Chapter 6

Respiration

Key Concepts

• acids• alkaline reserv

e• alveoli• anatomical de

ad space• bases• Boyle’s law• buffer system

• coefficient of oxygen utilization

• diffusion gradient• exercise-induced asth

ma (EIA)• expiratory reserve volu

me• external respiration

• functional residual capacity

• Gay-Lussac’s law• globin• heme• hemoglobin• Henry’s law• hyperventilation

• hypoventilation• inspiration phase• inspiratory capacity• inspiratory reserve

volume• internal respiration• law of partial

pressure

• lung ventilation rate• oxygen cost of

breathing• oxygen dissociation

curve• oxygenation• residual volume• respiratory center

• second wind• stitch in the side• tidal volume• total lung capacity• ventilation

equivalent• vital capacity

Review Questions

What are the three functions of the respiratory system?

• External respiration or pulmonary ventilation– gas exchange in the lungs, in which the

blood in the lung capillaries takes up oxygen and gives up carbon dioxide

• Gas transport and distribution from the lungs to the tissues via the blood

• Internal or tissue respiration—gas exchange between the blood and cells

Arrange the following in the correct sequence for air flow in external respiration.• Alveolar ducts

• Bronchioles• Glottis• Trachea• Lung• Terminal bronchioles• Nasopharynx• Nose• Alveoli• Respiratory bronchioles• Nasal cavity• Bronchi• Pharynx

1. Nose2. Nasal cavity3. Nasopharynx4. Glottis5. Pharynx6. Trachea7. Bronchi8. Lung9. Bronchioles10. Terminal bronchioles11. Respiratory bronchioles12. Alveolar ducts13. Alveoli

For air to flow into the lungs

The pressure within must be lower thanatmospheric pressure.

What is the respiratory cycle?

• Inspiration phase– Active phase

• Expiration phase– Passive phase

Name four changes that occur during the inspiration phase.

• The diaphragm descends and the external and anterior internal intercostal muscles raise the ribs

• Volume of lungs increases• Pressure lowered within the lungs

(creates a pressure gradient)• Air moves into the lungs

Name three changes that occur during the expiration cycle.

• The diaphragm and intercostals recoil to their resting length

• Recoil creates a higher-than-atmosphere pressure in the lungs

• Pressure gradient moves air out of the lungs

What are the four primary lung volumes?

1. Tidal volume2. Inspiratory reserve volume3. Expiratory reserve volume4. Residual volume

Do individuals with large lung volumes perform better during exercise?

In general, no. But it may make a difference to

elite athletes.

What are the four lung capacities measured?

1. Total lung capacity2. Vital capacity3. Inspiratory capacity4. Functional residual

capacity

Where in the brain is the respiratory center located?

Below the thalamus in the pons and medulla.

How does the respiratory center receive information about oxygen demands?

• From neural input within the brain• From neural input from muscles and joints• From humoral input

What is the ventilation equivalent?

• The number of liters of air breathed for every 100 ml of oxygen consumed.

• At rest, approximately 25.4 liters of air must be inspired for a person to consume 1 liter of oxygen.

Why does the ventilation equivalent get higher when exercise intensity increases?

Lactic acid accumulates and acts upon therespiratory center through lowering the pH.

As exercise intensity increases, what happens to the oxygen cost of breathing?

It increases disproportionately.

What is the most likely explanation for second wind?

A change in skeletal muscular efficiency,such as might be brought about byincreasing muscle temperature

What would be a good activity to recommend to an asthmatic?

• Swimming

A bad activity?

• Running

In what situations can hyperventilation be good?

In competitive athletics where breath-holdingtime is a factor in performance. An examplewould be swimming the crawl stroke.

Name four ways in which exposure to ozone affects athletic performance.

• Decreases distance running ability

• Reduces VO2 max

• Decreases maximum ventilation rate• Causes shallow rapid breathing during

submaximal exercise as well as a reduction in tidal volume

What are some of the effects that endurance training has on respiration?

• Makes breathing more efficient• Reduces metabolic acidosis• Increases oxidative capacity of the

respiratory muscles• Decreases functional residual capacity• Decreases residual volume• Decreases the ratio of residual

volume/total lung capacity• Increases vital capacity

What processes intervene between lung ventilation and tissue respiration?

• Diffusion of oxygen across the wall of the alveolus and the wall of the capillary

• Transport of oxygen in the blood to the capillary bed of the active muscles

• Diffusion of oxygen across the capillary wall to the active muscle fibers

What are some of the basic properties of gases?

• Composed of molecules that are in constant motion at high velocities

• Have no definite shape or volume, but conform to that of the container

• Pressure results from the constant impact of molecules on the wall of the container

• Pressure can be increased by confining gas to a smaller volume or increasing the activity of the molecules

• Heat increases the molecular velocity, which increases pressure

What is the diffusion gradient for oxygen?

60 mm Hg

What is the diffusion gradient for

carbon dioxide?5 to 6 mm Hg

What is the explanation for the need for a greater diffusion gradient of oxygen?

Carbon dioxide is more soluble in water

than oxygen; therefore, it can penetrate

through a membrane more easily.

What is the significance of the fact that the oxygen dissociation curve is steep when the partial pressure of oxygen is low?

• Small changes in the partial pressure of oxygen make large changes in the amount of oxygen that the hemoglobin can hold

• Large exchanges of gases are efficient when need is greatest

What happens to the coefficient of oxygen utilization during exercise?

• It increases three to four times that in resting state

• Blood leaving the active muscle tissue may approach zero saturation

What two processes are involved in the control of acid-base balance?

• Buffer systems, such as– Carbonic acid bicarbonate

system– Blood proteins– Hemoglobin and oxyhemoglobin

• Physiological changes, such as– In respiratory function– In kidney function

Why is acid-base balance a factor that limits performance?

• When exercise intensity increases beyond aerobic capacity, lactic acid becomes the end product of metabolism

• The body’s ability to buffer lactic acid plays a large role in determining the end point of anaerobic activity

How does lung diffusion change during exercise?

The diffusion of oxygen from the alveoli to the

pulmonary capillaries increases in directproportion to the intensity of the exercise

How useful is breathing oxygen-enriched gas before or after exercise for improving performance or aiding recovery?

It isn’t useful physiologically, although theremay be a psychological effect if the athletebelieves the oxygen helps.

What likely limits the maximal oxygen consumption rate (VO2 max) during:

• Activities involving large muscle groups?– Cardiac output

• Sports that involve only arms or only legs?– Muscular blood flow– Oxygen utilization

Useful Websites

AACVPR—American Association of Cardiovascular and Pulmonary Rehabilitationwww.aacvpr.org

National Jewish Medical and Research Centerwww.njc.org/main.html

American Lung Associationwww.lungusa.org

National Heart, Lung, and Blood Institutewww.nhlbi.nih.gov/index.htm

Chronic Obstructive Pulmonary Disease (COPD) Professional.orgwww.copdprofessional.org/index.asp

Selected Images

Figure 6.1 The respiratory system, showing the respiratory passages and the function of the alveolus to oxygenate the blood and to remove carbon dioxide.

Figure 6.2 Diagram of inspiration and expiration.