Chapter 44. Regulating the Internal Environment. Homeostasis. Thermoregulation Osmoregulation Excretion. Homeostasis. All organisms must maintain a constant internal environment to function properly Temperature pH ion levels hormones. Negative Feedback. Body Temperature Regulation.
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Regulating the Internal Environment
Body Temperature Regulation
Endotherms are thermoregulators
Many inverts- nonregulator
Spider crab Libinia
Some ectotherms that experience subzero body temperatures protect themselves by producing “antifreeze” compounds (cryoprotectants) that prevent ice formation in the cells.
Hibernation:long-term torpor as an adaptation to long-term winter cold and food shortage
Body Temperature and metabolism during hibernation of Belding’s ground squirrel
Osmoregulation- the control of the concentration of body fluids.
Diffusion- movement of substance from an area of greater concentration to an area of lower concentration
Osmosis- diffusion of water through a semipermeable membrane
Osmols- total solute concentration in moles of solute/liter of solution
Less salt than external environment
H2O continually leaves body
continually drinks seawater
excretes salt through gills
produces small amts of dilute urine
H2O continually enters body
does not drinks water
More salt than external environment
produces large amts of dilute urine
Maintains high levels of urea and TMAO in blood
excretes salt through rectal gland
Seawater concentration = internal concentration
Osmolarity- measure of total solutes(dissolved particles)
Ions FW m osmol/l SW m osmol/l
Na+ 1 470
Cl- 1 550
Ca++ variable 10
Total 10 1000
Crab-eating frog (Rana)
Concentration of Ions
Most excretory systems produce a filtrate by pressure-filtering body fluids into tubules.
Metanephridia consist of internal openings that collect body fluids from the coelom through a ciliated funnel, the nephrostome, and release the fluid through the nephridiopore.
Insects and other terrestrial arthropods have organs called Malpighian tubules that remove nitrogenous wastes and also function in osmoregulation.