ch. 44 Flashcards
(98 cards)
1
Q
where do physiological systems of animals operate
A
in a fluid environment
2
Q
osmoregulation
A
controls solute concentrations and balances water gain and loss
3
Q
desert and marine animals
A
face desiccating environments that can quickly deplete body water
4
Q
freshwater animals
A
conserve solutes and absorb salts from surroundings
5
Q
overview of excretion
A
rids body of nitrogenous metabolites and other waste products
6
Q
what is osmoregulation based on
A
balancing uptake and loss of water and solutes
7
Q
driving force for movement of water and solutes
A
concentration gradient of 1+ solutes across plasma membrane
8
Q
how does water enter and leave a cell
A
osmosis
9
Q
osmolarity
A
solute concentration of a solution
- determines water movement across selectively permeable membrane
10
Q
isoosmotic
A
water molecules will cross the membrane at equal rates in both directions
11
Q
hypoosmotic
A
- lower solute concentration
- higher free H2O concentration
12
Q
hyperosmotic
A
- higher solute concentration
- lower free H2O concentration
13
Q
net flow of water
A
hypo osmotic to hyperosmotic
14
Q
hypo
A
below
15
Q
hyper
A
more
16
Q
2 ways animals can maintain water balance
A
- osmoconformers
- osmoregulators
17
Q
osmoconformers
A
isosmotic with their surroundings and do not regulate osmolarity
18
Q
osmoregulators
A
expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment
19
Q
stenohaline
A
can’t tolerate substantial changes in external osmolarity
- most animals
20
Q
steno
A
narrow
21
Q
haline
A
salt
22
Q
euryhaline
A
animals can survive large fluctuations in external osmolarity
23
Q
eu
A
true
24
Q
what are most marine invertebrates
A
osmoconformers (isosmotic)
25
what are many marine vertebrates and some marine invertebrates
osmoregulators
26
what are bony fishes to seawater
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
27
what is osmoregulation frequently coupled to
elimination of nitrogenous waste products
28
sharks and urea
- high concentration of urea in bodies
- trimethylamine oxide (TMAO) protects them from its denaturing effect
29
how do sharks take in and lose water?
- take in water by osmosis and food
- water disposed of in urine
- urine also removes some of salt that diffuses into shark's body
30
osmoregulation in marine fish
- 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
31
osmoregulation in freshwater animals
- gain water through osmosis from hypoosmotic environment and some drinking
- gain salts through food and gills
- lose salts through diffusion and urine
32
how do freshwater animals maintain water balance
drinking almost no water and excreting large amounts of dilute urine
33
animals in temporary ponds
lose almost all their body water and survive in a dormant state - anhydrobiosis
34
tardigrades (water bears)
dehydrate from about 85% water to 2% water in dehydrated, inactive state
35
how to land animals maintain water balance
- body coverings prevent dehydration
- anatomical features/behaviors - nocturnal desert
- eating moist food
- producing water metabolically through cellular respiration
36
what must osmoregulators do to maintain osmotic gradients
expend energy
37
what does amount of osmotic energy depend on
- 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
38
transport epithelia
epithelial cells specialized for controlled movement of solutes in specific directions
39
how are transport epithelia arranged
complex tubular networks
40
ex. of transport epithelia
nasal glands of marine birds that remove excess NaCl from blood
41
most significant wastes
nitrogenous breakdown and products of proteins and nucleic acids
42
what do some animals do with toxic ammonia?
convert it to less toxic compounds before excretion
43
different forms of nitrogenous waste
ammonia, urea, uric acid
44
ammonia
- lots of water
- highly toxic
- little energy
- invertebrates: release across whole body surface
45
urea
- medium toxicity
- medium water
- more energy
46
what do most terrestrial mammals and many marine species excrete?
urea
- vertebrates: produced in liver, then carried to kidneys
47
uric acid
- little toxicity
- little water
- lots of energy
48
which animals excrete uric acid
insects, land snails, reptiles, birds
49
characteristics of uric acid
- doesn't dissolve readily in water
- secreted as paste with little water loss
50
what does gout result in
production of uric acid as metabolic byproduct
51
how do most excretory systems produce urine
by refining a filtrate derived from body fluids
52
key functions of excretory systems
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
protonephridium
network of dead-end tubules that branch throughout body
- smallest branches of network capped by flame bulb
- excrete dilute fluid, osmoregulation
54
metanephridia
- in each segment of an earthworm
- tubules that collect coelomic fluid and produce dilute urine, osmoregulation
55
Malpighian tubules
- remove nitrogenous waste from hemolymph, osmoregulation
- conserves water effectively
56
where are Malpighian tubules found
insects and other arthropods
57
what waste do insects produce
dry waste matter mainly composed of uric acid
58
kidneys
excretory organs of vertebrates that function in excretion and osmoregulation
59
2 types of nephrons
1. cortical - more in cortex
2. juxtamedullary - more in medulla
60
filtrate produced in Bowman's capsule
contains salts, glucose, amino acids, vitamins, nitrogenous waste, and other small molecules
61
descending limb of loop of henle
- 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
ascending limb of the loop of henle
- salt but not water is able to diffuse from tubule into interstitial fluid
- filtrate becomes increasingly dilute
63
distal tubule
- regales K+ and NaCl concentrations of body fluids
- controlled movements of ions (H+, HCO3-) contribute to pH regulation
64
collecting duct
- carries filtrate through medulla to renal pelvis
- reabsorption of solutes/water
- urine hyperosmotic to body fluids
65
what is a key terrestrial adaptation of the mammalian kidney
ability to conserve water
66
why can hyperosmotic urine be produced
because considerable energy is expended to transport solutes against concentration gradients
67
2 primary solutes affecting osmolarity
NaCl and urea
68
concentrating urine in mammalian kidney
- 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
what does NaCl diffusing from the ascending limb do
maintain a high osmolarity in the interstitial fluid of the renal medulla
70
what is expended to actively transport NaCl from filtrate in upper part of ascending limb
energy
71
countercurrent multiplier system (loop of Henle)
maintains high salt concentration in kidney
72
vasa recta
supplies kidney with nutrients without interfering w/ osmolarity gradient
73
osmolarity of urine
isosmotic to interstitial fluid of inner medulla, but hyperosmotic to blood and interstitial fluids everywhere else in the body
74
juxtamedullary nephron
key to water conservation in terrestrial animals
75
loops of Henle in dry environment animals vs. fresh water
- dry - long loops
- fresh water - short loops
76
kidney function in vampire bat
alternate rapidly between producing large amounts of dilute urine and small amounts of hyperosmotic urine
77
how do birds conserve water
- have shorter loops of Henle
- excrete uric acid instead of urea
78
where do reptiles reabsorb water from wastes
cloaca
- only have cortical nephrons
79
where do freshwater fishes conserve salt
in distal tubules and excrete large volumes of dilute urine
80
what is kidney function in amphibians similar to
freshwater fishes
81
how to amphibians conserve water on land
by reabsorbing water from urinary bladder
82
marine bony fish
- 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
what can mammals control the volume and osmolarity of urine in response to?
changes in salt intake and water availability
84
what kind of controls manage osmoregulatory functions of the mammalian kidney
nervous and hormonal
- contribute to blood pressure and blood volume
85
antidiuretic hormone (ADH)
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
another name for ADH
vasopressin
87
where are ADH molecules released from
posterior pituitary
88
what do osmoreceptor cells in the hypothalamus monitor
blood osmolarity and regulate release of ADH
89
what happens when osmolarity rises above its set point
ADH release into bloodstream increases
- opposite for decrease in osmolarity
90
alcohol
- diuretic
- inhibits release of ADH
91
what can mutation in ADH production lead to
severe dehydration and diabetes insipidus
92
renin-angiotensin-aldosterone system (RAAS)
part of complex feedback circuit that functions in homeostasis
93
what can a drop in blood pressure near the glomerulus cause
justaglomerular apparatus (JGA) to release enzyme renin
94
renin
triggers formation of peptide angiotensin II
95
angiotensin Ii
- raises blood pressure
- decreases blood flow to kidneys
- stimulates release of aldosterone (increases blood volume and pressure)
96
what do ADH and RAAS both increase
water absorption
- only RAAS will respond to decrease in blood volume
97
atrial natriuretic peptide (ANP)
opposes RAAS
- released by atria of heart
98
when is ANP released
in response to increase in blood volume and pressure, inhibits release of renin
