Homeostasis: Osmotic Regulation, Excretion, and Temperature Regulation

Salt-water fish

cartilagenous bones

freshwater fish

calcified bones

Osmoregulation

physiological challenge of Movement of jawed fishes to brackish water

higher

Body salt concentration must be kept ___ than the water they are in

Osmotically

Water enters their bodies

diffusion

salt is lost by

Hyperosmotic regulation

Water that enters the body by osmosis is pumped out by the kidney, which can form very dilute urine by reabsorbing sodium chloride

water blood

Salt-absorbing cells in the gills transport salt ions (Na+ , Cl- ) from ____ to _____

Hypoosmotic regulation

Marine bony fish drinks seawater, absorbed by the intestine, and NaCl is carried by the blood to the gills, where salt secreting cells transport it back to the sea

feces; kidneys

Ions remaining in the intestinal residue (Mg2+, SO4 2- , Ca2+) are voided with ____ or excreted by ____

urea, trimethylamine oxide

For Sharks and rays, Blood accumulates large amounts of ____ and ____ ____ (TMAO), raising blood osmolarity to equal or slightly exceed seawater

Terrestrial animals

lose water by evaporation from respiratory and body surfaces, excretion in urine, and elimination in feces

metabolic water

formed in cells by oxidation of metabolic fuel molecules, such as carbohydrates and fats; how water loss is replaced

ammonia

The primary end product of protein breakdown; highly toxic

diffusion across their gills

how fish excrete ammonia

uric acid

What terrestrial insects, nonavian reptiles, and birds convert ammonia to ; enables them to excrete a semisolid urine with little water loss

salt gland

Marine birds and turtles method of secreting excess salt; located above the eye

nares

birds way of secreting salt

Nephridium

a tubule open to the exterior which acts as an organ of excretion or osmoregulation

flame cell system

protonephridium; a closed system for acoelomates

metanephridium

open, or "true," nephridium; more advanced; found in several coelomate phyla such as annelids & molluscs

nephrostome

The tubule is open at both ends, allowing fluid to be swept into the tubule through a ciliated funnel-like opening

blood vessels ; salts sugars amino acids

a metanephridium is surrounded by a network of that assists in reabsorption from the tubular fluid of water and valuable materials such as __ , ___, ___ ___

Archinephros

segmentally arranged tubules, opened at one end into the coelom by a nephrostome and at the other end into a common archinephric duct

pronephros, mesonephros, and metanephros

During embryonic development of amniote vertebrates, kidneys develop in three successive stages:

Nephron

• basic functional unit

filtration, reabsorption, and secretion

Urine is formed by three physiological processes:

Countercurrent multiplication

refers to the opposite directions of fluid movement in the two limbs of the loop of Henle ; increasing osmotic concentration in the medulla surrounding the loops of Henle and the collecting ducts resulting from ion exchange between the two limbs of the loop

ectotherms

Cold blooded; Poikilothermic

endotherms

warm-blooded; homeothermic

ectothermal behavior

Behavioral adjustments, Metabolic adjustments - temperature compensation

endothermal temperture

mammals (36-38°C), birds (40-42°C)

smaller dessert animals

fossorial and/or nocturnal

large dessert ungulates

insulated; reflective coat. concentrated feces, concentrated fat in hump, succulent food

Decreased conductance, Increased heat production

Adaptations for Cold Environments

Decreased conductance

reduction of heat loss by increasing the effectiveness of the insulation • countercurrent heat exchange

Increased heat production

Augmented muscular activity (exercise or shivering) • Nonshivering thermogenesis - increased oxidation of foods, especially from stores of brown fat

Daily Torpor, Hibernation

Adaptative Hypothermia in Birds & Mammals

Daily torpor

an adaptive hypothermia that provides enormous saving of energy to small endotherms that are never more than a few hours away from starvation at normal body temperatures

Hibernation

a prolonged and controlled state of dormancy

True hibernation

entry is gradual; after a series of "test drops" (body temp decreases a few degrees and then returns to normal) the animal cools to within a degree or less of the ambient temperature; metabolism decreases to a fraction of normal

Prolonged sleep

little or no decrease in body temperature