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PHGY 1030- EXAM 6 > Chapter 40 : Urinary System Lecture 2 > Flashcards

Chapter 40 : Urinary System Lecture 2 Flashcards

1
Q

In a Nephron what are the two components it includes?

A

-A tubular component
-A vascular component

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2
Q

What are the renal tubules and what parts is it subdivided into it ?

A
  • Fluid filled tube formed by a single layer of epithelial cells
  • It is subdivided into four parts
    -Proximal Convoluted Tubule
    -Loop of Henle
    -Distal Convoluted Loop
    -Collecting tubule and duct that drains into renal pelvis
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3
Q

What are the two type of nephrons and their properties ?

A
  • Cortical
    -These are renal corpuscles in the cortex and the loop is a small loop going past the medulla
  • Juxtamedullary
    -These are renal corpuscles in the cortex near the medulla
    • They also have long loops that go deep into the medulla that allows for concentration of urine depending on need
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4
Q

What are the three things that make the Juxtaglomerular complex and what is the function of this complex?

A
  • It is a Distal Convoluted Tubule that pass through a fork formed by two afferent and efferent arterioles.
  • The function is to regulate filtrate formation
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5
Q

What does the Tubular and Vascular portion of the Juxtaglomerular complex consist of?

A
  • Tubular portion
    • This is just a tall and narrow epithelium of Distal Convoluted Tubule = Macula Densa
  • Vascular portion
    • This consist of the afferent and efferent arteriolar portion
    • There are also modified smooth muscle cells on afferent arteriole known as the granular (juxtaglomerular cells): There are meant to help maintain blood pressure and contain renin( enzymatic hormone)
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6
Q

What is the main function of the juxtaglomerular complex?

A

To regulate filtrate formation

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7
Q

What are the three basic process in the nephron that contribute to urine formation?

A
  • Glomerular Filtration
  • Tubular reabsorption
  • Tubular secretion
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8
Q

During the Glomerular filtration, what is the content being filtered and what is the overall pH level ?

A
  • Identical to plasma MINUS the large proteins
  • things like H20 , AA , Vitamins , Ions, Urea , small amount of SMALL proteins. And normally there is LESS than 1% albumin
  • The overall pH level is ~7.45
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9
Q

What is the term Albuminuria mean?

A

it is when in some renal diseases the filtration membrane allows excessive albumin in the urine that escape into the Bowmans Capsule

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10
Q

What is the Glomerular Filtration Rate and how much is left at the end of the collecting duct ?

A
  • ~180L/day filtrate in both kidneys
  • less than 1% of filtered volume remains at end of collecting duct
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11
Q

Why is the regulation of GFR important?

A
  • because if we don’t have regulation, whenever the MAP rises the GFR rises with it and we don’t want that
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12
Q

In the Two major control mechanisms to regulate the GFR, what are some similarities and differences ?

A
  • Similarities
    -They both regulate by adjusting the glomerular blood flow by regulating the radius and thus the resistance of the afferent arteriole
  • Difference
    1. Autoregulation (intrinsic) is aimed at preventing spontaneous changes in the GFR
    2. Extrinsic sympathetic control is aimed at long term regulation of MAP
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13
Q

During intrinsic regulation, how does the body use myogenic mechanisms to respond to elevated and below normal levels of MAP and to regulate the GFR and the BP in glomerular norm ?

A
  • When the MAP is elevated more than normal, it results in stretch which is then followed by a contraction ( this is caused as a refex) of the afferent arteriole wall. This then helps to keep the BP in Glomerular norm which then helps keep the GFR normal. The contraction happens to decrease the blood flow and bring things back to normal
  • When the MAP is below normal, it results in dilation of the afferent arteriole wall which then helps to keep the BP in glomerular normal and helps to keep GFR normal. The dilation essentially expands the vessel so more blood can flow though the arteriole and help keep the BP normal
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14
Q

During intrinsic regulation , how does the body use juxtaglomerular apparatus to respond to changes in GFR and the changes in the flow of filtrate past the macula densa cells?

A
  • When the GFR increases , the fluid being filtered also increases , which then also causes an increase in salt delivery to macula densa cells, this then causes the release of ATP, then extracellular degradation forms adenosine which then causes vasoconstriction of afferent arteriole which then brings the high GFR back down to normal.
    • ALL of these are a chain reaction that happens because of increase in GFR and when the vasoconstriction happens it causes a decrease in all of that flow and helps bring things back to normal
  • When the GFR decreases , the fluid being filtered also decreases, which then causes an decrease in salt delivery to macula densa cells, this can cause a decrease in release of ATP and then it causes a decrease in extracellular adenosine , then this causes vasodilation of afferent arteriole which then causes return back to normal.
    • ALL of these are a chain reaction that happens because of increase in GFR and when the vasodilation happens it causes a increase in all of that flow and helps bring things back to normal.
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15
Q

During Extrinsic regulation, what is used in the body to mediate the control? Can the GFR be changed on purpose even when the MAP is within the autoregulatory range by extrinsic control?

A
  • The sympathetic nervous system (SNS) is used to mediate extrinsic control
  • Yes it can be changed on purpose , this happens by extrinsic control by overriding the autoregulation.
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16
Q

Using extrinsic regulation how does your body response to stress to effect the afferent and efferent arterioles?

A

The sympathetic nervous system causes arteriole vasoconstriction ( this happens due to reflex contraction).

  • Afferent arteriole contracts and causes decrease in flow into the glomerulus
  • Efferent arteriole contracts and causes blood to back up into the glomerulus
17
Q

What happens to the extrinisc control of the GFR if the body faces extreme amount of stress ?

A

The blood rate being sent to the glomerulus decreases and the GFR decreases as well

18
Q

In Glomerular Filtration, what are some net filtrations changes that could take place?

A
  • Plasma colloid OP (PCOP)
    -e.g. dehydration causes increase in PCOP which then causes decrease in GFR
    -e.g. severe burns causes decrease in PCOP which then causes increase in GFR
  • Capsular HR
    -e.g. urinary tract obstruction can lead to kidney stones or enlarged prostate which causes an increase in Capsular HP which then causes decrease in GFR
19
Q

In tubular reabsorption, Where is most of the filtrate reabsorbed from tubules going into ?

A
  • The peritubular and vasa recta capillaries
20
Q

How do the constituents vary in concentration in the glomerular filtrate?

A

All constituents except the plasma proteins are at the same concentration in the glomerular filtrate as in plasma

21
Q

What are the two step processes that take place during tubular reabsorption ?

A
  1. Active or passive transport from the tubule fluid to renal IF
  2. Active or passive transport from IF to blood
22
Q

During active reabsorption, what is the most important component in the basolateral membrane and what is it important for ? Where is the most energy being spent in the kidney while reabsorption?

A
  • In the basolateral membrane the Na+–K+ ATPase pump is very important for the Na+ reabsorption.
  • The most energy is spent on Na+ transport, and around 80% is used on it.
23
Q

What does the term “Trans-epithelial Transport” mean ?

A
  • This is a transport when the reabsorbed substance must cross five barriers
24
Q

In the Proximal Convoluted Tubule (PCT) , what is the primary role and state 4 characteristics of the reabsorption process

A
  • The primary role is fluid and electrolyte transport
  • There is around 67% of Na+ being reabsorbed with active transport with the sodium potassium ATPase pump and while this happens, the chloride always follows along the Na+ passively because of the ion charges
  • There is obligatory reabsorption of about 65% of the H2O meaning there is no hormonal control and it is unregulated
  • NaCl account for more than 90% of the ECFs osmotic activity
  • Glucose and AAs are fully reabsorbed by the sodium using secondary active transport
25
Q

What happens in the Proximal Convoluted tubule as a result of the reabsorption?

A
  • Large amount of solute is removed and there is a decrease in filtrate volume
  • Filtrate is also isotonic to plasma
26
Q

What does the loop of Henle reabsorb into and what do the descending and ascending limb reabsorb ? Is there the use of hormones in loop of Henle and if yes what are they used for?

A
  • It reabsorbs into the vasa recta
  • the descending limb reabsorbs H2O only using passive transport
  • the ascending limb reabsorbs 25% NaCl only using active transport
  • There is also hormones being use here on the way up and this helps with the filtrate to be more diluted and change the osmolarity again as it comes up.
27
Q

What is the purpose of Aldosterone and ANP (atrial natriuretic peptide) in the body ?

A
  • Aldosterone is released when the body needs to reabsorb water
  • ANP is increased when the secretion of Sodium is needed
28
Q

In the DCT and collecting duct, what things get absorbed and which hormones help facilitate it when urine is DILUTE? Is BP low or high ?

A
  • High blood pressure
  • ANP is released which inhibits ADH and aldosterone and stop the reabsorption of H20 and NaCl
29
Q

In the DCT and collecting duct, what things get absorbed and which hormones help facilitate it when urine is CONCENTRATED? Is BP low or high ?

A
  • low blood pressure
  • Sodium is reabsorbed, this is done by increase in aldosterone
  • H20 is reabsorbed and this is done by increase in ADH
30
Q

In the filtrate what are some things that you will NOT find?

A
  • NO glucose and NO blood
31
Q

In the renin angiotensin system, the granular cells of the juxtaglomerular apparatus secrete renin in response to which of the 3 stimuli?

A
  • Decrease in blood pressure or ECF volume
  • Decrease in NaCl in filtrate
  • Increase in SNS activity
32
Q

What does the secretion of ADH (vasopressin) help with in the body?

A
  • increase in facultative reabsorption H20
  • it also increases the permeability of the tubule cells to water
33
Q

What is the average percentage of water , sodium, glucose, urea , phenol excreted as filtered substance ?

A
  • Water:1%
  • Sodium:0.5%
  • Glucose:0
  • Urea:50%
  • Phenol:100%

PHGY 1030- EXAM 6 (7 decks)

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