ch. 44 Flashcards

1
Q

where do physiological systems of animals operate

A

in a fluid environment

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2
Q

osmoregulation

A

controls solute concentrations and balances water gain and loss

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3
Q

desert and marine animals

A

face desiccating environments that can quickly deplete body water

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4
Q

freshwater animals

A

conserve solutes and absorb salts from surroundings

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5
Q

overview of excretion

A

rids body of nitrogenous metabolites and other waste products

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6
Q

what is osmoregulation based on

A

balancing uptake and loss of water and solutes

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7
Q

driving force for movement of water and solutes

A

concentration gradient of 1+ solutes across plasma membrane

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8
Q

how does water enter and leave a cell

A

osmosis

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9
Q

osmolarity

A

solute concentration of a solution
- determines water movement across selectively permeable membrane

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10
Q

isoosmotic

A

water molecules will cross the membrane at equal rates in both directions

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11
Q

hypoosmotic

A
  • lower solute concentration
  • higher free H2O concentration
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12
Q

hyperosmotic

A
  • higher solute concentration
  • lower free H2O concentration
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13
Q

net flow of water

A

hypo osmotic to hyperosmotic

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14
Q

hypo

A

below

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15
Q

hyper

A

more

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16
Q

2 ways animals can maintain water balance

A
  1. osmoconformers
  2. osmoregulators
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17
Q

osmoconformers

A

isosmotic with their surroundings and do not regulate osmolarity

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18
Q

osmoregulators

A

expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment

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19
Q

stenohaline

A

can’t tolerate substantial changes in external osmolarity
- most animals

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20
Q

steno

A

narrow

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21
Q

haline

A

salt

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22
Q

euryhaline

A

animals can survive large fluctuations in external osmolarity

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23
Q

eu

A

true

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24
Q

what are most marine invertebrates

A

osmoconformers (isosmotic)

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25
Q

what are many marine vertebrates and some marine invertebrates

A

osmoregulators

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26
Q

what are bony fishes to seawater

A

hypoosmotic
- water moves from bodies to sea water
- balance water loss by drinking large amounts of seawater and eliminating ingested salts through gills and kidneys

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27
Q

what is osmoregulation frequently coupled to

A

elimination of nitrogenous waste products

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28
Q

sharks and urea

A
  • high concentration of urea in bodies
  • trimethylamine oxide (TMAO) protects them from its denaturing effect
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29
Q

how do sharks take in and lose water?

A
  • take in water by osmosis and food
  • water disposed of in urine
  • urine also removes some of salt that diffuses into shark’s body
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30
Q

osmoregulation in marine fish

A
  • gain water through drinking seawater and food
  • gain salts through drinking seawater and food
  • lose salts through gills and urine
  • lose water through gills/surface and urine
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31
Q

osmoregulation in freshwater animals

A
  • gain water through osmosis from hypoosmotic environment and some drinking
  • gain salts through food and gills
  • lose salts through diffusion and urine
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32
Q

how do freshwater animals maintain water balance

A

drinking almost no water and excreting large amounts of dilute urine

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33
Q

animals in temporary ponds

A

lose almost all their body water and survive in a dormant state - anhydrobiosis

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34
Q

tardigrades (water bears)

A

dehydrate from about 85% water to 2% water in dehydrated, inactive state

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35
Q

how to land animals maintain water balance

A
  • body coverings prevent dehydration
  • anatomical features/behaviors - nocturnal desert
  • eating moist food
  • producing water metabolically through cellular respiration
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36
Q

what must osmoregulators do to maintain osmotic gradients

A

expend energy

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37
Q

what does amount of osmotic energy depend on

A
  • how different animal’s osmolarity is from surroundings
  • how easily water and solutes move across animal’s surface
  • work required to pump solutes across membrane
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38
Q

transport epithelia

A

epithelial cells specialized for controlled movement of solutes in specific directions

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39
Q

how are transport epithelia arranged

A

complex tubular networks

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40
Q

ex. of transport epithelia

A

nasal glands of marine birds that remove excess NaCl from blood

41
Q

most significant wastes

A

nitrogenous breakdown and products of proteins and nucleic acids

42
Q

what do some animals do with toxic ammonia?

A

convert it to less toxic compounds before excretion

43
Q

different forms of nitrogenous waste

A

ammonia, urea, uric acid

44
Q

ammonia

A
  • lots of water
  • highly toxic
  • little energy
  • invertebrates: release across whole body surface
45
Q

urea

A
  • medium toxicity
  • medium water
  • more energy
46
Q

what do most terrestrial mammals and many marine species excrete?

A

urea
- vertebrates: produced in liver, then carried to kidneys

47
Q

uric acid

A
  • little toxicity
  • little water
  • lots of energy
48
Q

which animals excrete uric acid

A

insects, land snails, reptiles, birds

49
Q

characteristics of uric acid

A
  • doesn’t dissolve readily in water
  • secreted as paste with little water loss
50
Q

what does gout result in

A

production of uric acid as metabolic byproduct

51
Q

how do most excretory systems produce urine

A

by refining a filtrate derived from body fluids

52
Q

key functions of excretory systems

A
  1. filtration - body fluids
  2. reabsorption - reclaiming valuable solutes
  3. secretion - adding nonessential solutes/wastes to filtrate
  4. excretion - processed filtrated released from body
53
Q

protonephridium

A

network of dead-end tubules that branch throughout body
- smallest branches of network capped by flame bulb
- excrete dilute fluid, osmoregulation

54
Q

metanephridia

A
  • in each segment of an earthworm
  • tubules that collect coelomic fluid and produce dilute urine, osmoregulation
55
Q

Malpighian tubules

A
  • remove nitrogenous waste from hemolymph, osmoregulation
  • conserves water effectively
56
Q

where are Malpighian tubules found

A

insects and other arthropods

57
Q

what waste do insects produce

A

dry waste matter mainly composed of uric acid

58
Q

kidneys

A

excretory organs of vertebrates that function in excretion and osmoregulation

59
Q

2 types of nephrons

A
  1. cortical - more in cortex
  2. juxtamedullary - more in medulla
60
Q

filtrate produced in Bowman’s capsule

A

contains salts, glucose, amino acids, vitamins, nitrogenous waste, and other small molecules

61
Q

descending limb of loop of henle

A
  • reabsorption of water through channels formed by aquaporin proteins
  • movement driven by high osmolarity of interstitial fluid (hyperosmotic to filtrate)
  • filtrate becomes increasingly concentrated
62
Q

ascending limb of the loop of henle

A
  • salt but not water is able to diffuse from tubule into interstitial fluid
  • filtrate becomes increasingly dilute
63
Q

distal tubule

A
  • regales K+ and NaCl concentrations of body fluids
  • controlled movements of ions (H+, HCO3-) contribute to pH regulation
64
Q

collecting duct

A
  • carries filtrate through medulla to renal pelvis
  • reabsorption of solutes/water
  • urine hyperosmotic to body fluids
65
Q

what is a key terrestrial adaptation of the mammalian kidney

A

ability to conserve water

66
Q

why can hyperosmotic urine be produced

A

because considerable energy is expended to transport solutes against concentration gradients

67
Q

2 primary solutes affecting osmolarity

A

NaCl and urea

68
Q

concentrating urine in mammalian kidney

A
  • proximal tubule: filtrate volume decreases, water and salt reabsorbed, osmolarity remains the same
  • descending Henle: soluties becomes more concentrated, water leaving tubule by osmosis
69
Q

what does NaCl diffusing from the ascending limb do

A

maintain a high osmolarity in the interstitial fluid of the renal medulla

70
Q

what is expended to actively transport NaCl from filtrate in upper part of ascending limb

A

energy

71
Q

countercurrent multiplier system (loop of Henle)

A

maintains high salt concentration in kidney

72
Q

vasa recta

A

supplies kidney with nutrients without interfering w/ osmolarity gradient

73
Q

osmolarity of urine

A

isosmotic to interstitial fluid of inner medulla, but hyperosmotic to blood and interstitial fluids everywhere else in the body

74
Q

juxtamedullary nephron

A

key to water conservation in terrestrial animals

75
Q

loops of Henle in dry environment animals vs. fresh water

A
  • dry - long loops
  • fresh water - short loops
76
Q

kidney function in vampire bat

A

alternate rapidly between producing large amounts of dilute urine and small amounts of hyperosmotic urine

77
Q

how do birds conserve water

A
  • have shorter loops of Henle
  • excrete uric acid instead of urea
78
Q

where do reptiles reabsorb water from wastes

A

cloaca
- only have cortical nephrons

79
Q

where do freshwater fishes conserve salt

A

in distal tubules and excrete large volumes of dilute urine

80
Q

what is kidney function in amphibians similar to

A

freshwater fishes

81
Q

how to amphibians conserve water on land

A

by reabsorbing water from urinary bladder

82
Q

marine bony fish

A
  • fewers/smaller nephrons than freshwater, lack distal tubule
  • small or no glomeruli
  • filtration rates lot, little urine excreted
  • osmoregulation relies on specialized chloride cells in gills
83
Q

what can mammals control the volume and osmolarity of urine in response to?

A

changes in salt intake and water availability

84
Q

what kind of controls manage osmoregulatory functions of the mammalian kidney

A

nervous and hormonal
- contribute to blood pressure and blood volume

85
Q

antidiuretic hormone (ADH)

A

activate membrane receptors on collecting duct cells
- initiates signal cascade leading to insertion of aquaporin proteins into membrane of collection duct
- increases water recapture to reduce urine volume

86
Q

another name for ADH

A

vasopressin

87
Q

where are ADH molecules released from

A

posterior pituitary

88
Q

what do osmoreceptor cells in the hypothalamus monitor

A

blood osmolarity and regulate release of ADH

89
Q

what happens when osmolarity rises above its set point

A

ADH release into bloodstream increases
- opposite for decrease in osmolarity

90
Q

alcohol

A
  • diuretic
  • inhibits release of ADH
91
Q

what can mutation in ADH production lead to

A

severe dehydration and diabetes insipidus

92
Q

renin-angiotensin-aldosterone system (RAAS)

A

part of complex feedback circuit that functions in homeostasis

93
Q

what can a drop in blood pressure near the glomerulus cause

A

justaglomerular apparatus (JGA) to release enzyme renin

94
Q

renin

A

triggers formation of peptide angiotensin II

95
Q

angiotensin Ii

A
  • raises blood pressure
  • decreases blood flow to kidneys
  • stimulates release of aldosterone (increases blood volume and pressure)
96
Q

what do ADH and RAAS both increase

A

water absorption
- only RAAS will respond to decrease in blood volume

97
Q

atrial natriuretic peptide (ANP)

A

opposes RAAS
- released by atria of heart

98
Q

when is ANP released

A

in response to increase in blood volume and pressure, inhibits release of renin