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Pathophysiology > Finals- Summer 2014 (Renal/Neuro) > Flashcards

Finals- Summer 2014 (Renal/Neuro) Flashcards

1
Q

5 regions of the Nephron

A
  1. Renal Corpuscle
  2. PCT
  3. Loop of Henle
  4. DCT
  5. Collecting Duct
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2
Q

At the renal corpuscle is the site of ______.

A

Filtration

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3
Q

The renal corpuscle is formed by (3 parts)

A
  1. Glomerulus
  2. Bowman’s Capsule
  3. Mesangial cells
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4
Q

The collecting system of calyces, renal pelvis, and ureters all contain ____ ______ to facilitate flow of urine into bladder

A

Smooth Muscle

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5
Q

Three regions where a potential kidney stone could be lodged

A
  1. Ureteropelvic junction (junction of renal pelvis and ureter)
  2. As ureter passes over pelvic brim
  3. As ureter enters the bladder
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6
Q

3 types of nephrons

A
  1. Superficial cortical - extend into medulla
  2. Mid-cortical nephron - short and long loops
  3. Juxtamedullary nephron - extend deep into medulla and are responsible for urine concentration
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7
Q

Three layers of glomerular filtration membrane

A
  1. Capillary endothelium (fenestrated) - microscopic openings of capillary wall
  2. Basement Membrane (holds a negative charge)
  3. Capillary epithelium (podocytes) - foot like projections that form matrix of filtration slits
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8
Q

Where does blood travel to after it leaves the glomerulus through the efferent arteriole?

A

Peritubular capillaries…this allows reabsorption and secretion along the tubles of the nephron

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9
Q

Juxtaglomerular apparatus (JGA) = _____ + _____.

A

Juxtaglomerular cells + macula densa

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10
Q

JGA plays a role in the regulation of: (3 things)

A
  1. Renal blood flow
  2. Glomerular filtration
  3. Renin secretion
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11
Q

These cells are a matrix of smooth muscle and phagocytic cells located between glomerular capillaries and Bowman’s capsule that play a role in regulation filtration

A

Mesangial cells

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12
Q

The space inside the glomerulus is known as

A

Bowman’s capsule

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13
Q

What is the PCT’s major function

A

Sodium reabsorption

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14
Q

The function of the Loop of Henle varies by location. Juxtamedullary nephron’s vs. Superficial cortical and mid-cortical nephron function

A

Juxtamedullary: concentrating urine

Superficial cortical/mid-cortical: DO NOT play a role in concentrating urine

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15
Q

Where does DCT begin and end?

A

Begins at macula densa and ends at connection to collecting ducts

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16
Q

Functions of early v. late DCT

A

Early - continues to dilute filtrate and reabsorb Na

Late - begins to concentrate fluid as it enters collecting duct

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17
Q

Collecting duct function

A

Final concnetration of urine

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18
Q

Pathway of blood supply to the kidneys

A

Descending aorta –> R/L renal arteries –> multiple branches evetually form afferent glomerular arterioles –> supply glomerular capillary beds

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19
Q

Where are peritubular capillary beds?

A

Surround the PCT, DCT, and some of the short Loop of Henle

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20
Q

Function of peritubular capillary beds

A

Secretion and reabsorption

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21
Q

Besides blood going to the peritubular capillaries, where else could it travel too?

A

Vasta Recta - runs parallel to long loops of Henle and plays a critical role in concentrating urine by regulating concentration gradients

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22
Q

________ runs parallel to the long loops of Henle and plays a critical role in concentrating urine by regulating concentration gradients along the loop.

A

Vasta Recta

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23
Q

Blood leaving efferent arteriole of a cortical nephron will proceed to _____ whereas blood leaving the efferent arteriole of a juxtamedullary nephron will proceed to _____.

A

Peritubular capillary

Vasta Recta

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24
Q

The blood pressure of the glomerular capillaries is ____. The blood pressure of the peritubular capillaries is ____. Explain why they are different.

A

Glomerular: 45 mmHg
–> High pressure system to encourage filtration

Peritubular Capillaries: 8 mmHg
–> Low pressure system to encourage exchange

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25
Q

RBF =

A

1.2 L/min (20-25% of resting CO)

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26
Q

How do you calculate renal plasma flow (RPF) and what is it’s average range?

A

RPF = RBF x (1 - hematocrit)

RPF = 600-700 ml/min

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27
Q

How do you calculate glomerular filtration rate (GFR) and what is it’s average number?

A

GFR = RBF x 20%

GFR = 120 ml/min

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28
Q

How much of the GFR is reabsorbed back into the bloodstream?

A

98-99% (into peritubular capillaries)

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29
Q

What is filtration fraction and what is it’s average?

A

Ratio of GFR to RPF
Average FF = 0.2
(120/660)

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30
Q

Urine output = ____ x _____

A

GFR x 1.5%

–> 1-2 ml/min

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31
Q

How much plasma do the kidneys filter in a day and how much urine is excreted?

A

Filter 180 L/day and excrete only 1-2L/day

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32
Q

How is RBF/GFR regulated?

A
  1. Autoregulation
  2. Neuroregulation
  3. Hromonal feedback mechanisms
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33
Q

SBP can vary from ____ to _____ without significant change in GFR

A

70-80 to 180-210

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34
Q

Explain how autoregulation maintains a constant GFR

A
  • Systemic pressure inc = AFFERENT arterioles constrict, limiting RBF
  • Systemic pressure dec = EFFERENT arterioles dilate, increasing RBF
35
Q

What are the two mechanisms of autoregulation of the kidneys?

A
  1. Myogenic mechanism

2. Tubuloglomerular feedback

36
Q

Does the parasympathetic or sympathetic nervous system provide feedback to regulate GFR?

A

Sympathetic

37
Q

Baroreceptors in the aortic arch/carotid sinus sense decreases in BP and stimulate the renal/glomerular arterioles to CONSTRICT, limiting RBF. Why??

A

Goal of SNS is to increase SBP

–> decreasing GFR = less Na/H20 being filtered and excreted which will promote an increase in SBP

38
Q

What are the two major hormonal mechanisms to balance GFR

A
  1. RAAS

2. Natriuretic peptides

39
Q

Where is renin synthesized and release from?

A

Juxtaglomerular cells of juxtaglomerular apparatus. They release it into afferent arteriole

40
Q

What is the goal of the RAAS system?

A

increase BP/blood volume

41
Q

Actions of angiotensin II (7 actions)

A
  1. Vasoconstriction of blood vessels
  2. Stimulate thirst
  3. Promote release of NE
  4. Stimulate adrenal cortex to release aldosterone
  5. Stimulate post. pituitary to release ADH
  6. Dec. peritubular capillary hydrostatic pressure
  7. Stimulates contraction of mesangial cells (resulting in a dec. GFR)
42
Q

Inhibition of renin will do 3 things…

A
  1. Increase GFR or Na/Cl flow
  2. Increase Systemic/glomerular BP
  3. Negative feedback of inc. AT2 and ADH
43
Q

The 4 Natriuretic peptides:

A

ANP
BNP
C-type
Urodilatin

44
Q

____ is produced and secreted from the right ventricle and ____ is produced and secreted from atrial walls of the heart.

A

BNP

ANP

45
Q

____ is secreted from vascular endothelium and ____ is secreted from DCT/collecting ducts

A

C-type

Urodilatin

46
Q

Functions of ANP/BNP

A
  1. Inhibit secretion of renin and aldosterone
  2. Vasodilate the glomerular afferent arterioles
  3. Inhibit sodium/water reabsorption in tubles
47
Q

Function of C-type natriuretic peptide

A

Promotes vasodilation of blood vessels

48
Q

Function of urodilatin

A

Promotes sodium/water excretion in DCT/collecting duct

49
Q

Substances the glomerulus filters in a healthy person (7)

A
  1. H20
  2. Electrolytes
  3. Creatinine
  4. Glucose
  5. Urea & uric acid
  6. Small AA
  7. Bicarbonates
50
Q

Are blood cells and most proteins filtered in the glomerulus usually?

A

NO! Not in a healthy person

51
Q

RBC/WBC are how much bigger than the size of a glomerular pore?

A

100-300x bigger!!

52
Q

What kind of molecules are allowed through the basement membrane of the glomerular filter system?

A

Neutral substances smaller than 4-8 nm

It repells negatively charged small molecules such as albumin

53
Q

Proteinuria v. Hematuria

A

Proteinuria = protein/albumin in urine

Hematuria = blood/RBC in urine

54
Q

Oliguria

A

low urine output/production

55
Q

Azotemia

A

Elevated blood urea nitrogen (BUN) and serum creatinine

56
Q

Nephritic syndrome v. Nephrotic syndrome

A

Nephritic: hematuria is consistent finding

Nephrotic syndrome: Proteinuria is consistent finding

57
Q

Is the permiability of glomerular capillaries greater or less than skeletal muscle?

A

Greater…50x greater

58
Q

Mesangial cells can determine filtration. How?

A

They can be functionally altered (contract) to decrease capillary surface area. Less surface area results in less filtration (dec. GFR)

59
Q

Substances that stimulate contraction of mesangial cells (3)

A
  1. Angiotensin II
  2. ADH
  3. NE
60
Q

Substances that stimulate relaxation of mesangial cells (2)

A
  1. ANP

2. Dopamine

61
Q

4 Overall factors that determine filtration across the glomeruli capillaries

A
  1. Renal blood flow
  2. Permeability of glomerular capillaries
  3. Size of capillary bed/mesangial cells
  4. Hydrostatic and osmotic pressures in glomerulus and Bowman’s capsule
62
Q

PCT reabsorbs…. (include percentages)

A

H20 and Sodium: 60-70%
Urea: 50%
Glucose, AA, Bicarb, other electrolytes: 90-100%

63
Q

Two pathways that sodium is reabsorbed from the PCT lumen into the PCT cell

A
  1. Co-transport

2. Active exchange of Na/H

64
Q

Where do carbonic anhydrase inhibitors work?

A

inhibit Na/H pathway to “block” Na reabsorption in the PCT

65
Q

The pathway that sodium is reabsorbed from the PCT cell into the peritubular capillaries

A

Active transport via sodium/potassium pump

66
Q

Explain how glucose is transported in the PCT (PCT lumen –> PCT cell –> peritubular capillaries

A

PCT lumen –> PCT cell: Co-transport w/ Na

PCT cell –> peritubular: diffusion via carrier GLUT

67
Q

What is the max plasma glucose levels that corresponds w/ transport maximum of glucose

A

> 350 mg/dl

68
Q

Elevated plasma glucose will:

A
  1. Inc. glucose filtered at glomerulus
  2. Inc. glucose of filtrate flowing through PCT
  3. If too much glucose in filtrate then transport max is reached and glucose is excreted in urine
69
Q

Glucose renal threshold

A

Plasma values at which glucose first appears in urine:

180-200 mg/dl

“glucose dumping”

70
Q

3 substances secreted in PCT?

A 
H ions
Creatinine
NH3 (ammonia)
Various other acid and bases
Metabolized meds/drugs
71
Q

How is sodium transported in the ascending loop of henle (loop–>loop cell–>peritubular capillaries

A

loop lumen –> cell: Na/K/Cl co-transport

peritubular capillaries: Na/K pump

72
Q

Loop diuretics inhibit _____

A

Na/K/Cl pump in ascending loop of henle

Reabsorption of K and Ca is also inhibited and thus hypokalemia and hypocalemia

73
Q

How is sodium reabsorbed in the early DCT (lumen–>cell–>peritubular capillaries)

A

lumen–> cell: NaCl co-transport

cell–> peritubular capillaries: Na/K pump

74
Q

How much sodium reabsorption takes place in the ascending loop of henle? the early DCT?

A

Loop: 25%

Early DCT: 5%

75
Q

Where do Thiazide diuretics work?

A

Inhibit Na/Cl co transport in early DCT

Reabsorption of Ca results in hypercalemia
May also see hypokalemia and metabolic acidosis

76
Q

What are the two cell types in Late DCT and collecting duct?

A
  1. Principle cell

2. Alpha - intercalated cells

77
Q

The principle cell secretes _____ and reabsorbs _____.

A

Secretes potassium and reabsorbs sodium and water

78
Q

The intercalated cell (alpha cell) secretes _____ and reabsorbs ______.

A

Secretes H+ ions and reabsorbs bicarbonate

79
Q

Two functions of late DCT

A
  1. Regulate final urine concentration

2. Maintain acid-base homeostasis

80
Q

_____ stimulates sodium reabsorption and potassium secretion in the late DCT and collecting ducts

A

Aldosterone

81
Q

K+ sparing diuretics

A

inhibit K secretion from principle cells

82
Q

How does the late DCT and collecting duct reabsorb water?

A

If ADH is present then principle cells of late DCT increase permeability to water

83
Q

How do intercalated cells of the late DCT and collecting ducts reabsorb K?

A

Only occurs if significantly low dietary intake of K+

84
Q

Go through fluid concentration in nephron (mOsm)

A

PCT: 300 mOsm

Loop: Start - 300 mOsm –> 1,200 mOsm –> 100 mOsm

DCT: Early 100 mOsm –> Late: 150 mOsm

Collecting Duct: Start w/ 150 mOsm –> 1,200 mOsm

Pathophysiology (12 decks)

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