Homeostasis

Physiological processes operate within limits -bodys tendency toward internal stability challenged by 1)metabolic needs and byproduces 2)external environment changes -maintained by the coordinated activities of bodily systems and organs

radiation-transfer of heat by electromagnetic radiation conduction-direct ranger of heat between objects touch cold/warm surface convection-transfer of heat via movement of gas/liquid (windy day) evaporation-energy needed to transfer grom liquid to gas

1_ warm-blooded vs cold-blooded Problem- cold-blooded animals achieve warm body temp 2) homeotherm vs poikotherm -homeotherms regulate their body temp around an elevated set point -poikilotherms conform to their environment problem- somve poik have stable temps, some home modulate their temps. Endotherm vs ectotherm- Endotherms rely on metabolic head (birs/mammals) Ectotherms rely on external sources of heat. (fish, amphibians, reptiles, arthropods.

Endotherms rely on the metabolic head (birds/mammals) Endotherms have a narrow range of temp. use most of their energy to maintain body temperature, etc. Ectotherms rely on external sources of heat. (fish, amphibians, reptiles, arthropods) tolerate wider ranges of temps than endo. Their activity is constrained by environmental temperature: endotherm is less affected.

gain lose heat from the external environment temperature regulation via behavioral 1)orientation to sun 2)color change 3)changes in shape and posture 4)shutting behavior 5)basking and shivering

the heat produced by metabolism 1)large quantities of food needed 2)behavior can reduce energy demands Heat lost by radiation, conduction, convection, evaporation -influenced by size and insulation -control blood flow to the surface and adjust hair/fur -sweating and panting, but losing water freezing adaptations countercurrent heat exchange can limit heat loss- cold blood is heated as it returns to core thermogensis- via shivering and fa metabolism

countercurrent heat exchange can limit heat loss- cold blood is heated as it returns to core thermogensis- via shivering and fa metabolism

by radiation, conduction, convection, evaporation -influenced by size and insulation -control blood flow to the surface and adjust hair/fur -sweating and panting, but losing water

temporary reduction in body temp during periods of inactivity slows metabolism Hummingbirds in the morning and night reduce heat Smaller endotherms only Hibernation- extended torpor that lasts several weeks.

Regulation of internal fluid and its composition, another form of homerostatis

fluids inside animals are isotonic with sea water, therefore no osmotic gradient exists -marine invertebrates -cartilaginous fishes

-most vertebrates must regulat blood osmoliarty to achieve homeostasis -water loss from respiration, evaporation and excretion replaced by drinking, food, and metabolic water Humans get water by drinking Rodendts metabolic water

ammonia is a toxic byproduct of protein oxidation direct elimination-immediate removal via gills or dilute urin (fish) Urea-less toxic than ammonia can be diluted, source of water loss (urine) fros, monkey us Uric acid- crystal can be exerted without water, energetically expensive eg) birds lizzards

goal-removal of harmful byproducts a)protonephridia with flame cells (flatworms) b)nephridium (annelids, mollusks) c)Malpighian tubules (insects) d) kidneys (vertebrates)

water tends to enter the body from the environment solutes tends to leave the body and enter environment excrete large volumes of dilute urine

water tends to leave the body and enter environment solute tend to enter water drink large amounts of water and produce little urine

osmoconformers-blood isotonic with water

-an organ of water regulation and nitrogenous waste removal 1) Blood enters glomerulus(bowman’s capsule) -acts as filter that removes water and small molecules(not blood cells or protein) from blood -filtrate continues to the proximal convoluted tubule 2)Proximal convoluted tubules - 2/3 of filrate volume and all its glucose, amino acids, and vitamins are reabsorbs via active tranporation 3)loop of henie - Descending lim permeable only to water 4)distal convoluted tubule -ascending lim impermeable to water and solutes, actively transports NaCl to surrounding 5)collecting ducts -fluid moves to collecting ducts solute outside the collecting ducts cause more water to leave urine 6)uterer to bladder

1) Blood enters glomerulus(bowman’s capsule) -acts as filter that removes water and small molecules(not blood cells or protein) from blood

Proximal convoluted tubules - 2/3 of filrate volume and all its glucose, amino acids, and vitamins are reabsorbs via active tranporation

loop of henie - Descending lim permeable only to water

4)distal convoluted tubule -ascending lim impermeable to water and solutes, actively transports NaCl to surrounding

5)collecting ducts -fluid moves to collecting ducts solute outside the collecting ducts cause more water to leave urine 6)uterer to bladder

-the final concentration of urine depends on the permeability of the walls of the duct and the collecting duct -permeability is controlled by antidiuretic hormone (ADH) - when osmotic pressure is low eg(dehydration) ADH is released and increases the permeability of ducts -more water is reabsorbed urine becomes more concentrated, thirst stimulated - Absence of ADH, collecting ducts remain impermeable, dilute urine