gas exchange in insects and fish

Question 1

what are the features of specialised exchange surfaces?

Answer 1

large SA:V ratio, thin, partially permeated, movement of the external and internal medium, fenestrations

Question 2

what is fick’s law?

Answer 2

the rate of diffusion is proportional to (SA x difference in concentration / length of diffusion pathway)

Question 3

what are tracheae?

Answer 3

large (relatively) tubes which facilitate air movement and are lined with rings of chitin to provide structure (like cartilage)

Question 4

what are tracheoles?

Answer 4

thinner tubes which branch off from tracheae and allow for movement of gases in and out of cells

Question 5

what are spiracles?

Answer 5

respiratory openings on an insect’s body which allow air to enter the tracheae

Question 6

what are air sacs?

Answer 6

extensions of the tracheal system in insects which act as pumps to circulate the oxygen around the insect’s body when it moves

Question 7

how many gill arches do fish typically have?

Answer 7

four on each side

Question 8

what is the structure of gills?

Answer 8

each gill arch has many stacked gill filaments, with many microscopic extensions called lamellae projecting at 90° from each one

Question 9

how are lamellae adapted for gas exchange?

Answer 9

they have walls of only a few cells thick and contain many capillaries

Question 10

what is parallel flow/counter current exchange?

Answer 10

when blood flows in the opposite direction to water along the gills, so that there is always a higher percentage of oxygen in the water than in the blood, maintaining the diffusion gradient