Kidney (K1-K9) Flashcards
(276 cards)
1
Q
these are firm, reddish brown glands, located close to the dorsal body wall high in the abdomen at the level of the thoracolumbar junction
A
kidneys
2
Q
this kidney is usually more cranial (except the pig)
A
right
3
Q
the right kidney is embedded in this of the liver, which secures its position
A
renal fossa
4
Q
this is tough and fibrous covering of the kidneys that restricts their ability to expand
A
capsule
5
Q
within the kidney, the parenchyma can be visually divided into these two sections
A
outer cortex and inner medulla
6
Q
this part of the kidneys contains the renal corpuscles and convoluted parts of renal tubules; it is light in color and granular in appearance
A
cortex
7
Q
this part of the kidney is characterized by its striated appearance and contains collecting ducts and nephric loops
A
inner medulla
8
Q
these are the functional units of the kidney, the structures that are apparent within the cortex and medulla
A
nephrons (corpuscle, tubules, loops, and ducts)
9
Q
these are paired tubes that form as the internal ducts within the kidneys join to form a common expansion (renal pelvis); exit the kidney at the hilus and follow a saggital course towards the pelvis
A
ureters
10
Q
the ureter bends medially to enter this in the male
A
genital fold
11
Q
the ureter bends medially to enter this in the female
A
broad ligament
12
Q
what are the three regions of the bladder
A
apex, the neck, body
13
Q
this region of the bladder is a cranial blind end
A
apex
14
Q
this region of the bladder is a funnel-shaped region between ureter openings and urethra
A
the neck
15
Q
this region of the bladder is situated between the neck and apex
A
the body
16
Q
this is the duct through which urine is discharged from the bladder
A
urethra
17
Q
the male urethra consists of these two components
A
pelvic and penile
18
Q
each kidney is supplied by this artery arising from the abdominal aorta
A
renal artery
19
Q
veins that correspond with the arteries of the kidney join to form this single vein that enters the vena cava
A
renal vein
20
Q
efferent arterioles arising from juxtamedullary nephrons descend into the medulla and give rise to this, which descend and re-ascend close to the Loops of Henle
A
vasa recta
21
Q
this is the functional unit of the kidney and consists of the renal corpuscles and renal tubules
A
nephron
22
Q
what are the two major parts of the nephron
A
renal corpuscles and renal tubules
23
Q
these are responsible for the filtration of blood and are made up of Bowman’s capsule and the glomerulus
A
renal corpuscles
24
Q
this part of the renal corpuscles consists of a single layer of flattened cells resting on a basement membrane
A
Bowman’s capsule
25
this is a network of capillaries that arise from the afferent arteriole, and invaginate Bowman's capsule
glomerulus
26
the renal cortex is easily identified at low magnification due to the presence of these, which are not found in the renal medulla
renal corpuscles
27
the capillary loops of the glomerulus are supported by specialized connective tissue called this
glomerular mesangium
28
these cells are contractile and can modify the diameter of glomerular capillaries (secrete vasoactive substances and other factors)
mesangial
29
this is the first part of the renal tubule which drains Bowman's capsule and is made up of a coiled section and a shorter straight segment
proximal tubule
30
this is the coiled section of the proximal tubule; it is lined by simple, cuboidal epithelium with a prominent brush border which increases surface area for absorption; it is the longest and most convoluted part of the nephron
proximal convoluted tubule (PCT)
31
this is the shorter straight segment of the proximal tubule; it is lined by low cuboidal epithelium with no brush border and leads onto the loop of Henle
proximal straight tubule (PST)
32
name the three parts of the loop of Henle
descending thin limb, ascending thin limb, thick ascending limb
33
the cells in th thick ascending limb of loop of Henle that lie closest to Bowman's capsule are specialized cells known as this; they mark the end of the thick ascending limb and start of distal convoluted tubule
macula densa
34
this is a group of specialized cells that regulate renal blood blow comprised of 3 cell types
juxtaglomerular apparatus
35
what are the 3 cell type that comprise the juxtaglomerular apparatus?
1. extraglomerular mesangial cells
2. granular cells
3. macula densa cells
36
once the fluid has been deposited into the calyx it is known as this and no longer changes
urine
37
this is an area of the urinary bladder and is a dorsal triangular area connecting the ureteral openings and urethral exit; has a smooth mucosa and originates from mesoderm
trigone
38
the male urethra is lined by this type of epithelium
stratified or psuedostratified columnar epithelium
39
the female urethra is predominately lined by this type of epithelium (but changes to stratified squamous epithelium near the external urethral orifice)
urinary epithelium
40
this species kidney has obvious external demarcation of the cortex and separation of the medulla into lobes/pyramids
bovine
41
what is the classification of the bovine kidney
multilobar or multipyramidal
42
this species kidney is multilobar, however has a single cortex with a smooth outer surface and has a flattened appearance
pig
43
these species (5) kidney is unilobar, the cortex and medulla fuse into a single unit and the linearly fused papillae form a renal crest
cat, dog, horse, rodent, and sheep
44
these 2 species have the standard smooth, bean-shaped kidneys that are reddish brown and cannot be distinguished from each other
dog and sheep
45
this species has a unilobular kidney with a fused cortex and is heart-shaped/triangle-shaped
horse
46
approximately 2/3 of total body water (40% total body weight) is located within cells and known as this
intracellular fluid (ICF)
47
one third (20% total body weight) is located outside of cells and known as this
extracellular fluid (ECF)
48
what are the two subcategories of extracellular fluid
interstitial or intravascular
49
what percent of total lean bodyweight is made up of water
60%
50
what is the ratio of fluid percentages in the body? (total lean bodyweight made of water:intracellular fluid:extracellular fluid)
60:40:20
51
the intracellular and extracellular fluid compartments are separated by this
cell membrane
52
the interstitial and intravascular fluid compartments are divided by this
vascular endothelium
53
what are the three main colloid particles within plasma?
vascular endothelium is not permeable to them
albumin, globulins, and fibrinogen
54
the particles within a particular fluid compartment exert this meaning they can cause fluid to move by osmosis to one or other side of the membrane, towards the area of higher solute concentration (higher osmolarity)
osmotic pressure (tonicity)
55
this is a measure of all particles dissolved within a fluid compartment , whether or not they can cross the semi-permeable membrane
total fluid osmolarity
56
particles that can cross the semi-permeable membrane contribute to this but not to this
osmolarity but not osmotic pressure
57
what is the average plasma osmolarity in a dog
300 mOsm/kg
58
this pressure is the contribution of colloid particles and their associated electrolytes towards plasma oncotic pressure
oncotic pressure (aka colloid osmotic pressure, COP)
59
this is the only difference between intravascular and interstitial fluid
the concentration of proteins
60
standard biochemical tests measure solutes within this fluid and may not reflect changes in total body solute levels
extracellular fluid
61
fluid flux across the capillary endothelium is described by this equation
Starling's equation
62
what are the Starling forces in Starling's equation
the oncotic and hydrostatic pressure gradient's between the capillary and interstitium
63
along the length of the capillary, this pressure increases and this pressure decreases
oncotic pressure increases, hydrostatic pressure decreases
64
fluid moves (into or out of?) the capillary at the arteriolar end/beginning
out of (into the interstitium)
65
fluid moves (into or out of?) the capillary at the end ?
into the capillary
66
why is plasma COP essential to prevent excessive fluid efflux into the the interstitium?
intravascular and interstitial osmolality would be identical and fluid would move freely out of capillaries causing oedema and potential loss of blood volume
67
this is a gel-like matrix on the luminal surface of endothelial cells now thought to determine transcapillary fluid flux
glycocalyx
68
these are fluids containing electrolytes and other solutes that can freely cross the capillary endothelium to pass between the intravascular and interstitial space
crystalloids
69
crystalloids are classified according to this
their osmolarity relative to that of plasma
70
fluids with osmolarity greater than plasma (300 mOsm/kg) are termed this
ex: 7.2% NaCl
hypertonic
71
fluids with osmolarity lower than plasma (300 mOsm/kg) are termed this
ex: 0.45% NaCl
hypotonic
72
fluids with osmolarity similar to plasma (300 mOsm/kg) are termed this
ex: 0.9% NaCl
isotonic
73
this type of saline is very effective for resuscitating patients in severe shock because water is pulled rapidly out of the intracellular space and redistributes between the interstitial and intravascular spaces
hypertonic saline
74
these losses of water are easy to measure, i.e. urine
sensible losses
75
these losses of water are difficult to measure, i.e. feces, saliva, evaporation from respiratory tract, skin
insensible losses
76
this component of urinary water loss is the amount of water required for the kidney to excrete solutes such as urea
obligatory loss
77
this component of urinary water loss is the removal of any water excess to body requirements
free loss
78
healthy dogs drink about this much water per day
50-60 mL/day
79
if a dog drinks more than 100 mL of water per day it is defined as this
polydipsia
80
what is the normal urine output of a healthy dog?
1-2 mL/kg/hour
81
name some causes of abnormal fluid loss
vomiting, diarrhea, polyuria, high body temp, excessive panting, hemorrhage, exudation/transudation into a body category, ongoing physiological losses due to reduced water intake
82
fluid is often lost first from here
extracellular fluid
83
a loss of hypotonic fluid will have this effect on ECF tonicity resulting in this shift of fluid
hypertonic, water moves out of ICF
84
a loss of hypertonic fluid will have this effect on ECF tonicity resulting in this shift of fluid
hypotonic, water moves into ICF
85
this type of fluid loss is loss of water in excess of solute
hypotonic
86
this type of fluid loss is loss of water and solute in equal proportions
isotonic
87
this type of fluid loss is loss of solute in excess of water
hypertonic
88
perfusion of tissue with blood depends on this fluid compartment
intravascular fluid compartment
89
hydration depends on these 2 fluid compartments
interstitial and intracellular fluid compartments
90
this is the process by which water and solutes leave the vascular system through the filtration barrier of the glomerular capillaries and enter the Bowman's space
glomerular filtration
91
the volume of filtrate formed per unit of time by glomerular filtration is known as this
Glomerular Filtration Rate (GFR)
92
this is a network of capillaries between the afferent and efferent arterioles, encased within the Bowman's capsule
glomerular filter
93
what are the three major layers of the glomerular capillary membrane which make up the filtration barrier
1. glomerular endothelium
2. basement membrane
3. podocytes
94
this layer of the glomerular capillary membrane prevents filtration of plasma proteins because of the strong negative electrical charges associated with the proteoglycan molecules
basement membrane
95
what 3 layers is the basement membrane of the glomerular capillary membrane made up of
1. lamina rara interna: fused to endothelium
2. lamina densa: middle
3. lamina rara externa: fused to epithelium
96
which is the most significant filtration barrier of the glomerular capillary?
basement membrane
97
this is a layer of intricate interlocking cells that make up the visceral epithelium of the glomerular capillary membrane
podocytes
98
this is the resulting product of glomerular filtration
an ultrafiltrate of plasma
99
solutes pass through the 3 layers of glomerular capillary membrane to form an ultra filtrate which enters this
proximal tubule
100
the glomerular filtration barrier restricts the filtration of molecules on the basis of these 3 things
size, weight, and electrical charge
101
all surfaces of the glomerular filtration barrier contained fixed polyanions, which repel macromolecules with this charge (prevents protein loss with urine since many proteins in the blood have this charge)
negative
102
which Starling's forces favor glomerular capillary filtration
hydrostatic pressure in glomerular capillary (oncotic pressure in Bowman's capsule is near zero so doesn't really favor filtration)
103
which Starling's forces oppose glomerular capillary filtration
oncotic pressure in glomerular capillary bed and hydrostatic pressure in Bowman's space
104
for glomerular capillaries, the net ultrafiltration pressure always (favors or opposes?) filtration
so, the direction of fluid movement is always (into or out of?) capillaries
favors filtration, out of capillaries
105
GFR is regulated by changes in the hydrostatic pressure within the glomerular capillary which is mediated by changes in this
resistance of the afferent and efferent arteriole
106
afferent arteriolar resistance is (positively or negatively?) correlated with the hydrostatic pressure in the glomerular capillary and therefore GFR?
negatively (decrease in resistance increases hydrostatic pressure and GFR)
107
efferent arteriolar resistance is (positively or negatively?) correlated with the hydrostatic pressure in the glomerular capillary and therefore GFR?
positively (decrease in resistance decreases hydrostatic pressure and GFR)
108
what is the equation for renal blood flow (RBF)?
RBF = (renal artery pressure - renal vein pressure) / total renal vascular resistance
109
the blood flow through the kidneys serves these 5 important functions
1. indirectly determines GFR
2. modifies rate of solute & water reabsorption by proximal tubule
3. participates in concentration & dilution of urine
4. delivers O2, nutrients, and hormones to cells of nephron and returns CO2 and reabsorbed fluid and solutes to general circulation
5. delivers substrates for urinary excretion
110
what are the 3 major sites for renal resistance
1. interlobular arteries
2. afferent arterioles
3. efferent arterioles
111
Vasodilation of the afferent arteriole (decreased resistance) will have this effect on RBF and GFR
increase both RBF and GFR
112
Vasoconstriction of the afferent arteriole (increased resistance) will have this effect on RBF and GFR
decrease both RBF and GFR
113
Vasodilation of the efferent arteriole (decreased resistance) will have this effect on RBF and GFR
increase RBF and decrease GFR
114
Vasoconstriction of the efferent arteriole (increased resistance) will have this effect on RBF and GFR
decrease RBF and increase GFR
115
what are the 2 autoregulation mechanisms that maintain constant RBF and GFR when the systemic blood pressure is between 80-200 mmHg
myogenic reflex and tubuloglomerular feedback
116
this reflex responds to changes in arterial blood pressure by constricting or dilating the afferent arteriole to maintain RBF and GFR at a constant level
myogenic
117
this reflex responds to changes in the NaCl concentration of tubular fluid and has a predominant effect on the afferent arteriole to regulate RBF and GFR
tubuloglomerular feedback
118
the NaCl concentration of tubular fluid is sensed by this part of the juxtaglomerular apparatus (JGA)
macula densa
119
what are the 3 components of the juxtaglomerular apparatus (JGA)?
1. macula densa
2. extraglomerular mesangial cells
3. juxtaglomerular cells
120
this component of the juxtaglomerular apparatus (JGA) is the thick ascending limb of Loop of Henle
macula densa
121
this component of the juxtaglomerular apparatus (JGA) surround the capillary loop
extraglomerular mesagnial cells
122
this component of the juxtaglomerular apparatus (JGA) are specialized smooth muscle cells and make up the afferent and efferent arterioles
juxtaglomerular cells
123
when increased tubular fluid NaCl concentration is sensed by the macula densa, ATP and adenosine are released by the macula densa cells which has this effect on the afferent arteriole
vasoconstrictive effect (decreases RBF & GFR)
124
when decreased tubular fluid NaCl concentration is sensed by the macula densa, signals are initiated with these 2 effects
vasodilation of afferent arteriole and increased renin release from JGA cells
125
the ideal glomerular biomarker for measuring GFR must have these 3 characteristics
1. be readily filtered across the glomerular capillaries, with no size or charge restrictions
2. be secreted unchanged
3. cannot effect GFR
126
this is the most tradition biomarker used for determining glomerular filtration; fructose polymer with 5000 Da molecular weight
inulin
127
this is an end-product of muscle catabolism and is an example of an endogenously produced biomarker for GFR
-it is freely filtered by the glomerulus at a constant rate but is a poor sensitive marker for GFR as blood serum levels do not increase until GFR decreases > 75%
creatinine
128
this is defined as the amount of substance filtered by the glomerulus into the Bowman's space per unit time
filtered load
129
this is the movement of filtered solutes and water from tubular lumen back into the peritubular capillary
reabsorption
130
what are the 4 general mechanisms for reabsorption within the nephron
diffusion, facilitated diffusion, coupled transport, and active transport
131
this is when solutes dissolved in water are also carried along with the water when it is reabsorbed across tubule segments
solvent drag
132
if both solutes are transported via coupled transport in the same direction, the carrier protein is known as this
symporter
133
name 2 examples of symporters (one in the proximal tubule and one in the thick ascending limb of the loop of Henle)
1. Na-glucose transporter
2. Na-K-2Cl transporter
134
if each solute is transported via coupled transport in opposite directions, the carrier protein is known as this
antiporter
135
name an example of an antiporter in the proximal tubule
Na-H transporter (Na into cell, H+ out of the cell into the lumen)
136
what is the most prevalent example of active transport within the kidney (within the basolateral membrane)
Na-K-ATPase pump
137
this is when solutes cross the tubular epithelium by passing BETWEEN the cells (through tight junctions)
paracellular transport
138
this is when solutes cross the tubular epithelium by passing THROUGH cells
transcellular transport
138
this type of junction in tubular epithelium promotes the reabsorption of a large concentration of solutes and water; commonly seen within the proximal tubule
leaky junction
139
this type of junction in tubular epithelium have a low basal water permeability and effectively bar paracellular flow of water and solutes; typically found within the distal tubule
tight junctions
140
most reabsorption of water and solutes that have been filtered by the glomerulus occurs here
proximal convoluted tubule (PCT)
141
this is the longest and most convoluted part of nephron with a rich capillary network of peritubular capillaries surrounding it
proximal convoluted tubule (PCT)
142
in mammals, the peritubular capillary originates at this and subdivides, wrapping closely around the proximal tubule, allowing for the return of reabsorbed molecules back into the bloodstream
efferent arteriole
143
what are 4 reasons the proximal convoluted tubule has such a high efficacy for solute reabsorption
1. rich peritubular capillary network
2. brush border of microvilli
3. lateral cellular interdigitations of basolateral cell membrane
4. large numbers of mitochondria and protein carrier molecules
144
this accounts for almost half of the total solutes in the tubular fluid entering the PCT and most of the rest are anions that must accompany it to maintain electroneutrality
sodium
145
this is the first step in the process of solute reabsorption in the PCT
-achieved by the Na-K-ATPase pump
active transport of sodium out of tubular epithelial cell into interstitium
146
how is glucose reabsorbed across the tubular epithelium in the PCT?
glucose transporters (not paracellular transport)
147
why is glucose able to be almost completely reabsorbed in the PCT?
it is impermeable to the tight junctions
148
how are many of the solutes (including urea, potassium, calcium and magnesium) reabsorbed in the PCT?
paracellular transport via leaky tight junctions
149
this is responsible for concentrating or diluting the tubular fluid using concurrent multiplication
loop of Henle
150
this limb of the loop of Henle has low, simple squamous epithelium with few mitochondria so there is relatively little active transport of solutes here; however it is highly permeable to water with aquaporin 1 receptors and is responsible for 20% of water resorption
thin descending limb
151
the descending limb of the loop of Henle does not reabsorb solutes, so the tubular fluid tonicity (increases or decreases?) along its length and becomes this
increases, hypertonic
152
solutes are reabsorbed within this limb of the loop of Henle (impermeable to water)
ascending limb
153
the epithelial cells within this segment of the loop of Henle are relatively tall with many mitochondria and membrane in-foldings to allow for high capacity active solute transport
thick ascending limb
154
these segments of the renal tubule are commonly referred to as the 'diluting segment' of the nephron because there is resorption of solutes without water which dilutes the tubular fluid
ascending limb of the loop of Henle & distal tubule
155
this is known as the connecting segment and has properties of both the distal tubule and the collecting duct
late distal tubule
156
this is the site for final urine processing by regulated tubular resorption and secretion largely by the actions of aldosterone and vasopressin
late distal tubule and collecting ducts
157
what are the two distinct epithelial cells found in the late distal tubule and collecting ducts
principal cells and intercalated cells
158
these cells in the late distal tubule/collecting ducts act to resorb both water and sodium & secrete potassium
principal cells
159
this hormone acts to amplify the process of principal cells by up regulating and activating the basolateral Na-K-ATPase pumps, up regulating the apical sodium channels, and stimulating potassium secretion into the tubular lumen
aldosterone
160
the water permeability of principal cells is directly controlled by this hormone which binds to specific receptors on the basolateral membrane, resulting in the insertion of water specific channels into the luminal membrane
vasopressin
161
these cells found in the late distal tubule/collecting ducts are largely involved with regulation of acid base balance
intercalated cells
162
name the 2 types of intercalated cells
alpha and beta
163
this type of intercalated cells are the most important and function to secrete H+ ions and reabsorb HCO3 ions (key role in acid-base regulation)
-also resorb potassium into tubular fluid
alpha intercalated cells
164
this type of intercalated cell functions to secrete HCO3 and reabsorb H+
beta intercalated cells
165
where is the majority of sodium (65%) reabsorbed?
PCT (proximal convoluted tubule)
166
these are channels for the transfer of water which are expressed in the luminal cell membranes in the descending limb of the loop of Henle
Aquaporins (AQP)
167
most of the nephrons in the kidney are short-loop nephrons, so they don't have this section
ascending thin limbs of Henle's loop
168
by what mechanism does the distal convoluted tubule reabsorb salt without water
Na-Cl symporter
169
what 3 types of baroreceptors are important in regulating sodium excretion
1. arterial baroreceptors
2. cardiopulmonary baroreceptors
3. intrarenal baroreceptors
170
these stretch receptors detect low perfusion pressure, usually when intravascular volume is too low
high-pressure arterial stretch receptors
171
these stretch receptors detect whether intravascular volume is too high
low-pressure venous stretch receptors
172
these cells in the brain have sensory sodium channels that detect and respond to extracellular sodium concentrations and respond by modulating the activity of nearby neurons involved in the control of body sodium
glial cells
173
this is the most important controller of sodium excretion and volume sensing
RAAS
174
this is the most important peptide produced by the RAAS,
angiotensin II
175
this is produced in the kidneys by the juxtaglomerular apparatus and converts angiotensinogen to angiotensin I
renin
176
this is the rate limiting step of the formation of angiotensin II
amount of renin available to convert angiotensinogen to AI
177
these are the 3 key regulators of renin production
1. sympathetic input
2. aferent arteriole pressure
3. macula densa response
178
this is released from postganglionic sympathetic nerve cells and activates the release of renin from the juxtaglomerular granular cells
norepinephrine
179
the granular cells respond directly to pressure in the afferent arteriole; when pressure decreases, renin production (increases or decreases?)
increases
180
what are the 4 key actions of angiotensin II via the RAAS?
1. stimulates behavioral actions
2. promotes sodium reabsorption
3. controls the secretion of aldosterone
4. vasoconstrictor
181
this is a key hormone secreted mainly by the heart; it inhibits the release of renin (and the actions of AII that promote sodium reabsorption), acts on the medullary collecting duct to inhibit sodium reabsorption, and relaxes the afferent arteriole promoting increased glomerular filtration
atrial natriuretic peptide (ANP)
182
these are agents that increase urine flow; their goal is to reduce ECF volume to correct or prevent edema and they work by increasing sodium excretion
diuretics
183
the most powerful diuretics act by blocking this in the thick ascending limb of the loop of Henle (called loop diuretics)
Na-K-Cl symporter
184
this group of diuretics block the Na-Cl symporter in the DCT
thiazide diuretics
185
what is the most dangerous unwanted side effect of many diuretics
increased secretion of potassium (hypokalemia)
186
the vast majority of body potassium is (intracellular or extracellular?)
intracellular
187
a patient with hypokalemia has a more (negative or positive?) resting potential than normal; this makes the cell (more or less?) excitable
negative (potassium ions diffuse faster out of cell); less excitable
188
this is the rapid homeostatic mechanism that prevents large post prandial swings in serum potassium
intracellular sequestration (extrarenal potassium homeostasis)
189
what are the two major factors that stimulate the Na-K-ATPase pump for potassium uptake?
insulin and adrenaline
190
what happens to potassium when extracellular hydrogen levels are high (acidosis) so H+ moves into the cells
potassium moves out of the cell to maintain electroneutrality
191
potassium can be both secreted and reabsorbed in this part of the kidney (reabsorption always but secretion only when the body needs to get rid of potassium)
distal nephron
192
Reabsorption of potassium always occurs at these 3 parts in the kidney
1. proximal convoluted tubule (paracellular route)
2. thick ascending limb of loop of Henle (Na-K-2Cl cotransporter)
3. Collecting ducts (intercalated cells)
193
Secretion of potassium only occurs when the body needs to get rid of potassium in this location in the kidneys
collecting ducts (principal cells)
194
these cells in the collecting ducts reabsorb sodium and secrete potassium
principal cells
195
this is the dominant stimulus for renal potassium excretion; it is secreted by the adrenal glands in response to angiotensin II and by increased plasma potassium concentration
it acts on the principal cells to enhance sodium reabsorption and potassium secretion
aldosterone
196
which one inhibits the Na-K-ATPase pumps and which stimulates them: acidosis and alkalosis?
acidosis inhibits, alkalosis stimulates
197
this is the most commonly used K+ wasting diuretic; it acts on the thick ascending limb of loop of Henle where it inhibits the luminal Na-K-Cl cotransporter, exacerbating potassium loss
furosemide
198
what are the 2 classes of potassium-sparing diuretics
1. aldosterone receptor antagonists
2. aldosterone independent mechanisms
199
this is an aldosterone receptor antagonist diuretic which blocks the aldosterone receptor located on basolateral side of the cortical collecting duct principal cells (causing lack of potassium excretion)
spironolactone
200
the production of either concentrated or dilute urine by the kidney is regulated via these 3 main mechanisms
1. dilution of tubule fluid by TAL and DCT
2. generation of hypertonic medullary interstitium
3. variability of water permeability of collecting duct in response to vasopressin
201
a change in this is the major determinant of the volume of water lost by the kidney
change in plasma osmolality
202
this is defined as 1 mole of any fully dissociated substance dissolved in water
osmole
203
this is defined as the concentration of osmoles in a mass of solvent (kg)
osmolality
204
this is defined as the concentration of osmoles in a volume of solvent (L)
osmolarity
205
this is the major determinant of plasma osmolality
serum sodium concentration
206
these are located within the hypothalamus and sense changes in plasma osmolality
osmoreceptors
207
an increase in plasma osmolality sensed by osmoreceptors in the hypothalamus results in increased production and release of this into circulation
vasopressin
208
name 3 effects of vasopressin that have a direct effect on both the volume of urine produced and the urine concentration/osmolality
1. net absorption of water from tubule lumen
2. stimulates reabsorption of urea
3. enhances reabsorption of NaCl
209
the formation of a dilute or concentrated urine is achieved via a countercurrent mechanism within the nephron including these 3 structures
1. loop of Henle
2. cortical and medullary collecting ducts
3. blood supply to these segments
210
what are the 2 countercurrent systems present within the nephron?
1. loop of Henle
2. vasa recta
211
this limb of the loop of Henle is permeable to water and impermeable to solutes
descending limb
212
this limb of the loop of Henle is permeable to solute and impermeable to water
ascending limb
213
at any point along the loop of Henle, the fluid in the ascending limb has (higher or lower?) osmolality than the fluid in the descending limb
lower
214
osmolality of the tubular fluid and interstitium at the tip of the hairpin turn of the loop of Henle is much (greater or lesser?) compared to those at the corticomedullary junction
greater
215
these are the most abundant solutes within the interstitial medulla
NaCl and urea
216
this is generated by the liver as a product of protein metabolism and is freely filtered by the glomerulus
urea
217
what are the 2 basic steps for the formation of dilute urine
1. NaCl reabsorption w/o water in the thick ascending limb of loop of Henle
2. absence of vasopressin causing no water reabsorption in collecting tubules
218
what are the two major steps for the excretion of a concentrated urine
1. medullary interstitium is made hyperosmotic by reabsorption of NaCl without water in ascending limb of loop of Henle
2. vasopressin increases permeability of collecting duct to water to be reabsorbed passively
219
this is a capillary network derived from efferent arterioles that form a parallel set of hairpin loops with the loop of Henle within the medulla;
highly permeable to solute and water & return NaCl and H2O back into systemic circulation; plays integral role in maintenance of medullary osmotic gradient
vasa recta
220
what percent of the total body calcium is distributed in the extracellular and intracellular fluid?
1%
221
what are the 3 forms of calcium present in the total extracellular calcium?
1. free (55%)
2. Protein bound (35%)
3. complexed to other anions (10%)
222
this is the biologically active form of calcium and is the most important for physiological control of calcium concentrations
ionized form
223
what form of extracellular Ca is favored with acidemia (increased acid w/in the blood)?
ionized Ca (free)
224
what form of extracellular Ca is favored with alkalemia (acid deficit w/in the blood)?
protein bound (albumin-bound)
225
what happens to the total calcium concentration when there is decreased albumin concentration?
decreases (decr. protein bound fraction of Ca)
226
what is the distribution of phosphorus in the body? (3 locations)
1. bone (80-85%)
2. soft tissues (15%)
3. extracellular space (1%)
227
where is the majority of filtered calcium reabsorbed?
proximal tubule
228
what percent of phosphorous is excreted with the urine
20% (bc it only reabsorbed in proximal tubule)
229
where is PTH synthesized?
parathyroid gland (by chief cells)
230
what is the major and principal stimulus for PTH release?
decreased plasma calcium concentration
231
what is responsible for the minut-to-minute control of serum [iCa]?
PTH
232
what effect does PTH have on serum [Ca] and serum [phosphorous] ?
increases serum [Ca], decreases serum [phosphorus]
233
what are the 3 mechanisms by which PTH increases serum [Ca] and decreases serum [phosphorus]
1. effect on nephron (incr. Ca reabsorption and Phosphorus excretion in urine)
2. effect on bone (activates osteoclasts to release Ca and phosphorous into circulation)
3. stimulates formation of active form of vitamin D (calcitriol)
234
this initial form of vitamin D is synthesized in the skin with the help of UV light
vitamin D3
235
this initial form of vitamin D is ingested in the diet
vitamin D2
236
the liver converts vitamin D2 and D3 to this (due to presence of 25-hydroxylase)
calcidiol
237
this is found within the proximal tubular cells of the nephron and acts on calcidiol to form calcitriol (the active form of vitamin D)
1⍺-hydroxylase
238
what affect does PTH have on the synthesis of 1⍺-hydroxylase (and therefore the formation of calcitriol)?
increases it
239
this is responsible for the day-to-day control of serum [iCa]
calcitriol
240
what effect does calcitriol have on the serum [Ca] and serum [phosphorus]
increases both
241
what is the major site of action for calcitriol
intestinal tract
242
what effect does calcitriol have on the intestinal tract?
increases calcium and phosphate absorption
243
what effect does calcitriol have on the kidney?
stimulates reabsorption of both calcium and phosphate w/in distal tubule
244
what effect does calcitriol have on the bones?
bone resorption (increases circulating Ca and phosphorous)
245
what effect does PTH have on the kidney?
stimulates Ca reabsorption by thick limb of LoH and inhibits phosphate reabsorption in proximal tubule
246
what effect does PTH have on bones
activates osteoclasts (bone breakdown so more Ca and Phosphorous into circulation)
247
name 4 factors that stimulates PTH release
1. hypocalcemia
2. hyperphosphatemia
3. decr. PTH
4. decr. calcitriol
248
name 4 factors that stimulates calcitriol release
1. hypophosphatemia
2. hypocalcemia
3. incr. PTH
4. decr. calcitriol
249
name 4 factors that inhibit PTH
1. hypophosphatemia
2. hypercalcemia
3. incr. PTH
4. incr. calcitriol
250
name 4 factors that inhibit calcitriol
1. incr. calcitriol
2. hypercalcemia
3. hyperphosphatemia
4. decr. PTH
251
name the effect hypercalcemia has on PTH, calcitriol, and calcitonin
decr. PTH, decr. calcitriol, incr. calcitonin
252
name the effect hypocalcemia has on PTH, calcitriol and calcitonin
incr. PTH, incr. calcitriol, decr. calcitonin
253
this is a hormone synthesized and released from the thyroid gland in response to increased calcium concentration
calcitonin
254
which hormone essentially has the opposite effects to PTH
calcitonin
255
this is a protein secreted mainly by osteocytes with the overall effect to decrease plasma concentration of ionized phosphorous
fibroblast growth factor 23 (FGF-23)
256
what is the equation for pH?
pH = -log[H+]
257
under this pH, the patient will be dead
< 6.8
258
above this pH, the patient will be dead
> 8
259
is considered normal pH
7.4
260
this is the main extracellular buffer
bicarbonate (HCO3-)
261
these are weak acids or bases which can either bind to or release H+ (H+ titration) to prevent large changes in pH
buffers
262
what is the equation for bicarbonate buffering with H+
HCO3- + H+ <-> H2CO3
263
when bicarbonate titrates H+, the extra CO2 produced stimulates this in order to eliminate it from the lungs
hyperventilation
264
what is the kidneys' role in maintaining acid-base balance (metabolic component)
reabsorption of filtered bicarbonate and generation of new bicarbonate
265
what is the lungs' role in maintaining acid-bace balance (respiratory component)
eliminate or retain CO2 based on H+ concentration
266
this acts as a urinary buffer to allow excretion of H+
ammonium (NH4)
267
Describe the process of renal ammoniagenesis in the proximal tubule and fate of the ammonium
1. glutamine is taken up by the proximal tubular cells and converted to bicarbonate and ammonium
2. ammonium is secreted into tubular lumen
3. ammonium is reabsorbed into medullary interstitium at LoH
4. ammonium is secreted again into the collecting duct
268
this is the enzyme which catalyzes H2O + CO2 <-> HCO3- + H+ reaction; it is present in large quantities in the proximal tubule brush border and cytosol of cells
carbonic anhydrase
269
what happens to H+ secreted from the proximal tubule into the tubular lumen?
recombine with filtered HCO3- (prevents loss of bicarbonate)
270
this is where 80%of bicarbonate is reabsorbed
proximal tubule
271
this part of the nephron secretes a quantity of H+ equal to that generated by the animal's metabolism; secrete H+ combines with a urinary buffer to be excreted in the urine
collecting duct (distal nephron)
272
this type of cell in the collecting duct secretes H+
type A intercalated cells
273
this type of cell in the collecting duct secretes HCO3-
type B intercalated cells
274
urine leaving the collecting duct of carnivores has this pH
5.5-7.5
275
urine leaving the collecting duct of ruminants has this pH
6-9
