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SUGER > Kidneys > Flashcards

Kidneys Flashcards

1
Q

25-hydroxycholecalciferol is converted to 1, 25-dihydroxycholecalciferol. In which of the following tissues does this occur?

A

Kidneys

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2
Q

What systemic mean arterial pressure range must renal blood flow, capillary pressure and GFR be maintained over

A

90-200 mmHg

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3
Q

Main extra cellular solute in kidneys

A

Na+

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4
Q

What can detect plasma volume

A

Baroreceptors

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5
Q

What does low total body Na+ lead to

A

Low plasma volume
Lower BP
—> decrease GFR and increase Na+ reabsorption to decreaase losses

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6
Q

Short term regulation of Na+

A

Changes in GFR

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7
Q

Long term regulation of Na+

A

Renin angiotensin aldosterone system

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8
Q

Effect of high total body Na+

A

Increased GFR
decreased Na+ reabsorption

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9
Q

What percentage of Na+ is reabsorbed in the proximal tubule

A

60%

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10
Q

What percentage of Na+ is reabsorbed in the loop of henle

A

25%

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11
Q

What percentage of Na+ is reabsorbed in the distal tubule

A

10%

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12
Q

What percentage of Na+ is reabsorbed in the collecting duct

A

4%
Regulated reabsorption - large effect due to high volumes of fluid filtered

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13
Q

What has a direct effect on GFR

A

Arterial blood pressure

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14
Q

GFR and reduced blood pressure

A

Reduced GFR
Blood osmolality and oncotic pressure also play a role in

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15
Q

What has an indirect effect on GFR

A

Sympathetic nerves

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16
Q

Sympathetic nervous system and GFR

A

Reflex of arterials in response to increased stretch of the vessels
Respond by constricting (mainly afferent arterioles) reducing blood entry into the glomerulus

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17
Q

What increases GFR again after sympathetic stimulation

A

Neuroendocrine inputs (aldosterone)- reabsorption of Na+ go increase plasma volume

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18
Q

Most abundant intracellular ion

A

K+

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19
Q

Percentage of total body K+ in extracellular fluid

A

2%

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20
Q

Function of extracellular K+

A

Excitable tissues (nerves and muscles)- affects the resting membrane potential

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21
Q

Result of hyperkalaemia or hypokalaemia

A

Abnormal heart rhythms
Abnormalities of skeletal muscle contraction and neuronal action potential conduction

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22
Q

How is K+ excreted

A

Urine- amount dependent on how much is ingested and losses in sweat/faeces

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23
Q

What percentage of filtered K+ is reabsorbed in the proximal tubule

A

90%

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24
Q

Where is K+ reabsorbed

A

Proximal tubule

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25
Q

How is K+ secretion related to Na+ in cortical collecting duct

A

During Na+ reabsorption, K+ is pumped into the cells by Na/K ATPase
K+ then diffuses out of collecting duct and Na+ is able to flow in

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26
Q

What cells can secrete K+

A

Cortical collecting duct cells

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27
Q

Factors affecting K+ secretion

A

A high K+ diet —>Increased plasma K+ concentration —> Basolateral uptake of K+ via the Na/K ATPase
Low K+ diet —> decreased plasma concentration —> reduced basolateral uptake and reduced secretion

Increased intake —> increased extracellular —> stimulates aldosterone production —> increases K+ secretion

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28
Q

What is aldosterone secreted by

A

Zona glomerulosa

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29
Q

What is the zona glomerulosa sensitive to

A

K+ concentration in ECF

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30
Q

What forms the juxtaglomerular apparatus

A

Afferent arterioles (granular cells) and distal convoluted tubule (macula densa cells)

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31
Q

Granular cells

A

Afferent arterioles endothelium expands to form mass of cells in juxtaglomerular apparatus

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32
Q

Macula densa cells

A

Cells of distal convoluted tubule at juxtaglomerular apparatus
Detect Na+ levels

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33
Q

What do macula densa cells secrete in response to low Na+

A

Prostaglandins

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34
Q

What do granular cells secrete

A

Renin

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35
Q

What stimulates granular cells

A

Prostaglandins

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36
Q

Role of macula densa cells if high Na+

A

Filtration is slow so more absorbed
Reduce afferent arterioles resistance and increase GFR

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37
Q

What are the 3 controlling steps of the RAAS

A

Macula densa cells detect less NaCl
Sympathetic stimulation
Little or no arteriolar stretch (from low blood volume)

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38
Q

Function of renin

A

Enters blood and cleaves larger plasma protein angiotensinogen into a smaller angiotensin I

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39
Q

Where is angiotensinogen produced

A

Liver

40
Q

Fate of angiotensin I

A

Cleaved by angiotensin converting enzyme (ACE) into angiotensin II

41
Q

Where is angiotensin converting enzyme (ACE) produced

A

Lungs

42
Q

Aim of RAAS

A

Increase circulating blood volume and blood pressure

43
Q

Effects of angiotensin II

A

Stimulates release of aldosterone, vasopressin and aldosterone
Stimulates thirst
Increases Na+ reabsorption in PCT
vasoconstriction of systemic arteries and renal arterioles (decreases GFR)

44
Q

How is thirst stimulated

A

Increases osmo-sensitivity of system

45
Q

How does vasoconstriction of renal arterioles decrease GFR

A

Effect is greater in efferent arterioles due to smaller basal diameter so increases pressure making it harder for blood to leave

46
Q

Which cells secrete aldosterone

A

Zona glomerulosa cells in adrenal cortex of adrenal glands

47
Q

Size of renin

A

40 kDa

48
Q

What is renin

A

Proteolytic enzyme

49
Q

Which transporter in macula densa cells takes up Na+

A

NKCC2

50
Q

What are granular cells affected by

A

Local factors: stretch, prostaglandin secretion, nitric oxide (cell stress)

51
Q

2 theories of signalling to granular cells

A

Nitric oxide
Adenosine secretion

52
Q

Granular cells and nitric oxide

A

Acts through extraglomerular mesangial cells to signal secretion

53
Q

Granular cells and adenosine secretion

A

By macula densa cells which bypass the mesangial cells and directly go to receptors on granular cells

54
Q

Which cells secrete adenosine

A

Macula densa cells

55
Q

What reduces the secretion of renin

A

Beta blockers - as block effects of adrenaline

56
Q

What 3 things stimulate renin secretion

A
  1. Reduced sodium delivery to the distal convoluted tubule detected by macular densa cells
  2. Reduced perfusion pressure in the kidney detected by baroreceptors in the afferent arterioles
  3. Sympathetic stimulation of the JGA via beta-1 adrenoreceptors
57
Q

Sympathetic receptors of juxtaglomerular apparatus

A

Beta-1 adrenoreceptors

58
Q

Which other hormone do kidneys produce

A

Erythropoietin- stimulates red blood cell production

59
Q

Major complications of chronic renal failure

A

• Fluid retention, which could lead to swelling in your arms and legs, high blood pressure, or fluid in your lungs (pulmonary oedema)
• A sudden rise in potassium levels in your blood (hyperkalemia)
• Anaemia
• Heart disease
• Weak bones and an increased risk of bone fractures
• Decreased sex drive, erectile dysfunction or reduced fertility
• Damage to central nervous system, which can cause difficulty concentrating, personality changes or seizures
• Decreased immune response
• Pericarditis, an inflammation of the pericardium
• Pregnancy complications that carry risks for the mother and the developing foetus
• Irreversible damage to your kidneys (end-stage kidney disease), eventually requiring either dialysis or a kidney transplant for survival

60
Q

Acute kidney injury

A

rapid decrease in glomerular filtration rate that results in abnormal fluid and electrolytes balance and azotaemia (high levels of nitrogen-containing compounds in blood)

61
Q

Pre renal kidney disease

A

sudden and severe reduction in bp or interruption of blood flow to the kidneys from severe injury or illness

62
Q

Causes of Pre renal kidney disease

A

• blood loss
• Dehydration
• Heart failure
• Sepsis (causes vasodilation- oedema)
• Vascular occlusion
• Hypotension
• Oedema

63
Q

Intra-renal kidney disease

A

direct injury to the kidneys by inflammation, drugs, toxins, infection or reduced blood supply

64
Q

Causes of intra-renal kidney disease

A

• acute tubular necrosis= drugs, toxins, prolonged hypotension
• Glomerulonephritis
• Acute interstitial nephritis
• Allergic reactions
• Small vessel vasculitis
• Eclampsia
• Chemotherapy

65
Q

Postrenal kidney disease

A

sudden obstruction of urine flow due to enlargedprostate, kidney stones, bladder injury or tumour

66
Q

Causes of Postrenal kidney disease

A

• benign prostatic hyperplasia
• Cervical cancer
• Retroperitoneal fibrosis
• Prostate cancer
• Urinary calculi
• Renal stone
• Prostate enlargement
• Lower urinary tract infection

67
Q

Common causes of chronic kidney disease

A

• diabetes
• Hypertension
• High cholesterol
• Heart disease/ heart failure
• Obesity
• Over the age of 60
• Family history
• Personal history of acute kidney injury
• Smoking
• Glomerulonephritis
• Interstitial nephritis
• Polycystic kidney disease
• Prolonged obstruction of the urinary tract eg from an enlarged prostate, kidney stones or cancer
• Vesicoureteral reflux
• Recurrent kidney infection

68
Q

Chronic kidney disease of unknown origin

A

A type of chronic kidney disease that mainly affects marginalized agricultural communities in specific areas of the world where a large number of people develop an unexplained, deadly form of kidney disease. In the clinical context, a patient is labelled as CKDu after excluding all the known causes of CKD. There are some common clinical characteristics that define CKDu and differentiate it from some of the known causes of CKD. Across locations reported globally, the disease is seen in young and middle-aged adults, mostly males who are engaged in strenuous work for their livelihood, like agriculture and manual labor. The patients have minimal or no proteinuria. CKDu patients typically are nondiabetic and have either normal blood pressure or are only mildly hypertensive. The disease is progressive leading to stage 5 CKD needing renal replacement therapy over a span of several months. Kidney biopsy, performed in few patients, has revealed varying degrees of tubular atrophy and interstitial fibrosis with inflammatory cells.

69
Q

Environmental factors of chronic kidney disease of unknown origin

A

heat stress, heavy metal exposure via potable water sources, exposure to pesticides via agricultural farming practices, physically stressful working environments and low altitude.

70
Q

Blood pressure is controlled in part by the renin-angiotensin-system.

How does renin convert angiotensinogen to angiotensin I

A

Renin cleaves the N-terminal of angiotensinogen

71
Q

What cells are stimulated to release renin

A

Beta adrenergic receptors on the JGC

72
Q

The ureter is a continuation of the renal pelvis.

Which type of cell lines the ureter?

A

Transitional epithelium

73
Q

Filtration is a key process in the production of urine.

Which of the following is not found in the glomerular filtrate of a healthy individual?

A

Albumin

74
Q

Blood pressure is controlled in part by the renin-angiotensin-system.

Angiotensin I is converted by renin from which of the following?

A

Angiotensinogen

75
Q

A 63-year-old patient presents with an acute kidney injury.

Which of the following would not cause pre-renal acute kidney injury?
A.
Benign prostatic hypertrophy
B.
Cellulitis
C.
Decompensated heart failure
D.
Decompensated liver failure
E.
Diarrhoea and vomiting

A

Benign prostatic hypertrophy

76
Q

Urine production is a key function of the kidney.

How does urine pass through the ureter

A

Urine passes through the ureter by peristalsis

77
Q

The kidneys play a key role in fluid balance.

Which of the following best describes the anatomical location of the kidneys?

A

Retroperitoneal space

78
Q

If the renal clearance of a substance X is 250ml/min.

Which best describes its method of clearance?

A

It must be secreted by the nephron

79
Q

Renal clearance

A

the volume of plasma cleared of that molecule per minute

80
Q

Clearance of molecule (mls/min) equation

A

Cx = (Ux X V)/Px

Ux = concentration of x in the urine

Px = concentration of x in the plasma

V = volume of urine formed per minute

81
Q

Renal clearance of 125 mls/min

A

molecule that is filtered and passes unchanged into the urine e.g. inulin has a renal clearance of ~125 mls/min

82
Q

Renal clearance of <125 mls/min

A

molecule that is filtered and reabsorbed will have a lower renal clearance e.g. urea ~ 80 mls/min

83
Q

Renal clearance >125 mls/min

A

A molecule that is filtered and actively secreted will have a higher renal clearance e.g Para-amino hippuric acid (PAH) ~ 650-700 mls/min

84
Q

Function of aldosterone

A

Acts on the distal collecting duct to cause an increase in the uptake of sodium.
• This increase in sodium causes an increase in the blood pressure
• Aldosterone has a diurnal pattern of release that mirrors that of cortisol

85
Q

To function the kidney requires an adequate blood supply.

How much of the cardiac output passes through the kidneys?

A

20%

86
Q

A 25-year-old patient awaiting a renal transplant is found to be anaemic.

Which of the following best describes the mechanism of anaemia in chronic renal failure?

A

Reduced production of erythropoietin

87
Q

A 78-year-old women presents with shortness of breath. On examination you find she has signs of heart failure.

Which of the following is true concerning Atrial Naturetic Peptides (ANPs)

A

They act on the renal collecting tubules to promote Na+ excretion.

88
Q

Release of ANP

A

released by the atrial myocytes in response to atrial stretch due to elevated atrial pressure and blood volume e.g cardiac failure

89
Q

What does ANP cause

A

An increased glomerular filtration rate
Increased sodium excretion
Inhibition of release of vasoconstrictors e.g. angiotensin II, aldosterone and endothelin
A decrease in blood pressure

90
Q

Regarding the anatomy of the kidney.

What name is given to the outermost layer of the kidney?

A

Capsule

91
Q

Example of substance that is filtered only

A

Inulin

92
Q

Example of substance that is filtered and secreted

A

Penicillin
Creatinine

93
Q

Example of substance that is filtered and reabsorbed

A

Glucose

94
Q

Example of substance that is filtered, reabsorbed and secreted

A

Potassium

95
Q

What percentage of cardiac output is filtered through the kidneys

A

20%

SUGER (17 decks)

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