7.4 Ventilation And Gas Exchange In Other Organisms

Question 1

What are spiracles?

Answer 1

Small openings along the thorax and abdomen of most insects

Question 2

What is the function of spiracles?

Answer 2

To allow enter to enter and leave systems through them. However, water is also lost.

Question 3

What is done to minimise the loss of water in insects through spiracles?

Answer 3

Spiracles have SPIRACLE SPHINCTERS. These sphincters open and close the spiracles, and they are often kept closed as much as possible to minimise water loss.

Question 4

When are the spiracles of an insect all closed?

Answer 4

When an insect is inactive and oxygen demands are very low.

Question 5

What do trachea do in an insect?

Answer 5

Transport air into the body and around it. Run into and along the body of an insect.

Question 6

What are tubes of trachea lined by (in an insect)?

Answer 6

Spirals of CHITIN, which keep the trachea open if they are bent or pressed.

Question 7

Why is there no gaseous exchange in the trachea of an insect?

Answer 7

Because it is lined with chitin, which is relatively impermeable to gases.

Question 8

What do the trachea branch to form (in insects)?

Answer 8

Narrower tubules, until they divide into the tracheoles

Question 9

What is a tracheole (in insects)?

Answer 9

A single, greatly elongated cell with no chitin lining

Question 10

Is gaseous exchange possible in a tracheole (in insects)? Why / why not?

Answer 10

Yes, because the tracheole have no chitin lining

Question 11

Where are the tracheoles (in insects)?

Answer 11

Spread throughout the tissues of the insect, running between individual cells

Question 12

Where does most gaseous exchange take place in an insect?

Answer 12

In the tracheal system

Question 13

What does tracheal fluid do?

Answer 13

Reduces water loss, limits the penetration of air for diffusion, and carries oxygen

Question 14

What happens in insects when oxygen demand builds up?

Answer 14

-Lactic acid build-up in the tissues results in water moving out of the tracheoles by osmosis, which exposes more surface area for gaseous exchange.
-Tracheal fluid is absorbed into muscle cells

Question 15

What are the 2 alternative methods used by larger insects to increase gaseous exchange?

Answer 15

-Mechanical ventilation of the tracheal system
-Collapsible enlarged trachea or air sacs

Question 16

Describe the mechanical ventilation of the tracheal system done by larger insects.

Answer 16

-Air is actively pumped into the system by muscular pumping movements of the thorax and/or abdomen.
-This changes the volume, and therefore the pressure of the body.

Question 17

Describe the collapsible enlarged trachea or air sacs of larger insects.

Answer 17

-These act as air reservoirs, used to increase the amount of air moved through the gas exchange system

Question 17

List the problems mites can cause if they enter an insect through the spiracles.

Answer 17

-Transmit diseases
-Lead to leakage of haemolymph
-Use up O2
-Restrict airflow in the trachea
-Release toxins

Question 18

What properties of water make it more difficult to use in gas exchange than air?

Answer 18

Water is thicker than air, more dense, and has a much lower oxygen content

Question 19

What are bony fishes’ organs of gaseous exchange?

Answer 19

Gills.

Question 20

What are the key features of gills?

Answer 20

Large surface area, good blood supply, thin layers.

Question 21

Where are gills contained?

Answer 21

In the gill cavity

Question 22

What are gills protected by?

Answer 22

An operculum (a bony flap)

Question 23

What is the function of the operculum in fish?

Answer 23

Protect the gills, and maintains a low of water over the gills.

Question 24

What is the function of gill rakers?

Answer 24

Help gather food and protect the gills

Question 25

What is the function of a bony gill arch?

Answer 25

Supports the structure of the gills

Question 26

Describe the gill lamellae.

Answer 26

Have a rich blood supply and large surface area, and are the main site of gaseous exchange in the fish

Question 27

What are gill plates?

Answer 27

Stacks that hold gill filaments

Question 28

What are gill filaments?

Answer 28

Parts of the gill that give it the large surface area needed for gaseous exchange.

Question 29

What has to be done to protect the gill filaments? Why?

Answer 29

Must have a constant flow of water to keep them apart.

Question 30

Why do fish need to maintain a continuous flow of water over the gills?

Answer 30

To allow efficient gas exchange at all times.

Question 31

How do bony fish maintain a current of water flowing over their gills at all times?

Answer 31

By opening their mouth and operculum.

Question 32

Describe what the bony fish does during inspiration.

Answer 32

-Mouth is opened, floor of the buccal cavity is lowered -Buccal cavity volume increases, pressure drops, and water flows into the cavity -Opercular valve is shut, and the Opercular cavity containing the gills expands, lowering pressure -Floor of the buccal cavity moves up, pressure increases, so water moves from the buccal cavity over the gills

Question 33

Describe what the bony fish does during expiration.

Answer 33

-Mouth is closed, the operculum closes, sides of the opercular cavity move inwards -So pressure increases, water is forced over the gills and out of the operculum -Floor of the buccal cavity is steadily moved up, maintaining a flow of water over the gills

Question 34

State the adaptations of gills to maximise gas exchange.

Answer 34

-Gills have a large surfacce area for diffusion -Gills have a rich blood supply -Gills have thin layers -Tips of adjacent gill filaments overlap -Water moving over the gills and the blood in the gill filaments flow in different directions

Question 35

What is the name of the system that bony fish use to breathe?

Answer 35

Countercurrent system.

Question 36

What is the name of the system that cartiligous fish use to breathe?

Answer 36

Parallel system.