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Physiology
Exam 4
172
Physiology
Undergraduate 4
10/22/2012

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Term
What term refers to the outer layer of the kidney?
Definition
Renal Cortex
Term
What does the term, renal medulla, refer to?
Definition
Inner layer of kidney
Term
True or False:

A nephron is found only throughout the renal medulla.
Definition
False:

Nephrons may be found in both the cortex and the medulla.
Term
What are the two components of a nephron?
Definition
The tubular and vascular components
Term
In respect to the nephron, where could one locate the afferent arteriole?
Definition
Prior to the glomerulus
Term
In respect to the nephron, where could one locate the efferent arteriole?
Definition
After the glomerulus through the rest of the nephron
Term
True or False:

The glomerulus filters large volumes of protein-containing plasma into the tubular component of the nephron.
Definition
False:

everything is true except the glomerulus filters protein-free plasma
Term
Which vascular component of the nephron functions to nourish the renal tissue and participate in fluid exchange?
Definition
Peritubular capillaries
Term
What percentage of total cardiac output is renal blood flow? What is the numerical value per minue?
Definition
20 percent or 1,200 mL/min
Term
What is the numerical value for glomerular filtration rate?
Definition
100-120 mL/min
Term
How much urine is created in our body per minute?
Definition
1 mL/min
Term
Where does filtration occur within the nephron?
Definition
Glomerulus
Term
What percentage of plasma entering the glomerulus leaves through the efferent arteriole?
Definition
80 percent
Term
What percentage of plasma entering the glomerulus enters the bowman's capsule?
Definition
20 percent
Term
What is tubular reabsorption within the nephron?
Definition
Selective movement of filtered substances from the tubular lumen into the peritubular capillaries
Term
Within the nephron, what is considered tubular secretion?
Definition
Selective movement of nonfiltered substances from the peritubular capillaries into the tubular lumen.
Term
True or False:

Objects entering the tubule component of the nephron from the peritubular capillaries are not filtered prior to entering.
Definition
True
Term
Per day, how much glomerular filtrate is produced?
Definition
180 liters
Term
Of the 180 liters of plasma filtered per day, how much is reabsorbed? How much urine is produced?
Definition
178.5 liters are reabsorbed leaving 1.5 liters of urine to be excreted
Term
What process is known as the first step in making urine?
Definition
Glomerular filtration
Term
True or False:

As you travel across the glomerulus, blood pressure drops, just as in every other cappilary.
Definition
False,

BP is constant across the glomerulus
Term
What two reasons account for why glomerular filtration has a greaters exchange rate compared to other capillaries?
Definition
1) Higher permeability
2) Higher capillary hydrostatic pressure
Term
True or False:

The afferent arterioles are larger in diameter than the efferent arterioles.
Definition
True
Term
True or False:

Regulation does NOT occur with afferent and efferent arterioles.
Definition
False
Term
Which way does each of the following forces wish to push fluid, with respect to glomerular filtration. What are typical values for each?

1) Glomerular capillary blood pressure
2) Plasma-colloid osmotic pressure
3) Bowman's capsule hydrostatic pressure
Definition
1) Into the bowman's capsule 55 mm Hg
2) Out of the bowman's capsule 30 mm Hg
3) Out of the bowman's capsule 15 mm Hg
Term
How could one calculate net filtration pressure?
Definition
By taking glomerular capillary blood pressure and subtracting plasma-colloid osmotic pressure and bowman's capsule hydrostatic pressure
Term
What is a typical value for net filtration pressure?
Definition
10 mm Hg
Term
What role does autoregulation play in controlling GFR? How does it work?
Definition
prevents spontaneuous changes in GFR and it works via intrinsic controls keeping GFR constant
Term
What is the function of sympathetic control of GFR? What is an example/
Definition
To override autoregulation

For example: during dehydration, sympathetic controls would override autoregulation and decrease GFR to conserve salts and water
Term
True or False:

GFR is controlled by regulating the radius of the efferent arteriole.
Definition
False

Afferent arteriole
Term
If the afferent arteriole of the nephron is dilated, what occurs?
Definition
Dilation of the afferent arteriole increase GFR because more blood can enter glomerulus
Term
What is the name of the major process involved with tubular reabsorption?
Definition
Transepithelial transport
Term
Generally, what are the 5 barriers a cell must cross during transepithelial transport? (In order)
Definition
1) Substance crosses luminal membrane of tubular cell
2) Substance passes through cytosol
3) Crosses basolateral membrane of the tubular cell and enter interstitial fluid
4) Diffuses through interstitial fluid
5) Penetrates capillary wall to enter plasma
Term
What percentage of sodium is reabsorbed within the proximal tubule? What is the purpose of the reabsorption?
Definition
67% with a purpose in reabsorbing glucose, amino acids, H20, Cl-, and urea
Term
What percentage of sodium is reabsorbed within the ascending limb of the loop of Henle? What is the purpose of the reabsorption?
Definition
25% with a purpose a varying the concentration of urine
Term
What percentage of sodium is reabsorbed within the descending limb of the loop of Henle? What is the purpose of the reabsorption?
Definition
Trick Question, the descending limb is NOT soluble to sodium
Term
What percentage of sodium is reabsorbed withing the distal can collecting tubules? What is the purpose of the reabsorption?
Definition
8% with a purpose in regulating ECF volume
Term
What hormone plays an important role in salt reabsorption throughout the distal and collecting tubules?
Definition
Aldosterone
Term
How does sodium cross the luminal surface during reabsorption? How does it cross the basolateral surface?
Definition
Diffusion through Na+ channels to cross luminal surface

Sodium Potassium pump to cross basolateral surface
Term
What does it mean that glucose and amino acids are reabsorbed by Na+ dependent secondary active transporters?
Definition
Meaning that the reabsorption of glucose cannot happen unless the sodium potassium pump on the basolateral surface is functioning properly
Term
How does glucose and other amino acids travel across the basolateral membrane into the plasma during reabsorption?
Definition
By passively diffusing down their respective concentration gradients
Term
Specifically, how do the kidneys contribute to phosphate handling?
Definition
Because the renal threshold for phosphate is equal to the normal plasma concentration of phosphate
Term
What is the result of an increase in the level of phosphate in the plasma?
Definition
Urine phosphate levels will also increase.
Term
What hormone can adjust the renal threshold for phosphate?
Definition
Parathyroid hormone
Term
True or False:

Renal reabsorption of Ca++ is subject to hormonal control.
Definition
True
Term
True or False:

The kidney plays a major role in controlling blood glucose.
Definition
False

The kidney does not play a role in controlling blood glucose. This would be the job of insulin.
Term
The normal blood phosphate level is 3.0. What is the renal threshold for phosphate?
Definition
3.0 because blood phosphate and renal phosphate are the same.
Term
True or False:

Water reabsorption is hormone controlled in the proximal tubule and the descending limb of the loop of henle.
Definition
False

Water reabsorption is only hormone controlled in the distal and collecting tubules
Term
What percentage of water is reabsorbed in the PCT? What is significant about this reabsorption
Definition
67 percent and the reabsorption of water is passive because it is only following the sodium that is being reabsorbed.
Term
What percent of water is reabsorbed in the descending limb of the loop of henle? What is significant about this reabsorption?
Definition
15 percent. Reabsorbing water at this point plays an important role in the kidneys' ability to produce urine of varying concentrations
Term
What percent of water is reabsorbed in the ascending limb of the loop of henle? What is significant about this reabsorption?
Definition
Trick question because water is NOT reabsorbed in the loop of henle.
Term
What percentage of water is reabsorbed in the distal and collecting tubules? What is significant about this reabsorption?
Definition
18 percent and this reabsorption is variable and subject to hormonal control. It also plays a role in regulating ECF osmolarity
Term
In the PCT, as water is reabsorbed, what happens to the concentration of urea? What is the ultimate result?
Definition
The urea concentration will increase in the PCT which will then form a concentration gradient to allow for the passive reabsorption of urea.
Term
What percentage of urea is reabsorbed in the PCT?
Definition
50 percent
Term
Generally, how can the body produce urine of varying concentrations? (Very Brief, not looking for how the kidney specifically does this)
Definition
By the body's state of hydration
Term
What is the normal value of osmolarity within the human body?
Definition
300 mosm/liter
Term
What is the range of osmolarity values seen within the renal medulla?
Definition
600-1200 mosm/liter
Term
What is the osmolarity of filtrate as it enters the loop of henle?
Definition
300 mOsm
Term
At the tip of the loop of henle, what is the state of osmolarity? (State and numerical value)
Definition
Hypertonic and 1200 mOsm
Term
What is the state of osmolarity of filtrate as it enters the collecting duct? (State and numerical value)
Definition
Hypotonic and 100 mOsm
Term
There are two sections of the ascending limb of the loop of henle. What moves out of each section and how does it do so?
Definition
The thin ascending limb is permeable to salt and salt is passively transported out of the tubule

The thick ascending limb is also permeable to salt. However, active transport is what pushes salt out of the tubule.
Term
What is the Vasa Recta and where is it found? What is its function?
Definition
The Vasa Recta is a peritubular capillary associated with the loop of henle. It functions to pick up salts and water from both limbs.
Term
Where at within the nephron would Potassium and Hydrogen be secreted? What controls the potassium secretion?
Definition
In the distal convoluted tubule and collecting ducts

Potassium secretion is controlled by aldosterone
Term
True or False:

Water reabsorption is variable is the DCT under the control of ADH.
Definition
False,

occurs in the collecting ducts
Term
True or False:

Na+ reabsorption in the DCT is variable under the control of aldosterone.
Definition
True
Term
With the renin-angiotensin system, what occurs with a decrease in blood pressure?
Definition
Renin is released
Term
True or False:

The renin-angiotensin system plays an influential role in the variability of Na+ reabsorption.
Definition
True
Term
Once renin is secreted from the kidneys, what does it complex with and where does the other molecule come from? Once complexed, what does it produce?
Definition
Renin from the kidneys complexes with angiotensinogen from the liver. Both molecules react and from Angiotensin I.
Term
How does angiotensin I become angiotensin II? Where does the molecule responsible for this conversion come from?
Definition
Angiotensin I reacts with Angiotensin-converting enzyme (ACE) (from the lungs) and forms Angiotensin II>
Term
What four functions does angiotensin II play?
Definition
Angiotensin II signals thirst, signals arteriolar vasoconstriction, stimulates ADH, and goes to the adrenal cortex which ultimately produces aldosterone.
Term
Where does angiotensin II travel to and what is the result?
Definition
Angiotensin II travels to the adrenal cortex which signals the adrenal cortex to produce aldosterone.
Term
Once aldosterone is produced, what occurs?
Definition
Increased sodium reabsorption which ultimately leads to water conservation
Term
Where does the secretion of organic ions take place within the nephron?
Definition
Proximal tubule
Term
How does aldosterone promote Na reabsorption and K secretion?
Definition
Because the sodium potassium pump moves in opposite directions
Term
How does vasopressin promote water reabsorption?
Definition
By inserting aquaporins into the luminal membrane
Term
When ADH is present what is the relative state of urine? (In other words, relative amount and dilution)
Definition
Small amount of concentrated urine
Term
What hormone promotes urea recycling?
Definition
ADH
Term
What is the general effect or urea recycling and where does the urea come from? Where does the urea go?
Definition
Urea moves out of the collecting duct, into the interstitial space. This enhances the osmotic gradient effect.
Term
If the maximum amount of ADH is present, what happens to urine concentration? What is the osmolarity value?
Definition
The urine becomes extremely concentrated and the osmolarity is 1200 mOsm. (Assuming no ADH inhibition)
Term
What molecule can be used to estimate GFR?
Definition
Creatinine
Term
True or False:

In early renal disease, the elevation of creatinine is extremely noticible on a creatinine vs. GFR graph.
Definition
False,

You won't notice much of a difference until kidneys are at 35 percent function or a GFR value of 40.
Term
What is micturition?
Definition
Emptying of urine stored in the bladder
Term
What process moves urine from the ureters to the urinary bladder?
Definition
Peristalsis
Term
How much urine can one hypothetically store in the bladder before stretch receptors initiate micturition reflex?
Definition
250-400 mL
Term
True or False:

Micturition can occur when only the internal urethral sphincter is open.
Definition
False

Both internal and external urethral sphincters must be opened.
Term
How is it possible for us to hold urine when mictuition is stimulated?
Definition
Because the external urethral sphincter is made of skeletal muscle and thus we can actively contract it.
Term
True or False:

Sympathetic neurons signal the smooth muscle of the bladder to contract.
Definition
False

Parasympathetic neurons
Term
Generally, what role does a countercurrent system play in the loop of henle?
Definition
It is responsible for establishing and maintaining the vertical osmotic gradient
Term
True or False:

Countercurrent multiplication is accomplished by the vasa recta of the juxtamedullary nephrons.
Definition
False

Accomplished by the loops of henle
Term
Why doesn't H20 diffuse out of the ascending loop of henle?
Definition
Because the thin portion releases salts to account for the hypertonicity of the filtrate while the thick limb actively transports salt out of the filtrate. The active transport is the reason why water doesn't move with the salt
Term
Why is it important for the water entering the DCT to be hypotonic?
Definition
Because it allows the kidney down stream of the loop to extract more water if needed
Term
True or False:

The blood osmolarity of the vasa recta is the same as the osmolarity of the interstitial fluid of the loop of henle at all locations.
Definition
True
Term
Why is the osmolarity of the vasa recta the same as the interstitial fluid of the loop of henle.
Definition
Because the vasa recta is permeable to both water and NaCl
Term
What is the purpose of measuring inulin clearance?
Definition
Because it is a good indicator of GFR
Term
True or False:

Inulin is filtered by the glomerulus but neiter reabsorbed or secreted.
Definition
True
Term
What is the purpose of PAH clearance measurements?
Definition
To estimate the amount of renal plasma flow
Term
True or False:

PAH is completely filtered at the glomerulus.
Definition
False

PAH is partially filtered at the glomerulus and whatever portion ends up in the peritubular capillaries is COMPLETELY filtered back into the tubular tract.
Term
True or False:

PAH clearance is only important to portions of the kidney which produce urine.
Definition
True
Term
True or False:

All of the salt which leaves the ascending loop of henle gets reabsorbed into the peritubular capillaries.
Definition
False

Some of it says in the interstitial space to maintain the osmotic gradient
Term
Describe how salt is reabsorbed in the DCT?
Definition
The first 5 percent is uncontrolled and occurs in the early DCT while the last 3 percent is dependent on aldosterone which occurs in the late DCT
Term
How does the glomerulus prevent small proteins like albumin from being filtered?
Definition
The glomerulus contains a negatively charged basement membrane which repels proteins.

Also there are podocytes that form filtration slits which act as pores. Under normal circumstances proteins and RBC's cannot pass through these
Term
Approximately what percentage of body weight accounts for the total body fluid? What is the numerical volume in liters?
Definition
60 percent or 42 liters
Term
What is the total volume of fluid in liters which occupy's the intracellular fluid? What percent of body weight is this?
Definition
28 liters or 40 percent body weight
Term
What volume of fluid in liters occupies the extracellular fluid? What percentage of body weight does this account for?
Definition
14 liters or 20 percent body weight
Term
True or False:

More fluid is contained within the plasma than the interstitial space.
Definition
False

The interstitial space has 4 times more fluid
Term
True or False:

Most of salts output occurs by obligatory loss, sweat, and feces.
Definition
False,

Most output comes from the controlled excretion in urine
Term
What is the efferent pathway involved in the regulation of ECF volume?
Definition
Renin System
Term
What is the regulated variable associated with the ECF volume regulation?
Definition
Total body sodium and ECF Volume
Term
True or False:

In respect to regulating ECF volume, the cardiovascular system acts as a long term effector while the kidney acts as a short term effector.
Definition
False,

exact opposite
Term
What sensors are involved in the regulation of ECF volume, and what do they sense?
Definition
The sensors are called vascular volume receptors and they sense the effective circulating volume
Term
What sensors are involved in regulating ECF osmolality and what do they sense?
Definition
Hypothalamic osmoreceptors which sense plasma osmolality
Term
What efferent pathway(s) is involved in regulating ECF osmolality?
Definition
ADH and thirst
Term
What are some causes of hypertonic ECF? What does this result in?
Definition
Insufficient water intake or excessive water loss which results in cells shrinking
Term
What are some of the symptoms that are associated with hypertonic ECF?
Definition
Shrinking of neurons
Circulatory disturbances
Term
What can cause hypotonic ECF? What does this result in with respect to cells?
Definition
Renal failure (water cant be excreted)
Rapid ingestion of large amounts of water

Results in cellular hypertonicity which eventually leads to cellular swelling
Term
What is the normal range of pH within our body?
Definition
7.35-7.45
Term
True or False:

Arterial blood is at the higher end of the normal pH range?
Definition
True
Term
If a cell become more acidic, what is the effect on nervous excitability?
Definition
More acidic means decreased excitability
Term
If a cell become more basic, what is the effect on nervous excitability?
Definition
More basic means increased excitability
Term
During acidosis, what happens to the hydrogen levels and potassium levels, in respect of the kidneys.
Definition
In acidosis, kidney will secrete H+ and retain K+
Term
What is the body's major source of hydrogen?
Definition
Carbonic acid formation
Term
What disease results from the accumulation of K+?
Definition
Hyperkalemia
Term
What is the first line of defense against acidic pH alterations? How do they work?
Definition
Acidic Buffers which work by binding up free H+ to control pH but doesn't remove it from the body.
Term
True or False:

When acidic buffers bind free hydrogens, the hydrogens are removed from the body?
Definition
False
Term
What happens when a buffer reach capacity?
Definition
Excess H+ spills into the ECF and the respiratory and urinary systems try to fix the pH alterations
Term
What is the primary buffer against carbonic acid changes?
Definition
Hemoglobin Buffer
Term
What is the purpose of the bicarbonate buffer (carbonic acid buffer)?
Definition
Primary ECF buffer against non-carbonic acid changes
Term
What buffer is the primary ICF buffer?
Definition
Protein Buffer System
Term
Which buffer is important in the urinary system?
Definition
Phosphate Buffer
Term
How does the respiratory system regulate pH?
Definition
By controlling the rate of CO2 removal
Term
True or False:

The respiratory system has the ability to fully compensate for pH adjustments.
Definition
False
Term
How does the respiratory system compensate for increased hydrogen levels?
Definition
Increases rate of breathing (faster and deeper) which leads to a decrease in CO2 because its being blown off more rapidly than its being formed. This leads to a lower carbonic acid level which leads to decreased H+ in the body
Term
How does the respiratory system compensate for decreased hydrogen levels?
Definition
Depresses respiratory system (slower and shallower) which leads to an increase in CO2 because CO2 is being produced more rapidly that its being blown off. Increased CO2 leads to increased carbonic acid which leads to increased H+
Term
What acts as the second line of defense against pH alterations?
Definition
The respiratory system
Term
What acts as the third line of defense against pH alterations?
Definition
The Kidneys
Term
True or False:

The kidneys can act within minutes to compensate for changes in the body fluid pH.
Definition
False

The kidneys require hours to days to compensate for changes in body-fluid pH
Term
What is the function of the kidneys in accounting for pH changes?
Definition
The kidneys remove the excess H+ that the buffers could not buffer out.
Term
What three ways does the kidney control the pH of body fluids? (What does it adjust to control pH)
Definition
1) H+ excretion
2) Ammonia excretion
3) Bicarbonate excretion (want to lower its excretion)
Term
If there is an increase in H+ levels how does the bicarbonate levels change in respect to the kidneys?
Definition
Increased H+ will conserve more HCO3- in order to attempt to buffer out H+
Term
True or False:

If the H+ concentration is lowered, the kidney can conserve H+ ions by reabsorbing them in order to prevent them from entering urine.
Definition
False,

The kidney cannot reabsorb H+
Term
How does the kidney compensate for decreased levels of H+? (2 ways)
Definition
1) Conserve H+ by reducing its secretion
2) Excreting more HCO3- into the urine by reabsorbing less HCO3-
Term
If there are decreased levels of hydrogen ions, what does the kidney do to compensate with respect to HCO3-?
Definition
The kidney will excrete more HCO3- by reabsorbing less.
Term
True or False

The kidney secretes ammonia during acidosis to buffer secreted H+.
Definition
True
Term
Why is the urine pH limit 4.5?
Definition
If it were lower, it would burn the urinary tract
Term
What is the purpose of ammonia secretion by the kidneys and when does this occur?
Definition
The kidney secretes ammonia during acidosis to buffer secreted H+
Term
True or False:

The kidney can excrete large amounts of phosphate and thus, the phosphate buffer is highly effective.
Definition
False,

The phosphate buffer is overwhelmed quickly because the kidney cannot excrete large amounts of phosphate
Term
How does the kidney compensate for the relative weakness of the phosphate buffer?
Definition
By an increased secretion of ammonia which functions to buffer additional H+ molecules
Term
What are the 4 general categories for acid/base deviations?
Definition
Respiratory acidosis and alkalosis
Metabolic acidosis and alkalosis
Term
What is the normal ratio of bicarbonate to CO2
Definition
20:1
Term
If the bicarbonate to CO2 ration were 5:1, what state of acid/base imbalance would you be in, if any?
Definition
Acidosis
Term
If the bicarbonate to CO2 ratio were 50:1, what state of acid/base imbalance would you be in, if any?
Definition
Alkalosis
Term
True or False:

An abnormal change in the concentration of CO2 would reflect a respiratory imbalance.
Definition
True
Term
True or False:

An abnormal change in the concentration of bicarbonate would reflect a respiratory imbalance.
Definition
False

It would reflect a metabolic imbalance
Term
True or False:

Hypoventilation would generally cause respiratory alkalosis.
Definition
False

It would cause respiratory acidosis
Term
If a man were to have a nerve disorder which reduced respiratory muscle activity, what would be the resulting acid/base imbalance?
Definition
Respiratory acidosis
Term
How does the body compensate from prolonged respiratory acidosis?
Definition
The kidneys will compensate by secreting H+ and conserving HCO3-
Term
With respect to the pulmonary system, how does the body compensate for metabolic acidosis?
Definition
Hyperventilation to blow off CO2
Term
Approximately how well can the lungs compensate for metabolic acidosis? (Percentage)
Definition
75%
Term
What type of metabolic acidosis does diabete mellitus and excessive fat metabolism cause?
Definition
Ketoacidosis
Term
What is the cause of uremic acidosis?
Definition
Renal failure
Term
What is the primary cause of respiratory alkalosis?
Definition
Excessive CO2 loss from hyperventilation
Term
What type of acid/base imbalance would a high altitude cause?
Definition
Respiratory alkalosis
Term
True or False:

Aspirin poisoning is a possible cause for respiratory alkalosis.
Definition
True
Term
What are the two types of nephrons and how do they differ?
Definition
Cortical nephron - shorter loop of henle

Juxtamedullary nephron - longer loop of henle

Loop of henle extends into different locations of the kidney
Term
What is the formula for calculating clearance?
Definition
Clearance rate = (urine [ ] of substance * urine flow rate)/(plasma [ ] of substance)
Term
With chronic renal failure, how much of the kidney must be non-functional before you notice effects?
Definition
75 percent
Term
What percentage of renal function loss is associated with end-stage renal failure?
Definition
90 percent
Term
What is the difference between onset of acute and chronic renal failure?
Definition
Acute has sudden onset while chronic is slow to progress
Term
True or False:

Sweating is associated with insensible loss?
Definition
False

Sweating is sensible
Term
How could one define an acid from a base?
Definition
In aqueous solutions acids produce H+ ions while bases produce OH- ions
Term
True or False:

Normal blood pH is slightly acidic and falls within the range of 7.35 to 7.45
Definition
False

Normal blood pH is slightly basic but the range listed is correct
Term
True or False:

Phosphate excretion is not effected by a change in the pH of body fluids.
Definition
True
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