unit 4: structure/ functions of kidneys Flashcards
(203 cards)
1
Q
Regulation of the extracellular fluid
environment in the body
A
kidney functions
2
Q
what do the kidneys regulate
A
-volume of blood plasma (which affects blood pressure)
-wastes
-electrolytes (fluid balance na,k,ca)
-pH
-secretes erythropoietin
3
Q
how do the kidneys regulate the volume of blood plasma
A
thru the renin-angiotensin- aldosterone system
4
Q
how do the kidneys regulate pH
A
by secreting H+ or HCO3-
5
Q
kidneys are able to regulate solutes thanks to
A
nephron
6
Q
how is urine transported
A
using peristalsis
7
Q
vital for homeostasis and help regulate the body’s internal environemnt
A
the kidneys
8
Q
what are the 2 regions of kidneys
A
-renal cortex
-renal medulla
9
Q
made up of renal pyramids and columns
A
renal medulla
10
Q
kidneys also function by—
A
gluconeogenesis
11
Q
produce glucose by prolonged fasting
A
gluconeogenisis
12
Q
functions of the nephron?
A
-filter blood
-reabsorb what the body needs
-sends wastes to urine
13
Q
filtration of blood,made out of capillaries
A
glomerulus
14
Q
reabsorbs water and nutrients
A
proximal tubule
15
Q
concentrates urine
A
loop of henle
16
Q
adjusts the ion levels and pH
A
distal tubule
17
Q
final urine concentration
A
collecting duct
18
Q
muscular contraction that propels food and waste thru digestive tract. moves urine and bile
A
peristalsis
19
Q
line the wall of the
urinary bladder
A
detrusor muscles
20
Q
connect smooth muscles
A
gap junctions
21
Q
innervated by parasympathetic neurons
A
detrusor muscles
22
Q
what do parasymp release
A
ACh onto muscarinic ACh receptors
23
Q
which sphincter is made out of smooth muscle
A
internal urethral sphincter
24
Q
which sphincter is made out of skeletal muscle
A
external urethral sphincter
25
main muscle responsible for micturition
detrusor muscles
26
what happens when detrusor muscles contract and relax
contract= force urine out
relax= allows bladder to fill with urine without pressure
27
what does the parasympathetic do to detrusor muscles
contract
28
these control when urine is held in or released
sphincters around urethra
29
stretch receptors in the bladder send
information to
s2-s4 regions of the spinal cord
30
prevents involuntary emptying of bladder
guarding reflex
31
your bodys "do not pee yet" signal
thesse normally inhibit parasymp nerves to the detrusor muscles, while somatic motor neurons to external urethral sphincter are stimulated
guarding reflex
32
Stretch of the bladder initiates
voiding reflex
33
this is the spinal and brain coordinated reflex that allows urine to be expelled from the bladder. it kicks in after the guarding reflex is overridden, when its safe and appropriate to urinate
voiding reflex
34
information about stretch passes up the spinal
cord to the
micturation center of the pons
35
cause detrusor
muscles to contract rhythmically
parasymp neurons
36
what causes the
internal urethral sphincter causes it to relax.
inhibition of symp innervention
37
when someone feels the need to urinate and can control when with
external urethral sphincter
38
is uncontrolled urination due to
loss of bladder control and has many possible causes.
urinary incontinence
39
is present when urine
leakage occurs due to increased abdominal pressure,
as during sneezing, coughing, and laughing.
stress urinary incontinence
40
involves uncontrolled contractions
of the detrusor muscle that produce a great urge to
urinate and the leakage of a large volume of urine
overactive bladder
41
consists of small tubules and
associated blood vessels
nephron
42
Blood is filtered, fluid enters the tubules, is
modified, then leaves the tubules as urine
nephron
43
what are the renal bood vessels
-affarent arterioles
-glomerulus
-efferent arterioles
-peritubular capillaries
44
continuous basement membrane and holes in endothelium (so things can pass thru)
Fenestrated
45
surrounds
the glomerulus. Together, they make up the
renal corpuscle
glomerular (bowmans) capsule
46
Filtrate produced in ---passes
into the proximal convoluted tubule
renal corpuscle
47
when in the nephron does fluid turn into urine
after passing thru collecting duct
48
2 types of nephrons
juxtamedullary and cortical
49
better at making concentrated urin
-associated with vasa recta
juxtamedullary
50
focuses on normal filtration
-mostly in cortex
-Associated mainly with peritubular capillaries
cortical
51
this cant make good urine. secreted in urine
cortical
52
good at water movement. more permeable. higher concentration in medulla and use interstitium
juxtamedullary
53
Juxtamedullary nephrons use the interstitium (the space between cells, especially in the medulla) because
the medullary interstitium is super salty (high osmolarity).
This salty environment pulls water out of the nephron tubules by osmosis
54
capillaries of glomerulus are
fenestrated
55
prebuilt holes that allow small things to pass
fenestrate
56
what do large pores allow to leave, and dont allow
water and solutes to leave
but not blood cells and plasma proteins
57
Fluid entering the glomerular capsule is
called
filtrate
58
what is the components of filtration barriers
-endothelium, 2 basement membranes, podocytes
59
special cells in the kidneys that wrap around capillaries in the glomerulus
-leaving tiny slits (called filtration slits).
-The slits control what can leave the blood and enter the kidney tubules — like water, ions, and small molecules — but block big stuff like proteins and blood cells.
podocytes
60
the foot like extensions on posocytes are called
pedicles
61
filtrates pass thru
-capillary fenestrae
-glomerular basement memb
-Visceral layer of the glomerular capsule composed of cells called podocytes with extensions called pedicles
62
Slits in the pedicles called ---are the major barrier for the filtration of plasma proteins
slit diaphragm
pores
63
defects in the podocytes or pedicles cause
proteinuria= proteins in urine
64
common causes of proteinuria
Diabetes (diabetic nephropathy)
High blood pressure (hypertension)
Certain autoimmune diseases (like lupus nephritis)
65
Some albumin is filtered out but is
reabsorbed by
active endocytosis
66
Fluid in glomerular capsule gets there via
-hydrostatic pressure of the blood,
-colloid osmotic pressure
-very permeable capillaries
67
volume of
filtrate produced by both kidneys each
minute
glomerular filtration rate (GFR)
68
what can change filtration rate
vasoconstriction or dilation of afferent arterioles
69
extrinsic regulation via
sympa nerv sys
70
intrinsic regulation via
signals from kidneys called renal autoregulation
71
the kidney's way of keeping blood flow and filtration steady even if blood pressure changes. makes sure GFR stays stable
renal autoregulation
72
when do we get vasoconstriction of affarent arterioles
fight/flight reaction
73
what helps divert blood to heart and muscles
SNS by vasoconstrict affarent arterioles
74
why does urine formation decrease during sns
to compensate for the drop in blood pressure
75
Smooth muscles in
arterioles sense an increase in blood
pressure.
myogenic constriction
76
(muscle reaction):
If blood pressure goes up, the blood vessels stretch.
The vessel walls automatically contract (tighten) to reduce blood flow into the glomerulus.
If pressure drops, they relax to let more blood in.
myogenic constriction
77
Cells in the
ascending limb of the loop of Henle called
macula densa sense a rise in water and
sodium as occurs with increased blood
pressure (and filtration rate).
-send a chem signal, atp, to constrict the affarent arterioles
tubuloglomerular feedback
78
(signal from the tubules):
Special cells (macula densa) in the nephron sense how salty the fluid is.
If the fluid is too salty (means filtration was too fast), they signal the afferent arteriole to constrict → slow down filtration.
If fluid is not salty enough, they signal it to dilate → speed up filtration.
tubuloglomerular feedback
79
what are the stimulus, affarent arteriole, and GFR of symp nerves
-activation by baroreceptor reflex or by higher brain centers (stim)
-constricts (aff. art.)
-decreases (GFR)
80
what are the stimulus, affarent arteriole, and GFR of autoregulation when stim is decreased BP
-stim= decreased blood pressure
-aff art= dilates
-gfr= no change
81
what are the stimulus, affarent arteriole, and GFR of autoregulation when stim is increased BP
-stim= increased blood flow
-aff art= constricts
-gfr=no change
82
return of filtered molecules to
the blood
reabsorption
83
how much water is filtered per day and how much is excreted as urine
180L of water is filtered per day
-only 1 to 2 L excreted as urine
84
what is obligatory water loss
a minimum of 400ml must be excreted to rid the body of wastes
85
85% of reabsorption occurs
in PCT and descending loop of henle
86
the osmolality of filtrate in the glomerular
capsule is equal to
that of blood plasma
87
what is isoosmotic
refers to two solutions having the same osmolarity, meaning they contain the same total concentration of solute particles per unit of solution.
88
what is actively transported out of the
filtrate into the peritubular blood
sodium
89
why is sodium is actively transported out of the
filtrate into the peritubular blood
to set up
a concentration gradient to drive osmosis.
90
how are cells of pct joined
by tight junctions on apical side (facing the inside of tubule)
91
what side of of pct contains microvilli and why
apical side
-increase SA for water and salts
-absorb glucose, amino acids, lipids
92
why do cells in pct have lower Na conc than the filtrate inside the tubule
due to Na+/K+
pumps on the basal side of the cells and low
permeability to Na+
93
what happens to sodium from the filtrate
diffuses into these cells and
is then pumped out the other side
94
the pumping of sodium into interstitial space attracts
negative Cl- out of filtrate
-passive transport
95
what follows Na and Cl into tubular cells and interstitial space
water
96
ions and water diffuse into
pertibular capillaries
97
the "pickup and drop-off" system around the nephron tubules, helping fine-tune what's kept and what’s lost.
peritubular capillaries
98
wrap around the nephron tubules to pick up water, ions, glucose, and other valuable substances that the body reabsorbs from the filtrate.
-main job includes reabsorbing useful things back into blood and delivering wastes from the blood into tubules to be eliminated in urine
peritubular capillaries
99
65% of the salt and water is reabsorbed, but that
is still too much filtrate
100
An additional 20% of water is reabsorbed through
the descending limb of the Loop of Henle
101
The final 15% of water (~27 L) is absorbed later in the
nephron under control of
the hormone Anti-Diuretic
Hormone (ADH)
102
Fluid entering loop of Henle is —- to extracellular
fluids.
isotonic
103
mechanism in LOH (specifically in the juxtamedullary nephrons) that create a concentrated medullary interstitium- essential for concentrated urine
countercurrent multiplier system
104
Cannot be actively pumped out of
the tubes, and it will not cross if isotonic to
extracellular fluid.
water
105
allows for
a concentration gradient to be set up for the
osmosis of water.
the structure of the LOH
106
what portion of LOH sets up the concentration gradient for osmosis of water
ascending portion
107
if fluid inside the tubules is isotonic to the surroinding the fluid, theres no net movement of water bc
there is no gradient. water only moves where fluid is hypertonic and membrane is perm
108
why does the ascending limb set up the gradient
this sets up gradient by pumping oit na/k/cl and impermeable to water. this makes surrounding area hypertonic, making the gradient that pulls water out of descending limb and collecting duct
109
actively pumped into the
interstitial fluid from the thick segment of the
limb
salt (nacl)
110
Movement of Na+ down its electrochemical
gradient from filtrate into tubule cells powers the
secondary active transport of Cl− and K+.
111
how is sodium moved into interstitial fluid
na/k pumps
112
what follows sodium passively due to electral attraction, and what diffuses passively back into filtrate
cl goes out, k goes in
113
cells move againt conc gradient without atp
-follows sodium
secondary active transport
114
what is impermeable in ascending limb
water
115
where does surrounding interstitial fluid become increasingly solute concentrated
bottom of ascending tube
116
tubular fluid entering the descending LOH becomes more --- as it descends
hypertonic
117
what is not permeable and permeable in LOH
not= salt
water is perm
118
in the descending limb, Water is drawn out of the filtrate and into the
interstitial space where it is quickly picked up
by
capillaries
119
as it descends, the fluid becomes more
solute concentrated
120
--- mechanism is created
between the two portions of the loop of
Henle
Positive feedback
121
why is the countercurrent multiplication system considered positive feedback
bc it enhances the others function (osmotic gradient)
122
The more salt the ascending limb removes, the
saltier the fluid entering it will be (due to loss of
water in descending limb).
123
step 1 of countercurrent multiplier system
interstitial fluid is hypotonic due to nacl pumped out of ascending limb
124
step 2 of countercurrent multiplier system
Water leaves descending limb by osmosis,
making the filtrate hypertonic going into the
ascending limb
125
step 3 of countercurrent multiplier system
more nacl in the ascending limb can now be pumped out into interstitial fluid
126
step 4 of countercurrent multiplier system
the greater concentration of the interstitial fluid draws more water from descending limb
127
step 5 of countercurrent multiplier system
filtrate in ascending limb now more concentrated
128
step 6 of countercurrent multiplier system
continues until maximum nacl concentration of inner medulla is reached (1200mOsm)
129
more salty
hypertonic
130
hypotonic
more water
131
Specialized blood vessels around loop of
Henle, which also have a descending and
ascending portion
vasa recta
132
Help create the countercurrent system
because they take in salts in the descending
region but lose them again in the ascending
region
vasa recta
133
keep salts in the interstitial space
vasa recta
134
oncotic pressure
high salt concentration
135
in the vasa recta, what pulls water in and is removed from interstitial space
high salt concentration (oncotic pressure) at beginning of ascending region
-this also keeps salt concentration in interstitial space high
136
in the vasa recta, what are present to aid in the countercurrent exchanges
urea transporters and aquaporins
137
these are apart of peritubular capalaries. function in preserving osmotic gradient in medulla- crucial for water reabsorption and urine concentration
vasa recta
138
last stop of urine formation
collecting duct
139
what is perm and imperm in collecting duct
imp to nacl
perm to water
140
the collectign duct is influenced by
hypertonicity of interstitial space- water will leave if able to
141
perm of water depends on what in the collecting duct
number of aquaporin channels
142
the availability of aquaporins are determined by
ADH
143
ADH binds to receptors on collecting duct, which follows by
cAMP 🡪 Protein kinase 🡪 Vesicles with
aquaporin channels fuse to plasma
membrane.
144
what happens when aquaporins fuse to plasma membrane
they are inserted into apical membrane (side facing urine). this allows water to reabsorb from urine to interstitial space thru osmosis
145
release of ADH stimulated by
increase in blood osmolality
146
diabetes insipidus is characterized by
polyuria (large urine volume) , thirst, and polydipsia (drinking lots of fluid)
-urine in dilute with a hypotonic concentration of less than 300 mOsm
147
may be caused by genetic defects in either the aquaporin channels or the adh receptors
nephrogenic diabetes insipidus
148
must
drink a lot of water to prevent dehydration
nephrogenic diapedes insipidus
149
can
take desmopressin when needed
central diabetes inspidus
150
match electrolyte excretion to ingestion
kidneys
151
adjust how much of each electrolyte they excrete based on how much youve ingested to keep blood levels stable
kidneys
152
Control of --- levels is important in blood
pressure and blood volume.
sodium
153
Control of --- levels is important in healthy
skeletal and cardiac muscle activity
potassium
154
---plays a big role in Na+ and K+
balance.
aldosterone
155
what happens when theres an increase of sodium in kidneys
kidneys excrete more, leads to lower bp and volume
156
what happens when theres a decrease of sodium in kidneys
kidneys conserve na, leading to raise bp and volume
157
About 90% of filtered --- is
reabsorbed early in the nephron
Na+ and K+
158
--- controls additional
reabsorption of Na+ and secretion of K+ in
the distal tubule and collecting duct.
aldosterone
159
Increase
in blood K+ triggers an increase in the number
of K+ channels in the cortical collecting duct.
1) When blood K+ levels drop, these channels are
removed
aldosterone indeoendent response
160
kidneys use this to help regulate potassium levels without aldosterone
ald. independent response
161
high blood potassium is named
hyperkalemia
162
-insert more potassium channels into apical memb
-more k secreted into urine and lowers blood k levels
hyperkalemia
163
low blood k is called
hypokalemia
164
-remones k channels
-reduces k secretion into urine, helps conserve k in body
hypokalemia
165
Increase in
blood K+ triggers adrenal cortex to release
aldosterone.
1) This increases K+ secretion in the distal tubule and
collecting duct.
aldosterone-dependent response
166
causes increase k secretion in urine
ald. dependent response
167
-aldosterone stims more na/k pumps on basolateral membrane and more k channels on apical side
-more k secreted in urine
ald. dependent response
168
what drives extra potassium secretion
increase in sodium absorption
169
why do Potential difference created by Na+ reabsorption
driving K+ through K+ channels
bc sodium reabsorption creates a neg charge in tubule lumen which pulls K out of cell
170
Increased flow rates bend cilia on the cells of the
distal tubule, resulting in
activation of K+ channels
171
low sodium or water in filtrate activates
Renin-angiotensin-aldosterone-system
172
what happens when raas is is activated
more aldosterone and more k secretion
173
what happens if sodium or water are low in filtrate
juxtamedullary releases renin, which activates raas, then aldosterone release
174
what directly stimulates production of
aldosterone in the adrenal cortex.
rise in blood k
175
what indirectly stimulates production of
aldosterone via the renin- angiotensin-aldosterone
system.
a fall in blood na
176
specialized structure in the kidney that plays a crucial role in regulating BP and GFR
juxtaglomerular apparatus
177
located where the dct comes in contact with affarent arteriole of same nephron
juxtaglomerular apparatus
178
what are the main components of juxtaglomerular apparatus
macula densa and granular cells
179
senses the nacl concentration in filtrate. if nacl is too low, it signals JG cells to release renin
macula densa
180
specialized smooth muscle cell that secrete renin in response to low BP or low nacl detected by macula densa. also responds to symp nerv system stimulation
granular cells
181
what is the function of juxtaglomerular apparatus
renin release
-activated raas
-raise BP and promote water retention
182
enzyme secreted by granular cells of kidneys affarent arteriole. plays a crucial role in regulating bp, bv, and na balance thru raas
renin
183
what triggers renin release (3 steps?)
-lower bp (detected by baroreceptors in affarent arteriole
-lower na concentration in dct (detected by macula densa)
-symp nerv system activation
184
what does renin do?
starts the raas cascade:
-converts angiotensinogen to angiotensin 1
-ace converts angiotensin 1 to angiotensin 2
185
what does angiotensin 2 do
-constricts bv= raise bp
-stimulate adrenal cortex to release aldosterone= kidneys retain na and excrete k
-stimulate thirst and adh release= more water retention
186
essential for maintaining bp and fluid balance, especially during dehydration, blood loss, and low salt intake
renin
187
a decrease in plasma na results in
a fall in bv
188
what senses the decrease in plasma na
juxtaglomerular apparatus
189
once the juxtaglomerular apparatus senses the decrease in plasma na, what happens
granular cells secrete renin into aff art
190
what happens once granular cells secrete renin into aff art
this converts angiotensinogen to angiotensin 1
191
what happens once angiotensinogen converts to angiotensin 1
angiotensin converting enzyme converts this into angiotensin 2
192
what stimulates the adrenal cortex to make aldosterone
angiotensin 2
193
when the adrenal cortex is stim to make aldosterone, what happens with na and k
na/k pumps in basal memb:
-promote reabsorption of na from cortical coll duct
-promotes secretion of k
-higher bv and higher bp
194
what does the inhibition of adh secretion result in
low salt levels which result in low bv
-less water reabsorbed in collecting ducts and more water excreted in urine
195
what detects reduced bv and act as baroreceptors
granular cells
196
part of the distal tubule that forms juxtaglomerular apparatus
macula densa
197
what is needed for regulation of GFR (give example)
sensor for tubuloglomerular feedback
-when theres more na and h20 in filtrate, a signal is sent to aff art to constrict limiting filtration rate
198
when theres more na and h20 in filtrate, a signal is sent to aff art to
inhibit production of renin
-results in less reabsorption of na and allowing more to be excreted
-helps lower na levels in blood
199
in the anp, Increases in blood volume also increase
the release of atrial natriuretic peptide
hormone from the atria of the heart when
atrial walls are stretched
200
what happens when the atrial walls are stretched
stimulates kidneys to excrete more salt and water
-decreases bv and bp
201
In addition to atrial natriuretic peptide (ANP),
scientists have discovered a natriuretic
hormone released by the heart’s ventricles
called
beta natriuretic peptide
202
is secreted in response to increased
volume and pressure within the ventricles,
and it acts like ANP to promote diuresis.
beta natriuretic peptide
203
The secretion of ---increases in congestive
heart failure (CHF) so measurements of the
blood level of ---are used clinically to help
diagnose CHF.
bnp
