Phys Exam 4 Flashcards
(187 cards)
1
Q
what is the ultimate functions of the kidneys
A
homeostatic regulation of the water and ion/salt content of the blood
2
Q
6 categories of renal function
A
regulation of extracellular fluid volume and blood pressure
regulation of osmolarity
homeostatic regulation of pH
waste/toxin management
production of hormones
3
Q
how does the urethra differ b/w genders
A
shorter in F -> higher risk for UTI
4
Q
what is the functional unit of kidneys
A
nephrons
5
Q
what makes up the renal corpuscle
A
glomerulus + bowman’s capsule
6
Q
where are 80% of nephrons
A
in the cortex
7
Q
what is the peritoneum
A
serous membrane forming the lining of the abdominal cavity
8
Q
what is each nephron composed of
A
initial filtering component (renal corpuscle) and a tubule specialized for reabsorption and secretion (renal tubule)
9
Q
can we live without our kidneys
A
no!! blood would become toxic
10
Q
does all blood get filtered in the glomerulus ?
A
NO!
11
Q
what is the purpose of the renal portal system
A
allows for filtering of blood, cleaning, reabsorption and secretion
12
Q
where are the 1st and 2nd capillary beds located from the renal portal system
A
1st: in renal cortex -> glomerulus
2nd: in renal cortex and medulla -> peritubular
13
Q
where does the renal portal system empty into
A
the renal vein
14
Q
route of the nephron tubule components
A
renal tubules begin at renal corpuscle -> PCT -> DL -> Loop of Henle -> AL -> DCT -> CD -> to bladder
collecting ducts typically receive drainage from ~8 nephrons
15
Q
where does filtration occur in a nephron
A
ONLY in the renal corpusle. creates protein free plasma!!!
16
Q
what 3 cellular layers facilitate filtration
A
- capillary endothelium -> fenestrated!!
- basal lamina
- podocytes (epi of bowmann’s)
17
Q
where does reabsorption occur in nephrons
A
ALL areas EXCEPT renal corpuscle/Bowman’s capsule!!!
18
Q
where does secretion occur in nephrons
A
PCT, DCT, CD
19
Q
what does the urinary excretion of substances depend on
A
filtration, reabsorption, and secretion
20
Q
what is glycosuria
A
glucose in urine. can be a sign of diabetes
21
Q
what is the epi around glomerular capillaries modified into
A
podocytes
22
Q
what are mesangial cells
A
provide structural support for the glomerular capillary loops
help regulate glomerular capillary flow and filtration
phagocytosis/endocytosis
secrete cytokines that interact with endothelial cells and podocytes
23
Q
what are the processes that surround each capillary, leaving slits through which filtration takes place
A
podocytes
24
Q
what are 3 filtration barriers
A
- glomerular capillary endothelium
- basal lamina
- capsule epi
25
3 primary influences on filtration
1. capillary blood pressure
2. osmotic pressure
3. capsule fluid pressure
26
does 80% of blood go through the afferent or efferent arteriole in glomerular filtration
efferent!
27
less or greater than 99% of plasma entering kidney returns to systemic circulation
GREATER!
28
less or greater than 1% of volume is excreted to external environment
LESS
29
what are 3 things glomerular filtration is influenced by
1. hydrostatic pressure - blood pressure
2. colloid osmotic pressure
3. fluid pressure created by fluid in Bowman's capsule
30
is glomerular capillary pressure higher/lower than pressure in a typical capillary
HIGHER -> this favors the movement of capillary contents into Bowman's capsule lumen (filtration)
31
inside glomerular capillaries, is the colloid osmotic pressure higher or lower
HIGHER inside -> favors movement of filtrate in Bowman's capsule BACK INTO capillary via osmosis
32
filtration pressure in the renal corpuscle depends on _______________ and is opposed by ___________ and ____________________
hydrostatic pressure
colloid osmotic pressure AND capsule fluid pressure
33
what is GFR
the V of fluid that filters into Bowman's capsule lumen per unit time
34
what is the most common and important measure of renal function
GFR
35
what are the 2 main mechs of autoregulations in glomerular filtration homeostasis
1. myogenic responses
2. tubuloglomerular feeback
autoreg maintains nearly a constant GFR!
36
why is local homeostatic control of GFR important
if you dont have it --> damage to filtration membrane
37
what is myogenic responses in GFR
mechanical autoregulation of bloodflow --> vasoconstriction/dilation of arterioles via stretch of mechanoreceptors
38
what is tubuloglomerular feedback in GFR
chemical autoregulation --> vasoconstriction/dilation of arterioles
39
what is autonomic neurons and hormones in GFR
systemic response. can alter the filtration coefficient and can also change arteriole resistance
40
factors controlling filtration homeostasis (3)
myogenic response
tubuloglomerular feedback
autonomic neurons and hormones
41
INCREASED resistance in AFFERENT arterioles leads to _______ GFR (myogenic response #1)
DECREASED GFR
42
INCREASED resistance in EFFERENT arterioles leads to _______ GFR
(myogenic response #2)
INCREASED GFR
Due to low RBF into the afferent arterioles
43
what is one of the most common causes of renal failure
high BP
44
what is proteinuria
damage to the renal corpuscle filtration layers leads to increased protein in the filtrate, resulting in protein in the urine
45
clinically GFR is used to assess
renal function/extent of damage
kidney disease/loss of surface area available for filtration
46
what is the juxtaglomerular apparatus
area between afferent and efferent arterioles
47
what cells are found in the juxtaglomerular apparatus area
1. macula densa
2. juxtaglomerular cells
48
what are macula densa cells
found in the juxtaglomerular apparatus
chemoreceptors, monitor NaCl osmolarity and urine volume -> signal JG cells
49
what are juxtaglomerular cells
found in the juxtaglomerular apparatus
also known as granular cells. modified smooth muscle cells, secrete renin in response to low BP
50
what NS influences the renal system and what does it change
the SNS
resistance in arterioles
51
what are the most important hormones that influence the renal system (2)
angiotension II -> vasoconstrict
prostaglandins --> vasodilators
52
angiotension II do what to arterioles
vasoconstrict
53
PG do what to arterioles
vasodilator
54
where does excretion occur
once filtrate has exited CD -> now is urine
55
what are the benefits of filtering a TON of stuff but excreting only a SMALL amount
it simplifies homeostasis and enables rapid clearance
56
T/F reabsorption is only active
FALSE. Active AND passive
recovers important nutrients
57
filtration is _____ and ______
passive and indiscriminate -> enables rapid removal of foreign substances
58
diffusion of permeable solutes (K+ Ca2+ and urea) out of tubule, back into ECF may occur by
transepithelial/transcellular transport (membrane transport)
paracellular pathway
59
what is transepithelial/transcellular transport (membrane transport)
substances cross apical and basolateral membranes of the tubule epithelial cell (pass through cell)
60
what is paracellular pathway
pass between cells
61
difference b/w diffusion and osmosis
diffusion: doesnt need membrane
osmosis: membrane involved. only things that can pass through membrane
62
what is the primary driving force for most renal reabsorption
active reabsorption of sodium
63
what is sodium symport
another form of active transport. involves co-transportation of molecules in conjunction with Na+ reabsorption
64
T/F: urea is passive if a gradient is present
TRUE -> passive reabsorption occurs through tubule epi cell junctions if a gradient is present (paracellular pathway)
65
how do big proteins get reabsorbed
endocytosis.
66
4 main methods of reabsorption
1. sodium transport starts the process (Na+/K+ pumps)
2. Secondary active transport: symport of additional molecules with sodium
3. passive reabsorption through paracellular pathway and passive transcellular (urea)
4. receptor-mediated endocytosis (small plasma proteins)
67
T/F: mediated transport cannot become saturated
FALSE! they can!
at saturation, no more substrate can be reabsorbed, thus it is excreted in urine.
68
T/F: filtration does not saturate
TRUE
69
excretion =
filtration - reabsorption
70
how does the fluid reabsorbed from the tubule lumen into the interstitial space re-enter the peritubular capillary to increase blood volume
capillary hydrostatic pressure is lower than the pressure in the interstitial space -> favors reabsorption into capillary
71
what is secretion
transfer of molecules from ECF back into the lumen of the nephron
always an ACTIVE process
72
what is an example of a competitive process in terms of secretion
penicillin vs probenecid. once added probenecid, penicillin wouldnt get excreted ASAP anymore -> good!
73
what is excretion
filtration - reabsorption + secretion
74
what is clearance
non-invasive way to measure GFR and determine how the kidney is removing a substance like a drug
rate at which a solute disappears from the BLOOD by excretion
aka the V of plasma from which a substance is completely removed by the kidney in a given amt of time
75
is all of inulin filtered excreted?
YES! none metabolized and no reabsorption or secretion
76
GFR value of what is normal
130-90
77
GFR value of what is considered kidney damage
<90-15
78
a substance that is 100% excreted, clearance will be _______ to GFR
EQUAL
79
when is clearance equal to its GFR
for any substance that is freely filtered but not absorbed or secreted
80
filtration is greater than excretion ->
molecule X is being reabsorbed
81
excretion is greater than filtration
molecule X is being secreted
82
filtration and excretion are the same
no net reabsorption or secretion of molecule X
83
clearance of X is LESS than inulin clearance
reabsorption of X
84
clearance is X is equal to inulin clearance
X is not reabsorbed or secreted
85
clearance of X is greater than inulin clearance
X is secreted
86
is glucose 100% reabsorbed from filtrate or secretion
filtrate -> NO excretion
**unless excessive amt in blood. glucose in urine
87
50% urea is _________ and other 50% is __________
excreted and reabsorbed
88
normal clearance values for
glucose
inulin
PAH
glucose: 0 (completed reabsorbed)
inulin: 125 (not reabsorbed or secreted = GFR)
PAH: 625 (completely secreted)
89
does your renal system produce urine even when you are severly dehydrated
YES! still needs to get rid of toxins cells are producing
90
are fluid and electrolyte levels constant?
NO! constantly fluctuating
91
is edema/swelling ICF or ECF
ECF
92
what conserves water but cannot replace it
kidneys. can only replace water by drinking it
93
what is the most common cause of severe dehydration
severe diarrhea
94
how do kidneys alter urine concentration
by varying the amounts of water and Na+ reabsorbed in the renal tubules (occurs in the loop of henle, distal tubule and collecting ducts)
95
2 types of urine
dilute and concentrated
96
osmolarity changes as
filtrate flows through the nephron
97
what does the final concentration of urine depend on
the water permeability of the distal tubules and collecting ducts to water
98
for water to flow out of the collecting duct via osmosis, the osmolarity of the surrounding interstitial space must be higher/lower than the osmolarity in the C-duct
HIGHER
99
what is another name for vasopressin
ADH
100
what makes ADH
posterior pituitary
101
what influences ADH
BP, blood volume, blood plasma osmolarity/concentration
102
if you have high blood plasma osmolarity, you are hydrated or dehydrated
dehydrated
103
what will happen to ADH production if you have high blood plasma osmolarity
increase bc you are dehydrated
104
what reabsorption is inhibited by
low ADH prodution
105
ADH in simple terms
NOT removing H2O from body
106
diuretic in simple terms
REMOVING H2O from body
107
what does in mean in terms of urine if we have LOW ADH
urine is diluted
108
water permeability is dependent on the amount of
ADH present
109
how does ADH work
causes insertion of aquaporins into the apical membrane of the collecting duct cells by exocytosis of these pores
110
when ADH is absent, what happens to the pores
withdrawn by endocytosis -> membrane recycling
111
what happens to ADH production when you are dehydrated
increases production
112
what is the most potent stimuli for ADH release
osmolarity --> direct connection to hypothalamus
113
is more or less ADH secreted at night (circadian rhythm)
more -> dont get up in middle of night to pee
114
which 4 electrolytes are essential for our bodies to function best
Na+
Ca2+
K+
Cl-
115
filtrate and blood flow moves in the same or opposite directions
opposite -> countercurrent exchange
116
what contributes to the high osmolarity in the renal medulla
urea
ADH influences the osmotic gradients of the renal medulla
117
what is happening at descending limb
water reabsorption. H2O moves from filtration out to interstitial area of renal medulla by osmosis and into vasa recta
118
where is filtrate at the highest concentration
loop turn
119
what is happening at the ascending limb
ion reabsorption: ions moved out to interstitial area of renal medulla by active transport
120
hyper/hypoosmotic interstitial fluid in the renal medulla
hyper
121
hyper/hypoosmotic filtrate leaving the loop of henle
hypo
122
what is necessary for the formation of concentrated urine as filtrate flows through the collecting tubules and ducts
high medullary osmolarity
urea is a key contributor to high osmolarity in the tissue surrounding the loop of henle in the renal medulla
123
how does the countercurrent multiplier system work
reabsorption of ions (through active transport) in the thick ascending limb through the NKCC symporter creates a dilute filtrate in the lumen
124
a drug that inhibits active transport of potassium out of the filtrate would promote what
urine production
125
what happens to V when ingest salt
NO CHANGE
126
what happens when you ingest salt
ADH secreted (via osmoreceptors) and thirst increased
127
why is drinking seawater so bad
bc osmolarity jumps up SUPER high. renal system has to excrete a HUGE amount to balance it --> die
128
what is aldosterone
hormone secreted by suprarenal glands regulates sodium reabsorption through channel expressions
primary site of action occurs in the last 1/3 of distal tubule
129
increased aldosterone means what in terms of Na
increased reabsorption of Na+
130
what is primary target of aldosterone
P cells (principle cells)
line the DCT, connecting tubule, and proximal collecting duct
131
what stimulates release of aldosterone
decreased BP and increased K+ in the blood plasma and ANG II
132
what does aldosterone promote
sodium reabsorption and potassium secretion
133
P cells have
Na+/K+/ATPase pumps on the basolateral membrane and a variety of channels and transporters on the apical membranes
134
stimulus for aldosterone release in blood
increased extracellular K+ concentration acts DIRECTLY on the adrenal cortex to increase aldosterone secretion
decreased BP (indirect)
135
what is ANG II
potent vasoconstrictor
136
ANG II stimulates
aldosterone secretion
ADH secretion
thirst sensation
vasoconstriction
activation of cardiovascular control center
137
what do ACE inhibitors/renin do
blocks cascade -> lowers BP
138
how does low BP stimulate renin production
decreases blood flow in afferent arteriole along with decrease in GFR stimulates renin release
139
what is the most direct effect of sodium homeostasis
kidney
140
what antagonizes ANG II
atrial natriuretic peptide (ANP)
brain natriuretic peptide (BNP)
increases BP
enhances Na+ and water excretion by increasing GFR
141
where does most sodium in our bodies exist
intracellular
142
hyperkalemia
high postassium levels
143
K+ levels affect the resting membrane potential of
ALL cells
144
hyperkalemia
high potassium levels
145
hypokalemia
LOW potassium levels
146
what are the 3 compartments total body Ca2+ is distributed among
extracellular fluid
intracellular fluid
extracellular matrix (bone)
147
what 3 hormones control calcium balance
1. parathyroid hormone
2. Calcitriol
3. Calcitonin
148
what is PTH and what produces it
produced by parathyroid glands
increases Ca2+ in ECF/plasma
removes Ca2+ from bone
promotes renal resorption of Ca2+
149
what does calcitriol do
increases Ca2+ uptake in plasma/ECF
removes Ca2+ from bone
promotes renal resorption of Ca2+
made from vit D and also is known as 1,25 dihydroxycholecalciferol = vit D3
**production is regulated at the kidney by PTH
150
what does calcitonin do and what produces it
opposite to PTH!
produced by thyroid gland
decreases Ca2+ in ECF/plasma
KEEPS Ca2+ in bone
promotes renal excretion of Ca2+
151
what can phosphate influence
calcium
**P is second key ingredient in the hydroxyapatite of bone
152
what is osteoporosis
bone loss
bone resorption exceeds bone deposition
153
what is normal pH of blood plasma
7.35-7.45 pH
**slightly alkaline!
154
what does acidosis do to neurons
neurons become less excitable and CNS depression occurs -> eventually coma
155
what does alkalosis do to neurons
hyper-excitable neurons -> muscle twitches/spasms
156
if ECF is acidosis, kidneys excrete and reabsorb what
excrete: H+
reabsorb: K+
157
if ECF is alkalosis, kidneys excrete and reabsorb what
excrete: K+
reabsorb: H+
158
where do we get our acid inputs
diet
metabolic intermediates --> cellular respiration
159
where is our largest source of acid come from
cellular respiration - aerobic (CO2 production)
CO2 is known as a volatile acid bc it can combine reversibly with water to form carbonic acid --> H+ and HCO3-
160
how is body fluid pH balanced maintained
if acid intake and production by the body = excretion
inputs are from external dit and internal metabolism
outputs are respiratory system mainly and some renal system
161
how does the body manage constant variability in pH
buffers <- controls the most
ventilation
renal regulation
162
what is the equation for carbonic acid
CO2 + H2O <-> H2CO3 <-> H+ + HCO3-
exhaled. acid buffer
163
key info about buffers
buffers moderate acidity but DOES NOT prevent changes in pH
buffers combine or release H+ ions from a combination
buffers include cellular proteins, phosphate ions, and Hb exchanges
164
HCO3- enters the plasma in exchange for
Cl- -> CHLORIDE SHIFT!!!
165
hypoventilation results in an
internal acidotic state
166
hyperventilation results in an
internal alkalosis state (to breathe off CO2 and increase H+)
167
what manages 75% of pH distrubances
ventilation!! breathing
168
what is the most direct approach of pH homeostasis management
renal regulation
but this also is the slowest mech!!
169
how does renal regulation work for pH homeostasis management
direct compensation through excreting or reabsorbing H+
in-direct compensation by changing the rate at which the HCO3- buffer is reabsorbed or excreted
apical -> active transport
basolateral -> symport and antiporter
170
renal collecting ducts intercalated cells type A do what
function in ACIDOSIS
bicarb reabsorption
hydrogen secretion into CD
171
what are intercalated cells of the CD
help maintain pH homeostasis
have high concentration of carbonic anhydrase in cytoplasm
172
how would excessive activity of type A intercalated cells affect K+ levels within the body
hyperkalemia -> create excessive amt K+ in plasma acidosis
173
what do renal collecting duct intercalated cells type B do
function in ALKALOSIS
bicarb secretion into CD
hydrogen reabsorption
174
disorders of CO2 are referred to as
respiratory disorders
175
disorders of HCO3- of fixed acids are referred to as
metabolic disorders
176
if pH shift is due to lung condition is is considered a
respiratory cause
177
if PCO2 and pH are in the SAME direction, then
the problem is METAbolic related
****he said this backwards in lecture have to double check
178
if PCO2 and pH are in REVERSE direction, then
problem is RESPIRATORY related
*****he said this backwards in lecture have to double check
179
what can cause respiratory acidosis
COPD/emphysema
180
what can cause metabolic acidosis
diabetes
181
what type of breathing will a person with metabolic acidosis exhibit that also has diabetes
hyperventilation
182
why do people with diabetes get metabolic acidosis
cant break down glucose bc not enough insulin so body starts breaking down fat for energy. bad!
183
what can result in respiratory alkalosis
panic induced hyperventilation
184
what can result in metabolic alkalosis
excessive puking
185
You are taking excessive amounts of antacids for heartburn on a frequent basis: what is the most likely effect of this on your blood plasma
metabolic alkalosis --> it will slow down breathing = hypoventilation
186
if you blood plasma is more alkaline what does this mean in terms of CO2
CO2 is LOW and a decrease in rate and depth of respiratory volume will occur as a compensation
187
if your blood plasma is more acidic, what does this mean in terms of CO2
CO2 is HIGH and an increase in rate and depth of ventilations will occur as a compensation
