Excretion Flashcards

1
Q

What are the main needs of terrestrial animals?

A

Need to obtain water
Need to avoid desiccation
Body surfaces are never totally impermeable thus will suffer continuous water loss

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2
Q

What is a terrestrial animal’s total input?

A

Food and drinks

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3
Q

What is a terrestrial animal’s total output?

A

Lungs and skin
Urine and faeces
Salt glands

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4
Q

What is a terrestrial animal’s obligatory output?

A

Lungs and skin

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5
Q

What is a terrestrial animal’s regulatory output?

A

Urine, faeces, and salt glands

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6
Q

What is the terrestrial animal’s primary regulatory organ?

A

Kidneys

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7
Q

How do terrestrial animals gain water?

A

Drinking
Uptake via body surfaces
Water available in food
Metabolic water production

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8
Q

Respiration equation

A

C6H12O6 + 6O2 → 6CO2 + 6H2O

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9
Q

What does ammonotelic mean?

A

An organism that excretes nitrogenous waste in the form of ammonia

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10
Q

What does ureotelic mean?

A

An organism that excretes nitrogen in the form of urea

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11
Q

What does uricotelic mean?

A

An organism that excretes nitrogen as uric acid or its salts

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12
Q

Describe the properties of ammonia

A

Cheap, soluble, toxic
Excreted by diffusion in water
Takes 0.5L of water to excrete 1g of nitrogen

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13
Q

Describe the properties of urea

A

Expensive, less soluble, less toxic
Takes energy to make
Takes 0.05L of water to excrete 1g of nitrogen

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14
Q

Describe the properties of uric acid

A

Very expensive, not soluble, can be stored
Takes lots of energy to make
Takes 0.001L of water to excrete 1g of nitrogen

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15
Q

What is the main factor that determines the nature of nitrogen excretion?

A

Water availability

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16
Q

How do terrestrial birds excrete nitrogen?

A

90% is as uric acid

17
Q

How do ducks excrete nitrogen?

A

50% as uric acid and 30% as ammonia

18
Q

How do tadpoles excrete nitrogen?

A

As ammonia

19
Q

How do frogs excrete nitrogen?

A

As urea

20
Q

How do annelids produce and excrete urine?

A

Coelomic fluid enters the metanephridium through a nephrostome
The tubule cells of the metanephridium alter the composition of the coelomic fluid
This produces a dilute urine that is excreted through the nephridopore

21
Q

How do insects produce and excrete urine?

A

Uric acid, Na+ and K+ are transported into the Malpighian tubules and water follows
Na+ and K+ are actively transported from the hindgut and rectum back to the coelomic fluid and water follows
Uric acid precipitates in the rectum and is secreted

22
Q

What are the main functions of the kidneys?

A
Ion balance 
Osmotic balance 
Blood pressure maintenance 
pH balance 
Excretion
Hormone production
23
Q

How much does a kidney weigh?

A

1% of body weight

24
Q

How much glomerular filtrate does the kidney see a day?

A

200L

25
Q

How much urine does the kidney produce per day?

A

1-2L

26
Q

What is the blood pressure in the glomerulus?

A

5kPa

27
Q

How much water and Na+ and glucose is reabsorbed in the proximal tubule?

A

75% water
Most Na+
All glucose

28
Q

What are the 3 stages of urine formation?

A

Filtration
Absorption
Secretion

29
Q

What is the purpose of the loops of Henle?

A

Allows urine to be more concentrated than blood

The ability to concentrate urine is related to the length of the loops of Henle

30
Q

Describe how the loops of Henle work

A

NaCl is transported- inside fluid is more dilute and outside is more concentrated
Water moves out via osmosis through water-permeable walls
Urea diffuses out where the walls are permeable to it
This raises the osmotic concentration outside the tubule
This causes water to move out
NaCl is drawn out by its concentration gradient