Homeostasis + excretory systems Flashcards
In our bodies, the primary nitrogen-containing compound excreted by our kidneys is…
urea
Most of our nitrogen-containing waste products are a result of __________.
protein metabolism
excretory system unit of annelids (earthworms)
Protonephyridia
-which form a network of dead-end tubules through which interstitial fluid is filtered.
-smallest branches capped by flame bulb
-excrete a dilute fluid
excretory system unit of insects + other terrestrial arthropods
Malpighian tubules
-which remove nitrogenous wastes and also function in osmoregulation.
-blind tubes arising from gut
-can conserve water very effectively
excretory system unit of vertebrates
kidney
-functions in both osmoregulation and excretion.
-nephrons are function units of vertebrate kidney
-produce urine hypertonic to body fluids ( conserves water )
Which of the following substances is generally filtered from the blood by the kidneys?
Glucose
Water
Sodium
Urea
All of the above
loop of Henle function
loop of Henle is specialized for water resorption
-critical for desert animals
What is the tube that carries urine from the kidneys to the urinary bladder in a mammal?
Ureter
The bed of capillaries in a vertebrate kidney where water, urea, and salts are filtered out of the blood is the __________.
Glomerulus
Which of the following have an excretory system that functions without a filtration step?
Marine fishes
Insects
Earthworms
Freshwater fishes
Flatworms
Insects
Osmoconformers
– Internal solute concentrations match environmental
solute concentrations
– Cells and body fluids isotonic to environment
Osmoregulators
– Actively control overall concentration of solutes in
cells and body fluids
– Maintain internal concentration different than
external concentration
Ionic regulation
– active control of the
concentration of individual solutes in body
fluids
Organisms can be a sodium conformer, but a calcium regulator
Ionic conformers
- maintain same solute
profile as environment
Organisms can be a sodium conformer, but a calcium regulator
Osmoregulation in freshwater fish
+gain water and ions in food
+uptake salt ions by gills
+osmotic gain through gills and body surface
-excretion of salt ions and large amounts of water in dilute urine from kidneys
Osmoregulation in a marine fish
+gain of water and ions in food
+gain of water and salt ions from drinking seawater
-excretion of salt ions through gills
-osmotic water loss through gills
-excretion of salt ions and small amounts of water in scanty urine from kidneys
Marine Bony Fish
- Marine bony fish are hypotonic to
environment, so they lose water across gills - Regain lost water by drinking seawater
- Eliminate excess salts with chloride cells in
gills
Freshwater Bony Fish
- Body fluids and cells are hypertonic to the
environment, and so gain water across gills - Produce large quantities of dilute urine
- Beta chloride cells in gills take up Cl- from
water
Key functions of most excretory
systems:
– Filtration
– Reabsorption
– Secretion
– Excretion
Filtration:
Filtering of body fluids
Reabsorption:
Recovering valuable
solutes
Secretion:
Adding nonessential
solutes and wastes to the filtrate
Excretion:
Releasing filtrate
(containing nitrogenous wastes) from
the body
Metanephridia
– open-ended tubules that collect coelomic fluid and
produce dilute urine
* Function in excretion and osmoregulation
* Found in Mollusca and Annelida
– Each segment of an earthworm has a pair of metanephridia.
