CHAPTER 44 REGULATING THE INTERNAL ENVIRONMENT

CHAPTER 44REGULATING THE INTERNAL

ENVIRONMENT

Regulators- animals that for a specific environmental variable use mechanisms of homeostasis to moderate internal changeConformers-animals that for a specific environmental variable allow the conditions inside their bodies to change with the environment

Partial Energy and material use for ten years of a young woman’s life

ThermoregulationQ10 effect- there is a 2-3 times increase for metabolic reactions for each 10°C rise in temperature. Conduction-direct transferConvection-movement of air or water past a surfaceRadiation-between objects not in contact through electromagnetic waves Evaporation-removal of heat from the surface of a liquid by losing molecules as a gas

Can all of these be a source of gain or loss?

Ectotherm-low metabolic rate does not generate enough heat to effect body temperature. Endotherm-High metabolic rate generates heat to maintain body temperatures higher than the environment

Thermoregulation• Adjusting the rate of heat exchange between the

animals and surrounding. Vasodilation--- vasoconstriction--- Countercurrent heat exchangers

• Cooling by evaporative loss. Panting and perspiration- only way to lose heat if environment is warmer than the body temperature

• Behavioral responses. Positioning; hibernation; migration

• Changing the rate of metabolic heat production. Shivering; Nonshivering thermogenesis-hormones cause mitochondria to increase their metabolic rate; special tissue called brown fat

Countercurrent heat exchangers

Countercurrent heat exchangers

Weighted Sec.I Score

1 2 3 4 5 Total

76-90 0.0% 0.0% 0.0% 0.3% 99.7% 3.9%

61-75 0.0% 0.0% 0.2% 32.9%66.8%18.9%46-60 0.0% 0.5% 40.1%56.1% 3.3% 28.9%

31-45 0.1% 51.1%47.0% 1.8% 0.0% 26.6%16-30 41.4%58.3% 0.3% 0.0% 0.0% 16.2%

0-15 99.7% 0.3% 0.0% 0.0% 0.0% 5.5%Total 12.2%23.2%24.2%22.9%17.5% 100.0

Most fish are conformers. Some larger fish use countercurrent exchange to keep body core warmer than their environment.

Some larger fish use countercurrent exchange to keep body core warmer than their environment.

Shivering of the huge flight muscles and countercurrent heat exchanger allow endothermic moths to generate temperatures up to 20°C higher than the environment.

acclimatization-

stress-induced proteins which include heat-shock proteins

torpor-general term for a physiological state in which activity is low and metabolism decreases

hibernation-

estivation-

daily torpor-

Belding’s ground squirrel hibernates to conserve energy

Osmoregulation Involves some type of transport epithelium that have selectively permeable membranes for the transport of specific solutes.Many tight junctions between cells. Use large amounts of ATP for active transport. Purpose is to maintain the composition of the cytoplasm of the body’s cells. Accomplished indirectly by maintaining the interstitial fluid and blood

can drink seawater

Most toxic-Low concentrations more

water released

Less toxic-Higher conc.

less water

Least toxic-Highest conc. least water

osmoconformer-does not actively adjust its internal osmolarity because it lives in an isoosmotic environment

osmoregulator-must control its internal osmolarity because it internal fluids are not isoosmotic with its environment

stenohaline-cannot tolerate substantial changes in external osmolarity and thus are usually osmoregulators

euryhaline-can tolerate substantial changes in external osmolarity

Anhydrobiosis- tardigrades (water bears) inhabit temporary ponds; can go from 85%-2% water and survive for ten years

Key functions of Excretory Systems

Protonephridia of planarian flame-bulb system-fluid is filtered into the bulb; produces very dilute urine but there is some reabsorption of solutes by the tubules.

Metanephridia-take in coelomic fluid (filtration) and then reabsorb the nutrients; produces a dilute urine that allows them to get rid of excess water absorbed from damp soil

Malpighian tubules of the insects; nitrogenous wastes are secreted into the lumen of the tubes from the hemolymph and then it passes into the rectum; nitrogenous wastes are converted to insoluble nitrogenous wastes and are released with the solid waste

vasa recta

Active transportPassive transport

Filtration

Reabsorption & Secretion

inte

rstit

ial f

luid

is

mor

e hy

pero

smot

ic

permeable to water but impermeable to NaCl

impermeable to water permeable to NaCl

Adjustments on NaCl, K+ and pH

perm

eabi

lity

to

wat

er is

affe

cted

by

AD

H

ADH-increases the permeability of the collecting ducts to water Juxtaglomerular apparatus near the afferent arteriole secrete renin when the BP drops; renin converts angiotensinogen to angiotensin II that increases BP in several waysAldosterone-causes distal tubules to reabsorb more NaCl and water thus increasing blood volume and pressureAtrial natriuretic factor lowers BP by opposing renin and aldosterone

Vampire bat

Harbor Seal