Ventilation and gas exchange in other organisms

Question 1

Do insects have a high or low metabolic rate?

Answer 1

High

Question 2

Do insects usually have blood pigments?

Answer 2

No

Question 3

What does the insects tough exoskeleton prevent?

Answer 3

Gaseous exchange

Question 4

What are along the thorax and abdomen of most insects?

Answer 4

small openings called spiracles

Question 5

What do the spiracles do?

Answer 5

Air enters and leaves the system through the spiracles.

Question 6

How can the spiracles be opened and close?

Answer 6

Via sphincters

Question 7

Why are the spiracle sphincters kept closed as much as possible?

Answer 7

To minimise water loss.

Question 8

What happens to the spiracles when the insect is inactive and oxygen demands are low?

Answer 8

They are kept closed.

Question 9

What happens to the spiracles when the oxygen demand is raised or the carbon dioxide levels build up?

Answer 9

More of the spiracles open.

Question 10

What is extended after the spiracles?

Answer 10

The trachea

Question 11

How big is an insects trachea?

Answer 11

1mm in diameter

Question 12

What does the trachea do?

Answer 12

Carry air into the body

Question 13

What is the trachea lined with?

Answer 13

Spirals of chitin

Question 14

What is chitin?

Answer 14

The material that makes up the cuticle. It is relatively impermeable to gases and so little gaseous exchange takes place in the trachea.

Question 15

What does the trachea divide into?

Answer 15

Narrow tubes called tracheoles.

Question 16

How large are tracheoles?

Answer 16

0.6-0.8 m

Question 17

What is the structure of the trancheoles?

Answer 17

Each trancheole is a single, greatly elongated cell with no chitin lining so they are freely permeable to gases.

Question 18

Were does most of the gaseous exchange take place?

Answer 18

Between the air and the respiring cells.

Question 19

What does the vast number of the tracheoles give the insect?

Answer 19

A very large surface area.

Question 20

What is towards the end of the tracheole?

Answer 20

The tracheal fluid!

Question 21

What does the tracheal fluid do?

Answer 21

The tracheal fluid limits air diffusion.

Question 22

Large insects such as bees, wasps and flies have high energy demands. To increase the level of gaseous exchange, these insects have special techniques. What are they?

Answer 22

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

Question 23

How does mechanically ventilating the tracheal system provide a higher level of gaseous exchange?

Answer 23

Air is pumped into the system via muscular pumping movements of the thorax and/or the abdomen. This changes the volume of the body and thus the pressure in the trachea and trancheoles. As the pressure changes in the insects body, the air is drawn into the trachea and tracheoles, or out.

Question 24

How does collapsing enlarged trachea or air sacs provide a higher level of gaseous exchange?

Answer 24

They act as air reservoirs and are used to increase the amount of air moved through the gas exchange system. They are usually inflated and deflated by the ventilating movements of the thorax and abdomen.

Question 25

What are the fishes organs for gaseous exchange?

Answer 25

The gills

Question 26

Where are the gills located in bony fish?

Answer 26

In the gill cavity

Question 27

What are the gills covered by?

Answer 27

Operculum (a bony flap that you cut of during dissection) :)

Question 28

What does the operculum do?

Answer 28

Maintains a flow of water over the gills

Question 29

Is diffusion faster in water or air?

Answer 29

Air

Question 30

How do the gills increase the rate of gaseous exchange?

Answer 30

They contain… A good blood supply A large surface area Thin layers

Question 31

In order to ventilate the gills, some fish (such as sharks) rely on continual movement. What is this known as?

Answer 31

Ram ventilation (They just ram the water past the gills)!

Question 32

In order to ventilate the gills, some fish (such as sharks) rely on continual movement. What is this known as?

Answer 32

Ram ventilation (They just ram the water past the gills)!

Question 33

Most bony fish rely on what to keep water flowing over the gills?

Answer 33

The operculum

Question 34

Describes the steps for inhalation for a fish

Answer 34

The fish opens the mouth and the floor of the buccal cavity is lowered. This increase the volume of the buccal cavity, and thus the pressure is lowered which causes the water to rush into the buccal cavity. The opercular valve shuts and the opercular cavity containing the gills expands. This lowers the pressure the the opercular cavity containing the gills. The floor of the buccal cavity moves up and the mouth closes. This increases the pressure in the buccal cavity and the water rushes over the gills.

Question 35

Describe the steps of exhalation for a fish

Answer 35

When the mouth closes the operculum opens and the sides of the opercular cavity move inwards. This increases the pressure in the opercular cavity and thus forces the water out and over the gills.

Question 36

What are the two extra adaptions that fish have for an even more efficient gaseous exchange?

Answer 36

The tips of the gill filaments overlap. The water moving over the gills and the blood in the gill filaments flow in a different direction.

Question 37

Why is it good that the gill filaments overlap?

Answer 37

It increases the resistance to the flow of water so that it slows down, so that there is more time for gaseous exchange.

Question 38

Why is it important that the the water moving over the gills and the blood in the gill filaments flow in a different direction?

Answer 38

Because a steep concentration gradient is needed for for fast and efficient gas diffusion. When the water and the blood flow in different directions a countercurrent exchange system is created which maintains a high concentration gradient. As a result more gaseous exchange can take place.

Question 39

Why is it important that the the water moving over the gills and the blood in the gill filaments flow in a different direction?

Answer 39

Because a steep concentration gradient is needed for for fast and efficient gas diffusion. When the water and the blood flow in different directions a countercurrent exchange system is created which maintains a high concentration gradient. As a result more gaseous exchange can take place.

Question 40

What percentage of oxygen is removed from the water with fish with countercurrent systems?

Answer 40

80%

Question 41

What percentage of oxygen is removed from the water with fish with parallel systems?

Answer 41

50%