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1
Q

Physiological systems of animals operate in what type of environment?

A

A fluid environment.

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2
Q

What range of limits must relative concentrations of water and solutes be maintained within?

A

Fairly narrow limits.

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3
Q

What does osmoregulation control and balance?

A

Osmoregulation controls solute concentrations and balances water gain and loss

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4
Q

Define desiccate.

A

To remove the moisture from something or cause something to become completely dry.

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5
Q

What environment and challenges do desert and marine animals face?

A

They live in desiccating environments that can quickly deplete body water.

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6
Q

How do freshwater animals regulate to survive in their environment?

A

They survive by conserving solutes and absorbing salts from their surroundings.

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7
Q

What is the driving force for the movement of water and solutes?

A

A concentration gradient of one or more solute across the plasma membranes.

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8
Q

How does water enter and leave cells?

A

Osmosis.

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9
Q

What is osmolarity and what does it determine?

A

Osmolarity, the solute concentration of a solution, determines the movement of water across a selectively permeable membrane.

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10
Q

What happens if two solutions have the same osmolarity?

A

They are said to be isoosmotic and water molecules will cross the membrane at equal rates in both directions.

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11
Q

What happens if two solutions differ in osmolarity?

A

The net flow of water will be from the hypoosmotic (less concentrated) solution to the hyperosmotic (more concentrated) solution.

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12
Q

Which has a higher free H2O concentration: hyperosmotic or hypoosmotic?

A

Hypoosmotic.

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13
Q

What are the two ways animals can maintain water balance?

A

Osmoconformers and osmoregulators.

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14
Q

What are osmoconformers?

A

Osmoconformers are isoosmotic with their surroundings and do not regulate their osmolarity.

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15
Q

What do osmoregulators do?

A

Osmoregulators expand energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment.

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16
Q

What does it mean for an animal to be stenohaline?

A

They cannot tolerate substantial changes in external osmolarity.

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17
Q

What does it mean for an animal to be euryhaline?

A

They can survive large fluctuations in external osmolarity.

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18
Q

Are most marine invertebrates osmoconformers or osmoregulators?

A

Osmoconformers.

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19
Q

Are most marine vertebrates osmoconformers or osmoregulators?

A

Osmoregulators.

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20
Q

Marine bony fishes are hypoosmotic to seawater. How do they regulate their salt and water?

A

Water moves from their bodies into the seawater. They balance water loss by drinking large amounts of seawater and eliminating the ingested salts through their gills and kidneys

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21
Q

What is osmoregulation frequently coupled with?

A

The elimination of nitrogenous waste products.

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22
Q

Sharks have a high concentration of urea in their bodies. What protects them from its denaturing effect?

A

Trimethylamine oxide (TMAO).

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23
Q

How do sharks osmoregulate?

A

Sharks take in water by osmosis and in their food. Excess water is disposed of in urine. The urine also removes some of the salt that diffuses into the shark’s body

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24
Q

How do freshwater animals osmoregulate?

A

Freshwater animals constantly take in water by osmosis from their hypoosmotic environment. They lose salts by diffusion and maintain water balance by drinking almost no water and excreting large amounts of diluted urine. Salts lost by diffusion are replaced in foods and by uptake across the gills.

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25
What does it mean for an animal to have anhydrobiosis
Some aquatic invertebrates in temporary ponds lose almost all their body water and survive in a dormant state
26
What adaptation do most terrestrial animals have to help prevent dehydration?
Body coverings.
27
How do desert animals adapt to save water?
Simple anatomical features and behaviors, such as a nocturnal lifestyle
28
What are two ways that land animals maintain water balance?
Eating moist food and producing water metabolically through cellular respiration.
29
Do osmoregulators need to expend or conserve energy to maintain osmotic gradients?
Expend energy.
30
The amount of energy osmoregulators must expend depends on which three things?
(1) How different the animal's osmolarity is from its surroundings. (2) How easily water and solutes move across the animal's surface. (3) The work required to pump solutes across the membrane.
31
What are transport epithelia?
Epithelial cells specialized for controlled movement of solutes in specific directions, typically arranged into complex tubular networks.
32
What is an example of transport epithelia?
The nasal glands of marine birds, which remove excess NaCl from the blood.
33
The type and quantity of an animal's waste products may greatly affect what?
Its water balance.
34
Among the most significant wastes are what?
Nitrogenous breakdown products of proteins and nucleic acids.
35
Animals excrete nitrogenous wastes in three different forms. What are they?
Ammonia, urea, and uric acid.
36
How do ammonia, urea, and uric acid differ?
They differ in toxicity and the energy costs of producing them. Habitat could relate to the type of nitrogenous waste produced.
37
Which waste product requires access to lots of water?
Ammonia
38
In many invertebrates, ammonia release occurs where?
Across the whole body surface.
39
Which waste needs no energy to produce and is highly toxic?
Ammonia.
40
Which waste do most terrestrial mammals and marine species excrete?
Urea.
41
Where is urea produced?
In the liver.
42
Where does urea go after it leaves the liver?
The circulatory system carries urea to the kidneys where it is excreted.
43
Which waste product needs moderate energy to produce and is low in toxicity?
Urea
44
Which animals produce uric acid?
Insects, land snails, most reptiles, and birds.
45
Where can uric acid be found in humans?
It is produced as a metabolic byproduct such as gout, a painful joint inflammation common among men.
46
Which waste product needs high energy and is very low in toxicity?
Uric acid.
47
How do most excretory systems produce urine?
By refining a filtrate derived from body fluids.
48
What are the four key functions of most excretory systems?
Filtration, reabsorption, secretion, and excretion.
49
What is reabsorption?
Reclaiming valuable solutes.
50
What is secretion?
Adding nonessential solutes and wastes to the filtrate.
51
What is excretion?
Processed filtrate containing nitrogenous wastes is released from the body.
52
What is a protonephridium?
A network of dead-end tubules that branch throughout the body.
53
What is a flame bulb?
The smallest branches of network are capped by a cellular unit called a flame bulb.
54
What do protonephridium tubules excrete?
A dilute fluid and function in osmoregulation.
55
What do metanephridia consist of?
Tubules that collect coelomic fluid and produce dilute urine for excretion.
56
What are malpighian tubules in insects and other terrestrial arthropods for?
Removing nitrogenous wastes from hemolymph and function in osmoregulation.
57
What are kidneys and what is their function?
Kidneys are the excretory organs of vertebrates. They function in both excretion and osmoregulation.
58
What are kidneys made of?
Numerous highly organized tubules, ducts, and other structures that carry urine from the tubules out of the kidney and out of the body.
59
What is contained in filtrates produced in Bowman's Capsule?
Salts, glucose, amino acids, vitamins, nitrogenous wastes, and other small molecules.
60
Where does reabsorption of ions, water, and nutrients take place?
In the proximal tubule.
61
Follow the filtrate through the proximal tubule.
Molecules are transported actively and passively from the filtrate into the interstitial fluid and then capillaries. As the filtrate passes through the proximal tubule, materials to be excreted become concentrated. Some toxic materials and drugs are actively secreted into the filtrate.
62
Reabsorption of water continues through channels formed by what?
Aquaporin proteins.
63
What is the movement of filtrates in the interstitial fluid driven by?
High osmolarity, which is hyperosmotic to the filtrate, causing the filtrate to become increasingly concentrated.
64
Where does reabsorption of water occur?
Descending Limb of the Loop of Henle.
65
What can diffuse in the ascending limb of the loop of Henle?
Salt but not water is able to diffuse from the tubule into the interstitial fluid, causing the filtrate to become increasingly diluted
66
What does the distal tubule regulate?
K+ and NaCl concentrations of body fluids.
67
What does the controlled movement of ions H+ and HCO3- contribute to?
pH regulation.
68
What does the collecting duct do?
Carries filtrate through the medulla to the renal pelvis.
69
What is the most important task of the collecting duct?
Reabsorption of solutes and water
70
Is urine hyper- or hypoosmotic to body fluids?
Hyperosmotic
71
What is the mammalian's key terrestrial adaptation?
The kidney's ability to conserve water.
72
Why can hyperosmotic urine be produced?
Considerable energy is expended to transport solutes against concentration gradients.
73
Which two solutes primarily affect osmolarity?
NaCl and urea.
74
What happens to filtrate volume in the proximal tubule?
Filtrate volume decreases as water and salts are reabsorbed, but osmolarity remains the same.
75
What happens as filtrate flows from the proximal tubule to the descending loop?
Solutes become more concentrated due to water leaving the tubule by osmosis
76
What happens as the filtrate flows from the descending to the ascending loop?
NaCl diffusing from the ascending loop maintains a high osmolarity in the interstitial fluid of the renal medulla. Energy is expended to actively transport NaCl from the filtrate in the upper part of the ascending loop.
77
What does the countercurrent multiplier system involving the loop of Henle do?
Maintains a high salt concentration in the kidney. This system allows the vasa recta to supply the kidney with nutrients without the osmolarity gradient.
78
What happens to the filtrate in the collecting duct after it leaves the loop of Henle?
Osmosis extracts water from the filtrate as it passes from the cortex to the medulla and encounters interstitial fluid of increasing osmolarity.
79
Urine produced is [1]osmotic to the interstitial fluid of the [2], but [3]osmotic to [4] and interstitial fluids elsewhere in the body.
1. iso 2. inner medulla 3. hyper 4. blood
80
What equips the kidneys of different vertebrates for osmoregulation in various habitats?
Variations in nephron structure and function.
81
What is the key to water conservation in terrestrial animals?
Juxtamedullary nephron.
82
Mammals that inhabit dry environments have [1] loops of Henle, while those in fresh water have relatively [2] loops
1. Long 2. Short
83
The vampire bat can alternate rapidly between producing what types of urine?
Large amounts of diluted urine and small amounts of very hyperosmotic urine.
84
Birds have [1] loops of Henle than mammals do, but conserve water by excreting [2] instead of [3].
1. Shorter 2. uric acid 3. urea
85
Reptiles have only [1] but reabsorb water from wastes in the [2] and excrete nitrogenous waste as [3].
1. cortical nephrons 2. cloaca 3. uric acid
86
Where do freshwater fishes conserve salts?
In their distal tubules, while excreting large volumes of very dilute urine.
87
How do amphibians conserve water on land?
By reabsorbing water from the urinary bladder.
88
How do marine bony fishes differ from those of freshwater fishes in terms of: 1. nephrons 2. kidneys 3. filtration 4. excretion 5. osmoregulation
1. Fewer and smaller nephrons that lack a distal tubule. 2. Their kidneys have small or no glomeruli. 3. Filtration rates are low 4. Very little urine is excreted 5. Osmoregulation relies on specialized chloride cells in the gills
89
Mammals control the [1] and [2] in response to changes in salt intake and water availability.
1. volume 2. osmolarity of urine
90
A combination of [1] and [2] controls manages the osmoregulatory functions of the mammalian kidney. These controls contribute to [3] for blood [4] and blood [5]
1/2. nervous 2/1. hormonal 3. homeostasis 4/5. pressure 5/4. volume
91
What does ADH stand for? What is another name for it?
Antidiuretic hormone, aka vasopressin
92
What do ADH molecules do? What does it initiate?
They are released from the posterior pituitary and bind to and activate membrane receptors on collecting duct cells. This initiates a signal cascade leading to insertion of aquaporin proteins into the membrane lining the collecting duct.
93
The increase in water recapture [1] urine volume.
1. reduces
94
What do osmoreceptor cells in the hypothalamus do?
Monitor blood osmolarity and regulate the release of ADH from the posterior pituitary.
95
What happens to ADH when osmolarity rises above or falls below a set point?
Rises above: ADH release into the bloodstream increases Falls below: Vauses a reduction in ADH secretion
96
Alcohol is a diuretic. What does this mean?
It inhibits the release of ADH.
97
What can mutations in ADH production cause?
Severe dehydration, possibly resulting in diabetes insipidus.
98
What does RAAS stand for?
Renin-Angiotensin-Aldosterone System.
99
What is the RAAS a part of?
A complex feedback circuit that functions in homeostasis.
100
What does a drop in blood pressure near the glomerulus do?
It causes the juxtaglomerular apparatus (JGA) to release the enzyme renin.
101
What does renin do?
It triggers the formation of peptide angiotensin II.
102
What does angiotensin II do?
It raises blood pressure, decreases blood flow to the kidneys, and stimulates the release of the hormone aldosterone.
103
What does aldosterone do?
It increases blood volume and pressure.
104
ADH and RAAS both increase water reabsorption, but only one will respond to a decrease in blood volume. Which one?
RAAS.
105
Which hormone opposes the RAAS and where is it released from?
Atrial natriuretic peptide (ANP) is released by the atria of the heart.
106
Why is ANP released and what does it inhibit?
ANP is released in response to an increase in blood volume and pressure and inhibits the release of renin

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