Gas Exchange

Question 1

What is this equation?
M= [D x A( Cext - Cin)]/L
What are the units?

Answer 1

Ficks
M = mass of gas
D = diffusion coefficient
A = area
Cext - Cin = concentration gradient 
L = thickness

Question 2

Name the 4 kinds of gas exchange

Answer 2

1. Skin/cutaneous
2. Gills
3. Trachae
4. Lungs

Question 3

Name 3 organisms that use cutaneous respiration

Answer 3

Sponges
Anemones
Platyhelminthes

Question 4

What is diffusion dependent on?

Answer 4

Total surface area of respiratory structure
Permeability of the surface
Gradient of gas

Question 5

Describe cutaneous respiration

Answer 5

direct gas exchange across the body surface

requires thin, moist, highly vascularized skin to be effective

Question 6

Route of water flow in sponges

Answer 6

1. dermal pores
2. incurrent canals
3. flagellated chambers lined with choanocytes
4. spongocoel (atrium)
5. osculum

Question 7

Name 2 organisms that use cutaneous respiration

Answer 7

Sponges (sycon)

Platyheminthes (giardia)

Question 8

Describe gills

Answer 8

evaginations of the body surface, which may open directly to the environment or may be enclosed in a cavity
thin-walled processes well supplied with blood or other bodily fluid that allow diffusion
highly folded
large surface area relative to their mass
need flow of water

Question 9

How do gills flow water?

Answer 9

1. move gill through water

2. move water over gills - ciliary flow or pump-like action

Question 10

why do gills need constant water flow?

Answer 10

need water so that oxygen does not become depleted, especially in the boundary layer

Question 11

Name 4 organisms that use gills

Answer 11

polychaeta (nereis)
feather dustres
squid
crayfish/crabs

Question 12

Polycheate gas exchange

Answer 12

use their body surface and additional specialized gills

segmental flaps or branchial tufts

Question 13

Nereis gas exchange

Answer 13

parapodium

Question 14

Feather duster gas exhange

Answer 14

brachial crowns

Question 15

Squid gas exchange

Answer 15

ventilate a protected chamber lined with feathery gills that contain capillaries

Question 16

Crayfish/crab gas exchange

Answer 16

gills enclosed in protective chambers and ventilation is provided by specialized appendages
faster crabs = more gill area
terrestrial crabs = reduction of gills
increase in ventilation = decrease in partial pressure of oxygen

Question 17

How to lungs work?

Answer 17

invaginations of the body surface that air moves in and out of the body through branched tubular pathways
air reaches membrane where gas exchange occurs then it’s circulated through the body
typically in terrestrial environments

Question 18

Spider gas exchange structure

Answer 18

book lungs

Question 19

insect, centipedes and millipedes gas exchange structure

Answer 19

tracheae

Question 20

Land snail and slug gas exchange structure

Answer 20

lung which open via pneumostome

Question 21

Describe pneumostome

Answer 21

small opening in the mantle cavity on the right-hand side of the organism
allows air to enter the highly vascularized lung

Question 22

Sea cucumber gas exchange structure

Answer 22

Respiratory tree

Question 23

Describe respiratory tree

Answer 23

branched hollow outpouchings of the cloaca (hindgut)

water pumped in and out by the action of cloaca

Question 24

Sea cucumber digestive system

Answer 24

mouth 
pharynx
calcareous ring 
esophagus
stomach
intestine
cloaca
cloacal dilator muscles 
anus

Question 25

Sea cucumber respiratory system

Answer 25

2 respiratory trees
inhale= close intestinal sphincter, relax anal sphincter, contract cloacal dilator muscles
inspires water into cloaca, sphincters close and circular muscles in the clocal wall are contracted forcing water into respiratory tree
gas exchange between coelomic fluid and seawater in walls of tree
exhale= contraction of muscles in the walls of tree with intestinal sphincter closed and anal sphincter open

Question 26

Describe book lungs

Answer 26

blind inpocketings with highly folded inner linings across which gasses diffuse between hemolymph and air

Question 27

Describe tracheae

Answer 27

invaginations of cuticular exoskeleton
highly branched
air-filled tubular passages connect the body surface with all internal structures

Question 28

Describe tracheoles

Answer 28

smallest tubes in tracheae

directly penetrate cells and serve as cites for diffusion for water oxygen and carbon dioxide

Question 29

Describe spiracles

Answer 29

external structures on exoskeleton of insects and most arthropods
open and close to prevent water loss during respiration