Chapter 29. Urinary System

This textbook is designed specifically for Kansas State's Biology 198 Class. The course is taught using the studio approach and based on active learning. The studio manual contains all of the learning objectives for each class period and is the record of all student activities. Hence, this textbook is more of a reference tool while the studio manual is the learning tool.
Authors: Robert Bear, David Rintoul, Bruce Snyder, Martha Smith-Caldas, Christopher Herren, and Eva Horne
Kansas State University Libraries
New Prairie Press
Bear, Robert; Rintoul, David; Snyder, Bruce; Smith-Caldas, Martha; Herren, Christopher; and Horne, Eva, "Principles of Biology" (2016). Open Access Textbooks. 1. https://newprairiepress.org/textbooks/1
The textbook was originally published and is also available to download at http://cnx.org/contents/[e-mail] is licensed under a Creative Commons Attribution License 4.0 license.

Episode Transcript

(00:00):
Welcome to Principles of Biology. Thisbook was written by the Open Alternative Textbook
Initiative at Kansas State University and isbeing released as a podcast and distributed under
the terms of the Creative Commons AttributionLicense. Today's episode is Chapter twenty nine
Urinary System. All hyperlinks, imagesand sources can be found at the link

(00:23):
to the book. In the descriptionwhat is man when you come to think
upon him? But immnutely sat ingeniousmachine for turning with infinite artfulness the red
wine of shiraz into urine Baroness KarenBlixen in The Dreamers nineteen forty three.
Osma regulation and osmotic balance. Osmosisis the diffusion of water across a membrane

(00:45):
in response to osmotic pressure caused bydifferences in the solute molecules on either side
of the membrane. Osmaregulation is theactive homeostatic process of the water content of
an organism, involving movement of solutesacross membranes so that water moves in response
to the ion concentration. It mightbe beneficial to review osmosis here link.

(01:06):
Osmoregulation involves control of the water andsolute content of all the fluids in the
animal body. There are three generalfluid pools in the typical animal, the
blood plasma, the cytosol within cells, and the interstitial fluid, the fluid
that exists in the spaces between cellsand tissues of the body. See figure
for a review of how solute concentrationsaffect the movement of water across plasma membranes.

(01:30):
The left part of this illustration showstriveled red blood cells bathed in a
hypertonic solution. The middle part showshealthy red blood cells bathed in an isotonic
solution, and the right part showsbloated red blood cells bathed in a hypotonic
solution. One of the bloated cellsin the hypotonic solution bursts. Cells placed

(01:51):
in a hypertonic environment tend to shrinkdue to loss of water. In a
hypotonic environment, cells tend to swelldue to intake of water. The blood
maintains an isotonic environment, so thatcells neither shrink nor swell. Credit Marianna
ruis vaaol need for osmaregulation the bodydoes not exist in isolation. There is

(02:15):
a constant input of water and electrolytesinto the system. Osmoregulation is thus a
constant process. Biological systems constantly interactand exchange water and nutrients with the environment
by way of consumption of food andwater and to excretion in the form of
sweat, urine, and feces withouta mechanism to regulate osmotic pressure, or

(02:36):
when a disease damages this mechanism bearsa tendency to accumulate toxic waste and either
gain or lose water, which canhave dire consequences. Mammalian systems have evolved
to regulate not only the overall osmoticpressure a cross membranes, but also specific
concentrations of important electrolytes and the threemajor fluid compartments blood plasma, extracellular fluid,

(02:58):
and intracellular fluid. Since osmotic pressureis regulated by the movement of water
across membranes, the volume of thefluid compartments can also change temporarily. Because
blood plasma is one of the fluidcomponents, osmotic pressures have a direct bearing
on blood pressure transport of electrolytes acrossplasmal membranes. Electrolytes such as sodium chloride

(03:22):
ionize in water, meaning that theydissociate into their component ions. In water,
sodium chloride NaCl dissociates into the sodiumion naplus and the chloride ion cl.
The most important ions whose concentrations arevery closely regulated in body fluids are
the catine sodium naplus, potassium CAplus, calcium ca aplus two, magnesium n

(03:46):
G plus two, and the anineeschloride cal carbonate Co three DASH two,
bicarbonate hco three, and phosphate POthree. Electrolytes are lost from the body
during urination and perspiration. For thisreason, athletes are encouraged to replace electrolytes
and fluids during periods of increased activityand perspiration. Osmotic pressure is influenced by

(04:11):
the concentration of solutes in a solution. It is directly proportional to the concentration
of solute atoms or molecules, andnot dependent on the size of the solute
molecules. Because some compounds, knownas electrolytes dissociate into their component ions,
they add more solute particles into thesolution and have a greater effect on osmotic
pressure per mass than compounds that donot dissociate in water, such as glucose

(04:36):
water can pass through membranes by passivediffusion. If electrolyte ions could passively diffuse
a cross membranes, it would beimpossible to maintain specific concentrations of ions in
each fluid compartment. Therefore, theyrequire special mechanisms to cross the semipermeable membranes
in the body. This movement canbe accomplished by facilitated diffusion and active transport.

(05:00):
Facilitated diffusion requires protein based channels formoving the solute. Active transport requires
energy in the form of ATP conversioncarrier proteins or pumps in order to move
ions against the concentration gradient. Osmaregulators and osmic informers. Persons lost at
sea without any fresh water to drinkare at risk of severe dehydration because the

(05:21):
human body cannot adapt to drinking seawater, which is hypertonic in comparison to
body fluids. Organisms such as goldfishthat can tolerate only a relatively narrow range
of salinity are referred to as stenahaline. About ninety percent of all bony fish
are restricted to either fresh water orsea water. They are incapable of osmotic

(05:43):
regulation in the opposite environment. Itis possible, however, for a few
fishes like salmon, to spend partof their life in fresh water and part
in sea water. Organisms like thesalmon that can tolerate a relatively wide range
of salinity are referred to as urahalineorganisms. This is possible because some fish
have evolved osma regulatory mechanisms to survivein all kinds of aquatic environments. When

(06:09):
they live in fresh water, theirbodies tend to take up water because the
environment is relatively hypotonic, as illustratedin Figuia. In such hypotonic environments,
these fish do not drink much water. Instead, they pass a lot of
very dilute urine, and they achieveelectrolyte balance by active transport of salts through
the gills. When they move toa hypertonic marine environment, these fish start

(06:33):
drinking seawater. They excrete the excesssalts through their gills and their urine as
illustrated in Figure EBB. Most marineinvertebrates, on the other hand, may
be isotonic with seawater. These areknown as osmic informers. Their body fluid
concentrations conform to changes in seawater concentrationcartilaginous fish's salt composition of the blood is

(06:56):
similar to bony fishes. However,the blood of sharks contains the and it
compounds urea and trimethylamine oxide TMAO.This does not mean that their electrolyte composition
is similar to that of sea water. They achieve isatinicity with the sea by
storing large concentrations of urea. Theseanimals that secrete urea are called ureatellic animals.

(07:18):
TMAO stabilizes proteins in the presence ofhigh urea levels, preventing the disruption
of peptide bonds that would occur inother animals exposed to similar levels of urea.
Sharks have a rectal gland which secretessalt and assists in osmaregulation. Illustration
A shows of fish and a freshwaterenvironment where water is absorbed through the skin

(07:40):
to compensate. The fish drinks littlewater and excretes dilute urine, sodium,
potassium, and chlorine. Ions arelost through the skin, and the fish
actively transports these same ions into itsgills to compensate for this loss. Illustration
beech shows of fish in a saltwaterenvironment where water is lost through the skin

(08:00):
to compensate. The fish drink samplewater and excretes concentrated urine. It absorbs
sodium, potassium, and chlorine ionsthrough its skin and excretes them through its
gills. Fish are osmaregulators, butmust use different mechanisms to survive in a
freshwater or bee saltwater environments. Creditmodification of work by Duane Raver Noah kidneys

(08:24):
and osmoregulatory organs. Although the kidneysare the major osmoregulatory organ the skin and
lungs also play a role in theprocess. Water and electrolytes are lost through
sweat glands in the skin, whichhelps moisturize and cool the skin surface,
while the lungs expel a small amountof water in the form of mucous secretions
and via evaporation of water vapor.Kidneys the main osmoregulatory organ The kidneys illustrated

(08:52):
in figure are a pair of beanshaped structures that are located just below and
posterior to the liver in the peritonealcavity. The adrenal glands sit on top
of each kidney. Kidneys filter bloodand purify it. All the blood in
the human body is filtered. Manytimes a day by the kidneys. These
organs use up almost twenty five percentof the oxygen absorbed through the lungs.

(09:13):
To perform this function, the filtratecoming out of the kidneys is called urine.
Illustration shows the placement of the kidneysand bladder in a human man.
The two kidneys face one another andare located on the posterior side about half
way up the back. A renalartery and a renal vein extend from the
inside middle of each kidney. Poureda major blood vessel that runs up the

(09:37):
middle of the body. A euretaruns down from each kidney to the bladder,
a sack that sits just above thepelvis. The urethra runs down from
the bottom of the bladder and throughthe penis. The adrenal glands are lumpy
masses that sit on top of thekidneys. Kidneys filter the blood, producing
urine that is stored in the bladderprior to elimination through the eurea credit modification

(10:01):
of work by NCI kidney structure.Externally, the kidneys are surrounded by three
layers illustrated in figure. The outermostlayer is a tough, connective tissue layer
called the renal fascia. The secondlayer is called the perirenal fat capsule,
which helps anchor the kidneys in place. The third and innermost layer is the

(10:22):
renal capsule. Internally, the kidneyhas three regions, an outer cortex,
a medulla in the middle, andthe renal pelvis in the region called the
highlum of the kidney. The highlumis the concave part of the bean shape
where blood vessels and nerves enter andexit the kidney. It is also the
point of exit for the uritors.The renal cortex is granular due to the

(10:43):
presence of nephrons. The functional unitof the kidney, the medulla, consists
of multiple pyramidal tissue masses called therenal pyramids. In between the pyramids are
spaces called renal columns through which theblood vessels pass. The tips of the
pyramids, called renal papilli, pointtoward the renal pelvis. There are on

(11:05):
average eight renal pyramids in each kidney. The renal pyramids, along with the
adjoining cortical region, are called thelobes of the kidney. The renal pelvis
leads to the eureder on the outsideof the kidney. On the inside of
the kidney, the renal pelvis branchesout into two or three extensions called the
major klysses, which further branch intothe minor klyses. The euretors are urine

(11:28):
bearing tubes that exit the kidney andempty into the urinary bladder. The kidney
is shaped like a kidney bean standingon end. Two layers, the outer
renal fascia and an inner capsule,cover the outside of the kidney. The
inside of the kidney consists of threelayers, the outer cortex, the mintle
medulla, and the inner renal pelvis. The renal pelvis is flushed with the

(11:52):
concave side of the kidney and emptiesinto the ereder, a tube that runs
down outside the concave side of thekidney. Nine renal pyramids are embedded in
the medulla, which is the thickestkidney layer. Each renal pyramid is teardrop
shaped, with the narrow end facingthe renal pelvis. The renal artery and
renal vein enter the concave part ofthe kidney just above the ureterer. The

(12:15):
renal artery and renal vein branch intoarterials and venules. Respectively, which extend
into the kidney and branch into capillariesand the cortex. The internal structure of
the kidney is shown credit modification ofwork by NZI. Because the kidney filters
blood, its network of blood vesselsis an important component of its structure and

(12:35):
function. The arteries, veins,and nerves that supply the kidney enter an
exit at the renal hylum. Renalblood supply starts with the branching of the
orda into the renal arteries and endswith the exiting of the renal veins to
join the inferior vena cava. Asmentioned previously, the functional unit of the
kidney is the nephron, illustrated infigure. Each kidney is made up of

(13:00):
over one million nephrons that DoPT therenal cortex, giving it a granular appearance
one section sagivali. A nephron consistsof three parts, a renal corpusal,
a renal tubule, and the associatedcapillary network, which originates from the arteries
that supply blood to the kidney.Illustration shows the nephron, a tube like
structure that begins in the kidney cortex. Here, arterials converge in a bulb

(13:24):
like structure called the glomerulus, whichis partly surrounded by a bowman's capsule.
Affering arterials enter the glomerulus and efferingarterials leave the glomerulus empties into the proximal
convoluted tubule. A long loop calledthe loop of Henley extends from the proximal
convoluted tubule to the inner medula ofthe kidney and then back out to the

(13:46):
cortex. There, the loop ofHenley joins a distal convoluted tubule. The
distal convoluted tubule joins a collecting ductwhich travels from the medulla back into the
cortex towards the center or of thekidney. Eventually, the contents of the
renal pyramid empty into the renal pelvisand then the ureterer. The nephron is

(14:09):
the functional unit of the kidney.The glomerulis and convoluted tubules are located in
the kidney cortex, while collecting ducksare located in the pyramids of the medulla.
Credit modification of work by Niddka.Renal corpusal. The renal corpusal,
located in the renal cortex, ismade up of a network of capillaries known
as the glomerulis and the capsule acup shaped chamber that surrounds it, called

(14:33):
the glomerular or Bowman's capsule. Renaltubule. The renal tubule is a long
and convoluted structure that emerges from theglomerulus and can be divided into three parts
based on function. The first partis called the proximal convoluted tubule PCT due
to its proximity to the glomerulus itstays in the renal cortex. The second

(14:54):
part is called the loop of Henleyor nephritic loop, because it forms a
loop with this sending and ascending limbsthat goes through the renal medulla. The
third part of the renal tubule iscalled the distal convoluted tubule DCT, and
this part is also restricted to therenal cortex. The DCT, which is
the last part of the nephron,connects and empties its contents into collecting ducks

(15:18):
that line the medillary pyramids. Thecollecting ducks and mass contents from multiple nephrons
and fuse together as they enter thepapillia of the renal medulla. Capillary network
within the nephron, The capillary networkthat originates from the renal arteries supplies the
nephron with blood that needs to befiltered. The branch that enters the glomerulis

(15:39):
is called the affron arterial. Thebranch that exits the glomerulis is called the
effron arterial. Within the glomerulus,the network of capillaries is called the glomerular
capillary bed. Once the effron arterialexits the glomerulus, it forms the peritubular
capillary network, which surrounds and interactswith parts of the renal tubule, kidney

(16:00):
function, and physiology. Kidney's filterblood in a three step process. First,
the nephron's filter blood that runs throughthe capillary network and the glomerulis.
Almost all solutes except for proteins,are filtered out into the glomerulus by a
process called glomerular filtration. The higharterial pressure and the permeable membranes of the

(16:22):
glomerulus see below combined to accomplish thisfiltration. Second, the filtrate is collected
in the renal tubules. Most ofthe solutes get reabsorbed in the PCT by
a process called tubular reabsorption. Inthe loop of Henley, the filtrate continues
to exchange solutes in water with therenal medulla and the peritubular capillary network.

(16:45):
Water is also reabsorbed during this step. Then additional solutes and wastes are secreted
into the kidney tubules during tubular secretion, which is in essence the opposite process
to tubular reabsorption. The collecting duckscollect filtrate coming from the nephrons and fuse
in the metillary popili. From here, the papilli deliver the filtrate, now

(17:07):
called urine, into the minor klysesthat eventually connect to the urtors through the
renal pelvis. This entire process isillustrated in figure Illustration labels parts of a
nephron and their function. The nephronbegins at the glomerulis, a spherical structure
that filters small solutes from the blood. The filtrate then enters a winding proximal

(17:30):
convoluted tubule, which reabsorbs ions,water and nutrients and removes toxins and adjust
the filtrate pH The proximal convoluted tubuleempties into the descending loop of Henley.
Aquiporns in the descending loop allow waterto pass from the filtrate to the interstitial
fluid. The descending loop of Henleyturns into the ascending loop of Henley.

(17:53):
Both the descending loop and ascending loopare thin at the bottom and turn thick
about a third of the way up. In the ascending loop of Henley,
sodium and chlorine ions are reabsorbed fromthe filtrate into the interstitial fluid. The
ascending loop of Henley empties into thedistal convoluted tubule, which selectively secretes and
absorbs ions to maintain blood pH andelectrolyte balance. The distal convoluted tubule empties

(18:18):
into a collecting duct, which reabsorbswater and salutes from the filtrate. The
collecting duct travels down towards the middleof the kidney. Each part of the
nephron performs a different function in filteringwaste and maintaining homeostatic balance. One,
the glomerulis forces small salutes out ofthe blood by pressure. Two, the

(18:41):
proximal convoluted tubule reabsorbs ions, waterand nutrients from the filtrate into the interstitial
fluid, and actively transports toxins anddrugs from the interstitial fluid into the filtrate.
The proximal convoluted tubule also adjusts bloodpH by selectively secreting ammonia n H
three into the filtrate, where itreacts with H plus to form n H

(19:02):
four plus. The more acidic thefiltrate, the more ammonia is secreted.
Three. The descending loop of Henleyis lined with cells containing aquaporins that allow
water to pass from the filtrate intothe interstitial fluid. Four. In the
thin part of the ascending loop ofHenley, now plus and c L ions
diffuse into the interstitial fluid. Inthe thick part, these same ions are

(19:25):
actively transported into the interstitial fluid.Because salt, but not water, is
lost. The filtrate becomes more diluteas it travels up the limb. Five
and the distal convoluted tubule. Kplus and H plus ions are selectively secreted
into the filtrate, while naplus,c l dash, and HCO three ions
are reabsorbed to maintain pH and electrolytebalance and the blood six, the collecting

(19:49):
duct reabsorbs solutes and water from thefiltrate, forming dilute urine credit modification of
work by Niddka glomerular filtrate. Glomerularfiltration filters out most of the solutes due
to high blood pressure and specialized membranesin the affrin arterial. The blood pressure
in the glomerulis is maintained independent offactors that affects systemic blood pressure. The

(20:14):
leaky connections between the endothelial cells ofthe glomerular capillary network allows solutes to pass
through easily. All solutes in theglomerular capillaries except for macromolecules like proteins,
pastored by passive diffusion. There isno energy requirement at this stage of the
filtration process. High arterial blood pressuredoes the work at this stage tubular reabsorption

(20:37):
and secretion. Tubular reabsorption occurs inthe PCT part of the renal tubule.
Almost all nutrients e g. Glucoseamino acids are reabsorbed, and this occurs
either by passive or active transport.Reabsorption of water and some key electrolytes are
regulated and can be influenced by hormones. Sodium noplus is the most abundant ion,

(21:00):
and most of it is reabsorbed byactive transport and then transported to the
peritubular capillaries. Because no plus isactively transported out of the tubule, water
follows it to even out the osmoticpressure. Water is also independently reabsorbed into
the peritubular capillaries due to the presenceof aquaporins or water channels in the PCT.

(21:22):
This occurs due to the low bloodpressure and high osmotic pressure in the
peritubular capillaries. However, every solutehas a transport maximum, and the excess
is not reabsorbed. In the loopof Henley, the permeability of the membrane
changes. The descending limb is permeableto water, not solutes. The opposite

(21:42):
is true for the ascending limb.Additionally, the loop of Henley invades the
renal medula, which is naturally highin salt concentration, and tends to absorb
water from the renal tubule and concentratethe filtrate. The osmotic gradient increases as
it moves deeper into the medu ula. Because two sides of the loop of

(22:02):
Henley perform opposing functions as illustrated infigure, it acts as a countercurrent multiplier.
The vase erecta around it acts asthe countercurrent exchanger. A U shaped
tube represents the loop of Henley.Filtrate enters the descending limb and exits the
ascending limb. The descending limb iswater permeable, and water travels from the

(22:23):
limb to the interstitial space. Asa consequence, the osmolality of the filtrate
inside the limb increases from three hundredmilliasmoles per leader at the top to twelve
hundred milliasmoles per leader at the bottom. The ascending limb is permeable to sodium
and chloride ions because the osmolality insidebottom part of the limb is higher than

(22:45):
the interstitial fluid. These ions diffuseout of the ascending limb. Higher up,
sodium is actively transported out of thelimb, and chloride follows. The
loop of Henley acts as a countercurrentmultiplier that uses energy to create centration gradients.
The descending limb is water permeable.Water flows from the filtrate to the

(23:07):
interstitial fluid, so osmolality inside thelimb increases as it descends into the renal
medulla at the bottom. The osmolalityis higher inside the loop than in the
interstitial fluid. Thus, as filtrateenters the ascending limb, noplus in clions
exit through ion channels present in theplasma membrane. Further up, noplus is
actively transported out of the filtrate andcl follows Osmolarity is given in units of

(23:33):
milliasmals per liter a mussum slash owl. Hypertension high blood pressure is a common
problem for humans and is usually treatedwith a variety of drugs that act on
various processes occurring in the kidney.One class of hypertension drugs is the so
called loop diuretics, which inhibit thereabsorption of noplus and cl ions by the
ascending limb of the loop of Henley. A side effect is that they increase

(23:57):
urination. Why do you think thisis the case. By the time the
filtrate reaches the DCT, most ofthe urine and solutes have been reabsorbed.
If the body requires additional water,all of it can be reabsorbed at this
point. Further reabsorption is controlled byhormones, which will be discussed in a

(24:18):
later section. Excretion of wastes occursdue to lack of reabsorption combined with tubular
secretion. Undesirable products like metabolic wastes, urea, uric acid, and certain
drugs are excreted by tubular secretion.Most of the tubular secretion happens in the
DCT, but some occurs in theearly part of the collecting duct. Kidneys

(24:40):
also maintain an acid base balance bysecreting excess h plus ions nitrogenous waste.
Of the four major macromolecules in biologicalsystems, both proteins and nucleic acids contain
nitrogen. During the catabolism or breakdownof nitrogen containing macromolecules, carbon, hydrogen,
and oxygen are extracted and stored inthe form of carbohydrates and fats.

(25:06):
Excess nitrogen is excreted from the body. Nitrogenous wastes tend to form toxic ammonia,
which raises the peach of body fluids. The formation of ammonia itself requires
energy in the form of ADP inlarge quantities of water to dilute it out
of a biological system. It isquite toxic, even at relatively low concentrations.

(25:27):
Animals that live in aquatic environments tendto release ammonia directly into the water
in the urine. They have accessto sufficient water to dilute this waste product
to non toxic levels. Animals thatexcrete ammonia are said to be a monotelic
Terrestrial organisms have evolved other mechanisms toprocess and excrete nitrogenous wastes. The animals

(25:49):
first detoxify ammonia by converting it intoa relatively non toxic form such as urea
or uric acid. Mammals, includinghumans, produce ura, whereas reptiles and
many terrestrial invertebrates produce uric acid.Animals that secrete urea as the primary nitrogenous
waste material are called uretallic animals.Nitrogenous waste in terrestrial animals. Urea urea

(26:15):
formation is the primary mechanism by whichmammals convert ammonia to urea. Urea is
made in the liver and excreted inurine. The overall chemical reaction by which
ammonia is converted to urea is twoNH three ammonia plus COO two plus three
ADP plus H two becomes H twon conh two urea plus two ADP plus

(26:37):
four pi plus amp. Evolution connectionexcretion of nitrogenous waste. The theory of
evolution proposes that life started in anaquatic environment. It is not surprising to
see that biochemical pathways like the ureacycle evolved to adapt to a changing environment.
When terrestrial life forms evolved arid conditionsprobably lead to the evolution of the

(26:59):
uric acid pathway as a means ofconserving water nitrogenous waste in birds and reptiles.
Uric acid birds, reptiles in mostterrestrial arthropods convert toxic ammonia to uric
acid or the closely related compound guanineguano instead of urea. Mammals also form
some uric acid during breakdown of nucleicacids. Uric Acid is a compound similar

(27:23):
to purines found in nucleic acids.It is water insoluble and tends to form
a white paste or powder. Itis excreted by birds, insects, and
reptiles. Conversion of ammonia to uricacid requires more energy and is much more
complex than conversion of ammonia to ureafigure, but the payoff is that uric
acid requires much less water when excreted. Partaise shows a photo of a freshwater

(27:48):
fish and states that many invertebrates andaquatic species excrete ammonia. The chemical structure
of ammonia is NH three. PartBeech shows a photo of a wood rat
and states that mammal, many adultamphibians, and some marine species excrete urea.
The chemical structure of urea is shown. Urea has two n H two
groups attached to a central carbon.An oxygen is also double bonded to this

(28:14):
central carbon. Part C shows aphoto of a pigeon and states that insects,
land, snails, birds, andmany reptiles excrete uric acid. The
chemical structure of uric acid is shown. Uric acid has a six membered carbon
ring attached to a five membered ring. Each ring has two NH groups embedded
in it. An oxygen is doublebonded to each ring. Nitrogenous waste is

(28:41):
excreted in different forms by different species. These include a ammonia, b urea,
and c uric acid. Credit Amodification of work by Eric Angretzen USFWS
credit B modification of work by BeingMoose Peterson USFWUS credit see David a.
Raintol gout. In some animals,uric acid can build up under certain conditions,

(29:06):
or as consequence of a diet highand nitrogenous compounds each nucleotides. In
those situations, uric acid tends tocrystallize and form kidney stones. Uric Acid
build up may also cause a painfulcondition called gout, where uric acid crystals
accumulate in the joints, as illustratedin figure. Food choices that reduce the

(29:26):
amount of nitrogenous compounds in the diethelp reduce the risk of gout. For
example, tea, coffee, andchocolate have puring like compounds called xanthines and
should be avoided by people with goutand kidney stones. Photo shows a toe
that is swollen and red. Goutcauses the inflammation visible in this person's left

(29:48):
big toe joint. Credit gonzost SlashWikimedia Commons. This podcast will be released
episodically and follow the sections of thetextbook in the description and for a deeper
understanding, we encourage you review thetext version of this work voice by voicemaker
Donayane. This was produced by BrandonCasturo as a creative Common Sense production.