Renal Hormones Flashcards Preview

Physiology > Renal Hormones > Flashcards

Flashcards in Renal Hormones Deck (94):
1

What is a hormone?

a chemical substance made in one or more locations which is carried by the blood to other areas where it has an effect on cellular function

2

What is an autacoid?

• Substance produced in an area that has an effect on tissue in the same area.

3

What is the GFR?

the total volume of fluid that is filtered from the plasma into the nephrons per unit time

4

What are the two intrinsic mechanisms of regulating GFR?

1. Myogenic mechanism
2. Tubuloglomerular feedback machanism

5

What is the myogenic mechanism of GFR control?

The rise in pressure in the afferent arteriole of the glomerulus causes the arteriole to vasoconstrict and vice versa

6

Usually the GFR remains autoregulated (i.e. relatively constant) despite the fluctuations in arterial pressure that occur during a person’s normal activities. When can this fail?

At extremes of blood pressure, autoregulation fails and GFR and RBF vary directly with the systemic blood pressure.

7

What is the MOA of the tubuloglomerular feedback mechanism?

Macula densa senses increased flow (and [NaCl]) from increased filtration rate, and changes arteriole resistance through chemical mediators

8

What is the function of adenosine in the kidney?

decreases GFR
Decreased renin

9

What are the two things that the macula densa is sensing?

Flow
Na delviery

10

What is the chemical released by the macula densa in response to increased flow? What does this cause?

Adenosine

Lowers GFR and lower renin (to lower BP)

11

What is the effect of renin?

Increase BP by reabsorbing Na and causing angiotensin II formation

12

What is the chemical released by the macula densa in response to decreased flow? What does this cause?

NO, prostaglandins

Increases GFR and renin

13

How are afferent and efferent arterioles regulated relative to one another (directly or inversely)?

Inversely

14

Why do we want to uncouple BP and excretion regulation?

Sudden BP changes could interfere in fluid and electrolyte balance.

15

True or false: the proximal tubule almost always removes about 2/3 of the solutes from the tubule?

True

16

What is pressure diuresis?

Increased loss of fluids when BP increases

17

What is pressure natriuresis?

Increased loss of fluids when plasma Na increases

18

What are the two ways the kidneys are related to HTN? What is the consequence of this?

1. Hypertension (for any reason) can cause renal damage and increased nephron flow
2. Any form of renal damage tends to cause hypertension

=bad feedback

19

What is the effect of PGE2 and PGI production when angiotensin II/norepi/vasopressin is released? What is the effect on the kidney?

Increases,
thus can oppose vasoconstrictors produced by the macula densa

20

What is the mechanism through which chronic aspirin or IBU use can lead to renal damage?

If you reduce the amount of PGE2 and PGI2 synthesized unopposed vasoconstriction might cause renal damage

21

What happens to a pt with kidney damage when they take NSAIDs?

Inhibit vasodilation (which would be up in a damaged kidney), leads to ischemic nephrons

22

Which part of a kidney is particularly susceptible to ischemia? What is the consequence of this?

medullary blood flow

If there is damage, one sign may be the inability to produce concentrated urine (since this is where juxtaglomerular nephrons are)

23

What is the effect of norepi and epi on the adrenal medulla?

Constrict both the afferent and efferent arterioles thus decreasing renal blood flow and GFR.

More alpha 1 on afferent arterioles

24

What is the effect of angiotensin II generally? On the kidneys?

Vasoconstrictor in the systemic circulation

preferentially constricts the efferent arteriole under most physiological conditions

25

Angiotensin II preferentially constricts the efferent arteriole under most physiological conditions How is the afferent arteriole protected from this?

Vasodilator release by macula densa

26

What is the effect of unopposed angiotensin II? How?

Increased GFR b/c efferent arterioles constricted while afferent not

27

What is the relationship of efferent arteriole resistance relative to GFR and renal blood flow?

Direct with GFR
Inversely with renal blood flow

28

What is the relationship of afferent arteriole resistance relative to GFR and renal blood flow?

Inverse with both GFR and renal blood flow

29

What is glomerular tubular balance?

1. Renal tubules increase their reabsorption rate when GFR increases

30

If the number of nephrons is decreased, the kidneys compensate how? How is this effected?

by increasing the filtration of each nephron

increasing PGE2 and PGI2 thus dilating afferent arterioles and increasing single nephron GFR.

31

What are the effects of Epi and norepi on the kidneys?

Constricts both the afferent and efferent arterioles thus decreasing renal blood flow and GFR

32

What is the effect of angiotensin II on the kidneys? (3)

preferentially constricts the efferent arteriole under most physiological conditions

Increase Na reuptake from tubules

Increases Aldosterone synthesis

33

What does the kidney do in response to low BP?

Releases renin

34

What is the function of renin?

Breaks angiotensinogen from liver into angiotensin I.

35

What converts angiotensin I to II?

ACE

36

What is the function of juxtaglomerular cells?

Release renin in response to BP changes in the kidney

37

What is the effect of aldosterone synthesis?

Increases renal reabsorption of sodium which can also raise blood pressure

38

What are the steps that the kidney takes in reposne to BP changes? (3)

1. Changes renin from juxtaglomerular cells
2. Renin converts Angiotensinogen to angiotensin I
3. Angiotensin II increases aldosterone

39

What are the two things that cause thirst?

1. Angiotensin II
2. Increased blood osmolality

40

Increased blood osmolality or decreased blood volume causes what?

increased release of ADH

41

What is ADH's effect on BP? How?

Increases via vasoconstriction

42

What are the two natriuretic peptides in the heart?

ANP
BNP

43

What is the signal for more ADH to be released?

Increased stretch on the right atrium

44

What is the effect ANP has on ADH, Renin?

Decreases both

45

What are the effects of ANP/BNP on the GFR?

Relaxes Arteriole to increase GFR

46

What are the effects of ANP/BNP on angiotensin II?

Decrease/inhibits

47

What are the effects of ANP/BNP on the Na/water reabsorption on the medullary collecting duct?

Inhibits

48

What are the effects of ANP/BNP on aldosterone?

Decreases

49

What is the overall effect of ANP/BNP?

Decreased BP

50

Where is erythropoietin mainly produced?

Kidney

51

What is the function of erythropoietin?

Goes to bone marrow to stimulate RBC production

52

What is the enzyme that creates calcitriol from 25-hydroxycholecalciferol?

1alpha- Hydroxylase

53

Where does the conversion of vit D3 take place?

Kidney

54

What is the prohormone of vit D that we take in via our diet? What is the first step to convert it to previt D?

7-dehydrocholesterol

Exposure to sunlight

55

After previt D is converted to Vit D3 via sunlight, what happens?

25-hydroxylase converts it to 25 hydroxycholecalciferol

56

What is the step after formation of 25 hydroxycholecalciferol?

1alpha hydroxylase converts it to calcitriol

57

What is the active form of Vit D?

Calcitriol

58

What are the effects of calcitriol? (3)

Stimulates renal tubule reabsorption of Ca and PO3

Suppresses PTH synthesis in the parathyroid

Stimulates FGF3 in bone

59

The final hydroxylation step of vit D is stimulated by what?

PTH

60

What is the effect of PTH?

controls plasma calcium concentration

61

What controls [PTH]? What is the relationship?

[Ca], inversely

62

What are the chemical reaction in the body that take place in response to lower [Ca]?

Increase PTH, Increasing Vit D activation, increasing Ca reabsorption/release from bones

63

What is the relationship between PO3 and PTH?

inverse relationship

64

Why is it important that PO3 an Ca vary inversely?

CaPO3 could precipitate out and cause renal stones

65

What is the effect of PTH on PO3 reabsorption in the kidneys and intestines?

Decreases PTH reabsorption in the kidneys

Increases in intestines

66

Where is the Ca drawn from bone via PTH?

The labile bone part

67

What are the three rapid responses to PTH synthesis?

Decreased renal PO3 reabsorption

Increased renal Ca reab

Increase bone Ca withdrawl

68

What are the two slow responses to PTH?

Increased osteoclast action

Increased intestinal Ca reabsorption

69

What is fibroblast growth factor 23 (FGF23)? (what makes it, what does it do [2])?

a peptide hormone that is made by osteoblasts and osteocytes in bone

Decreases PO3 reabsorption in the kidney, and decreases production of calcitriol

70

What stimulates FGF23 release?

Increased PO3 levels,

71

What is the effect of PTH on calcitriol synthesis? FGF23?

Increased by PTH
Decreased by FGF23

72

What is the effect of PTH on phosphate excretion? FGF23?

Both increase excretion

73

What is the effect of CKD on [PO3]? What is the consequence of this?

Lowers GFR, increasing [PO3]. This increases PTH, increasing bone reabsorption. =osteodystrophy

74

What is the effect of PTH on the kidney? Intestines?

Kidney = Increases Ca reabsorption, decreases PO3

Intestines = Increases Ca reabsorption, increases PO3

75

What cells synthesize FGF23?

Osteoblasts/clasts

76

What inhibits PTH?

Ca

77

What is the feedback mechanism for Vit D synthesis?

Increased Ca inhibits PTH. PTH no longer activates 1alpha hydroxylase

78

1alpha-hydroxylase is found where?

Kidney

79

25alpha hydroxylase is found where?

Liver

80

What are the two hormones that ANP inhibits?

ADH
Renin

81

Where is angiotensinogen produced?

Liver

82

What type of sympathetic adrenoceptors are found on the kidney? What do they do?

B1, stimulate renin release

83

Where are osmoreceptors found/what do they synapse to?

In the hypothalamus, synapsing on the paraventricular and supraoptic nerves

84

How can tubuloglomerular feedback help prevent excessive fluid losses if there is damage to kidney proximal tubules?

Can redirect blood to other, "good" nephrons

85

What is the effect of angiotensin II on vascular smooth muscle?

Contracts

86

What is the effect of angiotensin II on the adrenal cortex?

Stimulates aldosterone release

87

What is the effect of angiotensin II on the afferent and efferent arterioles?

Vasoconstricts efferent.

88

What is the effect of angiotensin II on the thirst center?

Increases thirst

89

What is the effect of angiotensin II on ADH release?

Increases

90

What is the effect of angiotensin II on sympathetic tone?

Increases

91

What are the two organs that make erythropoietin?

Liver and kidney

92

What is the major stimulus for erythropoietin secretion?

Hypoxia to kidneys

93

What is more important, the effect of vit D on the intestines or the kidneys?

Intestines

94

What is the effect of PTH on the kidney?

Increases PO3 secretion