ADH.html: 44_16KidneyHormoneControl_ADH.jpg
Antidiuretic hormone (ADH) is produced in the hypothalamus and stored in the
posterior pituitary gland.
When blood osmolarity rises, ADH is released and increases water reabsorption
in the distal tubule and collecting duct and reduces urine volume.
Aldosterone.html: 44_16KidneyHormoneControl_Aldosterone.jpg
Aldosterone is produced in the adrenal cortex to maintain a high blood volume and pressure
by promoting reabsorption of NaCl and water in the
distal tubules
of the kidney.
albatross.html: 44_07BirdSaltExcretGlands.jpg
1)
Secretory cells actively transport salt from the blood into the secretory tubules by
countercurrent exchange.
The
1)
secretory tubules make up the
1)
salt glands, which empty via a duct into the
nostrils.
albatrosses.html: 44_1Albatrosses_UP.jpg
Salvin's albatrosses (Diomeda cauta salvini), birds that can drink seawater with no ill effects.
excretory.html: 44_09ExcretorySystFunct.jpg
Key functions of excretory systems include:
excretory_system.html: 44_13MammalExcretSystA.jpg
The excretory system of mammals centers on the pair of kidneys.
Urine drains from each kidney through the ureter into the urinary bladder.
kidney.html: 44_13MammalExcretSystB.jpg
Blood enters the kidney from the outer renal cortex and filters through the inner renal medulla
of functional units called nephrons
.
Urine is then passed from the renal pelvis to the ureter.
malpighian.html: 44_12MalpighianTubules_L.jpg
Malpighian tubules of insects.
Malpighian tubules are outpocketings of the digestive tract that are immersed in hemolymph (circulatory fluid that contains the transport molecule heme).
The tubules produce nitrogenous wastes in the form of nearly dry uric acid.
metanephridia.html: 44_11Metanephridia_L.jpg
Metanephridia of an earthworm.
Each segment of the worm contains a pair of metanephridia, which collect coelomic fluid from the adjacent segment.
Fluid enters the nephrostome and passes through a tubule;
the filtrate is released to the outside through the nephridiopore.
nephron.html: 44_13MammalExcretSystC.jpg
The nephron consists of a single long tubule that ends in a swollen Bowman's capsule surrounded by
a ball of capillaries called the glomerulus.
Filtration occurs as blood pressure forces fluid from the blood in the glomerulus into the Bowman's capsule.
Blood cells and large molecules such as proteins stay are too large to pass through capillary membranes and stay in the blood stream.
The filtrate
consists of water and small solutes such as
salts, glucose, amino acids, vitamins, and urea.
nephron_function.html: 44_13MammalExcretSystD.jpg
The filtrate is passed through a series of tubules
to produce urine.
nephron_urine.html: 44_14Nephron_L.jpg
osmoregulation.html: 44_08NitrogenousWastes.jpg
Nitrogenous wastes are the nitrogen–containing breakdown products of
proteins and nucleic acids.
The main nitrogen product of metabolism is ammonia (NH3), which is toxic.
Some animals excrete ammonia directly, but many species first convert
the ammonia to less toxic compounds that require energy to produce.
protonephridia.html: 44_10Protonephridia_L.jpg
Protonephridia: the flame–bulb system of a planarian.
A network of tubules end in a flame bulb, where beating cilia filter body fluid through the
tubules and out through nephridiopores.
urine.html: 44_15UrineConcentration_1_L.jpg