exchange surfaces- ventilation and gas exchange in other organisms Flashcards

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1
Q

what are spiracles?

A

small openings along the thorax and abdomen of most insects.

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2
Q

How does gas exchange take place in insects?

A

air enters and leaves the system through spiracles. Water is also lost through spiracles therefore to minimise water loss but maximise efficiency of gas exchanges sphincters are closed as much as possible.

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3
Q

What are sphincters?

A

spiracles can be open or closed by sphincters

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4
Q

what occurs to the spiracles when the insect is inactive?

A

oxygen demands are low and the spiracles will be closed most of the time.

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5
Q

what occurs the spiracles when the oxygen demand is raised or the carbon dioxide levels build up?

A

spiracles open

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6
Q

Describe the trachea of the gas exchange system in insects?

A

spiracles lead to trachea which carry air to the body which are lined with spirals of chitin. These keep the tubes open if they are bent or pressed. Chitin makes up the cuticle. It is impermeable to gases so little gas exchange happens in the trachea.

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7
Q

what does trachea branch into?

A

trachea branches into narrower tubes called tracheoles. Each tracheole is a single greatly elongated cell with no chitin lining so it is freely permeable to gases. Because of their small size, they can spread through cells of tissue where most gas exchange takes place.

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8
Q

How has the gas exchange system adapted?

A

-vast numbers of tiny tracheoles create great surface area for gas exchange
-oxygen dissolves in moisture on walls of tracheoles and diffuses to surrounding cells.
-tracheal fluid at the end of tracheoles limit penetration of air for diffusion.

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9
Q

what happens to maximise surface area when oxygen demands increase (e.g when flying)?

A

water moves out tracheoles through osmosis which provides more surface area for gaseous exchange.

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10
Q

extend of gaseous exchange in most insects is controlled by?

A

the opening and closing of spiracles

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11
Q

how does mechanical ventilation increase levels of gaseous exchange in insects with high oxygen demand?

A

-mechanical ventilation of the tracheal system: muscular pumping movements of thorax and abdomen actively pump air into system. These movements changes volume of body and changes pressure in trachea and tracheoles causing air to be drawn in or forced out.

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12
Q

How do insects with high energy demand, needing extra oxygen, increase their levels of gaseous exchange?

A

mechanical ventilation and collapsible enlarged trachea or air sacs which act as air reservoirs.

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13
Q

How does collapsible enlarged trachea or air sacs which acts as air reservoirs increase levels of gaseous exchange in insects with high oxygen demand?

A

these are used to increase the amount of air moved through the gaseous exchange system. They are usually inflated and deflated by the ventilating movements of the thorax and abdomen

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14
Q

why do spiracles flutter, open and close rapidly?

A

this moves fresh air into the trachea to renew the supply of oxygen while minimising water loss-discontinuous gas exchange

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15
Q

how have the gills adapted to provide efficient gaseous exchange?

A

-bony fish maintain a flow of water in one direction over the gills.
-larg surface area
-good blood supply
-thin layers
-gill cavity covered by operculum which is active in maintaining a flow of water over the gills.

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16
Q

how do fish keep a current of water flowing over the gills?

A

by opening their mouth and operculum

17
Q

what is ram ventilation?

A

rating the water past the gills, fish with rely on continual movement to ventilate the gills.

18
Q

How do most bony fish keep a current of water flowing over their gills even when they are not moving? Describe when mouth is open

A

-mouth is opened and the floor of the buccal cavity (mouth) is lowered. This increases volume of buccal cavity, decreasing pressure causing water to rush in. At the same time the opercular valve is shut and the opercular cavity containing gills expands, lowering pressure. Floor of buccal cavity moves up, increasing pressure so water moves from buccal cavity over the gills.

19
Q

How do most bony fish keep a current of water flowing over their gills even when they are not moving?

A

mouth opens and closes causing constant flow of water over the gills. This is a continuous process.

20
Q

How do most bony fish keep a current of water flowing over their gills even when they are not moving? Describe when mouth is closed

A

Mouth closes, operculum opens and sides of the opercular cavity move inwards. This causes pressure to increase in opercular cavity and force water over the gills and out of the operculum. The floor of the buccal cavity is steadily moved up, maintaining a flow of water over the gills.

21
Q

The tips of adjacent gill filaments overlap, how does this provide efficient gaseous exchange?

A

This increases the resistance to the flow of water over the gill surfaces and slows down water movement so there is more time for gaseous exchange to occur.

22
Q

The water moving over gills and the blood in the gill filaments flow in different directions, how does this provide efficient gaseous exchange?

A

a countercurrent system is set up which ensures a steeper concentration gradient for diffusion then if they flowed in the same direction (parallel system).

23
Q

where does gas exchange occur in in the tracheal system?

A

in the tracheal fluid at the end of tracheoles

24
Q

why can’t gases diffuse into insects?

A

they have a waxy exoskeleton which doesn’t allow gas exchange

25
Q

how do muscles gain oxygen in insects?

A

tracheal fluid is drawn in by muscles which contain oxygen. This lowers pressure drawing in more air through spiracles and increases surface area

26
Q

what is the role of the air sacs in the trachea of insects?

A

changes in the volume of the thorax and abdomen can squeeze the air sacs causing air to move from the air sacs to the tracheoles. This is useful when spiracles are closed for water conservation.

27
Q

What occurs in the insects during anaerobic activity?

A

lactic acid is produced which lowers water potential in body cells causing tracheal fluid to move into the cells by osmosis. This also increases the area for oxygen and carbon dioxide to diffuse.