Chapter 40

Question 1

Osmoregulation

Answer 1

Control of water and solutes within cells (homeostasis)

The process by which an organism regulates the water balance in its body and maintains the homeostasis of the body

Question 2

What animals do not osmoregulate?

Answer 2

Marine invertabrates

Question 3

Osmoconformers

Answer 3

Match the environment in terms of concentration of solutes equal and outside the cell

Ex. marine invertabrates

Question 4

Diffusion

Answer 4

movement of substances from regions of higher concentration to regions of lower concentration, along concentration gradients

Question 5

Osmosis

Answer 5

Diffusion of water

Question 6

Osmoconformers

Answer 6

Marine invertebrates would not osmoregulate because seawater is s fairly constant
osmotically & matches solute concentrations within these animals

Question 7

Osmoregulators

Answer 7

Actively regulate osmolarity inside bodies to achieve homeostasis

Most marine vertebrates are osmoregulators because their tissues are hypotonic to salt water

They must drink large amount of water to replace loss of water which also brings more solutes

Question 8

Hyperosmotic

Answer 8

Solution inside cells contains
fewer solutes than seawater- lose water by
osmosis & gain solutes by diffusion

Seawater is hyperosmotic

Question 9

Osmotic stress of freshwater fish

Answer 9

Tissues of freshwater fish are hypertonic to water
– Solution in cells contains more solutes than outside
– Cells gain water through osmosis & lose solutes by diffusion

Question 11

How do land animals lose water and replace it

Answer 11

1. Evaporation
2. Produce urine and sweat

Replace it by drinking, ingestion in food, metabolic pathways

Question 12

Where does osmoregulation occur in land-dwelling vertebrates

Answer 12

Through the kidney (responsible for water and solute balance & excretion of nitrogenous waste)

Question 13

Pathway of urine

Answer 13

1. Formed in kidney
2. Transported through ureter to bladder
3. Urine transported out of body from bladder through urethra

Question 14

Nephrons

Answer 14

basic unit of kidney function responsible for water & solute balance

located in outer region of kidney
(cortex); inner region is the medulla

Question 15

Structure of the nephron

Answer 15

1. Renal corpuscle
2. Proximal tubule
3. Loop of Henle
4. Distal tubule
5. Collecting duct

Question 16

Renal corpuscle

Answer 16

filters blood, forming a “pre-urine”
consisting of ions, nutrients, wastes & water

Question 17

Proximal tubule

Answer 17

epithelial cells reabsorb nutrients,
vitamins, valuable ions & water

Question 18

Loop of Henle-

Answer 18

establishes strong osmotic gradient
in tissues outside the loop & osmolarity increases as loop descends

Question 19

Distal tubule

Answer 19

ions & water are reabsorbed
(under control of hormones)

Question 20

Collecting duct-

Answer 20

tube through which the final filtrate
(urine) leaves the nephron (altered by hormones)

Question 21

Renal Corpuscle anatomy

Answer 21

Glomerulus: : cluster of capillaries that bring blood to nephron from renal artery
Bowman’s capsule: region of nephron that
surrounds glomerulus

Question 22

Function of renal corpsucle

Answer 22

filtration device water & solutes forced
out of blood through pores
in glomerulus resulting in
formation of filtrate

Question 23

What occurs in proximal tubule

Answer 23

Active transport occurs of selected molecules out of filtrate valuable solutes & water are reabsorbed & returned to body.

Question 24

Three regions of Loop of Henle

Answer 24

1. Descending limb
2. Thin ascending limb
3. Thick ascending limb

Question 25

Descending limb

Answer 25

highly permeable to water (aquaporins) but impermeable to solutes Water leaves descending limb to maintain osmotic pressure

Question 26

Ascending limb

Answer 26

- Highly permeable to NA+ and Cl- - moderately permeable to urea - impermeable to water Salt leaves ascending limb to maintain osmotic pressure

Question 27

Distal tube process

Answer 27

The filtrate contains mainly urea and other waste products when it gets to distal tube and it empties filtrate into collecting dust that leads to ureter

Question 28

Antidiuretic hormone

Answer 28

When dehydrated the brain released ADH Triggers insertion of aquaporins in collecting duct more permeable to water & large amounts of water reabsorbed

Question 29

Types of nitrogenous wastes each terrestrial insects, freshwater fishes, and reptiles excrete

Answer 29

Terrestrial insects − uric acid Freshwater fishes − ammonia Reptiles − uric acid Marine fishes - urea

Question 30

Why must marine bony fishes drink large amounts of seawater?

Answer 30

Marine bony fishes are osmoregulators living in a hyperosmotic environment. They must compensate from excessive water loss due to hyperosmotic environment

Question 31

Characteristics of osmoregulating fish

Answer 31

1. Osmoregulating marine fish need to expend energy to excrete NaCl due to drinking large amounts of seawater 2. Osmoregulating marine fish need to drink large amounts of seawater. 3. Osmoregulating marine fish do not need to make special proteins to protect their cells from high urea concentrations in their tissues.

Question 32

Characteristics of osmoconformers

Answer 32

1. Do not lose water to their environment 2. Do not absorb as much NaCl from drinking 3. Must expend energy to make proteins that protect their cells from the toxic effects of maintaining high urea concentration in their tissues

Question 33

A mutation that results in the inability of a terrestrial insect to close the spiracles would likely be most disadvantageous in what environment?

Answer 33

Desert because insects would need to temporarily close spiracles to reduce water loss

Question 34

What is the function of the Loop of Henle in mammalian kidneys?

Answer 34

To create the kidney’s osmotic gradient that permits the reabsorption of water and various solutes

Question 35

What is the function of antidiuretic hormone, or ADH?

Answer 35

To signal the insertion of aquaporins in the collecting duct, promoting the reabsorption of water, resulting in concentrated urine

Question 36

Which type of nitrogenous waste would you expect to be produced by embryos inside eggs laid on land?

Answer 36

Uric acid

Question 37

Biologists have been able to produce mice that lack functioning genes for aquaporins. How would the urine of these mice compare with that of mice with normal aquaporins?

Answer 37

Without aquaporins in the collecting duct, water cannot be reabsorbed, which would result in increased urine volume and decreased urine osmolarity.

Question 38

In which environment are you most likely to find animals that employ uric acid as their primary form of nitrogenous waste?

Answer 38

Desert

Question 39

Why is uric acid advantageous for nitrogenous waste excretion in insects?

Answer 39

Due to its water insolubility, where its elimination does not involve much water loss

Question 40

The movement of substances from the blood into the proximal tubule is known as

Answer 40

Secretion

Question 41

How is glucose removed from filtrate in the Loop of Henle

Answer 41

Active transport

Question 42

What is the inner and outer part of the kidney

Answer 42

The inner part is the medulla, and the outer part is the cortex

Question 43

What is the driving force for the filtration of blood by the renal corpuscle?

Answer 43

Higher pressure in glomerular capillaries than in the surrounding Bowman's capsule.

Question 44

Which regions of the nephron function independently of hormonal control for the most part?

Answer 44

Renal corpuscle, proximal tubule, and loop of Henle.

Question 45

Which waste is excreted by bony fishes, by mammals, and by insects?

Answer 45

Bony fishes - ammonia Mammals - urea Insects - uric acid

Question 46

Are bony fishes osmoregulators or osmoconformers

Answer 46

Osmoregulatory since they are marine invertebrates

Question 47

Biologists have been able to produce mice that lack functioning genes for aquaporins. How would the urine of these mice compare to that of mice with normal aquaporins?

Answer 47

Higher volume and lower osmolarity because the aquaporins would not absorb the water in the urine, leaving it highly diluted in large quantities, resulting in low osmolarity

Question 48

What protein is responsible for forming gradients that favor the reabsorption of ions, water, and nutrients in the proximal tubule?

Answer 48

Na+/K+-ATPase