Ben Shaw

Ben Shaw

1. Gut Physiology

   • Ingestion, digestion, absorption and elimination
   • Carnivore, herbivore and omnivore
   • Prehension,
     • seizing and conveying feed to mouth
   • Monogastric; one compartment
     • simple stomach structure - carnivores and omnivors
   • Ruminant; four compartments
     • reticulum, rumen, omasum, abomasum
     • herbivores
   • dentition
   • small intestine; shorter in carnivores than herbivores
   • large intest; hind gut fermentation dictates variation
     • fermentation - digestability of fibre

2. Osmosis

   • maintaining water balance
     • osmosis
     • diffusion
     • active transport
   • osmolarity - osmotic conc/measure of solute conc
   • tonicity - measure of osmotic pressure

3. osmoregulation in vertebrates

   • osmoconformer; only isosmotic do not regulate
   • Osmoregulator; expend energy to control in hyper/hyposmotic enviro
   • epithilial cells = boundary between animals + enviro
   • marine/freshwater transition in Killifish
     • regulate influx + efflux of ions and water
   • amphibians; osmotic inflow is excreted, active uptake of salts, skin is osmoregualtor
   • marine birds; drink seawater, eliminate salts from glands above orbit of the eye
   • marine mammals; low permeability of skin, avoid drinking seawater, kidney is osmoregulator
   • marine repitles; drink seawater, eliminate salts through specialised glands

4. osmoregulation in aquatic animals

   • isosmotic - same blood solute conc as surroundings (equal)
     • salts and water diffuse equally
   • Hyperosmotic - blood osmotic conc is higher that surroundings
     • higher rate of diffusion of salts out and water in
   • Hyposmotic - blood osmotic conc is lower that surrounding medium
     • higher rate of diffusion of salts in and water out
   • aquatic body fluids
     • intracellular - 70% of cell volume
     • Extracellular - e.g. circulatory system
   • osmoregulation mechanism
     • Anisomotic - extracellular solute conc control
     • isosmotic - intracellular solute conc control
   • elimination of salts in marine teleosts
     • drink 75% of ingested water
   • chloride cells; in the gills
     • actively transport chloride ions out + allow sodium ions to follow passively