Lec 9 Flashcards
Lateral Ungulation
Side-to-side movement in a wave-like fashion
Ancestral trait
Achieves at simplest level with alternating contractions/relaxation of muscles on sides of body
Moving through a Fluid: Flow Mechanics
Turbulent flow:
- Swirling motion of water near surface
- Effect on drag: INCREASES drag; inhibits forward locomotion
Laminar flow:
- Smooth layered flow of water over surface
- Effect on drag: DECREASES drag
Moving through a Fluid: Drag
Inhibits forward motion
Due to friction with water
Affected by: -Surface characteristics -Width-to-length ratio = profile thickness = d/l --Around 25% is optimal
Moving through a Fluid: Thrust
Causes forward movement
Move forward if thrust > drag
Affected by amplitude (height of wavelength) and frequency (# wavelengths) of body bend
Fish pushes against water with tail creating diagonal force (Equal and opposite direction (for every action there is a reaction)
Thrust = component of reactive force (i.e. vector) in line with anteroposterior body axis
Moving through a Fluid: Down and Up
Gravity (down):
- -Effect?
- –Pulls the fish toward the ocean floor (i.e. the center of the Earth)
- -Countered by lift and buoyancy
Lift and Buoyancy (up);
- -Allow animal to maintain place in water column
- –Sharks have an oily liver (prevents it from sinking)
- –Most fishes have a gas bladder (aka swim bladder)
Temperature and Performance
Enzymes function best at specific temperatures
- -Ectotherms: increased metabolic rate and activity level possible at warmer temperatures (assuming that have the right enzymes)
- –Depend on ENVIRONMEnT to regulate temperautre
Endothermy: Specialized pathway in mitochondria to regulate temperature
Muscle performance is temperature dependent
Some fish maintain certain muscles at higher temperature than water
- How? Retain metabolic heat from muscles
- -~90% of energy lost as heat NORMALLY
- -These fish are bale to RETAIN that heat
- Characteristics of these fish? Fast and continuously swimming
- Includes tuna, mackerals, LAMNIFORM sharks
PROBLEM: Heat loss through skin and especially gills during circulation
–Gills are GREAT at diffusion, but a LOT of heat lost when going through gills
How do the fish keep their muscles warm? COUNTERCURRENT EXCHANGE SYSTEM
- -Movement of fluids in opposite directions
- -Heat energy is exchanged
Counter-Current Exchange System
Modeled as loop with sides separated and arrows indicating flow
One end of loop in cold (water) and other in hot (muscle producing metabolic heat)
Arrows indicate blood flow
Sides of loop further - What happens: Much heat transferred and lost to environment (i.e. water around gills)
Sides of loop close together - What happens: Heat transferred from outgoing to incoming side; less heat from muscles lost to environment
Counter-Current Exchange: Rete Mirable
“Wonderful net” (Latin)
-Refers to all of the little blood vessels
Arterioles and venules run parallel and close
Blood from gills warmed by blood from muscles
Effect? Blood reaching gill has transferred heat to arteriole flow back to muscles
Other Counter-Current Exchange Systems
Heat exchange (retention or elimination of heat) --Wolves' feet (WARM), whale flippers (WARM), African elephant ears (COOL), mammal testicles (COOL)
Mammal testicles:
- Pampiniform plexus
- In most mammals, testes are external; sperm production most effective a few degrees BELOW body temperature
Maintenance of solute concentration gradients/water balance
–Mammalian kidney: INCREASE solute concentrations
Gas exchange
- -Fish gas bladder, fish gills
- –Counter-current multiplier
- -Fish gills
Breathing in Fish
Breathing: Bulk flow of oxygen
Major structures and flow of water:
- Know MAJOR structures in flow of water
- -In the mouth
- -Through the gill slits
- -Filaments
- Buccal cavity:
- -AKA oral cavity
- -Mouth cavity
- Opercular cavity
- -Space between gill arches and exit to body
- Gross gill structure
- Close to continuous flow of water and thus oxygen across the gills and thus through the flesh
- MAJOR structures in flow of water:
- -Gill arches and filaments, secondary lamellae, blood vessels
Secondary lamellae = Great respiratory surface
- -Where oxygen diffuses
- -Gas exchange surgace
- -Water flow vs. blood flow - opposite directions = counter-current system
Efferent
To move away from
Afferent
To move towards
Respiratory/Gas exchange in fish
Countercurrent gas exchange system (generally seen in teleosts)
Effect? More oxygen extracted from water than in concurrent system
-Concurrent: Water and blood move in same direction or blood is pooled/not moving
Oxygen Transfer from Environmental Medium to Blood in a Concurrent Gas Exchanger
Flow of medium and blood is in SAME direction along membrane
Partial Pressure of Oxygen (PO2) difference drives oxygen exchange across membrane
Oxygen exchange DECREASES as PO2 difference DECREASES
PO2 of blood lower than exhaled medium
Oxygen Transfer from Environmental Medium to Blood in a Countercurrent Gas Exchanger
Medium and blood flow in opposite directions along membrane
PO2 of blood much higher than exhaled medium
Blood exposed to medium with increasing PO2 thus favoring continued oxygen exchange along membrane
