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Renal Physiology Overview
YOU ONLY NEED TO LEARN THE QUESTIONS IN YELLOW
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Where does plasma leak into from the
capillaries of the nephron?
What do the kidneys return to the plasma
before removing the waste products?
How do the kidneys maintain blood pH
balance?
Which two electrolytes are the most important
in maintaining acid-base balance when
aldosterone is present?
What must be constant to maintain BP?
Aside from acid-base balance, what three things
do the kidneys do that affect the blood?
How do the kidneys adjust the blood volume?
What 2 hormones tell the kidneys how much
water to excrete?
What effect does aldosterone have on the
kidneys themselves?
10. How do the kidneys affect blood composition?
11. How do the kidneys increase RBC production?
12. How do the kidneys affect blood pressure?
13. Release of renin does what to blood pressure?
14. In what three ways does the sympathetic
nervous system affect the kidneys?
15. How does the sympathetic nervous system
affect the rate of blood flow to the glomerulus?
16. What monitors the concentration of water in
the plasma?
17. What does it mean when the plasma is too
concentrated (high osmotic pressure)?
18. If a person’s plasma is too concentrated, is their
osmotic pressure high or low?
19. What condition can cause osmotic pressure to
be too high?
20. If a person is dehydrated what will happen to
the blood pressure?
21. If a person has high osmotic pressure in the
bloodstream, what is the current condition of
the blood pressure?
22. If water is drawn out of cells what will it cause
them to do?
23. If a person has high osmotic pressure in the
bloodstream, what will happen to nearby cells?
24. If the plasma if too dilute, is the osmotic
pressure high or low?
25. What does it mean when plasma is too dilute?
Glomerulus
Nutrients
By excreting the acidic and alkaline waste products, or
by stopping their reabsorption.
Sodium and potassium
Plasma volume must be constant
Kidneys can adjust blood volume, composition, and
pressure
By adjusting how much water is lost in the urine
Aldosterone and ADH
They cause the kidneys to increase sodium
reabsorption. Since water follows the sodium, water is
reabsorbed as well.
By increasing RBC production
By releasing erythropoietin, a hormone that signals the
bone marrow to make more RBCs
By secreting renin
Increases blood pressure
Changes the rate of blood flow to the glomerulus
Stimulates the release of renin
Changes water and sodium reabsorption
Decreases the rate of blood flow (and increases the
pressure) to the glomerulus by telling the precapillary
sphincters to contract
Hypothalamus
There are many electrolytes and not enough water
inside the blood vessels
High: water wants to enter the blood vessel
Dehydration
It will drop
It is low
Shrink
They will shrink as water is drawn out of them and into
the blood vessels
Low
There is too much water and too few electrolytes
inside the blood vessels
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Renal Physiology Overview
26. What condition can cause low osmotic
pressure?
27. If a person is over-hydrated what will it cause
the blood pressure to do?
28. When plasma osmotic pressure is too low, what
will it do to the nearby cells?
29. When plasma osmotic pressure is too low, what
will it do to the interstitial space (the fluid
between the cells)?
30. When a person is dehydrated and has low blood
pressure what will this do to the osmotic
pressure?
31. What part of the brain senses when plasma
osmotic pressure is too high?
32. What hormone does the hypothalamus release
when osmotic pressure is too high?
33. What does the pituitary gland release when the
osmotic pressure becomes too high?
34. What affect does aldosterone have on the
kidneys, and how does this affect blood
pressure?
35. When osmotic pressure is too high, what other
endocrine gland secretes a hormone, and what
is the name of the hormone?
36. What affect does aldosterone have on the
kidneys, and how does this affect blood
pressure?
37. If osmotic pressure is too high what is the
current condition of the blood pressure?
38. If osmotic pressure is too high what is the
eventual effect on the blood pressure?
39. If blood pressure is too high what two
hormones will be released?
40. If osmotic pressure is too low what is the
current condition of the blood pressure?
41. If osmotic pressure is too low what is the
eventual effect on the blood pressure?
42. If blood pressure is too low what two hormones
will not be released?
Over-hydration
43. What will be the result of ADH and aldosterone
not being released, and what effect does this
have on blood pressure?
44. Quiz Yourself
What does it mean when the osmotic pressure
is too high? Too low?
Excess water will pass out of the body as urine and BP
will go back down
Rise
Make them swell
Increase fluid to the interstitial space
Cause it to become too high
Hypothalamus
ADH-RH
ADH (anti-diuretic hormone)
It causes them to reabsorb more sodium. This will
cause water to also be reabsorbed. Blood pressure will
then go up.
Adrenal cortex, releases aldosterone
causes sodium ions to be reabsorbed by the kidneys
and water follows, so blood pressure goes up.
It is too low
Blood pressure will become more elevated as water is
drawn into the blood vessels from nearby cells
ADH and aldosterone
It is too high
Blood pressure will become lower
ADH and aldosterone
What are the causes of each of these
situations?
How does the body compensate for each of
these situations?
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Renal Physiology Overview
45. What does it mean when the plasma is too
dilute? Too concentrated?
What are the causes of each of these
situations?
How does the body compensate for each of
these situations?
46. What are 5 common things that can alter the
pH of the blood?
47. Why are pH imbalances are dangerous?
48. What are the basic mechanisms of urine
formation?
49. How do we determine excretion rates?
50. How does plasma enter the glomerulus?
51. Where does the filtered plasma go after it
enters the glomerulus?
52. What affects how fast the fluid can filter
through the fenestrations?
53. How does blood pressure affect the GFR?
54. What can also control how much blood
pressure is in the glomerulus?
55. Name the 3 different mechanisms that can
change the diameter of the afferent and
efferent arterioles to alter the GFR
Beverages we drink
Acids produced by metabolism
Breathing rate
Vomiting (loss of acid)
Diarrhea (loss of base)
many enzymes only function within a narrow pH range
1) Glomerular filtration
2) Tubular reabsorption
3) Tubular secretion
4) Excretion
Excretion = filtration – reabsorption + secretion
The capillaries in the glomerulus contain fenestrations.
As blood passes through the glomerulus, the plasma
passes through the fenestrations. Proteins and other
large substances do not cross through; they stay in the
bloodstream.
It enters the proximal convoluted tubule.
blood pressure in the glomerulus.
The higher the blood pressure, the higher the GFR
(except if the sympathetic nervous system that is
temporarily causing the increased BP…in that case, the
neurons cause vasoconstriction in the precapillary
sphincters, slowing GFR.
The pre-capillary sphincters
Hormones
Autonomic Nervous System
Autoregulation or local (smooth muscle sphincters
around arterioles or capillaries near the glomerulus)
56. What is Tubular Reabsorption?
The removal of water and solute molecules from
filtrate after it enters the renal tubules. These are
then transferred back into the bloodstream.
57. What substances are reabsorbed?
58. Describe the pathway that fluid takes in the
nephron.
Water and solutes
Fluid goes from the glomerulus to the proximal
convoluted tubule (PCT), down the loop of Henle and
back up, then into the distal convoluted tubule (DCT),
and into the collecting duct.
In the Proximal Convoluted Tubule
59. Where are nutrients reabsorbed in the
nephron?
a. Where do the excess nutrients (such as
glucose) go if they are not absorbed?
Into the Urine
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Renal Physiology Overview
60. When the nutrients in the PCT (proximal
convoluted tubule) are reabsorbed, what will
happen to the water in the tubule?
61. Where does this occur in the nephron
62. What types of solutes are left by the time the
fluid gets to the collecting tubule?
63. Name the capillaries that follow the tubules
longitudinally.
64. Name the capillaries that wrap around the
tubules.
65. What is the name of the space between the
peritubular capillaries and the tubules?.
66. How is water reabsorbed in the PCT?
67. What primarily causes water osmosis in the
PCT?
68. How do particles in the peritubular space enter
the peritubular capillaries?
69. What two regions of the nephron are
impermeable unless hormones cause
substances to move through their walls?
70. If blood is low in Na+ , what hormone will be
released to open up the Na+ pumps in the
tubules so sodium will leave the tubule, enter
the peritubular space, and then enter the
bloodstream?
71. What effect will the above hormone have on
water reabsorption?
72. What condition can cause low sodium levels?
73. What hormone is released when the
bloodstream needs more water?
74. What is another name for this hormone?
75. What effect do Aldosterone and ADH have on
BP and blood volume?
76. In which part of the tubule do ADH and
Aldosterone begin working?
77. What is the difference between ADH and
Aldosterone, and in what conditions does the
body need one or the other?
78. What are two examples of substances which
are unable to filter through the glomerulus, but
are not wanted by the body?
79. How do we get rid of these substances?
It moves from its high concentration (in the PCT) to its
low concentration, so it will leave the tubule and enter
the bloodstream.
Water is reabsorbed in the PCT.
Ammonia, urea, bilirubin (all waste products)
Vasa recta
Peritubular capillaries
Peritubular space
Osmosis
It occurs after reabsorption of sodium
By way of osmosis (that is how nutrients are
reabsorbed back into the bloodstream from the
tubules)
The ascending loop of Henle, and the DCT
Aldosterone (from the adrenal cortex)
Water will follow the sodium by osmosis, so water is
also reabsorbed.
Excessive sweating (physical activity). Sweat is salty, so
salt (sodium and chloride) is lost.
ADH
Vasopressin
They will cause both to Increase
The ascending limb
ADH will only raise the water levels in the bloodstream
(needed during dehydration from not drinking enough
water).
Aldosterone will raise the water and salt levels in the
bloodstream (needed if there is excessive sweating,
which causes loss of water and salt)
Both may be released if blood pressure or blood
volume is too low, but if you do not need the salt,
there will be more ADH than aldosterone.
pollutants like pesticides and many drugs.
These substances are removed as they pass through
the peritublar capillaries directly into the PCT & DCT
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Renal Physiology Overview
80. When waste products are dumped from the
peritubular capillaries into the tubules, what is
this process called?
81. What is the juxtaglomerular apparatus (JGA)?
Tubular secretion
82. What are the two main cell types in the JGA?
83. What does the Juxtaglomerular apparatus do?
A group of cells next to the glomerulus. They fill in the
space between the glomerulus and the distal
convoluted tubule.
Macula densa cells and juxtaglomerular cells
Alters BP and GFR
84.
By autoregulation
85.
86.
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89.
How does the nephron itself alter the blood
pressure and flow into the glomerulus?
When blood pressure is too low, what hormone
do the macula densa cells release?
What effect does that hormone have on the
nephron?
What effect does that hormone have on the
GFR?
What effect does that have on blood pressure?
If blood pressure is too high, how does the
macula densa compensate?
90. If the BP is still too low after adenosine has
caused vasoconstriction what hormonal enzyme
is released by the juxtaglomerular cells?
91. What effect does this hormonal enzyme have
on blood volume and blood pressure?
92.
How does renin work (directly)?
93.
94.
What effect does ACE have?
What two effects does A2 have?
95.
Will renin be produced when the blood
pressure is too high or too low?
96. What are three reasons the sodium and water
contents of the plasma change?
97. What are two hormones that affect the
ascending limb of the Loop of Henle are
98. Where is aldosterone produced?
99. What is the effect of aldosterone?
100. What is reabsorbed with sodium?
101. Where is ADH produced?
102. What is the effect of ADH?
103. Is sodium included in this process?
When blood pressure is too low, the macula densa
releases adenosine
Adenosine causes vasoconstriction of the afferent
arterioles (blood entering the nephron).
This will slow the GFR, so less water is lost
BP increases
The macula densa stops releasing adenosine, which
allows the sphincters on the afferent arterioles to
relax. This will increase the GFR so more water is lost,
and BP decreases.
Juxtaglomerular cells secrete renin.
Renin causes more sodium to be reabsorbed, and
water flows into the bloodstream, so blood volume
increases, so BP increases. Renin can also be released
independently of adenosine.
It makes the lungs secrete angiotensin-converting
enzyme (ACE).
It cuts angiotensin-1 (A1) into angiotensin-2 (A2).
It causes blood vessel constriction in the afferent
arterioles of the nephron. It also stimulates the
hypothalamus to secrete aldosterone releasing
hormone, which causes the adrenal cortex to release
aldosterone, which also increases blood pressure.
Renin is released when BP is too low.
Sweating from activities, eating salty food or has
diarrhea
aldosterone and antidiuretic hormone (ADH)
Adrenal cortex
Sodium ions are pumped out of the kidney tubules and
into the bloodstream.
WATER
Posterior pituitary gland
Causes reabsorption of additional water from the DCT
and collecting ducts. Sodium is not included in this
process.
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Renal Physiology Overview
104. What effect does ADH have on the plasma
concentration, and in what clinical condition
would ADH be produced?
ADH causes the plasma to become more dilute (more
water, fewer particles). It would be released when a
person is dehydrated from not drinking enough water,
but if the person is dehydrated from sweating, they
need to have ADH plus aldosterone released, because
only aldosterone increases plasma sodium also.
105. What organ monitors the oxygen content in
blood?
106. By what three mechanisms can the kidney
kidneys
adjust blood volume, composition, and
pressure?
107. If O2 levels are low, what hormone is
released by the kidney, and what part of the
kidney releases it? What is the effect of that
hormone?
108. What part of the autonomic nervous system
is activated during a fight or flight situation?
1) Adjusting the volume of water lost in urine by
responding to ADH or aldosterone
2) Releasing erythropoietin
3) Releasing renin and/or adenosine
Erythropoietin is released from the JGA. It stimulates
the bone marrow to produce more red blood cells
Sympathetic nervous system
What effect does this part of the nervous
system have on the kidneys?
Decreases renal blood flow (GFR)
Why do we need this effect during a fight or
flight situation?
The blood can be used for skeletal muscles
29. Sympathetic activation of the nerve fibers
innervating the kidney causes what three
effects?
A. Changes in glomerular blood flow and
pressure
B.The stimulation of renin release from the
juxtaglomerular apparatus
C. Changes in water and Sodium reabsorption
by the nephron
109. What ions are normally found in urine?
110. What other substances are normal in the urine?
sodium, chlorine, and potassium
suspended solids (sediments) such as cells, mineral
crystals, mucus threads, and sometimes bacteria.
111. What three main things can change the pH of
urine?
Food and drink that we ingest
Acids produced through metabolism
Changes in breathing rate
112. What can increase the concentration of urine?
113. What is a urinalysis used for?
114. What six substances are never normal when
found in the urine?
Losing fluids, such as during sweating and diarrhea
To identify abnormal process occurring in the body
Glucose
Blood
Protein
Pus
Bilirubin
Ketones
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Renal Physiology Overview
115. What can cause glucose in the urine?
116. What can cause blood in the urine?
117. What can cause proteins in the urine?
118. What can cause pus in the urine?
119. What can cause bilirubin in the urine?
120. What can cause ketones in the urine?
121. What is urination technically known as?
Diabetes mellitus
Urinary tract infection, trauma, kidney stones
Kidney disease, hypertension, excessive exercise,
pregnancy
Bacterial infection in the urinary tract
Liver malfunction
Ketones are the waste product of breaking down lipids
(lipid metabolism). We break down lipids for energy
when there is not enough glucose. Therefore, ketones
are in the urine because of starvation or diabetes
Micturition
122. What part of the autonomic nervous system is
activated to allow urination?
parasympatheitc nervous system
123. What is the difference between the internal
urethral sphincter and the external urethral
sphincter?
124. What are two clinical conditions where a
diuretic is needed?
125. What is the overall effect of a diuretic?
126. What effect does a diuretic have on the renal
tubules?
internal sphincter is smooth muscle (involuntary)
external sphincter is skeletal muscle (voluntary)
127. Compared to sodium, is the homeostatic range
of potassium broad or narrow?
128. What does that mean?
129. What type of diuretic inhibits reabsorption of
potassium more than other diuretics?
130. When a person is on Lasix, how do they need to
be careful with their diet?
131. What are low blood levels of potassium called?
132. What are high blood levels of potassium called?
Is that dangerous also?
133. List four diuretic drugs:
134. How does mannitol work as a diuretic?
135. What is a potassium sparing diuretic?
136. What are two examples of potassium sparing
diuretics?
Hypertension and congestive heart failure
Decreases plasma volume
inhibit the reabsorption of sodium and potassium from
the renal tubule, causing more water to pass out as
urine
Narrow.
If potassium levels are just a little too high or too low,
the body will be out of homeostasis and needs to
compensate or it might be fatal. Sodium levels can
fluctuate a little more before it causes problems.
Thiazide drugs such as Lasix (furosemide)
They need potassium supplements or they need to eat
fruits and vegetables that have a lot of potassium, such
as cantaloupe. Bananas do not have much potassium
(you have to eat one bunch per day; lot of calories!)
Hypokalemia
Hyperkalemia. Yes, it also can be fatal.
Furosemide (Lasix)
Mannitol
Spironolactone
Amiloride
Causes dieresis by reducing net water reabsorption
from the PCT.
One that allows for water dieresis without potassium
excretion
Spironolactone and amiloride
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Renal Physiology Overview
137. Which diuretic causes the greatest degree of
hypokalemia (loss of potassium)?
138. What is required for renal homeostasis?
139. If plasma is too concentrated with particles,
what happens to nearby cells?
140. If plasma is too dilute, what happens to nearby
cells?
Furosemide (Lasix)
Maintaining proper concentration of water and sodium
shrink & lose their function
water can enter the nearby cells and cause them to
expand, also decreasing their function
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