Chapter 11 (swim bladders) Flashcards
(30 cards)
2 types of gas filled structures
lungs, swimbladders
what is the difference between swimbladders and lungs? how are they similar?
lungs are used for respiration while swimbladders provide buoyancy. Both come as out-pouchings of the embryonic foregut. lungs from the ventral side, swimbladders from the dorsal margin
2 types of evidence that lungs came before swim bladders:
phylogenetic. early lungs come from ancient actinopterygian lineages.
Anatomical evidence: alveoli resembling those found in lungs of amphibians (gars and bowfin)
which paleontologist thinks there is lung-fossil evidence?
Robert. H. Denison
if an object weighs more than the equivalent weight of the water it displaces, it:
sinks
if an object weighs less than the the water it displaces it:
is positively buoyant
how much additional energy would fish have to spend if they didnt have weight reducing adaptations?
5 and 7 % (sw/fw)
what are some ways to become neutrally buoyant?
swimbladder, reduce density of bone and fill liver with SQUALENE (oil)
what 2 abilities does the hydrostatic function of a swimbladder depend on?
- maintain a gas-filled space inside the body cavity of the fish
- vary the volume of gas in response to changing hydrostatic demands
what 2 ways does a swimbladder allow a fish to save energy?
1: able to remain motionless
2: requires less power to swim horizontally
what are changes in the swimbladder’s volume proportional to?
the relative not absolute change in pressure
what happens to the changes in swimbladder volume the deeper you go?
gets progressively less
where does the greatest change in lung volume occur?
near the surface
what law describes lung overpressure injury? what does it mean?
Boyle’s law relationship (PV=K). As pressure falls on ascent, the lung volume expands
what is a unique property of a swimbladder?
its able to concentrate the partial pressure of oxygen and nitrogen 500 times (O2) and 25 time (Na).
2 types of swimbladders, who has em
Physostomous (sturgeon, primitive teleosts), Physoclistous (derived teleosts)
how are physostomous swimbladders connected to the foregut?
by the PNEUMATIC DUCT
how are physostomous swim bladders inflated?
swallowing air and forcing it into the bladder by the PNEUMATIC DUCT
How does deflation of a physostomous swimbladder work?
burping
how does a physostomes fish add/remove gas?
for air via gas gland, remove via diffusion
how does a physoclistous swimbladder differ from physostomous?
their swimbladders are completly closed: no pneumatic duct. gas comes in and out through SECRETION (at the GAS GLAND) or RESORBTION (at the OVAL)
what is more derived, physoclistous or physostomous air bladders?
physoclistous is more derived
how do physoclists fill their gas bladders without directly gulping air?
rete mirabile. used to augment the local gas concentrations in the gas gland and not temperatures
two important features of the rete mirabile in relation to gasbladder:
1- the close contact between the arterial blood going to teh gas gland and the venous blood leaving it
2- the sheer number of these capilaries
