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129 Cards in this Set

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What do the kidneys and their associated structures comprise?
They comprise the “Urinary System”
Pg. 270
Where are the kidneys located?
They are located posteriorly in the abdominal cavity, on either side of the vertebral column.
Pg. 270
Once urine has been produced in the kidneys what is the name of the structure it travels to next?
The Ureters
Pg. 270
What structure does urine arrive at after it enters the ureter?
The Urinary Bladder
Pg. 270
Once urine has been collected in the “Urinary Bladder” what is the final structure it travels through on its journey out of the body?
The Urethra
Pg. 270
The Urethra
1
Pg. 270
How many ureters does a normal person have?
2
Pg. 270
Who has the shortest urethras?
Females have the shortest urethras being approximately 4 cm in length.
It exits between the labia just above the vaginal opening
Pg. 270
What consequences result because of the urethra’s length in females?
1. The short length of the female urethra makes bacterial invasion easier
2. Because of the short length of the urethra in females, and also because it’s external opening is so close to the rectum, helps explains why females are more prone to Urinary Tract Infections (UTIs).
Pg. 270
Who has the longest urethra?
Males have the longest urethras.
Averaging approximately 20 cm in length when the penis is not erect.
Pg. 270
What structure encircles a males urethra as the urethra exits the urinary bladder?
The Prostate Gland
Pg. 270
What can conditions can enlargement of the structure that encircles the male’s urethra as it exits the urinary bladder cause?
Impedance of urination and emptying of the bladder
and
Makes elderly males more susceptible to UTIs
Pg. 270
What is the name of the muscular wall of the structure located between the ureters and urethra called?
The Detrusor Muscle
Pg. 270
How many associated sphincters does the urinary bladder have?
2
Pg. 270
The detrusor muscle can generate action potentials in response to __________.
Stretch
Pg. 270
The detrusor muscle receives parasympathetic axons, which release ______________.
Acetylcholine (Ach)
Pg. 270
What does the release of Ach from the parasympathetic axons stimulate?
It stimulates contraction and thus emptying of the bladder
Pg. 270
What type of muscle comprises the sphincters of the bladder?
1. The Upper “Internal Urethral Sphincter” = Smooth Muscle
2. The Lower “External Urethral Sphincter” = Striated Skeletal Muscle
Pg. 270
What is the relaxation of the 2 sphincters of the bladder required for?
It is required for urination
or
Micturation
Pg. 271
What is another name for urination?
Micturation
Pg. 271
What type of activity can strengthen the muscles of the pelvic floor and the external urethral sphincter?
Kegel Exercises
Pg. 271
What is the inability to control Micturation called?
Incontinence
Pg. 271
Micturation is controlled by a reflex center in the ______ regions of the spinal cord.
Sacral
Pg. 271
What happens when a person wants to consciously urinate?
Descending motor tracts to the micturation center produces inhibition of the somatic motor neurons to the external urethral sphincter (or to the sphincter that is composed of striated skeletal muscle) which causes it to relax.
Pg. 271
What would persons need who have damaged their spinal cord, which results in an interruption of voluntary signals to the pelvic muscles and external urethral sphincter, thus reverting to the spinal reflex of infancy and become incontinent?
A Urinary Catheter
or
Foley Catheter
Pg. 271
What do Nephrons consist of?
Nephrons consist of tubules and associated blood vessels
Pg. 271
What is the inner region of the kidney called?
The Renal Medulla
Pg. 271
What is the outer region of kidney called?
The Renal Cortex
Pg. 271
Where are the renal pyramids located?
The Renal Medulla
or
The Inner portion of the kidney
Pg. 271
What are the cup-shaped structures that the narrow portions of the renal pyramids project into called?
Calyces
Pg. 271
What is the structure called that the tip of each pyramid releases urine into?
Minor Calyx (and several of these drain into a Major Calyx)
Pg. 271
What is the name of the structure the Major Calyces merge to form?
The Renal Pelvis = A hollow cavity in each kidney
Pg. 271
What may occasionally form within the calyces or renal pelvis?
Kidney Stones
or
Renal Calculi
Pg. 271
What is it called when individual renal calculi merge?
When individual stones or calculi merge a “Stag Horn Calculus” is formed.
Pg. 271
The _________ receive plasma filtrate and then modify this filtrate to form the final urine.
Nephron Tubules
Pg. 272
What is the name of the structure that is the bulbous beginning of the tubule that first receives the filtrate from plasma called?
The Glomerular Capsule
or
Bowman’s Capsule
Pg. 272
Why is it vitally important that most of the glomerular filtrate produced by the kidneys be immedeiately reabsorbed?
To prevent an otherwise fatal drop in blood volume an pressure
Pg. 274
What region of the kidney are the Bowman’s capsules located?
In the Renal Cortex
or
The Outer region of the Kidney
Pg. 272
What is the name of the structure that receives the filtrate from the glomerular capsule?
The Proximal Convoluted Tubule
Pg. 272
What region of the kidney are the Proximal Convoluted Tubules located?
In the Renal Cortex
or
The Outer region of the Kidney
Pg. 272
What is the name of the structure that receives fluid from the proximal convoluted tubule?
The Loop of Henle
Pg. 272
What is the first portion of the Loop of Henle called?
What is the first portion of the Loop of Henle called?
Pg. 272
What is the first portion of the Loop of Henle called?
It takes the fluid from the cortex into the medulla.
Pg. 272
It takes the fluid from the cortex into the medulla.
It takes the fluid from the cortex into the medulla.
Pg. 272
It takes the fluid from the cortex into the medulla.
They are sometimes referred to as the “Thick Segments”
Because, the upper portions of the loop have thicker walls and different transport properties than the lower portions.
Pg. 272
What is the name of the tubule that receives fluid from the ascending limb of the loop of Henle called?
The Distal Convoluted Tubule
Pg. 272
What region of the kidney are the distal convoluted tubules located?
In the Renal Cortex
or
The Outer region of the Kidney
Pg. 272
In the Renal Cortex
or
The Outer region of the Kidney
The Collecting Duct
Pg. 272
What region of the kidney does the collecting duct begin and what is it sometimes separately identified as?
The Renal Cortex
It is sometimes identified separately as the “Cortical Collecting Duct”
Pg. 272
_______ functions depend on interactions between the tubules and associated blood vessels.
Nephron
Pg. 272
Arterial blood arrives in the _________and passes through branches into smaller arteries that extend into the __________.
Renal Artery
Renal Cortex
Pg. 272
What are the names of the blood vessels that deliver blood into the tightly wound capillary beds, and what are the tightly wound capillary beds called?
Afferent Arterioles
Afferent = towards the center of activity

Glomeruli
Pg. 272
Why is the vascular arrangement unique that is delivered to the glomeruli?
Because blood from the glomeruli doesn’t pass into venules as it does elsewhere in the body.
Pg. 272
Where does blood from the glomeruli enter?
It enters Efferent Arterioles
Efferent = away from the center of activity
Pg. 272
What are the capillaries downstream from the glomerulus called?
Peritubular Capillaries
(They are called Peritubular Capillaries because they surround the tubules)
Pg. 272
Peritubular Capillaries
(They are called Peritubular Capillaries because they surround the tubules)
They are called Fenestrae
Pg. 272
What does the Fenestrae of the capillaries allow for?
It makes them far more permeable to plasma fluid and dissolved solutes than typical capillaries, such as those in the skeletal muscles.
Pg. 272
What is the name of the lining that is found just outside of the endothelial cells that comprise the walls of the glomerular capillaries?
Glomerular Basement Membrane
Pg. 273
What is the Glomerular Basement Membrane a layer of?
It is a layer of glycoproteins that may provide a filtration barrier for proteins.
Pg. 273
What is the name of the extensions of cells that surround the glomerulus and its basement membrane and compose the inner (visceral) layer of the glomerular capsule?
Podocytes
Pg. 273
What force produces the glomerular filtrate?
The forces that produce the glomerular filtrate are similar to those that act on other capillary beds to cause the formation of interstitial fluid.

The capillary blood pressure which is caused by left ventricular systole provides the force for filtering blood out of the glomerulus
This is opposed by the colloid osmotic pressure of the plasma proteins which draws water into the capillaries by osmosis.
Pg. 273
What types of conditions might produce severe dehydration leading to hypotension?
Persons who have severe:
Diarrhea
Blood Loss
Heart Failure
Or who are simply deprived of water
Pg. 273
Reduction in what 2 things can lead to an increase in the transit time to move wastes from the tissues to the kidneys, increasing retention of metabolic wastes?
Reduction in blood volume
and
Reduction in blood pressure
Pg. 273
What are the end result(s) of severe dehydration?
Acidosis
Uremia
Impaired Cell Metabolism
And Eventually Death
Pg. 273
What is the term for the volume of filtrate produced by both kidneys per minute?
Glomerular Filtration Rate (GFR)
Pg. 273
True or False. Most of the salt and water in the glomerular filtrate are reabsorbed across the walls of the proximal tubules back into the blood.
True
Pg. 274
What substances does the transport process of filtrate passing through the Loop of Henle cause to be accumulated in high concentrations in the renal medulla?
Na+
Cl-
Urea
Pg. 274
What does the accumulation of high concentrations of Na+, Cl- and urea provide for?
This provides an osmotic force for water reabsorption out of the collecting ducts, which are made permeable to water by Antidiuretic Hormone (ADH) or Vasopressin
Pg. 274
What term refers to the transport processes that allow substances in the glomerular filtrate to be returned to the vascular system?
Reabsorption
Pg. 274
True or False. The glomerular filtrate is essentially hypertonic.
False. The glomerular filtrate is essentially “Isotonic” (or has the same solute concentration as) to the surrounding interstitial fluid of the renal cortex and the blood plasma.
Pg. 274
What must be established in order for water to be reabsorbed into the blood of the surrounding peritubular capillaries?
A concentration (osmotic) gradient across the wall of the tubule must first be produced.
Pg. 274
Which tubule reabsorbs most of the filtrate?
The Proximal Convoluted Tubule
Pg. 274
How is the osmotic concentration gradient established in order for water to be drawn out of the proximal convoluted tubules?
This involves transport processes across the plasma membrane of the epithelial cells that form the walls of the proximal convoluted tubules. The plasma membrane actively transports Na+ from the cytoplasm into the surrounding interstitial fluid and blood plasma.
Pg. 275
The higher ____ concentration of the fluid surrounding the proximal convoluted tubules serves as an osmotic gradient.
NaCl
Pg. 275
Why does water enter into the interstitial fluid and then into the peritubular capillaries?
Because the walls of the proximal tubules are permeable to water and water passively follows the NaCl whose concentration have been increased in the interstitial fluid and the blood plasma of the peritubular capillaries.
Pg. 275
Approximately what percent of the glomerular filtrate is immediately reabsorbed across the walls of the proximal convoluted tubule?
Approximately 65% (almost two-thirds)
Pg. 275
Because the walls of the proximal tubules are __________to water, water passively follows the____ into the _________and then into the ___________________.
Permeable
NaCl
Interstitial fluid
Peritubular capillaries
Pg. 275
What is responsible for maintaining a low Na+ concentration in the cytoplasm?
The Na+/K+ (ATPase) pumps responsible for active transport maintain a low Na+ concentration in the cytoplasm.
Pg. 275
____________ follows the Na+ passively by electrical attraction from the glomerular filtrate into the surrounding interstitial fluid and plasma.
Chloride ion (Cl-)
Pg. 275
What structure is responsible for reabsorbing approximately 20% of glomerular filtrate?
The descending limb of the loop of Henle
Pg. 275
What are the names of the 2 structures that are responsible for reabsorbing about 15% of the glomerular filtrate?
The Distal Convoluted Tubule
and
The Collecting Duct
Pg. 275
The loop of Henle produces a __________ renal medulla.
Hypertonic
Pg. 275
Where does an equal amount of water and NaCl removal occur, so that the filtrate’s volume is reduced but its concentration remains unchanged?
The Proximal Convoluted Tubule
Pg. 275
True or False. The filtrate that leaves the proximal convoluted tubule to enter the descending limb of the loop of Henle retains its same concentration as blood plasma.
True. It was isotonic to blood plasma when it entered the glomerular capsule, and it is still isotonic when it leaves the proximal convoluted tubule to enter the descending limb of the loop of Henle.
Pg. 275
What is Osmolarity?
It is a measurement of total solute concentration of solutions.
Pg. 275
What is a solution that has a concentration of 300 milliosmolar (300mOsM) called?
Isotonic
Pg. 275
Solutions with a higher osmolarity are more ________ .
and
What are they referred to as?
Concentrated
and
Hypertonic
Pg. 275
Solutions with a lower osmolarity are more ________.
and
What are they referred to as?
Dilute
and
Hypotonic
Pg. 275
True or False. The osmolarity of the fluid remains constant as it descends from the renal cortx to the medulla.
False. The osmolarity increases as the fluid descends from the cortex to the medulla, going from isotonic 300 mOsM to the very hypertonic 1,400 mOsM at the bottom of the loop.
Pg. 276
What is the increasing concentration of the filtrate in the descending limb produced by?
By the removal of water by osmosis into the surrounding Peritubular Capillaries.
Pg. 276
Why is water drawn out of the descending limb?
Because the interstitial fluid of the renal medulla is very hypertonic and thus has a higher osmotic pressure.
Pg. 276
What does the thick segment of the ascending limb of the Loop of Henle actively pump out into the surrounding interstitial fluid of the renal medulla?
NaCl
Pg. 276
True or False. Salt is removed from the filtrate into the surrounding fluid in both the Proximal Convoluted Tubule and the Ascending limb of the Loop of Henle.
True
Pg. 276
If the Ascending limb of the Loop of Henle has salt removed from the filtrate as is done in the Proximal Convoluted Tubule, why does the filtrate not remain isotonic as is does in the Proximal Convoluted Tubules?
Because the Ascending limb of the Loop of Henle is not permeable to water
Pg. 276
How does the concentration of the interstitial fluid and the filtrate that ascends into the Distal Convoluted Tubule in the Renal Cortex change?
As a result of the Ascending limb of the Loop of Henle not being permeable to water:
The interstitial fluid becomes Hypertonic
and
The filtrate that ascends into the distal convoluted tubule in the renal cortex becomes hypotonic
Pg. 276
What other structure in the renal medulla also forms loops, allowing them to carry away water but leave the NaCl to accumulate in the interstitial fluid of the medulla?
Blood Vessels
Pg. 276
What is the name that refers to the interactions between the descending and ascending limbs that operates to increase the concentration of the renal medulla?
Countercurrent Multiplier System
Pg. 276
What is occurring in the Countercurrent Multiplier System?
-The ascending limb pumps out salt and this action produces the hypertonic medulla.

- This draws water from the descending limb which produces a hypertonic filtrate that arrives at the ascending limb, which then allows it to pump out even more NaCl.
Pg. 276
Why does the renal medulla become increasingly salty and hypertonic?
Because of the transport processes in the loops of Henle (the countercurrent multiplier system).
Pg. 276
What other substance besides salt contributes to the hypertonic concentration of the renal medulla?
Urea
Pg. 276
What is Urea?

What structure produces urea?
It is a waster product of the metabolism of amino acids

and

Urea is produced by the Liver.
Pg. 276
What does the breakdown of amino acids in the liver release?
Ammonia (NH3)
Pg. 276
What does the liver rapidly combine the breakdown of amino acids with and what does this produce?
It combines the breakdown of amino acids (Ammonia or NH3) with Carbon Dioxide.

This produces Urea
Pg. 276
True or False. Ammonia is very toxic to cells but urea is much less toxic.
True
Pg. 276
What is the name of the clinical test that can monitor levels of urea in the blood?
Blood Urea Nitrogen (BUN)
Pg. 276
In which part of the medulla does some urea diffuse through channels in the collecting ducts to enter the interstitial fluid?
The Inner Medulla
Pg. 276
What other substance besides salt is the Ascending limb of the Loop of Henle permeable to?

Where is this substance recycled?
Urea

Urea can recycle between the ascending limb and the collecting duct as it accumulates in the interstitial fluid of the medulla.
Pg. 276
What 3 functions do the transport processes of the Loops of Henle?
1. Some water is reabsorbed across the walls of the descending limb.
2. The filtrate in the distal tubule in the renal cortex is made hypotonic (dilute, with a concentration as low as 100 mOsM
3. The interstitial fluid of the renal medulla is made very hypertonic (concentrated), with a concentration as high as 1,400 mOsM.
Pg. 276-277
What does water reabsorption from the collecting duct require?
ADH
Pg. 277
What is the nature of the fluid and its concentration in the Distal Convoluted Tubules?
It is Hypotonic at a concentration of 100 mOsM
Pg. 277
Why is the function of making the interstitial fluid of the renal medulla very hypertonic (concentrated), with a concentration as high as 1,400 mOsM the most important of the three functions accomplished by the transport processes of the Loops of Henle?
The hypertonic environment of the renal medulla provides the osmotic gradient for the reabsorption of water across the walls of the collecting ducts.
Pg. 277
What does the hypertonic environment of the renal medulla allow us to produce?
It allows us to produce a small volume of very concentrated urine when we need to conserve water.
Pg. 277
What is the path of the Collecting Ducts?
The collecting ducts begin in the cortex and plunge into the medulla, all the way to the tips of the renal pyramids where they empty into the calyces.
Pg. 277
What part of the kidney do the Collecting Ducts receive hypotonic fluid from the distal tubules?
The Cortex
Pg. 277
What part of the kidney does the walls of the collecting ducts separate the hypotonic from the surrounding hypertonic interstitial fluid?
The Medulla
Pg. 277
Why is there a steep concentration gradient promoting the osmosis of water from the collecting ducts into the interstitial fluid and then into the peritubular capillaries?
Because the collecting ducts receive hypotonic fluid from the distal tubules in the renal cortex and the walls of the collecting ducts separate this dilute fluid from the surrounding hypertonic interstitial fluid in the renal medulla.
Pg. 277
Why is the reabsorption of water from the collecting ducts variable despite the constant concentration gradient between the collecting ducts, the surrounding interstitial fluid, and the peritubular capillaries?
Because the permeability of the collecting duct walls to water is dependent on Antidiuretic Hormone (ADH).
Pg. 277
Where is ADH manufactured?

Where is ADH stored?
ADH is manufactured by the Hypothalamus

ADH is stored in the Posterior Pituitary Gland
Pg. 277
How does ADH stimulate water reabsorption in the collecting ducts?
ADH stimulates the insertion of “Aquaporin” channels into the walls of the collecting ducts.
Pg. 277
When will the urine have a concentration of 1,400 mOsM and as a result an individual will excrete only about 400 ml of urine per day?
When ADH secretion and water reabsorption are at a maximum
Pg. 277
What occurs when ADH is absent?
Very little water can be reabsorbed across the walls of the collecting ducts, and an individual will excrete a large volume of dilute urine (with a minimum concentration of 100 mOsM).
Pg. 278
When is ADH secreted by the posterior pituitary?
It is secreted when stimulated by Osmoreceptor neurons in the hypothalamus.
Pg. 278
How are the neurons responsible for stimulating the secretion of ADH activated?
They are activated by an increase in the plasma osmolarity
(which can be produced by dehydration or eating too much salt)
Pg. 278
What action can lower the osmolarity of the blood so that the osmoreceptors are less stimulated?
Drinking too much water
Pg. 278
What structure is known as the “Thirst Center?”
The Hypothalamus
Pg. 278
Why do people who loose excessive water through perspiration, blood loss, or who are denied normal intake of water become extremely thirsty?
Because of nerve impulses from the Hypothalamus
Pg. 278
Secretion of ________ accordingly so that the kidneys will retain water or excrete more water as needed is important to maintain homeostasis of the plasma osmolarity.
Antidiuretic hormone (ADH)
Pg. 278
Why should a person lost at sea not drink the salty seawater?
-The high salt content in seawater contains more sodium and chloride than the body needs and it must be excreted by the kidneys.
-This causes water to remain inside the tubules and be urinated out along with the sodium, chloride, and other salts in seawater.
-More water is urinated out than the seawater taken in and you remain thirsty.
(This is a losing equation because you will die quicker than if you didn’t drink at all)
Pg. 278
What is the term used to describe when a solute causes water to remain inside the tubules and be urinated out along with the sodium and chloride?
Osmotic Diuresis
Pg. 278