Urinary System Flashcards
1
Q
Functions of the kidneys
A
- regulation of water, inorganic ion balance, and acid-base balance
- removal of metabolic waste products from the blood and their excretion in the urine
- removal of foreign chemicals from the blood and their excretion in the urine
- gluconeogenesis
- production of hormones / enzymes
a. EPO (erythropoietin), which controls erythrocyte production
b. renin, an enzyme that controls the formation of angiotensin and influences blood pressure and sodium balance
c. PTH, which influences calcium balance
2
Q
why is the right kidney lower than the left?
A
because of the liver
3
Q
nephron
A
“functional unit”
~ 1 million / kidney –> can’t make more but can increase workload
4
Q
renal cortex
A
outer layer
5
Q
renal medulla
A
inner layer
6
Q
series of tubules
A
capillaries
7
Q
portal system
A
2 sets of arterioles + 2 sets of capillaries
8
Q
types of nephrons
A
- juxtamedullary
2. cortical
9
Q
juxtamedullary nephron
A
- 15%
- long nephron loop
- generate gradient in medulla needed for water reabsorption from collecting duct
- vasa recta
10
Q
Cortical nephron
A
- 85%
- short nephron loop
- majority of filtration
- do not contribution to hypertonicity in medulla
- peritubular capillaries
11
Q
juxtaglomerular (JG) apparatus
A
macula densa + juxtaglomerular (JG) cells
- important in regulation filtration rate
12
Q
macula densa
A
- distal convoluted tubule (located)
- senses Na+ / Cl-
13
Q
Juxtaglomerular (JG) cells
A
- afferent arteriole
- secrete renin
14
Q
basic regnal processes
A
- glomerular filtration
- tubular reabsorption / secretion
- water conservation
15
Q
glomerular filtration
A
creates a plasma like filtrate of blood
–> renal corpuscle
16
Q
tubular reabsorption
A
removes useful solutes from the filtrate, returns them to the blood
- in the PCT and DCT
17
Q
tubular secretion
A
removes additional wastes from the blood, adds them to the filtrate
- in the PCT and DCT
18
Q
water conservation
A
removes water from the urine and returns it to the blood; concentrates wastes
- in the PCT, collecting duct, and loop of nephron
19
Q
what substances are filtered + secreted but not reabsorbed?
A
drugs / toxins
20
Q
what substances are filters and some of it is reabsorbed?
A
Na+ / water
21
Q
what substances are filtered and completely reabsorbed?
A
glucose
22
Q
renal corpuscle
A
glomerular capillaries + glomerular capsule
glomerular capillaries + podocytes = glomerulus
23
Q
layers of glomerular filtration
A
- capillary endothelium
- basement membrane
- podocytes
LEAKY!!
24
Q
glomerular filtration filters based on:
A
- size
2. charge
25
basement membrane
gel like negative charge: repels large, charged molecules
26
substances that are turned back during glomerular filtration
- blood cells
- plasma proteins
- large anions
- protein-bound minerals and hormones
- most molecules >8 nm in diameter
27
substances passed through the filter during glomerular filtration
- water
- electrolytes
- glucose
- amino acids
- fatty acids
- vitamins
- urea
- uric acids
- creatine
28
GFR
glomerular filtration rate
29
GFR average
125 mL/day
30
favoring filtration:
- PGC (glomerular capillary blood pressure)
31
opposing filtration:
- PBS (fluid pressure in Bowmen's space)
| - πGC (osmotic force due to proton in plasma)
32
average of PCG
60
33
net glomerular filtration pressure equation
PGC - PBS - πGC
34
PGC > PBS + πGC means
movement of fluid into capsule
35
vasomotion __
of the afferent and efferent arteriole alters PGC to change GFR
36
constrict afferent arterioles means
- decreased PGC
| - decreased GFR
37
dilate efferent arterioles means
- decreased PGC
| - decreased GFR
38
constrict efferent arterioles means
- increased PGC
| - increased GFR
39
dilate afferent arterioles means
- increased PGC
| - increased GFR
40
renal auto regulation (intrinsic control)
ability of nephrons to adjust blood flow in order to maintain GFR despite changes in blood pressure ---> ordinary daily changes
41
intrinsic controls on regulation of GFR
1. myogenic mechanism
| 2. tubuloglomerular feedback
42
myogenic mechanism
- smooth muscle contracts when stretched
- increased BP = increased stretch of afferent arteriole = increased vasoconstriction = decreased PGC = maintain GFR despite increased BP
43
tubuloglomerular feedback
- high GFR
- rapid flow of filtrate in renal tubules
- sensed by maculae densa via Na+ / Cl-
- paracine secretion --> adenosine
- constriction of afferent arteriole --> decreased PGC
- reduced GFR
44
effects of autoregulation
- when BP changes rapidly, GFR does not change much (maintains fluid/electrolyte balance)
- if no renal auto regulation:
MAP: 100 --> 125 mmHg
urine output would go from 1-2 L/day to 45 L/day
45
extrinsic control on regulation of GFR
- sympathetic nervous system
- when BP change is dramatic / persistent (strenuous exercise / shock)
- SNS = vasoconstrict afferent arteriole (also help redirect blood flow to heart, brain, muscles) = decreased PGC = decreased GFR
46
tubular reabsorption
- filtered loads are huge
- reabsorption of water, ions, nutrients, etc. is almost complete
- --> water and ions are regulated
- --> nutrients are NOT regulated
- reabsorption of wastes is incomplete --> excreted
- most reabsorption occurs in PCT (65%)
- 99% of filtrate is reabsorbed
- occurs by diffusion and thru transporters
- --> not regulated in the PCT
47
transport maximum
- substances needing protein carriers have a "transport maximum"
- if all transporters are occupied some solute won't be reabsorbed and will appear in urine
- only occurs in a diseased state
48
tubular secretion
- to dispose of substances at higher rate than filtered load
- foreign chemicals (drugs) and toxins
- --> 80% of penicillin lost in 3-4 hours
- metabolic wastes (urea, uric acid, creatinine)
- H+ / K+
- via active transport (usually coupled to sodium)
- --> can also have transport maximum, foreign chemicals compete for same transporters
- most secretion is into proximal tubules (not regulated)
- -> except K+ and H+ are in the distal (regulated)
49
Na+ is regulated by ______ and ______ in the ______ during tubular _______
aldosterone and ANP in the DCT during tubular reabsorption
50
K+ is regulated by _____ in the ____ during tubular ____
aldosterone in the DCT during tubular secretion
51
water is regulated by _____ in the _____ during _____
ADH in the collecting duct during tubular reabsorption
52
water follows solute via _____
osmosis
53
Na+ determines amount of water in the extracellular fluid means
increased Na+ = increased water = increased blood volume = increased blood pressure
54
sodium reabsorption
- most Na+ is reabsorbed in the PCT (not regulated)
- Na+ reabsorption is regulated in DCT
- aldosterone builds Na+ channels and Na+/K+ pumps
- ANP inhibits Na+ channel activity
55
effects of angiotensin II
1. widespread vasoconstriction (increase TPR)
2. increased aldosterone = increase Na+ reabsorption in DCT
3. increased ADH = increased water reabsorption in collecting duct
56
result of angiotensin II
when plasma volume drops, an increase in RAA reduces Na+ and water loss to increase BP
57
atrial natriuretic peptide (ANP)
increased BP/BV = stretch in right atria = increase ANP =
1. afferent dilation & efferent constriction = increase GFR
2. decreased aldosterone
3. decreased ADH
4. decreased Na+ reabsorption
- -> increase Na+ and water excretion
58
ANP result
when plasma volume increases, ANP increases Na+ and water loss to decrease BP
59
water reabsorption
- proximal tubule; water follows Na+ --> osmotic drage
- not regulated
- osmosis is ALWAYS the driving force for water
- regulation of water reabsorption in the distal nephron requires an osmotic gradient in the medulla
60
countercurrent multiplier
in loop of nephron = creates gradient in vasa recta
- effect is "multiplied" as move deep into medulla"
- urea from collecting duct contributes to increased osmolarity of ECF
61
countercurrent exchanger
maintains gradient
62
ascending limb (countercurrent multiplier)
- active transport of salt --> into medulla (ECF)
- impermeable to water
- water does not follow
63
descending limb (countercurrent multiplier)
- impermeable to salt
- permeable to water
- water moves out until concentration in/out are equal
64
higher protein diet leads to
increased urea = increase ability to concentrate urine
65
renal regulation of water
- osmotic gradient is used in collecting duct to concentrate urine
- --> gives water a reason to move
- presence of water channels in collecting duct is regulated by ADH
66
when is ADH secreted?
when blood osmolarity is high (dehydrated)
67
+ADH
increased number of Aquaporins in collecting duct = increased water reabsorption
68
- ADH
decreased number of Aquaporins in collecting duct = increased excretion (collecting duct is relatively impermeable to water)
69
what gland secreted ADH?
posterior pituitary
70
main function of ADH
regulate plasma osmolarity
71
renal regulation of potassium
- potassium is the main intracellular ion
- small changes in [K+] of ECF can cause lethal malfunction of excitable tissues
- K+ is absorbed in the PCT by diffusion
- excess K+ is secreted in the DCT (regulated by low)
72
norokalemia
- K+ concentrations in equilibrium
- equal diffusion into and out of cell
- normal resting membrane potential (RMP)
73
hypokalemia
- reduced extracellular K+ concentration
- greater diffusion of K+ out of cell
- reduced RMP (cells hyper polarized)
- cells less excitable
74
hyperkalemia
- elevated extracellular K+ concentration
- less diffusion of K+ out of cell
- elevated RMP (cells partially depolarized)
- cells more excitable
75
aldosterone
- regulates the secretion of K+ in the distal nephron by building pumps and channels
- cells are directly sensitive to K+ levels (no renin involved)
76
H+ gain
- generation of H+ from CO2
- production of acids from metabolism of proteins and other organic molecules
- gain H+ due to loss of bicarbonate in diarrhea or other non gastric GI fluids
- gain of H+ due to loss of bicarbonate in the urine
77
H+ loss
- utilization of H+ in the metabolism of various organic anions
- loss of H+ in vomit
- loss of H+ (primarily in the form of H2PO4- and NH4+) in urine
- hyperventilation
78
urine is usually ____
acidic
| - except for strict vegetarians
79
buffers
- first line of defense
- short-term
- msec-sec
80
buffers buffering capacity
low
81
buffers response time
fast
82
respiratory
- via changes in CO2
- intermediate
- sec - min
83
respiratory buffering capacity
intermediate
84
respiratory response time
intermediate
85
renal
- via bicarbonate / H+ excretion
- long-term
- hours - days
86
renal buffering capacity
high
87
renal response time
slow
88
buffer systems ICF
- phosphates
| - proteins
89
buffer systems ECF
- bicarbonate
| - proteins
90
what happens when there is too much acid/base in the buffer system?
shift equilibrium = release or accept H+
91
respiratory system
CO2 + H2O -->
92
what happens when there is too much acid in the respiratory system?
hyperventilate to decrease CO2 = decrease H+
93
what happens when there is too much base in the respiratory system?
hyperventilate to increase CO2 = increase H+
94
renal regulation of pH
kidneys filter bicarbonate but CANT reabsorb it directly
95
renal regulation: when pH is balanced
filtered bicarbonate is recovered and "recycled" into new bicarbonate ion
96
what if blood is alkalotic?
bicarbonate ions that are filtered run out of H+ to recombine with = excreted
- more bicarbonate than H+
- not regulated = no active response = it just happens
97
Renal regulation: Excess H+
- after all filtered bicarbonate is gone, secreted H+ combines with phosphates and is excreted
- net gain of bicarbonate
- H+ excretion bound to HPO4-2
98
renal regulation: excess H+ w/ glutamine
- secrete H+ with ammonium
- net gain of bicarbonate
- H+ excretion bound to NH3-
- urine pH can be as low as 4.5 then transporters stop working
99
acidosis
- pH < 7.35
- decrease CNS function (confusion, disorientation, coma)
- pH < 7.0 quickly fatal
100
alkalosis
- pH >7.45
- increase muscle contraction (spasms, convulsions, paralysis)
- pH > 8.0 quickly fatal
101
respiratory
change in pH caused by change in CO2
102
metabolic
change in pH not caused by change in CO2
103
respiratory acidosis problem
increased CO2
104
respiratory acidosis causes
- hypoventilation
| - emphysema
105
respiratory acidosis respiratory compensation
increase ventilation
106
respiratory acidosis renal compensation
increase H+ excretion
| - bound to H2PO4- or NH4+
107
respiratory alkalosis problem
decreased CO2
108
respiratory alkalosis cause
hyperventilation
109
respiratory alkalosis respiratory compensation
decrease ventilation
110
respiratory alkalosis renal compensation
increase bicarbonate excretion
| - nothing to bind to
111
metabolic acidosis problem
increased H+ or decreased bicarbonate
112
metabolic acidosis causes
- diarrhea
- diabetes
- exercise
113
metabolic acidosis respiratory compensation
increase ventilation
114
metabolic acidosis renal compensation
increase H+ excretion
| - bound to H2PO4- or NH4+
115
metabolic alkalosis problem
decreased H+ or increased bicarbonate
116
metabolic alkalosis causes
- vomiting
- increased aldosterone
- exchange K+ for Na+ first then will use H+
117
metabolic alkalosis respiratory compensation
decrease ventilation
118
metabolic alkalosis renal compensation
increase bicarbonate excretion
| - nothing to bind to
119
renal clearance
- the volume of plasma from which all of a substance is removed (cleared by the kidney per minute
- also a measure of efficiency of kidneys
120
equation of renal clearance
C = [U] x V / [P]
121
clearance is used to determine
- GFR
- renal plasma flow
- handling of new substances
122
inulin
polymer of fructose from plants
- must infuse at a constant rate
- is used to measure GFR with renal clearance
123
what is used for a more practical way for renal clearance?
Creatinine
124
Creatinine
- produced by muscles at a constant rate
- freely filtered
- not reabsorbed
- only slightly secreted
- measuring creating clearance gives a 10% overestimate of GFR
125
PAH
para-amino hippuric acid
126
clearance of PAH
- infused like inulin
- PAH is completely secreted and all removed in one pass
- so clearance of PAH is about renal plasma flow
- decrease C PAH = decrease renal plasma flow = blockage of renal artery
127
urine
- shade of yellow
| - clear
128
specific gravity range
1. 002 - 1.030
| - used to estimate osmolarity
129
osmolarity range
about 80 - 1200 mOsm/L
130
pH range
4.5 - 8.2
131
urine volume range
1-2 L/day
132
what shouldn't be in urine
- protein
- blood
- ketones
- glucose
- bilirubin
- urobilinogen
- nitrites
- leukocytes
133
protein
- trace amounts okay
| - kidney disease
134
blood
- kidney stones
| - infection
135
ketones
- product of fat metabolism
| - fasting, keto diet, increased diabetes
136
glucose
hyperglycemia, increased diabetes
137
bilirubin
- increase in liver disease
| - metabolite of Hb degradation, normally lier puts in bile
138
urobilinogen
from eating fatty foods/meals
139
nitrites
- increased infection
| - metabolite of bacteria
140
leukocytes
- increased infection
| - WBC's
141
UTI
- increased WBC's
- bacteria
- +/- nitrites
142
glomerular nephritis
- increased WBC's
- increased protein
- pus
143
bilirubin formation and excretion
- normally removed by liver and put in bile
- small amounts are normal in urine
- increased by GI tract during fatty meals
144
diuresis
> 2L urine / day
145
diuretic
any chemical that increases urine volume
146
diuretic: caffeine
dilates afferent arteriole = increased GFR
147
diuretic: alcohol
inhibits ADH = increased water excretion
148
diuretic: nicotine
antidiuretic = increase ADH release
149
diabetes mellitus (osmotic diuresis)
- failure to reabsorb glucose --> Tm
- more water is excreted with glucose
- water follows glucose into urine
150
diabetes insipidus (water Diuresis)
- failure of posterior pituitary to release ADH or failure of kidney to respond to ADH
- water permeability in collecting duct is low
- increased water loss
- 25 L / day
151
what type of muscle is the detrusor
smooth muscle
152
detrusor innervation type
PSNS causes contraction
153
detrusor during filling
inhibited
154
detrusor during micturition
stimulated
155
what type of muscle is the internal urethral sphincter
smooth muscle
156
internal urethral sphincter innervation type
SNS causes contration
157
internal urethral sphincter during filling
stimulated
158
internal urethral sphincter during micturition
inhibited
159
what type of muscle is the external urethral sphincter
skeletal muscle
160
external urethral sphincter innervation type
somatic motor causes contraction
161
external urethral sphincter during filling
stimulated
162
external urethral sphincter during micturition
inhibited
