Chapter 34 Study Guide

What is gas exchange?

Movement of oxygen and carbon dioxide between an organism and its environment.

What is diffusion?

Molecules move from high to low concentration.

What is a concentration gradient?

A difference in concentration between two areas. It drives diffusion.

In the lungs, oxygen diffuses in which direction?

Alveoli to blood.

In body tissues, carbon dioxide moves in which direction?

Cells to blood.

What is the difference between breathing and cellular respiration?

Breathing moves air; cellular respiration releases energy from nutrients.

Which structure is the main muscle used for breathing?

Diaphragm.

What happens to the diaphragm during inhalation?

It contracts and moves downward, increasing chest-cavity volume.

What happens during normal exhalation?

The diaphragm relaxes and moves upward, decreasing chest-cavity volume and pushing air out.

How is most oxygen transported in human blood?

Attached to hemoglobin in red blood cells.

In what form is most carbon dioxide transported in blood?

Bicarbonate ions (HCO₃⁻).

Where does gas exchange occur in human lungs?

Alveoli, tiny air sacs surrounded by capillaries.

What is the function of the trachea?

Conduct air toward the bronchi.

What are bronchioles?

Small branching airways that lead to alveoli.

What is the function of the epiglottis?

It covers the larynx during swallowing, helping direct food into the esophagus.

Why are alveoli effective at gas exchange?

Thin, moist walls and a large surface area allow rapid diffusion.

Why must respiratory surfaces remain moist?

Gases must dissolve in water before diffusing across cell membranes.

How do fish obtain oxygen?

Through gills as water passes over them.

What are spiracles in insects?

Openings that allow air into and out of the insect tracheal system.

What is cutaneous respiration?

Gas exchange through the skin. Earthworms and many amphibians use this method.

All organisms that generate energy (ATP) aerobically need to take in oxygen and remove carbon dioxide from their bodies. This process is known as

respiration

The carbon dioxide that is exhaled when you breathe is produced during

cellular respiration.

Which of the following is NOT a feature shared by all animal respiratory surfaces?

They are associated with a capillary bed.

Why are respiratory surfaces, such as living cell membranes, moist?

Gases must dissolve in water to cross cell membranes.

Respiration provides the body with oxygen and also eliminates __________, one of the waste products of cellular respiration.

carbon dioxide

Aquatic animals that lack a circulatory system for transporting gases __________.

often have flattened bodies

What happens during countercurrent exchange in fishes?

Gas exchange occurs as blood and water move in opposite directions across a respiratory surface.

All flatworms use their skin as a respiratory organ.

true

Which of the following groups of animals is most efficient at extracting oxygen from the atmosphere?

Birds

Which of these structures is analogous in function to the tracheoles of insects?

Bronchi of a human

If a respiratory surface dries out, gas exchange will

not occur

The surface area of all respiratory systems must be large compared with the size of the animal involved because diffusion is a relatively slow process.

true

Vertebrate lungs probably evolved from simple outpocketings of the digestive tract of a freshwater fish.

true

Why does a typical fish die quickly when it is removed from water?

The gills collapse and dry out in the air.

Some fishes can extract 80% of the oxygen from water flowing through their gills through countercurrent exchange.

true

Gills are respiratory structures found in fish, nudibranch mollusks, and some amphibians.

true

In the lungs, oxygen moves from air into blood by

diffusion

Which of the following statements about gas exchange in animals with interacting circulatory and respiratory systems is FALSE?

Oxygen is actively transported into the circulatory system.

Sea jellies lack specialized organs for gas exchange because

their tissues have low energy demands.

Which of these structures is analogous in function to the alveoli of humans?

Parabronchi of a bird

Birds have air sacs and lungs that allow a one-way flow of fresh, oxygenated air through the lungs. What purpose does this serve?

Bird lungs receive fresh air both as they breathe in and as they breathe out.

Most carbon dioxide is transported in red blood cells bound to hemoglobin.

false

Which of the following passageways delivers air directly into each lung?

bronchus

What causes smoker's cough?

Smoking damages the cilia that normally remove debris-laden mucus.

Which of the following is NOT part of the conducting portion of the human respiratory system?

Alveoli

Which of the following structures serves as a passageway for both air and food?

Pharynx

Where does gas exchange occur in the mammalian lung?

Alveoli