controlling the internal environment (kidneys) Flashcards
1
Q
what are the two ways that animals can manage their internal environment
A
they either conform or regulate
2
Q
what is a regulator
A
an animal that uses internal mechanisms to control internal change in the face of external fluctuation
3
Q
what is a conformer
A
an animals who’s internal conditions change in accordance with external changes
4
Q
can an animal regulate some internal conditions while allowing others to conform to the environment
A
yes - e.g. largemouth bass conforms to the temperature of the surrounding water but it regulates the solute concentrations in its blood and interstitial fluid
5
Q
the steady temperature of a river otter and the stable concentration of solutes in a bass are examples of what
A
homeostasis
6
Q
what does homeostasis mean
A
the maintenance of a constant internal environment
7
Q
what are examples of homeostasis in humans
A
temperature regulation
blood pH regulation
blood glucose concentration regulation
8
Q
what is the normal range of blood glucose concentration per 100ml blood
A
70-110mg glucose
9
Q
what does homeostasis require
A
control system
10
Q
in homeostasis the response reduces/dampens the stimulus what kind of feedback response is this
A
negative feedback
11
Q
are physiological responses to stimuli instantaneous
A
no - homeostasis moderate but does not eliminate changes in the internal environment
12
Q
what would positive feed back involve
A
amplification of the stimulus - generally not in animal homeostasis but in other processes e.g. giving birth - stimulus drives completion of process
13
Q
in all mammals and plants, certain cyclic alterations in metabolism reflect what
A
a circadian rhythm
14
Q
what is a circadian rhythm
A
a set of physiological changes that occur every 24 hours - e.g. the body clock
15
Q
which hormone is secreted at night
A
melatonin
16
Q
can external stimuli reset the biological clock
A
yes - but it takes a while, this is why we get jet lag
17
Q
what is jet lag
A
a miss match between the circadian rhythm and local environment that persists until the clock fully resets
18
Q
acclimatization can alter homeostasis, what is it
A
an animals physiological adjustment to changes in its external environment e.g. when an elk moves up into the mountains from sea level, the lower oxygen concentration stimulates the animal to breathe more rapidly and deeply. As a result more CO2 is lost through exhaling, raising the blood pH above its normal range
19
Q
is acclimatization a permanent or temporary change
A
temporary
20
Q
how is the fluid balance of tissues maintained
A
relative concentrations of water and solutes are kept within fairly narrow limits. ions must be maintained at concentrations that permit normal activity of muscles, neurons and other body cells
21
Q
homeostasis requires osmoregulation, what is this
A
the processes by which animals control solute concentration and balance water gain and loss
22
Q
in order to safeguard their body fluids freshwater animals must deal with what toxic metabolite
A
ammonia
23
Q
which process remove nitrogenous waste and other metabolic waste products
A
excretion
24
Q
if water uptake to cells is excessive what happens to them
A
they can burst
25
if water loss from cells is substantial what can happen to them
they shrivel and die
26
what is the ultimate driving force for the movement of water and solutes
a concentration gradient of one or more solutes across the plasma membrane
27
water enters and leaves cells by which process
osmosis
28
what is the unit of measurement for solute concentration
osmolarity (the number of moles of solution per litre of solution)
29
what is the osmolarity of human blood
300mOsm/L
30
two solutions with the same osmolarity are said to be what
isosmotic
31
what is a hyperosmotic solution
the solution with the higher concentration of solutes
| low free H2O concentration
32
what is a hypoosmotic solution
the solution with the lower concentration of solutes
| high free H2O concentration
33
in which direction does water flow by osmosis:
hyperosmotic to hypoosmotic
hypoosmotic to hyperosmotic
hypoosmotic to hyperosmotic - reducing the concentration difference in solutes and free water
34
what are the two ways that an animal can maintain water balance
either by being an osmoconformer or an osmoregulator
35
which term defines the relationship between the osmolarity of the an osmoconformer to its surroundings
isosmotic - internal osmolarity is the same as that of the external environment
many osmoconformers life in an environment that has a stable composition so they will have a stable internal environment
36
what does an osmoregulator do
control their internal osmolarity, independent of that of the external environment
37
can osmoconformers move between freshwater and marine (sea water) environments
no they are all marine animals
38
can osmoregulators move between freshwater and marine (sea water) environments
yes
39
in a hypoosmotic environment an osmoregulator must discharge/take in water
discharge - the water is going to flow into them so in order to maintain a constant internal environment they need to combat this by discharging the excess water
40
in a hyperosmotic environment an osmoregulator must discharge/take in water
take in - the water is going to flow out of them so in order to maintain a constant internal environment they need to combat this by taking in water
41
what does it mean if an organism is stenohaline
they cannot tolerate substantial changes in external osmolarity
42
what does it mean if an organism is euryhaline
it can survive large fluctuations in external osmolarity
43
most marine invertebrates are osmoconformers/regulators
osmoconformers
44
invertebrate marine osmoconformers have not trouble in water balance but they must actively transport specific solutes that establish what
levels in haemolymph (circulatory fluid) different form those in the ocean
45
marine bony fish constantly lose water by osmosis, they balance water loss by drinking a lot of sea water. how are the excess salts ingested eliminated
through the gills and the kidneys
46
osmoregulation is frequently coupled to elimination of what
nitrogenous waste products e.g. urea
47
why must urea be eliminated
high concentrations can denature proteins and thus disrupt cellular functions
48
sharks have high concentrations of urea in their body. how do they survive
trimethylamine oxide (TMAO) is produced by sharks and it protects proteins from the denaturing effect of urea
49
as well as protecting sharks from the effects of urea, what else is TMAO responsible for
osmoregulation
50
how does TMAO participate in osmoregulation
sharks have a lower salt content than sea water
salt tends to diffuse into their bodies, especially across the gills
the combination of TMAO with salts and urea results in sharks having a high solute concentration
water then slowly enters the shark by osmosis (they don't drink)
51
the body fluids of freshwater animals must be hyperosmotic/hypoosmotic
hyperosmotic
52
why do the body fluids of freshwater animals need to be hyperosmotic
animal cells cannot tolerate salt concentrations as low as that of lake or river water
53
freshwater animals have internal fluids with an osmolarity higher/lower than that of their surroundings
higher
54
why do freshwater animals face problems gaining water by osmosis
because the osmolarity of internal fluids is greater than that of their surroundings their solute concentration is greater and their water concentration is lower leading to and influx of water. this means they have to balance water content to stabilise the influx
55
how do freshwater organisms with the influx of water into their bodies
they excrete large amounts of very dilute urine and they drink almost all water. slats lost by diffusion and in urine are replenished by eating and uptake across their gills
56
what is another word for extreme dehydration
desiccation
57
when ponds dry up what is the dormant stage that animals enter without water
anhydrobiosis
58
what adaptations does anhydrobiosis require
ones that keep cell membranes intact or else they would shrivel up and die
59
adaptations that reduce/increase water loss are key to survival on land
reduce
60
how do land animals maintain water balance
by drinking and eating moist foods and by producing water metabolically through cellular respiration
61
in most animals, osmoregulation and metabolic waste disposal rely on what for moving particular solutes in controlled amounts in specific directions
transport epithelia
62
what is transport epithelia
one or more epithelial cells specialized for moving particular solutes in controlled amounts in specific directions
63
why do humans become dehydrated when they drink salt water
they must use a greater volume of water to excrete the salt load so there is a net loss of water from the body
64
even though drinking sea water brings a lot of salt, the salt glands enable marine invertebrates to achieve a net gain/loss of water
gain
65
what functions does the kidney have
osmoregulation and excretion
66
what do the kidneys consist of
tubules , ducts and other structures
67
how are kidney tubules arranged
in an organised manner and are closely associated with a network of capillaries
68
are kidneys typically segmented or non segmented
non segmented
69
how many kidneys are in the body
2
70
urine produced in the kidneys exits through a duct called the ……………..
ureter
71
where to the 2 ureters coming from the kidneys drain into
the urinary bladder
72
during urination, the urine is expelled through a tube called the ……………, which empties to the outside of the body
urethra
73
what structure regulates urination
sphincter muscles near the junction of the urethra and bladder
74
each kidney has an outer ………… ……….. and an inner …….… ………...
renal cortex
| renal medulla
75
what are the outer renal cortex and inner renal medulla supplied with blood by
the renal artery
76
what are the outer renal cortex and inner renal medulla drained by
the renal vein
77
what structures are packed inside the cortex and the medulla
tightly packed excretory tubules and associated blood vessels
78
what do the excretory tubules do
carry and process a filtrate produced form the blood entering the kidney
79
nearly all of the fluid in the filtrate is reabsorbed into the surrounding ………. ………. and exits the kidney in the renal vein
blood vessels
80
the remaining fluid in the excretory tubules leaves as ..……..
urine
81
the urine is collected in the inner …………. ………… and exits the kidney via the ureter
renal pelvis
82
weaving back and forth across the renal cortex and medulla are the …………….
nephrons
83
what structures are the functional units of the vertebrate kidneys
nephrons
84
85% of the nephrons are ……………… nephrons which reach only a short distance into the medulla and the remainder are …………………. nephrons which extend deep into the medulla
cortical
| juxtamedullary
85
juxtamedullary nephrons are essential for production of urine that is hyper/hypoosmotic to body fluids, key for water conservation
hyperosmotic
86
what does a nephron consist of
a single long tubule and a ball of capillaries called the glomerulus
87
the blind end (a cavity open at one end) of the tubule forms a cup shaped swelling known as the …………...
Bowman's capsule
88
what does the Bowman's capsule surround
the glomerulus
89
When Is filtrate formed in the nephrons
when blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman's capsule
90
how is the filtrate processed
as it passes through the 3 major regions of the nephron: the proximal tubule, the loop of henle (a hairpin turn with a descending limb and an ascending limb) and the distal tubule
91
what are the 3 major regions of the nephron
proximal tubule
loop of henle
distal tubule
92
what receives the processed filtrate from the nephrons and transports it to the renal pelvis
collecting duct
93
each nephron is supplied with blood by an …………. arteriole, an offshoot of the renal artery that branches and forms the capillaries of the glomerulus
afferent
94
as the capillaries leave the glomerulus, they converge, forming the …………. arteriole
efferent
95
branches of the efferent arteriole form the …………….. capillaries
peritubular
96
peritubular capillaries surround the ……………… and …………….. tubules
proximal
| distal
97
other branches of the peritubular capillaries extend downward to the loop of henle and form the ……….. …….….
vasa recta
98
what are the vasa recta
hairpin shaped capillaries that serve the renal medulla, including the loop of henle of juxtamedullary nephrons
99
the glomerular capillaries and specialized cells of the bowman's capsule retain blood cells and large molecules, such as plasma proteins, but are permeable to ……. and small ………...
water
| solutes
100
the filtrate produced in the Bowman's capsule contains what
salts, glucose, amino acids, vitamins, nitrogenous waste and other small molecules - the concentration of these molecules id the same in the initial filtrate as in the blood plasma because they all pass freely between the glomerular capillaries and the Bowman's capsule
101
reabsorption in the proximal tubule is critical for the recapture of what form the large volume of the initial filtrate
ions, water and valuable nutrients
102
NaCl in the filtrate enters the cells of the transport epithelium by ………. ………… and cotransport mechanisms . it is then transferred to the interstitial fluid by ……….. …………..
facilitated diffusion
| active transport
103
the transport of positive charge out of the tubule drives the passive transport of what
chlorine ions
104
as salt moves from the filtrate to the interstitial fluid, what follows, resulting in a considerable reduction in filtrate volume
water follows by osmosis
105
the salt an water that exit the filtrate, diffuse from the interstitial fluid into what
the peritubular capillaries
106
what other substances as well as salt and water are also transported from the filtrate to the interstitial fluid into the peritubular capillaries
glucose, amino acids, potassium ions etc.
107
processing of the filtrate in the proximal tubule helps maintain a relatively constant ……… in the body fluids
pH
108
how is pH controlled
cells of the transport epithelium secrete H ions into the lumen of the proximal tubule and also synthesise and secrete ammonia which acts as a buffer to trap H ions in the form of ammonium ions
109
the more acidic the filtrate is, the more............the cells produce and secrete and the animals urine usually contains some ammonia from this source (even though most nitrogenous waste is excreted as urea
ammonia
110
the proximal tubules also absorb about 90% of what from the filtrate, contributing further to pH balance in body fluids
buffer bicarbonate
111
as the filtrate passes through the proximal tubule, the materials to be excreted become ………….
concentrated
112
what can be secreted into the filtrate from the surrounding tissues
drugs and toxins that have been processed in the liver can pass from the peritubular into the interstitial fluid then secreted by the transport epithelium into the lumen of the proximal tubule
113
where does the filtrate g after leaving the proximal tubule
the loop of henle
114
what happens to the filtrate in the loop of henle
filtrate volume is reduced via distinct stages of water and slat movement
115
what is the first portion of the loop of henle called and what happens here
the descending limb
numerous water channels formed by aquaporin proteins make the transport epithelium freely permeable to water. In contrast there are almost no channels for salt and other small solutes, resulting in very low permeability for these substances
116
for water to move out of the tubule by osmosis, what must the osmolarity of the interstitial fluid bathing the tubule be compared to the filtrate
hyperosmotic
117
the osmolarity of the interstitial fluid increases/decreases progressively form the cortex through the medulla
increases - as a result the filtrate loses water and increases in solute concentration along its journey down the descending limb
118
where is the osmolarity of the filtrate highest
at the elbow of the loop of henle
119
once the filtrate reaches the tip of the loop where does it return to
the cortex via the ascending limb
120
unlike the descending limb, the ascending limb has a transport epithelium that lacks what type of protein
water channels
121
the epithelium membrane that faces the filtrate in the ascending limb is permeably to what
water
122
what are the two specialised regions of the ascending limb
a thin segment near the loop tip and a thicker segment adjacent to the distal tubule
123
as the filtrate ascends in the thin segment of the ascending limb what diffuses out of the permeable tubule and into the interstitial fluid
NaCl
124
in the thicker segment of the ascending limb NaCl movement out of the tubule also occurs but in what way is the movement different from that in the thin segment
the NaCl is actively transported instead of passively diffusing
125
what essentially happens to the filtrate in the ascending limb of the loop of henle
the filtrate loses salt but not water and so the filtrate becomes more dilute as it moves up to the cortex in the ascending limb
126
what does the distal tubule play a key role in regulating
the concentration of potassium ions and NaCl in the body fluids
also pH regulation
127
how does the distal tubule regulate potassium ion and NaCl concentration
it can vary the amount of potassium secreted into the filtrate as well as the amount of NaCl reabsorbed from the filtrate
128
what is the role of the collecting duct
it processes the filtrate coming the distal tubule into urine which it carries to the renal pelvis
129
in the collecting duct the filtrate becomes increasingly …….……., losing more water by osmosis to the hyper/hypoosmotic interstitial fluid
concentrated
| hyperosmotic
130
in the inner medulla the collecting duct becomes permeable to what
urea
131
urine is hyper/hypoosmotic to the general body fluids
hyperosmotic
132
what is the presence of water channels in the collecting duct epithelium controlled by
hormones that regulate blood pressure, volume and osmolarity
133
filtrate passing from Bowman's capsule to the proximal tubule has the same osmolarity as what
the blood
134
what is reabsorbed from the filtrate as it flows through the proximal tubule in the renal cortex
salt and water - the filtrate volume decreases but the osmolarity remains the same
135
as the filtrate flows from the cortex to the medulla via the ………….. …………… water leaves the tubule by osmosis
descending limb
136
what does the reabsorption of water in the descending limb result in
solutes become more concentrated increasing the osmolarity of the filtrate
137
where is diffusion of salt out of the loop of henle at its maximal
at the elbow of the loop
138
the ascending limb of the loop of henle is permeable to ..………. but not …………...
salt - this helps maintain a high osmolarity in the interstitial fluid of the renal medulla
water
139
what is the countercurrent system
the loop of henle and the surrounding capillaries act as a type of countercurrent system too generate the steep osmotic gradient between the medulla and the cortex
140
the transport of NaCl in the upper thick part of the ascending limb is passive/active
active - this transport maintains a high salt concentration in the interior of the kidney enabling it to form concentrated urine
141
countercurrent multiplier systems expend ………… to create a ………….. ………….
energy
| concentration gradients
142
the ascending and descending vessels of the vasa recta carry blood in ………… …………. through the kidneys osmolarity gradient
opposite directions
143
the kidney has one of the highest/lowest metabolic rates or any organ
highest
144
dues to active transport of NaCl out of the ascending limb the filtrate is hypo/hyperosmotic to body fluids by the time it reaches the distal tubule
hypoosmotic
145
the collecting duct is permeable to …….. but not to …….…..
water
| salt
146
animals that excrete the most hyperosmotic urine have many ………………. nephrons that extend deep into the medulla
juxtamedullary
147
aquatic animals have mostly cortical nephrons which results in production of dilute/concentrated urine
dilute
148
in mammals, urine volume and osmolarity are adjusted depending on what
he animals water and salt balance and its rate of urea production
149
describe the urine produced when an animal's salt intake is high but its water availability is low
excretion of small volumes of hyperosmotic urine with minimal water loss (this is how the urea and salt are removed form the body)
150
describe the urine produced when an animal's salt intake is low but its water availability is high
excretion of large volumes of hypoosmotic urine (the excess water is eliminated with little salt loss)
151
what manages the osmoregulatory function of the kidney
a combination of nervous and hormonal controls
152
what is the key hormone of the kidneys
Antidiuretic hormone (ADH)
153
where is ADH released from
the posterior pituitary
154
What does ADH activate
it binds to active membrane receptors on the surface of the collecting ducts. the receptors then initiate a signal transduction cascade that directs insertion of aquaporin proteins into the membrane lining the collecting duct.
155
more aquaporin channels result in more water recapture. what is the effect on the volume of urine
because the water is reabsorbed by the body the volume of urine decreases and we are left mainly with a concentrated mixture of solutes
156
what is the response when osmolarity rises above the normal range
osmoreceptor cells in the hypothalamus trigger release of ADH from the posterior pituitary
water reabsorption in the collecting duct is increased
the result is increased concentration urine, decreased urine volume and decreased blood osmolarity back the set point.
157
what is the response when osmolarity goes below the normal range
a negative feedback mechanism reduces the activity of the osmoreceptor cells in the hypothalamus and ADH secretion is reduced
158
how does alcohol affect ADH release
it inhibits its release, leading to excessive urinary water loss and dehydration - causing a hangover
159
what is the disorder called that results in no ADH production or inactivated ADH receptors (dues to mutations in genes that render them inactive)
diabetes insipidus - it causes severe dehydration and solute imbalance due to production of huge volumes of very dilute urine
160
what is heterothermy
when some parts of the body are warmer than others
161
what would be an example of behavioural temperature regulation in ectotherms
lizards basking in the sun
162
A solution with few solutes in it will have lower/higher osmotic pressure than one with many solutes.
lower
163
water will move from a low/high to a high/low osmotic pressure system
low
| high
164
what is ammonia secreted as in birds
uric acid/guano
165
what is ammonia released as in fish
ammonia/ammonium
166
what is ammonia released as in mammals
urea
167
where are the kidneys
located against the back wall of the abdomen on either side of the body
168
what is hydrostatic force
the force a liquid exerts on the walls of its container
169
what are the steps in countercurrent heat exchange
1. Arteries carrying warm blood are in close contact with veins carrying cooler blood.
2. Heat from the artery is absorbed by the vein
3. As the blood in the veins nears the centre it is almost as warm as the body core
170
what is another name for ADH
vasopressin
171
what is countercurrent multiplication
Countercurrent multiplication is the process of using energy to generate an osmotic gradient that enables reabsorption of water from tubular fluid, leading to production of concentrated urine. The ascending limb of the loop of Henle helps to maintain a gradient of salt concentration in the kidney interior.
