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Urinary Lecture
Urinary Lecture
193
Anatomy
Undergraduate 2
07/24/2011

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Term
Metabolic wastes are excreted in urine: Urea comes from where?
Definition
Urea is from protein breakdown
Term
Metabolic wastes are excreted in urine: Uric acid comes from where?
Definition
Uric acid - from nucleic acid breakdown
Term
Metabolic wastes are excreted in urine: Bilirubin comes from where?
Definition
Bilirubin comes from hemoglobin breakdown.
Term
Metabolic wastes are excreted in urine: Creatinine comes from where?
Definition
Creatinine - from creatine phosphate breakdown (muscle).
Term
Kidneys conserve nutrients & blood, enters renal hilum, nuproteins:
Definition
Nutrients like glucose, amino acids; blood proteins like albumins
Term
What organs are used for urine storage and elimination?
Definition
ureters (2), urinary bladder, urethra
Term
Muscular tubes that transport urine to the urinary bladder?
Definition
ureters
Term
What kind of muscle are in the ureters?
Definition
smooth muscle
Term
What is the muscular sac that stores urine until voiding?
Definition
urinary bladder
Term
As bladder fills, ____________ openings close preventing backflow.
Definition
ureteral
Term
The urinary bladder is lined with what type of tissue?
Definition
transitional epithelium
Term
What features are unique to the urinary bladder?
Definition
transitional lining stretches as urinary bladder fills. Goblet cells secrete a protective coating of mucus that is both acidic and alkaline and holds for a # of hours.
Term
The internal urethral sphincter of the bladder is what type of muscle and nervous system?
Definition
smooth muscle and involuntary
Term
The external urethral sphincter of the bladder is what type of muscle and nervous system?
Definition
skeletal muscle and voluntary
Term
How does the male urethra differ from the female?
Definition
male urethra is longer and also conducts semen.
Term
Where are the kidneys located in the body?
Definition
the kidneys are located lateral to vertebral column, levels T12-L3. Right kidney is slightly lower than the left because of the liver superior to the kidney.
Term
The peritoneum is a serous membrane that lines the abdominal cavity of the body. Where are the kidneys located relating to the peritoneum?
Definition
behind the peritoneum
Term
Where are the adrenal glands related to the kidneys?
Definition
adrenal gland is on the superior aspect of each kidney
Term
Kidneys are protected by 3 layers of connective tissue. What are the 3 layers of tissue?
Definition
Renal fascia, adipose capsule, renal capsule
Term
Near the center of the medial concave border is an indentation that connects with ureter, renal artery, renal vein, and nerves.
Definition
renal hilum
Term
A shallow internal cavity divided into minor calyces, 2-3 major calyces, renal pelvis.
Definition
renal sinus
Term
________ work nonstop to filter blood and produce urine.
Definition
nephrons
Term
There are approximately 1 million of these per kidney.
Definition
nephrons
Term
Where does the nephron become urine?
Definition
along the collecting duct
Term
How many pyramids does the average adult kidney have?
Definition
about 10
Term
Where does the blood supply of the kidney go through?
Definition
through the columns in the kidneys
Term
There are typically 100,000 of these __________ in the cortex of the kidney.
Definition
nephrons
Term
The kidneys receive approximately ______ of cardiac output (left ventricular output) which is equal to 1L of blood per _________.
Definition
20%, minute, at rest.
Term
Branches from abdominal aorta, supplies each kidney with blood, enters renal hilum, numerous branches in renal cortes, each nephron is supplied by an afferent arteriole, each nephron is drained by peritublar capillaries.
Definition
renal artery
Term
Drains blood from each kidney, returns blood to inferior vena cava.
Definition
renal vein
Term
Each nephron has two capillary networks: _______ & _________.
Definition
glomerulu peritubular capillaries
Term
Blood flow in to renal artery from ___________ and flow out of renal vein by ______.
Definition
aorta, inferior vena cava
Term
Each nephron is supplied blood by an ___________ going into the glomerulus (fenestrated capillaries).
Definition
afferent arteriole
Term
Each nephron is drained by ___________ flowing from the efferent arterioles.
Definition
peritubular capillaries
Term
Each nephron has 2 sections: _____________ & __________.
Definition
renal corpuscle and renal tubule
Term
What is the function of the renal corpuscle?
Definition
Function of renal corpuscle is filtration. There is a selective removal of filtrate from the blood.
Term
Through what structures are the filtrate removed from the blood?
Definition
Glomerulus (fenestrated capillaries), and Glomerular capsule (surrounds the glomerulus and captures the filtrate.
Term
The filtrate is modified by the _________.
Definition
Renal tubule.
Term
Filtrate is modified by the renal tubule through two functions: ___________ & _________.
Definition
reabsorption & secretion
Term
What structures are used to modify the filtrate?
Definition
Proximal convoluted tubule (PCT), loop of henle, distal convoluted tubule (DCT)
Term
What is the purpose of the reabsortion function?
Definition
reabsorption returns filtered substances to the blood.
Term
What is the purpose of the secretion function?
Definition
Secretion adds specific substances to the urine.
Term
What are the two types of nephrons?
Definition
cortical and juxtamedullary. 90% are cortical and 10% juxtamedullary
Term
What type of nephron are most nephrons?
Definition
cortical
Term
Does a cortical nephron have a short or long loop of henle?
Definition
short
Term
how much urine does a well hydrated person void a day?
Definition
1 - 2 liters, about 30 ml an hour
Term
Other __________ hook into the openings along the top of the collecting duct.
Definition
nephrons
Term
In the _____________ urine is present. Water absorption is about done at this point.
Definition
collecting duct.
Term
The glomerulus is surrounded by the _________, which captures the filtrate.
Definition
glomerulus capsule
Term
______________ are close to the renal tubule.
Definition
peritubular capillaries
Term
Describe the flow of fluid through a cortical nephron?
Definition
Glomerular capsule, proximal convoluted tubule, descending limb of the loop of henle, ascending limb of the loop of henle, distal convoluted tuble.
Term
Are the peritubular capillary fenestrated?
Definition
No
Term
The glomerulus are what type of capillary?
Definition
fenestrated.
Term
The _________ arteriol is after the glomerulus.
Definition
efferent
Term
The _______brought blood from renal artery
Definition
arcuate
Term
Each _____________ nephron has a long loop of henle extending deep into the medulla.
Definition
juxtamedullary
Term
This nephons specialize in concentrating the urine.
Definition
jaxtamedullary
Term
Modified peritubular capillaries, associated with the long loop of henle are the ____________.
Definition
Vasa Recta
Term
Flow of fluid through a juxtamedually nephon?
Definition
glomerular capsule, proximal convoluted tubule, descending limb of the loop of henle, thin ascending limb of the loop of henle, thick ascending limb of the loop of henle, distal convoluted tubule (drains into collecting duct)
Term
Why is the step of filtration so important in the nephon?
Definition
Because if the filtration step isn't done correctly none of the rest of the process is correct.
Term
Filtrate is produced from the ____________, and captured in the _________ of the glomerular capsule.
Definition
fenestrated glomerulus, capsular space
Term
Several DCT's drain into a __________.
Definition
collecting duct
Term
The first step of renal physiology is __________.
Definition
filtration
Term
What is filtration?
Definition
a process where water and most solutes are removed from the blood in the nephron. This fluid is called filtrate. It is not yet urine.
Term
Where does filtration take place?
Definition
In the renal corpuscle (glomerulus and glomerular capsule)
Term
What is reabsorption?
Definition
What was lost in the filtrate is returned to the blood in peritubular caps.
Term
Reabsorption & secretion occur ________.
Definition
simultaneously
Term
Where is reabsorption performed?
Definition
PCT (90%,almost all reabsorbtion is done in PCT, + loop + DCT + collecting duct)
Term
What is secretion?
Definition
Transfer of specific substances from peritubular blood to the tubular fluid. Opposite direction of reabsorption.
Term
___________ production is completed in the collecting ducts (since they participate in reabsorption and secretion).
Definition
Urine
Term
__________ supplies blood to the glomerulus.
Definition
afferent arteriole
Term
______ drains the glomerulus.
Definition
efferent arteriole
Term
____________ is a coiled network of fenestrated capillaries located inside the glomerular capsule.
Definition
glomerulus
Term
_________ enters glomerular capsular space, then moves into PCT.
Definition
glomerulus
Term
______ are cells clinging to the surface of glomerulus.
Definition
podocytes
Term
____________ have long footlike processes called pedicels.
Definition
podocytes
Term
___________ are found between coils of glomerulus and are ___________.
Definition
mesangial cells, contractile
Term
Mesangial cells help to regulate __________. How?
Definition
filtration, by reducing the surface area for filtration by tigthening the coils of the capillaries. Also lets contraction happen more often.
Term
Which has a greater diameter, the afferent arteriole or the efferent arteriole. What purpose does this larger size serve?
Definition
afferent has greater diameter, the larger size increases the blood pressure in the glomerulus, promoting filtration.
Term
These cells are contractile, having actin and mosin like filaments reducing the surface area of filtration.
Definition
Messangial cells
Term
A large total surface area promotes filtration.
Definition
Term
________ help strengthen capillary wall by wrapping around capillary and act as another layer of filtration.
Definition
podocyte
Term
What are the filtration membrane layers involved in filtration?
Definition
1)Fenestrations, 2)basement membrane, 3) filtration slits
Term
If a substance can be filtered, it passes through __________ .
Definition
all three layers of the filtration membrane
Term
____________ (pore) of glomerular endothelial cell: prevents filtration of blood cells but allows all components of blood plasma to pass through.
Definition
Fenestration
Term
_________ of glomerulus: prevents filtration of larter proteins. It's the basement membrane of the glomerulus. It's the extracellular material between glomerulus and podocytes.
Definition
basal lamina
Term
__________ between pedicels: prevents filtration of medium sized proteins. Located between pedicels of podocytes, and covered by a then membrane.
Definition
Filtration slit membrane
Term
Features that promote filtration are : _________, _________, _________
Definition
large total surface area, thin and porous filtration membrane, relatively high glomerular blood pressure.
Term
Each glomerulus is long and coiled: approximately ___________ per kidney.
Definition
one million
Term
The glomerulus is regulated by ____________.
Definition
mesangial cells
Term
Relaxed mesangial cells of glomerulus membrane increase _________.
Definition
filtration surface area
Term
Contracted mesangial cells of glomerulus membrane decrease _________.
Definition
filtration surface area
Term
__________ mesangial cells "tug" the glomerulus into tighter coils.
Definition
contracted
Term
Relatively high glomerular blood pressue is due to diameter difference of ____________ and efferent arterioles. This difference boosts glomerular blood pressure to approximately ________
Definition
afferent, 55mmHg to 60mmHg (avg = 18 mmHg). This is 3X higher blood pressure than other systemic capillaries.
Term
All substances are filtered on the basis of ______. Some substances (ex. some proteins) are also filtered on the basis of ____________.
Definition
size, electric charge
Term
What is not filtered (cannot cross filtration membrane?
Definition
Blood cells and platelets, most medium and large blood proteins (ex. albumins), and normally white blood cells also are not filtered.
Term
What is filtered (becoming the filtrate)?
Definition
Water and most plasma solutes, including ions and very small proteins, nutrients (ex. glucose, amino acids) we must obsorb nutrients, Metabolic wates (ex. urea, uric acid).
Term
Filtration is __________ driven.
Definition
pressure
Term
Glomerular blood pressure __________ filtration
Definition
promotes
Term
Capsular pressure _________ filtration.
Definition
opposes
Term
Blood's osmotic pressure ________ filtration
Definition
opposes
Term
Considering all pressures, net filtration pressure = __________.
Definition
10mmHg
Term
Capsular hydrostatic pressure (15mmHg) is not higher because ___________.
Definition
It has a way out of the glomerulus through the proximal convoluted tubule.
Term
How is Net Filtration Pressure (NFP) determined?
Definition
Net Filtration Pressure=
GBHP - CHP - BCOP
= 55mmHg- 15mmHg - 30mmHg
= 10mmHg
Term
Does blood or filtrate have more solutes?
Definition
blood
Term
Glomerular filtration rate (GFR) = volume of __________ formed by the kidney per minute.
Definition
filtrate
Term
Normal audit male GFR = ?
Definition
125 ml/min
Term
Normal adult female GFR = ?
Definition
105 ml/min
Term
What is GFR?
Definition
measure of amount of filtrate pushed out of glomerulus
Term
Urine output averages only ______ liters per day.
Definition
1-2 liters a day
Term
Little/Most of the filtrate is reabsorbed.
Definition
Most
Term
The only place in the kidney where filtration occurs is in the________.
Definition
renal corpuscle
Term
Homeostasis of body fluids requires that the kidneys maintain a relatively constant ____.
Definition
GFR
Term
What happens if the GFR is too low?
Definition
filtrate is produced too slowly. As it travels slowly through the renal tubule, too many SOLUTES are reabsorbed.
Term
Abnormally low GFR causes increased levels of blood ______ & ________.
Definition
urea, uric acid
Term
If GFR is too low are there unwanted wastes that could be reabsored?
Definition
Yes reabsorbed., creatinine waste is overly
Term
What happens if GFR is too high?
Definition
Filtrate is produced too fast. Not enough solutes - such as nutrients - are reabsorbed.
Term
Abnormally high GFR causes what?
Definition
An abnor nutrumally high GFR causes too nutrients (glucose) and ions to be lost in the urine.
Term
Mechanisms that regulate GFR work in what two main ways?
Definition
1)By adjusting the amount of blood flow to the glomerulus 2)By changing the glomerular surface area available for filtration.
Term
Three mechanisms that regulate GFR are: 1)________ 2)_________ 3)__________
Definition
1)Renal autoregulation
2)Neural regulation
3)Hormonal regulation
Term
What is Renal autoregulation?
Definition
The capability for each nephron to reulate its own GFR despite small, normal fluctuations in systemic blood pressure.
Term
What is the dominant mechanism regulating GFR under normal circumstances?
Definition
Renal autoregulation
Term
When does the Neural Regulation of GFR act?
Definition
During periods of high sympathetic stimulation. For example, during periods of intense exercise, extreme physical stress, hemorrhage or other physiological emergency. The body looks at these activities and sees that the least important thing is for the kidneys to get blood flow and redirects blood to other body tissues.
Term
When does Hormonal regulation of the GFR happen?
Definition
Hormonal regulations of the GFR takes place when the body needs to control blood volume and systemic blood pressure. The kidneys are used in hormone regulation as a "tool" for blood pressure homeostasis.
Term
What are the two methods of Renal Autoregulation?
Definition
1)Myogenic mechanism - gives a fast response in seconds.
2)Tubuloglomerular Feedback - gives a somewhat slower response, in minutes.
Both methods adjust GFR as needed during small, normal blood pressure changes.
Term
The Renal autoregulation that involves smooth muscle walls of the kidney is ________. It prevents normal, small changes in BP from affecting GFR by a local automatic response of _________.
Definition
Myogenic mechanism, afferent arterioles
Term
How does myogenic mechanism use the afferent arteriole to decrease GFR?
Definition
If systemic BP increases, a stretch-reflex response will trigger contraction of the smooth muscle wall constricting the afferent arteriole. The constriction reduces renal blood flow, deceasing GFR to normal levels (despite a small increase in systemic BP.)
Term
Does myogenic mechanism involve nerves?
Definition
no, it just controls blood volume flow.
Term
When the afferent arteriole is constricted during myogenic mechanism won't the pressure be increased and reduce blood flow which will increase BP?
Definition
No, the afferent arteriole has stretch-reflex that allows the smooth muscle fibers in the wall of the afferent arteriole to contract or dilate, increasing or decreasing blood pressure and renal blood flow and GFR are normalized in seconds after a change in BP.
Term
If BP decreases how does myogenic mechanism react?
Definition
The arteriole stretches less which signals it to relax. Dilated afferent arterioles help increase GFR to normal levels.
Term
Tubuloglomerular feedback is so named because why?
Definition
Because part of the renal tubules - the macula densa - provides feedback to the glomerulus.
Term
When GFR is above normal due to elevated systemic BP, filtered fluid flows more rapidly along the renal tubules. As a result, the proximal convoluted tubule and loop of Henle have less time to absorb Na+, Cl-, and water. ___________ cells are thought to detect the increased delivery of Na+, Cl-, and water and inhibit release of nitric oxide (NO) from cells in the juxtamedullary apparatus (JGA)
Definition
Macula densa
Term
When macula densa cells inhibit release of nitric oxide (NO) what happens?
Definition
Because NO causes vasodilation, JG cells and afferent arterioles constrict when the level of NO declines. Less blood flows into the glomerular capillaries and the GFR decreases. When blood pressure falls, causing GFR to be lower than normal, the opposite sequence of events occurs, although to a lesser degree.
Term
What is the name of the cells that begin the tubuloglomerular feeback loop?
Definition
macula densa cells
Term
What is the job of macula densa cells?
Definition
They sense the increased concentration of tubular fluid and believed to secrete less nitric oxide (NO).
Term
What happens if GFR is too high?
Definition
Not enough reabsorption occurs as the fluid races through the renal tube. This will make the tubular fluid too concentrated in solutes.
Term
Where are the macula densa cells located?
Definition
In the ascending loop of Henle, adjacent to afferent arteriole, backed up to Juxtaglomerular (JG) cells.
Term
Chemoreceptors that sense the concentration of tubular fluid.
Definition
macula densa cells
Term
What is the function of macula densa cells?
Definition
to signal release or inhibit of NO so that JG cells can contract during the tubuloglomeruler feedback to correct a small increase in GFR due to a small increase in systemic BP.
Term
_______________ are specialized smooth muscle cells of the afferent arteriole.
Definition
Juxtaglomerular cells
Term
These cells contract during tubuloglomerular feedback decreasing blood flow and GFR.
Definition
Juxtaglomerular (JG) cells
Term
How often does the tubuloglomerular feedback respond to disruptions in homeostasis?
Definition
continually, 24/7
Term
What is the juxtaglomerular apparatus?
Definition
jaxtaglomerular apparatus refers to the two interacting areas of macula densa cells and JG cells.
Term
Do large increases in sympathetic stimulation vasoconstrict afferent arterioles more than efferent arterioles.
Definition
yes, afferent arterioles have more sympathetic receptors.
Term
When is Neural regulation important for the regulation of GFR?
Definition
During periods of intense exercise, or during physiological emergencies.
Term
What takes place during Neural Regulation?
Definition
Large increases in sympathetic stimulation to nerves vasoconstrict arterioles. This shunts blood away from the kidneys to other tissues, while also decreasing GFR. Urine volume decreases, conserving blood volume.
Term
One hormone that the kidneys use to help regulate blood volume and blood pressure is atrial natriuretic peptide. Where does this hormone come from and why?
Definition
Atrial natriuretic peptide is a protein released by the atria of the heart in response to increased atrial stretch. For example with blood volume increases.
Term
What effect does the hormone atrial natriuretic peptide have?
Definition
ANP relaxes glomerular mesangial cells, loosening glomerular coils in an attempt to lower BP. The result is increased urine volume/output; and decreased blood volume and BP.
Term
Urine consists mostly of what?
Definition
water
Term
How does the hormone Angiotensin II regulate GFR?
Definition
Angiotensin II corrects a drop in BP.
Term
Where does the hormone angiotensin II come from and what is it's targeted effect?
Definition
Angiotensin II is produced in capillaries everywhere in response to decreased blood volume and BP (i.e., dehydration, Na+ deficiency, hemorrhage. Production is catalyzed by the kidney enzyme "renin".
Term
A hormone that is a potent vasoconstrictor?
Definition
Angiotensin II, results in decreased urine volume; increased blood volume and BP. Retaining water increases BP.
Term
__________ is the return of water and solutes to the blood.
Definition
Reabsorption
Term
Where does reabsorption take place?
Definition
reabsorption occurs all along the renal tubule and collecting duct. However, most reabsorption (90%) occurs along the PCT (proximal convoluted tubule).
Term
Where are water and solutes returned to?
Definition
the peritubular capillaries and vasa recta
Term
Methods of reabsorption vary depending on __________.
Definition
the substance reabsorbed.
Term
Methods are reabsorption are ________.
Definition
active (require ATP) or passive (ex. diffusion, osmosis) The method depends on what's being absorbed but only water moves by osmosis.
Term
ALL water reabsorption is ________.
Definition
passive: water moves by, "following" solutes.
Term
Water is drawn to where _________ are more at.
Definition
solutes
Term
99% of filtered water and most solutes are ___________.
Definition
reabsorbed
Term
Reabsorbed solutes include:
Definition
glucose, amino acids (proteins) and ions.
Term
What percentage of filtered water and most solutes are reabsorbed.
Definition
99%
Term
What is one waste that is not reabsorbed?
Definition
creatinine
Term
Creatinine is produced by the breakdown of creatine phosphate in the skeletal muscles. It is useful for determining glomerular filtration rate (GFR) because it is_________?
Definition
filtered but not reabsorbed or secreted
Term
Metabolic wastes _________ and _________ are reabsorbed to a lesser degree than water and other solutes.
Definition
urea, and uric acid
Term
creatinine (another waste) is used to clinically estimate ______ by measuring urine's creatinine during 24 hours in a test called _______________.
Definition
GFR, creatinine clearance test
Term
The largest amount of reabsorption is conducted along the __________.
Definition
proximal convoluted tubules.
Term
PCT cells have _________, greatly enhancing its surface area.
Definition
microvilli
Term
What is the second basic function of the nephron and collecting duct?
Definition
Reabsorption
Term
____________ along the loop of henle is very important in water reabsorption. The chemical composition of the tubular fluid now is quite different than in the PCT. Glucose, amino acids, and other nutrients are no longer present.
Definition
Reabsorption
Term
The ___________ vs __________ loop of henle are functionally different, creating an osmotic gradient for water reabsorption. How does this work?
Definition
descending vs. ascending,
the ascending loop reabsorbs Na+ and CL-, but cannot reabsorb water. Water moves out the descending loop by osmosis ("following" solutes)
Term
Called the _____________, it is highly efficient in the juxtamedullary nephrons, simply because they have extra long loops.
Definition
countercurrent mechanism
Term
__________________ refers to the flow of fluid down, than back up the loop of henle
Definition
countercurrent
Term
water flows by __________ out the descending loop, following the Na+ and CL- moving out of the ascending loop.
Definition
osmosis
Term
____________ nephrons are very good for the countercurrent mechanism.
Definition
Juxtamedullary. There is an endless cycle of water chasing solutes along the loop!
Term
The ascending loops on the loop of henle reabsorbs Na+ and CL-, but cannot reabsorb _________.
Definition
water
Term
A hormone _________ regulates water reabsorption in late DCT and collecting duct (CD).
Definition
Antidiuretic hormone (ADH); also called vasopressin
Term
Where is ADH produced and secreted and why?
Definition
Antidiuretic hormone is produced by the hypothalmus (brain) and secreted by the posterior pituitary gland when blood's water concentration decreases.
Term
What is facultative water reabsorption?
Definition
facultative water reabsorption is adaptive or adjustable. It is adaptable to the body's needs for more or less water. This is regulated by the hormone.
Term
Water reabsorption along the PCT and loop is not facultative water reabsorption but instead is called ________ because it is not regulated by hormones.
Definition
obligatory water reabsorption
Term
What is the result of ADH?
Definition
ADH increases water reabsorption along late DCT and CD, increasing blood volume. ADH causes the insertion of additional water channels in the DCT and CD. More holes are inserted into the membrane to hydrate with more water.
Term
____________ hormone increases water reabsorption and partners together with ADH.
Definition
Aldosterone
Term
Where is aldosterone produced, and how?
Definition
aldosterone is produced by the adrenal cortex (superficial layer of adrenal glands). Release is triggered by angiotensin II
Term
What is the result of aldosterone?
Definition
aldosterone increases Na+ and Cl- reabsorption along the late DCT and CD. Water follows by osmosis. More aldosterone channels are inserted so more water water can flow out. Blood volume increases.
Term
The most important hormone for calcium ion homeostasis is ____________.
Definition
parathyroid hormone (PTH)
Term
Where does PTH come from and how?
Definition
PTH is synthesized and secreted by the parathyroid glands. PTH is secreated in response to decreases Ca2+ in blood and ECF.
Term
Where are the parathyroid glands located?
Definition
usually four parathyroid glands that lie on posterior aspect of thyroid gland. PTH affects kidneys, bone, small intestine
Term
Kidney result from PTH?
Definition
PTH increases CA2+ reabsorption along DCT, conserving more Ca2+ in blood. PTH increases Vitamin D activity by kidneys.
Term
___________ is the transfer of solutes to the tubular fluid.
Definition
secretion
Term
Where does secretion occur?
Definition
secretion occurs all along the renal tubule and collecting duct. However, most secretion occurs along the PCT.
Term
Secretion is very important for pH homeostasis, why?
Definition
H+ (hydrogen ions (acid)) is secreted as HCO-3 (bicarbonate (base)) is reabsorbed. Urine is acidic.
Term
Secretion is also very important for waste excretion, why?
Definition
urea and uric acid are secreted. This is helpful because these wastes are partially reabsorbed.
Term
For any one sustance, the quantity excreted (amount in urine) = quantity filtered - quantity reabsorbed + quantity secreted
Definition
For any one sustance, the quantity excreted (amount in urine) = quantity filtered - quantity reabsorbed + quantity secreted
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