Gas Exchange, Gas Transport, Regulation Of Ventilation

Front 1

T or F: Because the alveolar wall and pulmonary capillaries are both only 1 cell thick, there is rapid diffusion of 02 and CO2 in both direction.

Back 1

True

Front 2

3 variables upon which the ability of a gas to dissolve in blood depends:

Back 2

1) Pressure gradient (air to blood)
2) Solubility of gas in blood
3) Temperature of the blood

Front 3

T or F: PO2 and PCO2 are measurements of the concentrations of these gases dissolved in RBCs.

Back 3

False. P02 and PCO2 are a measure of the concentration of these gases dissolved in PLASMA. However, these values ultimately determine the quantity of these gases in RBCs (where the majority of 02 and CO2 is transported) and therefore provide a good index of lung function.

Front 4

Normal alveolar pressure is 100 mmHg. When arterial blood reaches the cells, the partial pressure gradient causes diffusion of 02 from blood into the cells. The P02 drops to what?

Back 4

40 mmHg

Front 5

in the lungs, blood PCO2 is 46 mmHg and alveolar PC02 is 40 mmHg. Diffusion of CO2 from the blood into alveolar air occurs until blood CO2 drops to what?

Back 5

40 mmHg

Front 6

T or F: Blood returns to the heart by pulmonary arteries.

Back 6

False. Blood returns to the heart by pulmonary veins.

Front 7

T or F: Blood returns to the lungs by pulmonary arteries.

Back 7

True.

Front 8

Hypoxia

Back 8

Deficiency of 02 in the tissues.
Hypoxia is caused by hypoxaemia, a low arterial P02.

Front 9

T or F: Hypoxia may be evident as a paler skin.

Back 9

False. Hypoxia may be evident as cyanosis (a bluish coloration of the skin/mucous membranes).

Front 10

Causes of hypoxaemia (3):

Back 10

1) High altitudes; Since atmospheric pressure falls, less PO2 enters the lungs.

2) Obstructive pulmonary disorders: Ventilation is diminished, decreasing delivery of fresh air to the alveoli.

3) Defects in gas exchange:
A) Pulmonary disorders (like emphysema) cause detruction of alveoli, resulting in decreased diffusion of 02.
B) Increased fluid in the tissue fluid of alveoli increase the diffusion distance btw blood and air, reducing amount of diffused 02.

Front 11

What are the two ways oxygen can be transported in the blood?

Back 11

Dissolved in plasma or attached to hemoglobin.
The later is much more common...more than 98% is transported attached to hemoglobin.

Front 12

The amount of O2 bound to hemoglobin is dependent upon what 2 factors?

Back 12

1) The P02 of the plasma*
2) Total amount of hemoglobin in the blood.
*primary determinant

Front 13

How many O2 molecules can hemoglobin potentially bind with?

Back 13

4

Front 14

T of F: The loading reaction of O2 to hemoglobin occurs in the pulmonary capillaries.

Back 14

True

Front 15

Wedge Salad

Back 15

WEDGE
Wedge of iceberg lettuce, chopped bacon, grape tomatoes, onions. W/ blue cheese dressing, crumbles, and a sweet balsamic glaze.

Front 16

T o F: Muscle contractions are spontaneous.

Back 16

False.

Front 17

What are muscle contractions initiated by?

Back 17

Somatic motor nerves, which are stimulated by other neurons in the CNS.

Front 18

T or F: Sensory input from chemoreceptors alters the rate of the firing of neurons in the rhythmicity centre of the pons.

Back 18

False: Sensory input from chemoreceptors alters the rate of the firing of neurons in the rhythmicity center of the medulla oblongata.

Front 19

External respiration refers to gas exchanges that occur between atmospheric air and the blood.

Back 19

True.

Front 20

Gas exchange between the lungs and the blood, and between the blood and tissue fluid, is an active transport process.

Back 20

False. Gas exchange is passive.

Front 21

Regardless of the temperature of the environmental air, inspired air has a temperature of 37°C by the time it reaches the alveoli.

Back 21

True

Front 22

The alveoli have ciliated cells in them to help expel dust particles that make it this far down into the respiratory tract.

Back 22

False. Cilia are found only on the cells of the conducting zone.

Front 23

There is no real space in the pleural cavity of a healthy individual.

Back 23

True because the two pleural membranes are in contact.

Front 24

It normally requires no muscular effort to exhale.

Back 24

True. Normal expiration is a passive process and occurs when the muscles relax.

Front 25

The surface tension exerted by water in the alveoli prevent collapse of the alveoli during exhalation.

Back 25

False. Surface tension prevents lung tissue from stretching.

Front 26

During a relaxed inspiration the diaphragm is the only inspiratory muscle that is required.

Back 26

True

Front 27

Asthma greatly reduces the vital capacity of the lungs.

Back 27

False

Front 28

Bronchoconstriction due to cigarette smoke or air pollution will lower the FEV1.0 but will not lower the vital capacity.

Back 28

True

Front 29

In adults, pulmonary blood pressure is lower than systemic blood pressure.

Back 29

True.

Front 30

Hyperventilation substantially increases the PO2 of the blood.

Back 30

False. Hyperventilation has no effect on P02

Front 31

When the temperature of a tissue increases through usage, the unloading of oxygen from hemoglobin increases.

Back 31

True. An increase in temperature decreases the affinity hemoglobin has for oxygen.

Front 32

The amount of oxygen bound to hemoglobin decreases at higher altitudes which can result in fatigue when a person first moves to a higher altitude.

Back 32

True. At higher elevations hemoglobin binds less oxygen due to the lower partial pressure of oxygen.

Front 33

People conditioned to high altitudes have higher hemoglobin concentrations than people conditioned to low altitudes.

Back 33

True.