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Integrated clinical studies > the renal system > Flashcards

the renal system Flashcards

1
Q

two types of nephron

A

superficial cortical

juxtamedullary

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2
Q

superficial cortical

A

-glomeruli in outer cortex- shorter loop of Henle which only dips slightly into the medulla – lost entirely embedded in the outer medulla

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3
Q

juxtamedullary

A

dips deep into the medulla–> LONG loop of Henle –> near corticomeduallry border.
-larger glomeruli= higher filtration rate

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4
Q

glomereulus

A

sack of blood vessels situated in the bowman capsule

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5
Q

what leads into the glomeruli

A

afferent arterioles

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6
Q

what leads from he glomeruli

A

efferent arteries- proximal convoluted tubule, loop of henle, distal convoluted, collecting duct

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7
Q

corpuscle

A

always in the cortex–> glomerulus and bowman capsule

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8
Q

how does afferent and efferent arterioles control blood flow into the glomerulus

A

total resistance of afferent and efferent arteries, which is determined by the contraction of them, determines the renal blood flow-> contraction and dilation is important to maintain an even blood flow

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9
Q

what is filtered out of the blood at the bowman capsule

A

water,
salts,
glucose,
urea

these are filtered out due to their physical size–> water and solute have a relatively low molecular mass

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10
Q

of what molecular mass can be filtered at the corpuscle

A

68,000

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11
Q

what is filtrate produced at the glomerulus called

A

glomerulus filtrate–> forms 123cm per min in humans

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12
Q

what is filtration referred to at the bowman capsule

A

ultrafiltration–> the force of hydrostatic pressure in the glomerulus is the driving force which pushes the filtrate out of the capillary

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13
Q

what is ultrafiltration controlled by

A

1) size of the endothelium fenestrations (70-100nm)
2) filtration slits in the podocytes (25nm)
3) -ve charge of the endothelium

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14
Q

filtration slits and podocytes

A

Blood flows through the capillaries of the glomerulus (10), where it is filtered by pressure. The podocytes (3a and 3b, green) are wrapped around the capillaries. Blood is filtered through the slit diaphragm (or filtration slit), between the feet or processes of the podocytes.

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15
Q

how much filtrate actually leaves the body

A

1%–> the rest is reabsorbed

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16
Q

tubule reabsorption 3 types

A

active transport
osmosis
diffusion

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17
Q

reabsorption in the proximal convoluted tubule

A
  • -> where most absorption happens–. water and glucose.
  • ->most of kidneys energy goes into reabsorption of na+ ions–> through symporters therefore active transport
  • -> water follows sodium (obligatory water reabsorption)
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18
Q

reabsorption in the loop of henle

A

due to counter flow arrangement, countercurrent multiplication is facilitated.–> this creates a high solute conc in the tissue fluid of the medulla

1_ descending: permeable to water, less permeable to na+ and cl- and to urea. H2O moves into the interstitum
2_Ascending (thin): not permeable to water. highly permeable to Na+ and Cl—> diffuse int the instersitium
3_Ascending (thick): more NaCl reabsorbed

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19
Q

why is reabsorption efficient in the loop of Henle

A

countercurrent system–> maintains high conc gradient

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20
Q

what does the distal convoluted tubule react to

A

the amount of anti-diuretic hormone (ADH) in the blood

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21
Q

the higher the ADH levels

A

the more water is reabsorbed - due to ADH cuisine the cells in the last section of the DCT to become more permeable to water and therefore urine will be more concentrated

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22
Q

the lower the ADH levels

A

the less water is reabsorbed due to the lasts section of the DCT being less permeable to water–> therefore urine will be more dilute

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23
Q

what may affect levels of ADH in the blood…

A

conditions like diabetes insidious or by the consumption of diuretics

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24
Q

diuretic

A

anything that increases the production of urine

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25
Q

what does ADH to cells

A

inserts aquaprotins in the membrane –> increasing permeability to water

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26
Q

how is water reabsorbed in the loop of Henle

A
  • -> countercurrent multiplication
    1) filtrate in proximal tubule has the same osmolarity as (300) as the instistial tissue (iso-osmotic)
    2) in the ascending limb Na+ is pumped out into the instistial tissue- cl- also follows. This makes the medulla a concentrated and salty region
    3) H2O moves passively into the instistial tissue and out of the nephron
    4) this increases the conc of the filtrate in the LofH
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27
Q

what cells are there in the collecting duct

A

principle cells

intercalated cells

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28
Q

what do the principle cells in the collecting duct do

A

react to ADH

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29
Q

what do intercalated cells secrete

A

alpha ones secrete H+

Beta ones secrete HCO3-

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30
Q

what is eGFR

A

estimated glomeruli filtration rate
-estimate fo kidney function
IF YOUR GFR NUMBER IS LOW THEN YOU KIDNEY IS FAILING

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31
Q

what is used to calc GFR

A

serum creatine levels, cystitis c levels, age, gender, race, assays

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32
Q

disease of the bowman capsule

A

glomerulonephritis

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33
Q

what can glomerulonephritis do

A

cause blood and albumin to be found in the blood

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34
Q

what is glomerulonephritis

A

a group of diseases which injure the glomeruli–> when this structure is damaged, larger molecule like albumin and RBC will not be filters and will pass through the podacytes and be ejected from the body via the urine

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35
Q

what hormones are released/ synthesised from the kidneys

A

-erythropoietin (EPO)

Calcitriol (acts like hormone)

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36
Q

Erythropoietin (EPO)

A

a glycoprotein that control ERYTHROPOIESIS (red blood cell production)

  • -> a cytokine (protein signalling molecule) which causes RBC to mature
  • -> secreted from interstitial fibroblasts in the kidney
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37
Q

Calcitriol

A

activates vitamins D–> which helps with the absorption of calcium and phosphorus from food (s.intestine)

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38
Q

hormones in system

A

ADH, aldosterone, ANP

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39
Q

what are the capillaries surrounding nephrons called

A

pertitubular

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40
Q

cortical

A

80%

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41
Q

juxtamedullary

A

20%

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42
Q

Loop of hence gets..

A

more salty the further you go down–> very permeable to water in descending loop and not to salts

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43
Q

mechanisms that take place within the nephron

A

ultrafiltration
reabsorption
secretion
EXCRETION

44
Q

how much blood is filtered via ultrafiltration

A

20%

45
Q

three layers of glomerulus membrane

A

1) capillary endothelial fenestrations
2) gel like basement
3) slit diaphragms within filtration slits –> between foot processes of podocytes

46
Q

GFR

A

the amount of filtrate that form sin both kidneys per min

47
Q

how much cardiac output do kidneys receive

A

25%

48
Q

normal GFR in women

A

105ml/min (1 litre in 9-10 mins)

daily: 150l

49
Q

normal GFR of men

A

125 ml/min (1 litre in 8 mins)

daily:180l

50
Q

GFR THAT IS TOO HIGH COULD MEAN

A

diabetes mellitus, diabetes insipidus

51
Q

GFR THAT IS TOO LOW COULD MEAN

A

waste products are not excreted–> chronic renal failure

52
Q

how is GFR calculated

A

INULIN is used
GFR= conc of insulin in urine x urine flow/conc of inulin in arteriole plasma

creatine can also be used

53
Q

what sort of substance is used to measure GFR

A

1) freely filtered by glomerulus
2) it is not reabsorbed or secreted
3) is non toxic and not metabolised

54
Q

why is creatine not great to measure GFR

A

some secreted and absorbed in tubule

55
Q

kidney failure could lead to

A
  • waste products accumulating in blood
  • pH and electrolyte balance jeopardised
  • blood volume control impaired (oedemas etc)
56
Q

3 ways of GFR control

A

myogenic regulation
tubuloglomerular feedback
neuronal regulation

57
Q

myogenic autoregulation

A

constriction/dilation of afferent arterioles in response to changes in blood pressure

58
Q

if blood pressure drops..

A

GFR also drops- due to vasoconstriction of afferent arteriole , therefore decrease in pressure on glomerulus

59
Q

if blood pressure increases..

A

GFR also increases- due to vasodilation and therefor increase in blood flow and therefor glomerular pressure increases and net filtration increases

60
Q

tubuloglomerulus feedback

A 
macla densa (specialised cells) within the distal tubule monitor filtered NA+ 
-if Na+ flow rate increase, GFR is decreased
61
Q

countercurrent multiplier

A

blood flow runs in pop direction to urine –> increases the conc gradient

62
Q

what is released form the pituitary which affects the renal system

A

ADH

63
Q

if you are over hydrated you need

A

more ADH to cause diuresis

64
Q

if you are dehydrated you need

A

less ADH to cause anti-diuresis

65
Q

osmolarity in PCT

A

300

66
Q

osmolarity in DCT

A

100

67
Q

osmolarity in LoH

A

1200

68
Q

what controls reabsorption of water in the collecting duct

A

ADH

69
Q

Renin- angiotensin aldosterone system

A

BP

extra-cellular volume in the body

70
Q

JGA

A

juxtaglomerular apparatus

71
Q

2 types of cells of the JGA

A

1) juxtaglomerular cells- modified s.muscle cells in afferent arteriole- secretes renin
2) macula densa- distal tubule, monitors filter Na+ within DCT (also regulates GFR)

72
Q

RAAS mechanism

A

1) blood pressure falls (low fluid vol in the nephrons)
2) renin is released and hydrolyses angiotensinogen (pre-enzyme released from the liver)
3) angiotensinogen is converted to angiotensin 1 which enter the blood
4) ACE (angiotensin converting enzyme) from the lungs reacts with angiotensin 1 to form angiotensin 2
5) angiotensin 2 has remodelling affects on the hearts, but also causes the adrenal gland to produce aldosterone (steroid hormone)
6) aldosterone causes the collecting duct to retain more water–> therefore BP increases

73
Q

if calcium drops to half its amount

A

titanic skeletal muscle contractions

74
Q

if K+ conc is reduced by 1/3-

A

paralysis–> nerves unable to generate action potentials

75
Q

sodium in the urinary system is largely loacted

A

extracellulary

76
Q

disorders related to Na+

A

HypoNatramia

HyperNatramia

77
Q

Hyponatramia

A

Na+ conc too low in extracellular space–> causes cells to swell.
-hypovolaemia, evvolaemia and hypervolaemia

78
Q

hypernatramia

A

Na+ conc too high- much rarer. Associated with increase in plasma osmolarity
-stimulator of thirs

79
Q

disorders related to K+

A

HypoKalaemia

HyperKalaemia

80
Q

HypoKalemia

A

caused by diuretics, diarrhoea, vomiting. Majority of deficit is intracellular. Causes muscle weakness.
K+ conc too low

81
Q

HyperKaleamia

A

renal failure, issue damage, acidosis, aldosterone impairment
-hyperventilation, ECG changes
-Depolarisation of excitable cells
K+ conc too high

82
Q

majority of K+ i loacted

A

intracellulary

83
Q

principle cells

A

secretes K+ (exchanges with Na+)

84
Q

intercalated cells

A

reabsorbs K+ –> exchange with H+

85
Q

types of aqua porins

A

1- PCT, LoH- constant presence, continous H2O absorption
2-CD, Luminal mem.-inserted in response to ADH- variable H2O absorption
3-constsnt presence
4CD, basal mem- constant presence

86
Q

pH outside….. is not conducive with life

A

6.8-8.0

87
Q

acidosis

A

<7.35–> depression of the CNS (coma, disorientation, death)

88
Q

alkalosis

A

> 7.35 – over excitability of stimuli (pins and needles)

  • muscle spasms and twitches
  • difficulty breathing
  • convulsions
89
Q

acidosis is the result of..

A

increased secretion of H+ and zero excretion of HCO3-

-urine will be acidic

90
Q

alkalosis is the result of..

A

created H+ secretion and increased HCO3- excretion– basic urine

91
Q

how does ADH adjust body fluid

A
  • increased body fluid levels.
    ADH binds to V2 receptors on the basolateral men. in the collecting auction. The increased insertion of aquaproins 2increases the amount of water reabsorbed.
92
Q

why are V2 receptor antagonist not an effective diuretic

A

patients with high blood pressure, who are hypervolemic (too much volume)do not produce ADH in the CD–> inhibiting the V2 receptor will not make much of a difference to H2O reabsorption in the nephron

93
Q

tubuloglomerular feedback

A

maula dense cells within DCT lie next to the granular cells (lining of the afferent arteriole)–> which secrete vasoactive chemicals –> causing vasodilation/constriction.

If GFR increases, the amount of filtered Na+ will be deleted by macula dense cells within the DCT–> therefore granular cells will produce vasoactive chemicals causing vasoconstriction, therefore BP will decrease, as well as GFR.

94
Q

the reabsorption of H2O,cl- and amino acid absorption in the PCT relies on…

A

reabsorption of Na+

95
Q

hypervolemic

A

too much fluid in the blood

96
Q

ADH

A

produced in poster pituitary (exocrine signalling). causes the secretion of K+ into the CD. Affects V2 receptors–> more aquaporins 2

97
Q

aldosterone

A

DCT and CD–> increases reabsorption of Na+ and H2O (less excretion). Produced in the adrenal cortex/gland. Steroid hormone. Causes H2O retention and therefore causes blood pressure to increase

98
Q

ANP- atria natriuretic peptide

A

produced in the atria of the heart in response to changes in blood pressure (increases) -prevents Na+ reabsorption from DCT and CD- increasing excretion and decreasing blood pressure.

Inhibits the release of aldosterone and renin

99
Q

why does Na/K+ play a large role in Na+ and water reabsoprtion

A

the pump removes 3 Na for every 2K.
This keeps the conc of Na+ in the tubular cell low–> meaning there is a higher conc gradient and more Na+ will be reabsorbed from the tubules and therefore porewater will follow

100
Q

how does aldosterone work

A

enhances the activity of Na/K+ pumps within the DCT and CD

-more Na+ reabsorbed, therefore more K+ secreted (hperkalaemia.

101
Q

three types of diuretic

A

thiazide
loop
osmotic

there ar more types

102
Q

thiazide

A

targets DCT and Na/cl- luminal symporters

103
Q

loop

A

targets LofH and the Na+/K+/Cl- symporters

104
Q

osmotic

A

targets whole nephron. Increases osmotic pressure within filtrate

105
Q

aim of diuresis

A

increase salt load of filtrate by suppressing Na+ reabsorption within the nephron tubule
–> increases water loss in urine

diuresis helps prevent: oedemas, heart failure, hypertension, renal failure (increases GFR and restores normal renal function)

106
Q

secondary role of diuretics

A

the removal of toxic substances e,g, drugs

-will also alte Ruhe pH of the urine

Integrated clinical studies (23 decks)

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