excretory system chapter 36 Flashcards
Osmoregulation
Balancing the levels of water and salts in the body
Excretion
The process by which metabolic wastes are removed from the body by the osmoregulatory system of an animal
Within animals, the breakdown of amino acids and nucleic acids results in
amonia
amonia
a compound of nitrogen and hydrogen with the formula NH₃, highly soluble
High solubility
permits it to be excreted directly by many aquatic animals
Terrestrial animals must convert ammonia to, why?
urea or uric acid (part of urine) because ammonia is very toxic.
Urea
Can be excreted in a moderately concentrated solution
Produced by mammals, sharks, and adult amphibians
Allows body water to be conserved
Requires more energy than ammonia
Uric acid
Requires much less water per unit of nitrogen excreted
Synthesized by a long, complex series of enzymatic reactions
Produced in reptiles, birds, and insects
Requires more energy to produce than urea
Allows invasion of drier habitats far from standing water
Advantageous for shelled embryos
Nitrogenous wastes are stored in shell until hatching
gout
Buildup in blood and precipitation around joints produces in humans
Urine
is a liquid that contains metabolic wastes, excreted salts and water.
It’s 95% water.?
Over a lifetime, the kidneys will clean approximately one million gallons of water into pee.
Pee is sterile.?
In the bladder, that is. But as soon as it leaves your body, it can pick up bacteria from the urethra and air.
Excretory System!
Blood plasma hypotonic to sea water
Passively lose water through gills
Must constantly drink seawater to compensate
Excess salt ions actively transported back into seawater through the gills
Marine environment
High in dissolved salts
Hypertonic to blood plasma of bony fishes
Tends to promote the osmotic loss of water
The gain of ions by drinking water
Freshwater bony fishes, Freshwater environment
Tends to promote a gain of water by osmosis, and
A loss of ions as excess water is excreted
Freshwater bony fishes, Excretory system
Blood plasma hypertonic to fresh water
Passively gain water through gills
Eliminate excess water through copious hypotonic urine
Blood nearly isotonic to seawater!
Same concentration of salts/sugars/nutrients/waste etc
Cartilaginous fishes
The largest known cartilaginous fish ever to have lived isMegalodon(about 70 feet long and 50-100 tons). Other large cartilaginous fish include the manta ray (about 30 feet long) and the basking shark (about 40 feet long and 19 tons).
Blood contains enough urea to
match the tonicity of sea water.
Special cells in the rectal gland of these fish excrete
whatever excess salt does enter the system.
Osmoregulation by Terrestrial Vertebrates
Terrestrial animals lose water through excretion and respiration.
Must drink water to make up for loss
urine is the most… (kangaroo rat)
hypertonic known among animals
fecal palletes are (kangaroo rat)
dry
kindneys of marine mammals and ea birds, vertbrates
their kidneys are good at conserving water.
Some have become secondarily adapted to living in or near the sea.
Some have specialized salt glands that function to actively transport salt from the blood to the external environment.
In sea birds, salt-excreting glands are near
the eyes
In sea turtles, the salt gland is a
modified tear gland.
These glands are regulated by the nervous system.
Human kidneys
Bean-shaped, reddish-brown organs, about the size of a fist
Located on each side of vertebral column, just below the diaphragm
kidneys are connected to!
a ureter
Ureters
conduct urine from the kidneys to the urinary bladder.
Urinary bladder
Stores urine
Urine voided through the single urethra
Kidneys
Composed of three major parts
`Renal cortex Outer region Granular appearance `Renal medulla 6–10 cone-shaped renal pyramids `Renal pelvis Hollow-chambered innermost part of the kidney
Nephrons
Each kidney is composed of over 1 million tiny tubular nephrons that produce urine.
Each nephron is made of several parts
Glomerular capsule (Bowman’s capsule) Glomerulus Proximal convoluted tubule Loop of the nephron (loop of Henle) Distal convoluted tubule Collecting duct
The kidneys have 4 homeostatic functions
Excretion of metabolic wastes
Maintenance of water-salt balance
Maintenance of acid-base balance (pH balance)
Secretion of hormones
Erythropoietin
to stimulate red blood cell production
pH is regulated by
The bicarbonate buffer system
pH adjusted by either
The reabsorption of the bicarbonate ions, or
The secretion of hydrogen ions
