Chapter 17 - Renal Physiology Flashcards
1
Q
Compare the renal artery from the renal vein
A
renal artery: supplies oxygenated blood to kidneys (unfiltered blood)
renal vein: leaves kidney as deoxygenated blood (filtered blood)
2
Q
Name the structures that urine passes through once it leaves the kidney
A
kidney ⮕ ureter ⮕ urinary bladder ⮕ urethra
3
Q
What are the major functions of the urinary system?
A
WEB PM
- Maintains water volume regulation (reabsorbs H20 into BV)
- Electrolyte balance
- BP (blood pressure); BP increases when H2O reasborbed into BV
- pH
- Metabolic waste product levels (ex: produce, store, eliminate urine)
4
Q
What is the composition of urine?
A
Mainly water, electrolytes (Na+, K+, Cl-), urea, and urochrome/urobilin (give urine color)
5
Q
Urine is formed through ________ _______ in the kidneys (by the ________)
A
blood filtering
nephron
6
Q
What is filtrate?
A
a type of waste product
(is the stuff that is removed from blood)
7
Q
Describe the relationship between blood, filtrate, and urine
A
Blood is filtered by nephrons (in kidney), and removed substances are called “filtrate.” Once filtrate enters the urinary tubes (collecting duct), it becomes urine (and is then eliminated from body)
8
Q
When/where does filtrate become urine?
A
at the collecting duct
9
Q
Water, urea, electrolytes, and additional substances are ______ OUT of the blood by nephrons (at the renal corpuscle)
A
filtered
(reminder: stuff filtered out is called filtrate)
10
Q
At what location do water, electrolytes, and urea get filtered out of the blood?
A
renal corpuscle
11
Q
Describe renal filtration
A
unwanted substances are moves from the glomerulus (capillary) to the glomerular capsule
12
Q
Describe renal reabsorption
A
when most water and electrolytes are reabsorbed back into the blood/BV (keeping particles in BV)
13
Q
Describe renal secretion
A
some substances are secreted directly into the nephrons (tubules) from the blood/BV (particles get eliminated)
14
Q
“Cleaned blood” exits kidney via _______ ______
A
renal vein
15
Q
Describe the traveling of blood through the kidney
A
aorta ⮕ renal artery ⮕ interlobar arteries ⮕ arcuate arteries ⮕ interlobular arteries ⮕ afferent arterioles ⮕ glomerulus (capillary) ⮕ efferent arterioles ⮕ peritubular capillaries ⮕ interlobular veins ⮕ arcuate veins ⮕ interlobar veins ⮕ renal vein
16
Q
Compare the location in which filtration, reabsorption, and secretion take place.
A
filtration: renal corpuscle
reabsorption and secretion: nephron tubule
17
Q
Generally describe how filtration, reabsorption, and secretion all work together
A
unwanted particles from the glomerulus are filtered into the glomerular capsule -> filtrate
filtrate enters the nephron tubule (PCT) where it can either be reabsorbed back into BV/peritubular capillaries or substances in BV/peritubular capillaries can be secreted into the nephron tubule (PCT)
18
Q
A kidney has 2 distinct regions. Name these regions and what they make up/consist of
A
Renal cortex: outer portion (of kidney)
Renal medulla: inner portion (of kidney)
- contains renal pyramids and columns
- many nephrons
19
Q
In the renal medulla, each pyramid drains into a…
A
minor calyx ⮕ major calyx ⮕ renal pelvis ⮕ ureter⮕ (urinary bladder ⮕ urethra)
20
Q
What is a nephron? (include what it consists of)
A
Functional unit of the kidney made up of several cells, consisting of a renal corpuscle and renal tubules
21
Q
Blood is filtered ⮕ filtrate enters the _______ ⮕ fluid/filtrate is ________ ⮕ leaves the tubules as _________ ⮕ urine drains into _______ ⮕ urinary bladder ⮕ eliminated through _________
A
tubules
modified
urine
ureters
urethra
22
Q
What are two types of capillaries that you can find involved with the nephron?
A
glomerulus
peritubular capillaries (+ vasa recta)
23
Q
What structures can be found within the renal corpuscle?
What structures can be found within the renal tubules?
A
renal corpuscle: FILTRATION ONLY
- glomerulus (capillary)
- glomerular capsule (Bowmans capsule)
renal tubules
- PCT
- LH (nephron loop)
- DCT
- CD
24
Q
(ultra) filtrate is formed at a rate of _________/day for ______ kidneys
T/F: All of this filtrate will be lost as urine
A
180L/day
both
False, some can be reabsorbed (ex: H2O)
25
What if GFR, and why is this value helpful to know?
glomerular filtration rate
measures the filtration rate at the renal corpuscle
measure of kidney function
26
TRUE or FALSE: If a particle reaches the nephron, and it does not get filtered, then this particle may be reabsorbed later on
False, if a particle reaches the nephron and does not get filtered, the particle can be secreted later on
27
Know the relationship between afferent arteriole, efferent arteriole, and glomerulus
Afferent arteriole arrives at renal corpuscle and then becomes glomerulus (capillary). After filtration, blood will move into the efferent arteriole
28
Where are the renal pyramids and columns located in the kidney, and how do they differ?
Renal pyramids and columns: renal medulla
Pyramids contain nephrons, while columns consist of BV
29
TRUE or FALSE: The PCT and DCT are present in the renal medulla
False, they are located at the renal cortex
30
Which part of the nephron lies in the renal medulla? What other things associated with the nephron are found here?
LH
vasa recta ("type" of peritubular capillaries)
31
Define vasa recta
are peritubular capillaries located at the medulla
32
Know the different parts of the Loop of Henle
Descending limb (thin) - outer and inner medulla
ascending limb (thin) - inner medulla
ascending limb (thick) - outer medulla
(All in renal medulla)
33
Compare active transport vs. passive transport
active transport: low⮕high (req. ATP)
passive transport: high⮕low
34
What substances can be found in filtrate
"HUGS"
H+
H2O
HCO3-
Urea
Glucose amino acids (nutrients)
Salts (NaCl)
Some drugs
35
Know which substances can be either secreted or reabsorbed, where this happens in the nephron, and if this movement happens passively or actively
*check answer on slide 11*
36
Given an image of a nephron, using an arrow, indicate on place where the following are happening: K+ is passively reabsorbed, NH3 is passively secreted, NaCl is actively reabsorbed, etc
check slide 11
37
What location of the nephron is most H2O and Na+ (salts) reabsorbed?
PCT
38
What do Na+ (salts) and glucose pass through to move from the lumen into the PCT cell?
Where is this "thing" located on the PCT cell?
Na+/Glucose symporter
apical surface of PCT cell
39
How does Na+ (salt) and glucose move as they pass through the Na+/Glucose symporter @ PCT cell?
Na+ - passively/by diffusion (high -> low)
Glucose - actively/against diffusion (low -> high)
40
How do Na+ (salt) and glucose exit the PCT cell and move into the peritubular capillaries?
Where is this taking place in the PCT cell?
Na+ - actively through Na+/K+ pump (low->high) to exit PCT cell and then goes through Na+ channel passively (high->low) into BV
Glucose: passively through glucose channel to exit PCT cell and enter BV
Basal surface
41
Na+ is actively reabsorbed at the level of the PCT. With respect to the PCT cell, explain how this happens? Which transporters/facilitators are involved in Na+ reabsorption at the PCT?
Na+ is found in the lumen of the PCT and goes through a Na+/Glc symporter by diffusion (high -> low) at the apical surface of the PCT cell. As Na+ moves toward the basal surface of the PCT cell, it moves via 1° AT (low -> high) through the Na+/K+ pump and then passively through a Na+ channel (high -> low) to move into the peritubular capillary
Transporters/facilitators involved: Na+/Glucose symporter (2° AT) and Na+/K+ pump (1° AT)
42
Na+/K+ pumps are commonly found on the nephron cell surfaces. On which cell surface would you find Na+/K+ pumps on the PCT and thick ascending LH?
Na+/K+ pumps found on basal surface of the PCT and basal surface of thick ascending LH
43
Why is the movement of Na+ and glucose considered active transport although they move by diffusion in some parts of the PCT cell?
as long as one step in the Na+ and glucose transport is active, then the overall process is considered active
44
At what location of the PCT cell is Na+ and Glucose actively reabsorbed?
Na+: basal surface
Glucose: apical surface
45
TRUE or FALSE: the active movement of Na+ and Glucose out of the PCT cell is an example of secretion
False, Na+ and Glucose move out of the PCT cell and into the blood vessels, which is considered reabsorption (keeping)
46
The Countercurrent Multiplier system at the level of the LH is responsible for the production of ___________ _________ at the _________
concentrated urine
CD (collecting ducts)
47
TRUE or FALSE: H2O in the medulla contributed to it being hypertonic
False, lack of H2O in renal medulla will make it hypertonic
48
Know what substances LEAVE the LH and where this is happening. Know if these substances are moving passively or actively
H2O - passively - descending LH
NaCl - passively - thin ascending LH
NaCl - actively - thick ascending LH
49
At the descending LH, what is it permeable and impermeable to? Where does it go/what is the result?
At the ascending LH, what is it permeable and impermeable to?
Where does it go/what is the result?
descending LH:
- permeable to H2O ➜ leaves to ascending VR
- impermeable to NaCl ➜ remains in descending LH (filtrate becomes more concentrated)
ascending LH
- permeable to NaCl ➜ leaves to descending VR (passively @ thin segment; actively @ thick segment)
- impermeable to H2O ➜ remains in ascending LH (filtrate becomes less concentrated)
50
Why does H2O want to leave the descending LH?
medulla becomes hypertonic because of NaCl leaving the ascending LH and urea leaving CD. H2O wants to move towards hypertonicity, which is why it diffuses out
51
Why does NaCl leave passively at the thin ascending LH, but actively at the thick asceding LH?
passively at thin bc its more hypertonic in LH than medulla, so is able to passively diffuse out (high -> low) via Na+ channel
actively at thick because filtrate is now less concentrated than medulla (bc NaCl loss earlier), so its actively transported out through Na+/K+ pumps and Cl- channels (low -> high)
52
Where does H2O that leaves the descending LH go to?
Where does the NaCl that leaves the thin ascending LH go?
Where does the NaCl that leaves the thick ascending LH go?
H2O enters the ascending VR
NaCl at thin ascending LH enters the descending VR
NaCl at thick ascending LH enters the descending VR
53
TRUE or FALSE: The countercurrent multiplier takes place at the vasa recta
False, it takes place at the LH
54
Explain why the LH gets more hypertonic/has more concentrated filtrate the deeper you get into the medulla
LH becomes more concentrated because water moves OUT at the descending LH and enters the ascending vasa recta
(Removing water means only solutes will be in the filtrate, therefore increasing hypertonicity/concentration the deeper you go into medulla)
55
Explain why filtrate in the LH gets less hypertonic/less concentrated the closer you get to the cortex
NaCl leaves both segments of the ascending LH (and into the descending VR), which dilutes the filtrate to make it less concentrated
56
*Give 2 reasons why H2O leaves the descending LH? What eventually happens to that H2O after it leaves the tubules?
H2O leaves descending LH because the medulla is more hypertonic than the descending LH, which draws water out
H2O will leave the tubule via AQP and enter the ascending VR
57
Regarding the cell of the thick segment of the ascending LH, on which cell surface will you find the Na+/K+/2Cl- transporters and on which surface will you find Na+/K+ pumps and Cl- channels? On which of these two surfaces is Na+ transported actively?
Na+/K+/2Cl- transporters (passive): apical surface on cell of thick ascending LH
Na+/K+ pump and Cl- channel(active): basal surface on cell of thick ascending LH
58
Describe how NaCl (salt) moves actively through the thick ascending LH cell and into the descending VR.
Na+ and Cl- move from the lumen and passively into the thick ascending LH cell through the Na+K+2Cl- transporter (by diffusion; high -> low) at the apical surface
There is a low concentration of Na+ and Cl- in the thick ascending LH cell, so it must move out actively.
Na+ moves actively through the Na+/K+ pump and Cl- moves actively through the Cl- channels (both against diffusion; low ->high) at the basal surface
Na+ enters descending VR passively through Na+ channel (by diffusion; high -> low)
59
Explain why blood pressure drops when the Na+/K+/2Cl- transporter is blocked
What happens to the concentration of urine as a result?
If the Na+/K+/Cl+ transporter is blocked, then solutes will never move into medullar space (stay in LH). This will make medulla hypotonic, which will NOT encourage for water to move out of the descending LH via osmosis (because water wants to move from hypotonic area to hypertonic area). If water does not move out, it will never be able to diffuse into blood vessels (vasa recta), meaning blood pressure will decrease. This will also lead to dilute urine and cause someone to lose lots of water.
60
TRUE or FALSE: The number of Na+ channels and Na+/K+ pumps on the nephron serve as a physiological limit to how much H2O can leave the descending LH
True
61
In regards to the countercurrent multiplier system, how does the body maintain a physiological limit as to how much H2O can leave the descending LH?
- limits number of Na+ channels at thin ascending LH
- limits number of Na+/K+ pumps at thick ascending LH
62
TRUE or FALSE: In order for the countercurrent multiplier to work, the distance between descending and ascending limbs of LH does not matter
False, its needs proximity between the limbs for the countercurrent multiplier to work
63
What is the difference between the peritubular capillaries and the vasa recta?
Peritubular capillaries: renal cortex
Vasa recta: renal medulla
64
TRUE or FALSE: The countercurrent exchange takes place at the LH
False, countercurrent exchange takes place at the vasa recta
65
Given an image of the vasa recta already labeled with the ascending and descending limbs, know in which limb H2O is leaving and entering the vasa recta. Know in which limb of the vasa recta are salts/urea leaving and entering.
Ascending VR: solutes LEAVING (to descending VR); H20 ENTER (from descending VR)
Descending VR: solutes ENTER (from ascending VR); H2O LEAVING (to ascending VR)
66
Explain why the vasa recta get more hypertonic/has more concentrated blood the deeper you get into the medulla
At descending VR, solutes are entering and H2O is leaving, so the blood becomes severly concentrated.
67
Explain why the vasa recta gets less hypertonic/less concentrated blood the closer you get to the cortex
At the ascending VR, solutes are exiting and H2O is entering, which dilutes the blood, making it less concentrate
68
Why does NaCl and urea want to leave the ascending VR?
at the ascending VR, the blood is more hypertonic than to the medulla, so solutes want to move out (to lower concentrated areas)
69
Name the 3 sources of H2O which all eventually enter the ascending vasa recta
H2O leaving descending LH -> ascending VR
H2O leaving descending VR -> ascending VR
H2O leaving CD -> ascending VR
70
Know what the descending and ascending segment of the VR are permeable to
descending: permeable to solutes (NaCl, urea); limited H2O permeability
ascending: permeable to solutes (NaCl, urea); unlimited H2O permeability
71
TRUE or FALSE: Na+ that leaves the PCT and DCT enter the descending VR
False, Na+ that leaves the PCT and DCT enter peritubular capillaries
72
TRUE or FALSE: A person with dilute blood would likely have low blood pressure.
False, a person with dilute blood means there is lots of water, therefore increasing BP.
73
What produces nitrogenous waste products?
protein (amino acids) and nucleic acid (nucleotides)
74
What is the most common nitrogenous waste in humans?
NH3 (ammonia)
75
What is NH3 (ammonia)?
nitrogenous waste that is toxic and reactive (can get converted into urea; nontoxic and nonreactive)
76
Describe the characteristics of urea. Include: toxicity/reactiveness, where its produced and how, where is it released into and solubility/elimination
- nontoxic/ low reactivity
- produced in the liver by urea cycle
- released into blood
- water-soluble and easily eliminated
77
What is the goal of the urinary system?
to concentrate filtrate/urine and minimize H2O loss
78
Where is urea released in the nephron, and where does it go after it temporarily remains in the medulla?
Released from CD
Diffuses into ascending limb of LH via urea transporters (regulated by ADH)
79
TRUE or FALSE: Urea transporters are present at the ascending LH
False, urea transporters are located at the CD
80
urea contributes to the ____________ system
countercurrent (multiplier)
81
TRUE or FALSE: Urea transported out of the collecting duct does not contribute to the hypertonicity of the deep medulla
False, urea (along with NaCl) contribute to medulla hypertonicity
82
Urea transporters are regulated by what hormone?
ADH (vasopressin)
83
What are aquaporins (AQP)? What do they do
AQP are water channels that form pores in the membrane of cells allowing for the passive movement of H2O, while preventing passage of ions and other small molecules
84
Name the channels that release H2O. Where in the nephron are these water channels located?
aquaporins (AQP)
PCT, descending LH, descending VR, DCT, CD
85
What would happen if urea remained in the medulla indefinitely
Medulla would become extremely concentrated, which means more water would want to diffuse out of descending LH, leading to super-concentrated filtrate and less concentrated blood
86
Where is ADH stored and secreted by?
posterior pituitary
87
Explain the term “diuretic” or “diuretic effect”
Promotes urination (lots of water in renal tubules = dilute urine)
88
TRUE or FALSE: High ADH promotes secretion of H2O
False, high ADH promotes reabsorption of H2O
89
What channels/transporters are increased due to increases in ADH?
1. # of urea transporters
2. # of AQP
90
What is ADH, where does it come from, and what is its function? What is another name for ADH?
ADH is an antidiuretic hormone secreted by the posterior pituitary that responds to high Na+ or low H2O intake by promoting H2O reabsorption (increases blood volume; decreases urine volume) into ascending VR (and PT capillaries). It does this by increasing the number of urea transporters and the number of AQP (at CD).
AKA: Vasopressin
91
TRUE or FALSE: ADH will form concentrated urine
True, because H2O is reabsorbed into BV, meaning that lots of solutes will be left in tubules
92
Explain why low ADH would have a diuretic effect
Low ADH promotes urination because there will be fewer urea transporters at CD and fewer AQP, meaning less water will get reabsorbed into BV. This means more water will remain in the renal tubules (dilute urine), thus promoting urination
93
Explain how increases in ADH/Vasopressin works to reduce urination
ADH will increase the number of urea transporters at the CD
More urea will enter medulla
medulla becomes hypertonic
increases number of AQP
more H2O leaves the CD, descending LH and descending VR
H2O enters ascending VR = H2O rebsorption
94
Describe what will happen to the concentration of urine and blood when there are increases in ADH. What happens to BP? Promote or decrease urination?
Describe what will happen to the concentration of urine and blood when there is low ADH. What happens to BP? Promote or decrease urination?
Draw it out
high ADH: concentrated urine, dilute blood, increase BP, decreases urination
low ADH: dilute urine, concentrated blood, low BP, increases urination
check answer on slide 29
95
TRUE or FALSE: Diuretic effects promote reabsorption of H2O into BV
False, diuretic effects promote secretion of H2O from BV to renal tubules. antidiuretic effects promote reabsorption of H2O into BV
96
Why is increased blood pressure a consequence/side effect of high ADH?
ADH promotes water reabsorption into BV, so blood volume will be high. High blood volume leads to increased BP
97
*What part of the nephron is stimulated by ADH? What does ADH do to this part of the nephron?
CD (collecting duct)
ADH increases urea transporters (for urea to leave) and increases AQP (for water to leave) at CD
98
Explain why the urine filtrate would be dilute AND the blood would be concentrated if you block the urea transporters
If you block urea transporters, urea would not leave the CD and would decrease hypertonicity of medulla. Therefore, less H2O would come out and more H2O would remain in the tubules. This makes the urine dilute. Because less water moves out, less water will be reabsorbed into ascending VR, increasing blood concentration.
99
TRUE or FALSE: Blocking urea transporters would have a diuretic effect and the urine would be light-yellow color
true
100
Explain how low H2O intake/high salt intake leads to increase ADH secretion (hint - does ADH lead to H2O secretion or reabsorption)
Low H2O intake (dehydration) and high salt intake leads to increases in blood concentration, which is sensed by osmoreceptors in hypothalamus. This triggers the secretion of ADH by the posterior pituitary (increases ADH) to increase water reabsorption to dilute blood (increases blood volume and BP; urine will be concentrated)
101
Explain why high H2O intake/low salt intake leads to no/decreased ADH secretion (hint - does ADH lead to H2O secretion or reabsorption)
High H2O (hydrated)/low salt intake means the blood is dilute/low in concentration, which is sensed by osmoreceptors in hypothalamus. This signals for the posterior pituitary to decrease ADH secretion to which promotes water secretion into tubules -> urination (diuretic effect). This creates dilute urine and concentrated blood (decreasing blood volume and BP)
102
How does high/increased ADH secretion lead to increased H2O reabsorption (into the ascending VR)?
High levels of ADH increase urea transporters and AQP, which promote the release of H2O from tubules. All of this H2O is then reabsorbed by the ascending VR
103
TRUE or FALSE: Decreased H2O reabsorption leads to low/decreased blood volume and low blood pressure
true
104
What is the JGA (juxtaglomerular apparatus)?
region where the afferent arteriole comes into contact with the thick segment ascending limb of Lh and early DCT
105
What two cells are involved with the JGA? Where are they located?
granular cells - part of afferent arteriole
macula densa - part of thick ascending LH
106
What is the function of granular cells?
release enzyme called renin
107
What is the function of the macula densa cells?
Macula densa cells sense changes in blood volume and are activated by low blood volume (which was a result of low Na+ intake or high H2O intake)
also releases prostaglandins!!
108
TRUE or FALSE: If your blood is less concentrated, macula densa cells will be activated
False, less concentration means there is a lot of H2O in the blood, meaning high blood volume. Macula densa cells are only activated by low blood volume
109
TRUE or FALSE: JGA is involved in the RAA system
true
110
What is the general purpose of the RAA system
Na+ regulation (increase Na+ reabsorption)
111
What cell of the JGA releases prostaglandins (PG)?
macula densa cells
112
What is the stimulus for PG to be released? What is the relationship between PG and renin?
PG is stimulated by low blood volume (sensed by macula densa)
Macula densa cells release PG, which stimulates granular cells to release renin
113
TRUE or FALSE: Renin is an enzyme that converts Angiotensin I into Angiotensin II
False, renin is an enzyme that converts angiotensinogen into AT I
114
Explain how the RAA system works
macula densa cells detect low blood volume (as result from low Na+ intake)
macula densa cells release PG (made in kidney/nephron)
PG stimulates granular cells to release renin (enzyme) into blood
Renin converts angiotensinogen (made by liver) to angiotensin I (AT I)
AT I gets converted gets converted into AT II by ACE (made by lung)
AT II stimulates adrenal cortex to make aldosterone
Aldosterone increases the number of Na+/K+ pumps at late DCT and early CD
More Na+ gets reabsorbed into BV (K+ excreted)
increased Na+ reabsorption = more H2O reabsorption = increase blood volume = increase in blood pressure
115
What does ACE do?
ACE is an enzyme made by the lungs that converts AT I into AT II
116
TRUE or FALSE: High ADH will eventually lead for the stimulation of RAA system
False, low ADH will stimulate RAA system because it leads to low blood volume
High ADH means water reabsorption, which increases blood volume. In order for RAA system to be activated, there needs to be low blood volume. This would be achieved by low levels of ADH because it will have a diuretic effect, meaning urination and more H2O in tubules. This means less H2O in BV leading to decrease in blood volume.
117
What organs are involved in the RAA system? What does it make?
renin - made by kidney
angiotensinogen - made by liver
ACE - made by lung
aldosterone - made by adrenal cortex
118
Where does aldosterone come from, and what is its function? What part of the nephron is affected by aldosterone?
Aldosterone is released from the adrenal cortex of the adrenal gland (in the kidney)
Function: increases the number of Na+/K+ pumps at the late DCT and early CD
119
Explain why aldosterone increases blood volume
Aldosterone increases Na+/K+ pumps (at late DCT and early CD) to increase Na+ reabsorption in BV. Increases in Na+ in BV will attract H2O and H2O will be reabsorbed into BV. Increases in H2O increases blood volume (also increases BP)
120
Explain why low/decreased ADH eventually leads to increased aldosterone
Low ADH will lead to concentrated blood, which means low blood volume. This is sensed by macula densa cells of the JGA and stimulates the RAA system to eventually release aldosterone. Aldosterone will promote Na+ reabsorption, which also increases H2O reabsorption, therefore increasing blood volume and blood pressure.
