affects pulmonary gas exchange is the degree of match between the amount of air reaching the alveoli, or ventilation, and the amount of blood flow, called perfusion, int he pulmonary capillaries. This relationship is known as __________-__________ __________.

thickness of the respiratory membrane

Another factor that determines the efficiency of pulmonary gas exchange is the __________ __________ __________ __________ __________, which is the distance over which gas must diffuse. Normally the respiratory membrane is extremely thin. Anything that increases the thickness of the respiratory membrane, such as inflammation, increases the amount of time it takes for oxygen and carbon dioxide to be exchanged and so decreases the efficiency of gas exchange.

efficiency

Aside from the partial pressures of oxygen and carbon dioxide, three additional factors impact the __________ of pulmonary gas exchange: 1) surface area of the respiratory membrane, 2) thickness of the respiratory membrane, and 3) ventilation-profusion matching

760 mm Hg

Atmospheric pressure at sea level

pulmonary gas exchange

During __________ __________ __________, oxygen diffuses from the air in the alveoli into the blood in the pulmonary capillaries, and carbon dioxide flows in the opposite direction.

nitrogen gas

Henry's law also explains the behavior of gases we find in air when they come in contact with water in the body, stating: Although __________ __________ has a high partial pressure in air, very little of it is present in the plasma. The reason is its low solubility in water, too low for any of it to dissolve in appreciable amounts.

oxygen gas

Henry's law also explains the behavior of gases we find in air when they come in contact with water in the body, stating: Even though __________ __________ has a lower partial pressure than nitrogen, a small amount of it is found dissolved in plasma. Because its solubility in water, although fairly low, is still higher than that of nitrogen.

carbon dioxide

Henry's law also explains the behavior of gases we find in air when they come in contact with water in the body, stating: __________ __________ has a very low partial pressure, yet is is found dissolved in plasma. Because it has a relatively high solubility in water. In fact, it is about 20 times more soluble in water than is oxygen.

hypercapnia

High levels of carbon dioxide in the blood.

diffuse

In reference to the distance over which diffusion must occur. Stratified epithelial tissues can only have so many layers of living cells because oxygen can only __________ so far. The less distance to diffuse results in more efficient gas exchange.

blood

In reference to the perfusion of the tissue. Tissue gas exchange is most efficient when tissues are adequately supplied with __________ via the capillaries. Greater blood supply results in more efficient gas exchange.

branched

In reference to the surface area available for gas exchange. Most capillaries exist in __________, weblike capillary beds. This increases the surface area available for tissue gas exchange and makes it a more efficient process.

blood

Like the movement of all gases, pulmonary gas exchange is driven by pressure gradients; in this case we are dealing with the differences in partial pressure between the oxygen and carbon dioxide int he alveoli and in the __________.

hypoxemia

Low levels of oxygen in the blood.

7 mm Hg

Partial pressure of argon and other gases.

593 mm Hg

Partial pressure of nitrogen.

170 mm Hg

Partial pressure of oxygen.

converts

Pulmonary gas exchange __________ the oxygen-poor, carbon dioxide-rich blood delivered by the pulmonary artery into oxygen-rich blood that contains less carbon dioxide.

external respiration

Pulmonary gas exchange, (also called __________ __________) is the diffusion of gases between the alveoli and the blood.

alveoli

Pulmonary ventilation only brings new air into and removes oxygen-poor air from the __________.

Dalton's law of partial pressure

States that each gas in a mixture exerts its own pressure, called its partial pressure, so the total pressure of a gas mixture is the sum of the partial pressures of its gases.

Henry's law

States that the degree to which a gas dissolves in a liquid is proportional to both its partial pressure and its solubility in liquids.

surface area

The __________ __________ of the respiratory membrane in an average person is about 80-100 meters squared for both lungs. But, only about 75-100 ml of blood is in the pulmonary capillaries at any given time. The huge surface area of the respiratory membrane is enough for essentially every erythocyte in this volume of blood to be in contact with the respiratory surface. So, any factor that decreases the surface area of the respiratory membrane, decreases the efficiency of pulmonary gas exchange.

partial pressure

The __________ __________of a gas is symbolized by Pgas and is equal to its percent of gasses times the total pressure of all gases.

low

The cells are constantly using oxygen for cellular respiration, and for this reason the partial pressure oxygen in the tissues is __________, averaging about 40 mm Hg.

very efficiently

The deoxygenated blood entering the pulmonary capillaries has a very low partial pressure of oxygen of about 40 mm Hg, compared with the air in the alveoli, with a partial pressure of oxygen of about 104 mm Hg. This steep gradient drives the movement of oxygen from the alveoli to the blood __________ __________.

tissue gas exchange

The exchange of oxygen and carbon dioxide between the blood and the tissues is called __________ __________ __________ (or internal respiration).

partial pressure oxygen

The main driving force for tissue gas exchange is a pressure gradient - the difference in the __________ __________ __________ between blood and tissues.

lower

The partial pressure carbon dioxide in the blood is _________ than in the tissues.

True

The partial pressure gradient of oxygen determines the direction of the movement of this respiratory gas. True False

45 mm Hg

The partial pressure of carbon dioxide in the blood of pulmonary capillaries is approximately __________. 35 mm Hg 45 mm Hg 50 mm Hg 70 mm Hg

high

The partial pressure oxygen in the systemic capillaries is __________, measuring about 100 mm Hg.

diffusion

The partial pressures of nitrogen, oxygen, argon and other gases determine where a gas move by ___________.

solubility

The pressure gradient for carbon dioxide isn't as steep as the gradient for oxygen. The partial pressure of carbon dioxide in the blood of pulmonary capillaries is about 45 mm Hg, and in the alveoli it is about 40 mm Hg. Yet even with this smaller gradient, approximately equal amounts of carbon dioxide and oxygen are exchanged. This is due again to Henry's law. Remember that it is not just partial pressure that determines gas movement, but also __________.

rapid transport

The pressure gradient of partial pressure carbon dioxide in the tissues and the blood combined with carbon dioxide's high solubility in water, facilitates its __________ __________ into the system capillaries.

rapid

The steep pressure gradient between partial pressure oxygen in the tissues and the systemic capillaries facilitates __________ exchange of oxygen between the capillaries and the tissues.

carbon dioxide

The tissues produce large quantities of __________ __________ as a wast product of cellular respiration, so the partial pressure carbon dioxide in the tissues is relatively high.

ventilation/perfusion ratio

The two processes that keep ventilation and perfusion closely matched combine to ensure that pulmonary ventilation and pulmonary capillary perfusion match one another as closely as possible. A value called the __________/__________ __________.

tissues

Tissue gas exchange works via essentially the same mechanisms as pulmonary gas exchange, however, in tissue gas exchange, oxygen moves from the blood in the systemic capillaries into the __________.

matched

Two phenomena keep ventilation and perfusion closely __________: 1) Changes in alveolar ventilation lead to changes in perfusion, so flood flow is directed to areas with the most oxygen. 2) Changes in the efficiency of perfusion lead to changes in the amount of ventilation, so air flow is directed to areas with the most blood flow.

partial pressure gradient

What determines the direction of respiratory gas movement? temperature partial pressure gradient gas solubility in water molecular weight of the gas molecule

mismatch

When ventilation does not match perfusion to an area of the lung, the result is call a V/Q __________.

pulmonary gas exchange

__________ __________ __________ involves the exchange of gases between the alveoli and the blood.

tissue gas exchange

__________ __________ __________ involves the exchange of gases between the blood in system capillaries and the body's cells.

gas behavior

__________ __________ are important factors that drive pulmonary and tissue gas exchange, including the pressure that a gas exerts and its ability to dissolve in water.

gas exchange

__________ __________ brings oxygen into the blood, removes carbon dioxide from the blood and delivers oxygen to our cells. Two processes are pulmonary gas exchange and tissue gas exchange.

physical factors

__________ __________ play a role in the efficiency of tissue gas exchange. These factors include the following: 1)The surface area available for gas exchange, 2) The distance over which diffusion must occur, and 3) The perfusion of the tissue

atmospheric pressure

nitrogen + oxygen + argon + others = __________ __________