5 - Gas exchange (1) Flashcards
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Gaseous exchange def
Uptake of oxygen (O2) from the surrounding environment and the release of carbon dioxide (CO2) which is a metabolic waste product of respiration
Where does gas exchange usually occur in invertebrates?
Across the integument of the animal or via specialized structures
(Cellular/ internal) Respiration def
Respiration is the energy-producing metabolic activities within cells
Metabolism def
Consists of “all of the biochemical reactions involved in the uptake & use of energy & materials by organisms”
Catabolic rxn def
Biochemical rxn where large molecules are broken down into small ones
Catabolic rxn equation explained
The substrate (e.g. glucose) is broken down, which requires 6 molecules of oxygen O2 and several enzymes. The reaction releases 6 molecules of carbon dioxide (CO2) and 6 molecules of water (H2O), and generates energy in the process.
Catabolic rxn equation
C6H12O2 + 6O2 —> 6CO2 + 6H2O
Respiratory rates def
rates of oxygen uptake and/or carbon dioxide release
What is metabolism estimated by?
Respiratory rates
Skin/ integument def
Invertebrate will use the skin or integument as the structure for gas exchange and will typically lack other specialized structures.
- Propensity (natural tendency) to lose water
Gas exchange structures
- Skin/ integument
- Gills
- Lungs (book lungs)
- Tracheae
Skin/ integument examples
- Seaspiders (Order: Pantopoda)
- Micro-scorpions (Order: Palpigradi)
- Cnidarians (Phylum: Cnidaria)
Ways of preventing water loss of skin
- Small body size - require less oxygen = less gas exchange demand = less water loss
- Large body size, soft-bodied forms (cnidarians & flatworms) = low surface-to-volume ratios = lose water at a lower rate per unit volume
- Inhabit aquatic habitats or damp terrestrial environments
Tracheal system def
An open respiratory system composing of spiracles, trachea and tracheoles
Spiracles def
The openings of the tracheae onto the body surface; there are closable and non-closable spiracles (depending on the organism)
Trachea def
- A tube-like structure that conveys air (with needed oxygen) from external environment to tissues and vice-versa (also conveys carbon dioxide from tissues to the outside environment).
- They are invaginations of the cuticular exoskeleton and extend towards multiple tracheoles
Tracheoles def
The smallest branches of the tracheal system where the transfer and diffusion of oxygen occurs into and out of the tissues and cells.
Cambrian fossils (500Ma) name
Xenusians
Ancestors of Onychophorans
Xenusians
Xenusians are ancestors of who?
Onychophorans
Earliest terrestrial ancestor of Onychophorans originated ?
In the upper carboniferous
300Ma
Why do velvet worms have their name?
Their thin cuticle has numerous sensory papillae
Onychophora structures & characteristics
- Terrestrial in moist habitats (leaf litter & rotten logs) - typically forests
- 1 pair of antennae, 2 eyes with spherical lenses
- 13 to 43 pairs of legs (also called ‘oncopods’)
- Thin cuticle has numerous sensory papillae
- Have malleable body and use hydrostatic muscle skeleton using pressurized fluid in the body to extend and contract their body and legs
Oncopods def
How do onychophora exchange gas?
Use multiple non-closable (continuous gas exchange) spiracles to exchange O2 and CO2 with environment.
Continuous gas exchange def
Spiracles cannot open and close, we call this mode of gas exchange a “continuous” gas exchange
Scientific name of velvet worm
P. capensis
