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1
Q

Urea is essential in allowing the kidney to:

A

develop concentrated urine

this is why people with high protein diets can concentrate urine better

2
Q

The _______ serve as countercurrent exchangers, minimizing the washout of solutes from the medullary interstitium.

A

vasa recta

3
Q

An increase in medullary blood flow would have what effect on urine concentration?

A

Decreased ability to concentrate urine d/t decreased solute load

4
Q

Why does a decrease in ADH lead to a less concentrated renal medulla?

A

Less urea is being reabsorbed in the medulla

5
Q

Why is tubular fluid in the thick ascending loop so dilute?

A

the loop is completely impermeable to water

BUT

all of the sodium, chloride etc is sucked out, leaving dilute tubular fluid

6
Q

In the late distal tubule and cortical collecting tubules, the osmolarity of the tubular fluid depends on:

A

the amount of ADH

7
Q

How can you tell if DI is nephrogenic or central?

A

Give desmopressin

If it gets better, it has to be caused by decreased ADH (central)

If it doesn’t get better, the problem is that the kidneys can’t respond to ADH

8
Q

Plasma osmolarity can be roughly calculated by:

A

multiplying serum sodium by 2.1

9
Q

A more exact calculation for plasma osmolarity would be:

A

POSM = 2.1 [PNa + PGluc + PUrea]

10
Q

How does increased plasma sodium concentration stimulate ADH secretion?

A

Causes osmoreceptor cells in the hypothalamus to shrink

Shrinkage of these cells causes them to fire

Action potentials are conducted to the posterior pituitary

ADH is released

11
Q

What effect does nausea have on ADH levels?

A

Increases ADH levels for up to an hour after vomiting

12
Q

Name six stimulants of ADH

A
  1. Increased osmolarity
  2. decreased blood volume
  3. decreased blood pressure
  4. nausea
  5. hypoxia
  6. Morphine and Nicotine
13
Q

Name three drugs that decrease ADH stimulation

A

clonidine

haldol

alcohol

14
Q

Name five things that increase thirst

A

increased plasma osmolarity

decreased BP

decreased blood volume

increased angiotensin II

dry mouth

15
Q

What effect do aldosterone and angiotensin have on sodium plasma concentration?

A

None! They control the total body sodium. Not sodium concentration.

16
Q

Name four factors that cause potassium to shift into cells

A

Insulin

Aldosterone

B-adrenergic stimulation

alkalosis

17
Q

Name 7 factors that cause potassium to shift out of cells

A

insulin deficiency (diabetes)

Aldosterone deficiency (addison disease)

B-adrenergic blockade

Acidosis

Cell Lysis

Exercise

Increased plasma osmolarity

18
Q

Most of the daily potassium reabsorption and excretion occurs where?

A

the late distal and cortical collecting tubules

19
Q

Which cells in the late distal and cortical collecting tubules secrete potassium?

A

Principal cells

20
Q

In patients with Addison’s disease, serum potassium levels are:

A

extremely high

21
Q

In a high-sodium diet, aldosterone would be low, so you’d think potassium would be high. But it isn’t. Why?

A

the low aldosterone decreases the amount of K secreted, but the high tubular flow rate that results from being fluid overloaded increases potassium excretion, so the balance stays pretty much the same

22
Q

Acute acidosis ______ potassium secretion

A

reduces

23
Q

How is most calcium excreted?

A

feces

24
Q

Hypocalcemia causes ________ excitability

Hypercalcemia causes _______ excitability

A

increased

decreased

25
Q

Why are patients with alkalosis more susceptible to hypocalcemic tetany?

A

hydrogen ion concentration alters calcium binding. When there’s a high hydrogen ion concentration, more calcium is free (ionized). When there’s a low hydrogen ion concentration, less calcium is free (ionized), which means less calcium is technically available for use

26
Q

Name six factors that decrease calcium excretion

A

Increased PTH

decreased BP

decreased blood volume

Increased plasma [phos]

Alkalosis

Vit D

27
Q

Name five factors that increase Ca excretion

A

Decreased PTH

increased blood volume

increased BP

decreased plasma [phos]

acidosis

28
Q

Name four factors that increase Phos excretion

A

increased dietary intake

PTH

metabolic acidosis

HTN

29
Q

Name four factors that decrease Phos excretion

A

decreased intake

Vit D

Alkalosis

Thyroid Hormone

30
Q

Magnesium concentration is directly related to _______ concentration

A

calcium

as calcium excretion increases, magnesium excretion increases (and vice versa)

31
Q

What is pressure natriuresis?

A

As blood pressure increases, sodium excretion increases

32
Q

what is pressure diuresis?

A

An increase in BP increases diuresis

33
Q

Why do so many patients in heart failure need ACE inhibitors?

A

under normal circumstances, angtiotensin II causes a large amount of water and sodium to be reabsorbed

BUT with a normal heart, this results in almost no change in ECF volume BECAUSE the increased volume causes increased pressure diuresis.

BUT in a sick heart, it can’t pump effectively enough to increase pressure in the kidney and cause pressure diuresis. So angiotensin II is still retaining Na, but the kidney isn’t compensating via pressure diuresis.

Water accumulates and causes CHF

34
Q

Which does ADH effect more: ECF volume or plasma [Na]?

A

Plasma sodium concentration

ADH actually causes very little ECF overload, even when present in large amounts BECAUSE of pressure natriuresis

BUT excess ADH creates ECF that is extremely low in sodium, because sodium is not being reabsorbed with the water

AND sodium excretion is increased by pressure natriuresis

35
Q

destruction of ______ causes an inability to create ADH

A

supraoptic nuclei

36
Q

Why does blood volume increase as a woman becomes more pregnant?

A

As vascular capacitance increases (due to the constant formation of new blood vessels), the kidneys retain salt and water to add volume to essentially fill a bigger tank

37
Q

Why are the kidneys more resilient to ischemia than other organs?

A

As perfusion decreases, so does the GFR, which means the kidney is expending WAAAYY less energy reabsorbing sodium

38
Q

What causes acute glomerulonephritis?

A

abnormal immune reaction that damages the glomeruli

occurs 1-3 weeks after infection d/t antibody production

39
Q

What kind of pathogen is usually the instigator of glomerulonephritis?

A

Group A Beta Strep

40
Q

What is tubular necrosis?

A

destruction of the epithelial cells of the tubules

41
Q

What causes Acute Tubular Necrosis?

A

Either severe ischemia or toxins/meds

42
Q

In CKD, serious symptoms aren’t seen until the number of functional nephrons decreases to ______

A

20-25% of normal

43
Q

What is the most common cause of ESRD?

A

Diabetes

44
Q

Why does lupus often lead to kidney failure?

A

Causes chronic glomerulonephritis

45
Q

minimal-change nephropathy is:

A

protein loss with no visible defect in the basement membrane

most common in children aged 2-6

46
Q

What is isosthenuria?

A

inability of the kidney to concentrate urine

47
Q

What is renal tubular acidosis?

A

Inability of the tubules to secrete H results in a severe loss of bicarb

48
Q

What is Fanconi Syndrome?

A

increased urinary excretion of virtually all amino acids, glucose, and phosphate

49
Q

What is Bartter Syndrome?

A

Decreased Sodium, Chloride, and Potassium Reabsorption in the Loops of Henle

Impaired NCCK

50
Q

What is Liddle Syndrome?

A

Increased sodium reabsorption

autosomal-dominant disorder resulting from various mutations in the amiloride-sensitive epithelial sodium channel (ENaC) in the distal and collecting tubules

51
Q

Renal glucose release is stimulated by _____ and inhibited by ______

A

epinephrine

insulin

52
Q

_______ suppresses glucose release in both the kidneys and liver

A

insulin

53
Q

All glomeruli are located in the _______

A

cortex

54
Q

The structural unit of the kidney is the ______

the functional unit of the kidney is the _______

A

lobe

nephron

55
Q

How many lobes are there in each kidney?

A

14

56
Q

Each lobe is composed of:

A

a medullary pyramid and the overlying cortex

57
Q

______ cells create a matrix and support the glomerular capillaries

A

mesangial

58
Q

Podocytes are responsible for forming:

A

filtration slits that modulate filtration

59
Q

The endothelium, basement membrane, and podocytes are covered with ______ to prevent proteinuria

A

anionic protein molecules

60
Q

juxtaglomerular cells are located in the ______ and release ________ in response to ______

A

Afferent arteriole

renin

sodium changes in the macula densa

61
Q

the wall of the ______ is the only surface in the nephron that contains microvilli

A

proximal convoluted tubule

62
Q

Compare the ascending and descending thin loops of henle

A

Descending: no active transport, highly permeable to water

Ascending: permeable to ions, impermeable to water

63
Q

The distal tubule extends from the ______ to the _____

A

macula densa

collecting duct

64
Q

Principal cells and intercalated cells make up the epithelium of the:

A

distal tubule

65
Q

Principal cells reabsorb _____ and secrete ______

A

sodium and water

potassium

66
Q

The ________ is the only blood supply to the medulla

A

vasa recta

closely follows the loop of henle

67
Q

What is the function of the uroepithelium?

A

lines the entire urinary tract

maintains barrier between water and solutes in the urine and the blood supply

68
Q

What is the trigone?

A

smooth triangular area lying between the openings of the two ureters and the urethra

69
Q

the internal urethral sphincter is made of:

the external is made of:

A

smooth muscle

striated muscle (under voluntary control)

70
Q

Which nerves innervate the external urethral sphincter?

A

somatic motor neurons in the pudendal nerves

71
Q

Where does blood that is not filtered through the glomerulus go?

A

Through the efferent arteriole into the peritubular capillaries

72
Q

What effect does parasympathetic stimulation have on renal perfusion?

A

There’s almost no parasympathetic innervation to the kidneys

73
Q

What is the role of prostaglandins in regulation?

A

dampen vasoconstriction caused by sympathetic nerves and angtiotensin II

Prevent harmful vasoconstriction and renal ischemia

74
Q

Low serum plasam levels will ______ the GFR

A

decreases the effective oncotic pressure that would normally keep fluid in the glomerular capillaries instead of flowing into the capsule (being filtered)

increases GFR

75
Q

High serum plasma levels will ______ the GFR

A

decrease

Keeps fluid in the glomerular capillaries instead of being filtered into the glomerulus

76
Q

How are chloride, water, and urea absorbed?

A

passively

but linked to the active transport of sodium

77
Q

What is the primary function of the proximal tubule?

A

active sodium reabsorption

everything else is cotransported with sodium and water is reabsorbed by osmosis with sodium concentration

78
Q

How does the structure of the loop of henle alter the efficiency of water conservation?

A

The longer the loop, the greater the ability to concentrate urine