Chapter 30: The Respiratory System

Question 1

LO: List four things necessary for gas exchange to occur in multicellular animals and explain why each is required (Lab Guide, Minicourse 2, p. 2).

Answer 1

Check answer

Question 2

Aerobic respiration

Answer 2

Consumes oxygen gas and generates carbon dioxide gas as a waste product.

Question 3

Respiratory system

Answer 3

Organ system that does the breathing, works with the circulatory system to deliver oxygen gas (O2) to cells and to eliminate carbon dioxide (CO2) to cells.

Question 4

Respiration

Answer 4

Means:
- Breathing: the physical movement of air into and out of the body
- The act of exchanging gas
External respiration: gas exchange between an animal’s body and its environment
Internal: gas exchange between tissue cells and bloodstream

Question 5

Respiratory surface

Answer 5

Area of animal’s body where external expiration occurs.

Humans: lungs

Shares three characteristics:

1. Surface area must be large
2. Must come into contact with either air or water. Air has a higher concentration of O2 and is lighter so less energy is required to move air across a respiration surface.
3. Consist of moist membranes across which O2 and CO2 diffuse.

Question 6

Where does gas exchange occur in very small or flat animals?

Answer 6

Gas exchange occurs across the moist body wall, as gases simply diffuse into and out of each cell.

Question 7

Tracheae

Answer 7

Internal, air-filled tubes that connect to the atmosphere though openings, called spiracles, along each side of the abdomen. It branches into tiny tubules that extend around individual cells.

Question 8

What animals have a tracheae?

Answer 8

Insects and many arthropoda.

Question 9

Gills

Answer 9

Highly folded structures containing blood vessels that exchange gases with water across a thin layer of epithelium. Mollusks, fishes and amphibians.

Question 10

Countercurrent exchange

Answer 10

Two adjacent currents flow in opposite directions and exchange materials with each other.

How bony fish’s gills work

Question 11

LO: describe how the respiratory surfaces of unicellular organisms, insects, fish and animals (30.1 and figure 30.2) maintain an adequate surface area to volume ratio for gas exchange.

Answer 11

See respiratory surface.

Question 12

Capillaries

Answer 12

The tiniest of blood vessels. Each filament includes platelike lamellae that house a dense network of capillaries.

The direction of water flow across lamellae opposes that of blood flow in the capillaries. The concurrent relationship maximizes gas exchange between water and blood.

Question 13

Lungs

Answer 13

Saclike organs that exchange gases. Homologous to the gas bladders of bony fish.

Question 14

Nose

Answer 14

Forms the external entrance to the nasal cavity, functions in breathing, immunity, and the sense of smell.

Epithelial tissue secretes a sticky mucus.

Nasal cavity adjusts temperature and humidity of incoming hair. Back of nose leads to the pharynx

Question 15

Upper respiratory tract

Answer 15

Nose, pharynx, and larynx

Lined with epithelium that secretes mucus. Inhaled particles are swept away by waving cilia.

Question 16

Pharynx

Answer 16

Throat. Inhaled air and swallowed food pass through here.

Question 17

Larynx

Answer 17

A boxlike structure that produces the voice.
Located below and in front of the pharynx. Adam’s apple.

Direct ingested food and drink away from the respiratory system.

Question 18

Vocal cords

Answer 18

Stretched over the larynx. Two elastic bands of tissue that vibrate as air from the lungs passes through the glottis.

Question 19

Glottis

Answer 19

Slit like opening. Vibrations of the vocal cords produce the sound of speech.

Question 20

Epiglottis

Answer 20

Cartilage flap that covers the glottis so that food enters the digestive tract instead of the lungs.

Question 21

Lower respiratory tract

Answer 21

Trachea and lungs

Question 22

Trachea

Answer 22

Windpipe. Tube just below the larynx.

C-shaped rings of cartilage hold the trachea open and accommodate the expansion of the esophagus.

Branch into two bronchi

Question 23

Bronchi

Answer 23

Branched from the trachea. Each bronchi leads to each lung.

Question 24

Bronchioles

Answer 24

Finest branches of bronchi. Contain no cartilage, but their walls contain smooth muscle. The automatic nervous system controls contraction of these muscles.

Narrows into several alveolar ducts, and each duct opens into a grape like cluster of alveoli, where gas exchange occurs.

Question 25

Alveolus

Answer 25

Tiny sac with a wall of epithelial tissue is one cell layer thick. Gas exchange occurs here. Branched from bronchioles.

Question 26

Respiratory cycle

Answer 26

Consists of one inhalation and one exhalation.

Question 27

Inhale

Answer 27

Air moves into the lungs

Skeletal muscles of the rib cage and diaphragm contract,,

Question 28

Exhale

Answer 28

Air flows out of the lungs

Does not require ATP

Question 29

What drives the back and forth motion of breathing?

Answer 29

Air flows from areas of high concentration to low. Air enters the body when the pressure inside the lungs is lower than the pressure outside the body.

Question 30

Hiccup

Answer 30

Diaphragm contracts unexpectedly, causing a sharp intake of air. The hic sounds occur when the epiglottis closes.

Question 31

Tidal volume

Answer 31

Amount of air inhaled or exhaled during a quiet breath taken at rest.

Question 32

Vital capacity

Answer 32

Total amount of air that a person can exhale after taking the deepest possible breath.

Question 33

Functions of the human respiratory system: a summary

Answer 33

1. Gas exchange: lungs exchange oxygen and carbon dioxide with blood.
2. Olfaction (sense of smell): breathing moves air across the nose’s olfactory epithelium, which detects odors.
3. Production of sounds, including speech: movement of air across the vocal cords in the larynx produces sounds.
4. Maintaing blood pH homeostasis: breathing more slowly or rapidly adjusts the concentration of CO2 in blood, which affects blood pH.

Question 34

Why do we exhale a different gas composition than inhaled air?

Answer 34

O2 from the atmosphere enters the capillaries surrounding the alveoli; CO moves in the opposite direction from the capillaries to the alveioli.

Question 35

Blood

Answer 35

Connective tissue consisting of cells and platelets suspended in plasma.

Question 36

Plasma

Answer 36

Liquid component of blood. Only 1% of O2 in blood is dissolved in plasma. Red blood cells transport the rest.

Question 37

Red blood cells

Answer 37

Transports the rest of the O2 not dissolved by plasma. Contains hemoglobin.

Question 38

Hemoglobin

Answer 38

Iron-rich pigment protein that binds with O2. Can carry up to 4 O2 molecules.

Question 39

Blood carries CO2 absorbed at tissue cells in three ways

Answer 39

1. About 5% to 10% is dissolved in plasma
2. Hemoglobin transports 23%
3. Most CO2 (75%) is transported by as bicarbonate ions.

Question 40

What are the important parts that contribute to blood’s ability to buffer pH changes and maintain homeostasis?

Answer 40

Carbonic acid and bicarbonate

Question 41

External respiration and gas exchange

Answer 41

Occurs in the lungs. O2 diffuses from the alveoli into the bloodstream where the concentration of O2 is lower.

Question 42

Internal respiration and gas exchange

Answer 42

O2 diffuses from the bloodstream to the tissue fluid and then into the body’s respiring cells which have the lowest O2 concentration. CO2 diffuses in the opposite direction.

Question 43

Brain’s breathing controls

Answer 43

Pons and the medulla. Chemoreceptors in the medulla and in the body’s largest arteries monitor blood CO2 levels.