Chapter 44 Osmoregulation and Excretion Flashcards
What does osmoregulation control?
Controls solute concentrations and balances water gain and loss.
What does excretion do?
Rids the body of nitrogenous metabolites and other waste produces.
What is the body’s base product?
Nitrogenous metabolites (base product); dangerous to keep in body
What is the driving force behind the movement of solutes and movement?
The driving force is a concentration gradient of one or more solutes across the plasma membrane
What is osmosis?
The diffusion of water
What is osmolarity?
The solute concentration of a solution
What does osmolarity determine?
Determines the movement of water across a selectively permeable membrane
What happens if two solutions are issosmotic?
Water molecules will cross the membrane at equal rates in both directions
How does water diffuse in terms of solute concentration?
Moves from low solute concentration to high solute concentration
What is an isotonic solution?
Solute concentration is equal b/w 2 solutions
Does water move in an isotonic solution?
No net movement
What is a hypertonic/hyperosomotic solution?
A solution with a high solute concentration
What is hypotonic/hypoosmotic solution?
A solution with a low solute concentration
What are osmoconformers?
Some marine animals that are isoosmotic with their surroundings and don’t regulate their osmolarity
- same amount of solute outside and inside of animal
What are osmoregulators?
Animals that expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment
What is stenohaline?
Animals that cannot tolerate substantial changes in external osmolarity
Are marine invertebrates osmoconformers or osmoregulators?
Osmoconformers
Are marine vertebrates and some marine invertebrates osmoregulators or osmoconformers?
Osmoregulators
Marine bony fishes are what to seawater?
Hypoosmotic/hypotonic
How do marine bony fishes balance water loss?
By drinking large amounts of seawater and eliminating the salts through their gills and kidneys
How do freshwater animals balance their hypoosmotic environment?
By losing salts via diffusion and maintaining water balance by drinking almost no water
- also excretes large amounts of dilute urine
What is anhydroiosis?
The adaptation of an invertebrate that loses almost all their body water and surviving in a dormant state
How do land animals maintain water balance?
by eating moist food and producing water metabolically through cellular respiration
How do desert animals preserve water?
By having a nocturnal lifestyle; doing most things at night
How do most terrestrial animals prevent dehydration?
Via body coverings
Do osmoregulators use energy to maintain osmotic gradients?
Yes! In the form of ATP
What does the amount of energy for osmotic gradients depend on? (3)
- How different the animal’s osmolarity is from its surroundings
- How easily water and solutes move across the animal’s surface
- The work required to pump solutes across the membrane
What is transport epithelia?
Epithelial cells that are specialized for moving solutes in specific directions
How are transport epithelial arranged?
Arranged into a complex tubular networks
What is an example of transport epithelia?
Nasal glands of marine birds
What is the most significant waste of animals?
Nitrogenous breakdown products of proteins and nucleic acids
What happens to ammonia before excretion?
Ammonia is converted to less toxic compounds before excretion
What are the 3 forms of nitrogenous wastes?
- ammonia
- urea
- uric acid
What do animals that excrete nitrogenous waste as ammonia need?
Need access to lots of water; lots of water is loss
Is urea less toxic than ammonia?
Yes, it’s less toxic
Which uses less water, urea or ammonia?
Urea
In vertebrates, where is urea produced?
In the liver
Where is urea excreted?
In the kidneys
What do insects, land snals, and many reptiles usually excrete?
Uric acid
Which requires more energy to produce, urea or uric acid?
Uric acid
Is uric acid toxic?
No, relatively nontoxic
Does uric acid require water?
No it doesnt
What is the 4 functions of the excretory systems?
- filtration
- reabsorption
- secretion
- excretion
What is filtration?
Filtering of body fluids
What is reabsorption?
Reclaiming valuable solutes
What is secretion?
Adding nonessential solutes and wastes to the filtrate
What is excretion?
Processed filtrate containing nitrogenous waste is released from the body
What is filtrate?
Product of filtration
What is protonephridia?
A network of dead end tubules connected to external openings
What does the protonephridium do? (2)
- Excretes a dilute fluid
- Functions in osmoregulation
What does metanephridia consist of?
Consist of tubules that collect coelomic fluid in earthworms
What does metanephridia produce?
Produces dilute urine for excretion in earthworms
What is a flame bulb?
A cellular unit that caps the branches of protonephridium
What do malpighian tubules do? (2)
- They remove nitrogenous wastes from hemolymph in insects and other terrestrial arthropods
- Function in osmoregulation
What do insects produce as waste?
They produce uric acid in a dry waste form
What are the kidneys?
Excretory organs of vertebrates that function in both excretion and osmoregulation?
What does the vertebrate excretory systems also include?
Includes other ducts and other structures that carry urine from the tubules out of the kidney and out of the body
What consists of the nephron? (6)
Renal Corpuscle
- Glomerulus
- Borman’s capsule
Proximal tubule
Peritubular capillaries
Loop of Henle
What does the filtrate produced in Bowman’s capsule contain? (6)
Contains salt, glucose, amino acids, vitamins, nitrogenous wastes, and other small molecules
What happens in the proximal tubule?
Reabsorption of ions, water, and nutrients
What happens to molecules in the proximal tubule?
Molecules are transported actively and passively from the filtrate into the interstitial fluid and then capillaries
- Filtrate becomes more concentrated with excreted materials thru proximal tube
What do aquaporin proteins do?
Creates channels where water continues to be reabsorb in the descending loop of henle
What drives the movement in the loop of henle?
High osmolarity (high concentration of solutes)
What happens during the ascending loop of henle?
Filtrate becomes diluted because salt diffuses from the tubule into interstitial fluid
What the distal tubule do? (2)
- Regulates potassium and sodium concentration of body fluids
- controls movement of ions (hydrogen and bicarbonate(HCO3-)) for pH regulation
What does the collecting duct do?
Carries filtrate through the medulla to the renal pelvis
- location of where the most important tasks of reabsorption of solutes and water takes place
Urine is what to body fluids?
Urine is hyperosmotic/hypertonic to body fluids
What two primary solutes affects osmolarity?
Sodium (NaCl) and urea
What happens as the filtrate volume decreases in the proximal tubule?
Osmolarity doesn’t change
As the filtrate moves in the the descending limb of the loop of henle, what happens to solute?
Solute becomes more concentrated because water leaves the tubule
What does the countercurrent multiplier system involve?
It involves the loop of Henle that maintains a high salt concentration in the kidneys
Urine is what to the interstitial fluid of the inner medulla?
Urine is isosmotic to the interstitial fluid of the inner medulla
Urine is what to blood and the other interstitial flood in the body?
Urine is hyperosmotic/hypertonic to blood and other interstitial fluids elsewhere in the body
Difference b/w mammals in dry habitats vs fresh water habitats in terms of loop of henle
Dry habitats: Mammals have long loops of henle
Fresh water habitat: Mammals have short loops of henle
How do birds conserve water?
By excreting uric acid instead of urea
How do amphibians conserve water?
By reabsorbing water from the urinary bladder
What do the nervous and hormonal controls do? (2)
- Manages osmoregulatory functions of the mammalian kidney
- Contribute to homeostasis for blood pressure and blood volume
What does the antidiuretic hormone (ADH)/vasopressin do?
ADH is released into the blood stream when osmolarity is high.
- Reabsorbs water
What is the renin-angiotensin-aldosterone system?
A system apart of the complex feedback circuit that functions in homeostasis
Explain the steps of the renin-angiotensin-aldosterone system? (5)
- The enzyme renin is released by the juxtaglomerular apparatus (JGA) b/c of a drop in blood pressure near the glomerulus.
- When renin is released, this triggers the formation of the peptide angiotensin II.
- Angiotensin II increases blood pressure and decreases blood flow to the kidneys.
- The increase in blood pressure and drop of blood flow stimulates the hormone aldosterone.
- Aldosterone increases blood volume and pressure.
What does the hormone atrial natriuretic peptide (ANP) do?
This hormone opposes RAAS
What are the functions of ANP? 2
- Released as a response to an increase in blood volume and pressure
- Inhibits the release of renin
What do ADH AND RAAS both have a function in?
Both have a function in increasing water absorption
What does RAAS respond to but not ADH?
A decrease in blood volume
