Genitourinary Systems Flashcards

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1
Q

What are the functions of the kidney?

A
Excretion of metabolic products
Excretion of foreign substances
Regulation of body fluids, acid-base regulation and electrolytes
Control of Blood Pressure
Secretes Hormones
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2
Q

What metabolic products does the kidney excrete?

A

Urea, Uric acid Creatinine

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3
Q

What foreign substances does the kidneys excrete?

A

Drugs

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4
Q

What hormones does the kidney secrete?

A

Erythropoietin, Renin

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5
Q

Why does the medulla have a striated appearance?

A

Due to the loops of Henle extending into the medulla

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6
Q

Why does the cortex of the kidney have a granular appearance?

A

Due to other components of the nephron other than the loops of Henle

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7
Q

Describe the blood vessels which blood passes into the kidney and out the kidney by?

A
Renal Artery
Segmental Artery
Interlobar Artery
Arcuate Artery
Interlobular Artery
Afferent Arteriole
Glomerular Capillaries
Efferent Arteriole
Peritubular Capillaries
Interlobular Vein
Arcuate Vein
Interlobar Vein
Renal Vein
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8
Q

After the bowmans capsule, describe the passage of the urine?

A
Filtrate into the Proximal Convoluted tubule
Loop of Henle
- Thin Descending loop of Henle
- Thin Ascending loop of Henle
- Thick Ascending loop of Henle

The Distal Convoluted Tubule
Collecting Duct

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9
Q

What is the purpose of the detrusor muscle?

A

To contract and build pressure in the urinary bladder to support urination

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10
Q

Where is the trigone found?

A

At the base of the bladder, near the ureteric opening

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11
Q

What does the trigone do?

A

Stretching of the triangular region of the trigone signals the brain about the need for urination

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12
Q

What does the bulbourethral gland do?

A

Produces thick lubricant which is added to watery semen to promote sperm survival

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13
Q

What type of muscle is the internal sphincter?

A

Smooth muscle

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14
Q

What type of control is the internal sphincter under?

A

Involuntary control

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15
Q

What type of control is the external sphincter under?

A

voluntary control

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16
Q

What type of muscle is the external sphincter?

A

Striated muscle

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17
Q

Where is the external sphincter muscle found?

A

Surrounding the urethra

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18
Q

What are the two types of cells found in the collecting duct?

A

Principal cells and intercalated cells

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19
Q

How does the mitochondrial density differ between the principal and intercalated cells?

A

Principal = low density of mitochondria

Intercalated = rich in mitochondria

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20
Q

What is the mitochondrial density of the epithelial cells in the proximal convoluted tubule?

A

Rich in mitochondria

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21
Q

What is the mitochondrial density of the epithelial cells in the distal convoluted tubule?

A

rich in mitochondria

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22
Q

What is the mitochondrial density of the epithelial cells in the thin descending Loop of Henle?

A

Low density of mitochondria

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23
Q

What is the mitochondrial density of the epithelial cells in the thin ascending Loop of Henle?

A

Low in mitochondria

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24
Q

What is the mitochondrial density of the epithelial cells in the thick ascending Loop of Henle?

A

rich in mitochondria

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25
Q

What are the two types of nephron?

A

Superficial and juxtamedullary nephrons

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26
Q

What is the difference between the superficial and juxtamedullary nephrons?

A

Superficial - loop of Henle only extends into the outer medulla, not inner

Juxtamedullary - loop of Henle extends further into the inner medulla, and the glomeruli lie closer to the border between the medulla and the cortex

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27
Q

What is the ratio of superficial to juxtaglomerular?

A

10:1

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28
Q

What are the constituents of the juxtaglomerular apparatus?

A

Macula densa
Extraglomerular mesangial cells
Juxtaglomerular cells

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29
Q

Where is the macula densa found?

A

In the distal convoluted tubule

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30
Q

Where are the juxtaglomerular cells found?

A

In the afferent arteriole

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31
Q

Which cells are involved in renin secretion?

A

Juxtaglomerular cells

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32
Q

What is the function of the macula densa?

A

GFR regulation through tubulo-glomerular feedback mechanism.

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33
Q

What are the four renal processes which can occur?

A

Glomerular filtration, reabsorption, secretion, excretion

34
Q

What is meant by glomerular filtration being a passive process?

A

Fluid is ‘driven’ through the semipermeable glomerular capillaries into the Bowman’s capsule space by the hydrostatic pressure of the heart.

35
Q

What is the filtration barrier dependant on?

A

Size and charge of the molecules

36
Q

What is the filtration barrier permeable to?

A

Fluids and small solutes

37
Q

What is the filtration barrier impermeable to?

A

Cell and Proteins

38
Q

What type of capillary endothelium is present in the glomeruli?

A

Fenestrated capillaries

39
Q

What is the diameter of the fenestrae in the glomeruli? And what can pass through?

A

70nm - water, ions, and small proteins

40
Q

Which charged molecules cannot pass through the glomerular filtration barrier?

A

negatively charged proteins

41
Q

What is the effect of inflammation on the filtration barrier?

A

Damages it as it becomes leaky - sometimes blood can pass into the filtrate making urine have blood in it

42
Q

What are the epithelial cells of the bowmans capsule called?

A

Epithelial podocytes

43
Q

What can pass through the slit diaphragm?

A

Thin and porous so water and small solutes can pass

44
Q

What does the hydrostatic pressure of the blood do?

A

Pushes solutes and fluid out the blood into the urine

45
Q

What does the hydrostatic pressure of the IF do?

A

Pushes solute and molecules out IF and into the blood

46
Q

What does the oncotic pressure of the blood do?

A

Fluid molecules are pulled in from the IF into the blood across a semi-permeable membrane

47
Q

What is the formula for the net ultrafltration pressure?

A

Puf = HPblood - HPinterstitial fluid - OPblood

HPblood = Hydrostatic pressure of the blood / glomerular capillaries

HPinterstitial = Hydrostatic pressure of the interstitial fluid of the Bowmans Capsule

OPblood = Oncotic pressure of the blood / glomerular capillaries

48
Q

What is the definition of the Glomerular Filtration Rate?

A

The amount of fluid filtered from the glomeruli into the bowmans capsule per unit of time (ml/min) - it is the sun of filtration rate across all functioning capillaries

49
Q

what is Kf?

A

The ultrafiltration coefficient - calculated from the membrane permeability and the surface area available for filtration

50
Q

What is the formula for GFR?

A

GFR = Puf x Kf

Glomerular Filtration Rate = Net Ultrafiltration Pressure x Ultrafiltration coefficient

51
Q

What is the healthy range for GFR is women?

A

80-125ml/min

52
Q

What is the healthy range for GFR in men?

A

90-140mL/min

53
Q

What is the cardinal feature of renal disease?

A

A fall in GFR, with a buildup of excretory products in the plasma

54
Q

Describe the myogenic mechanism for regulation of GFR?

A
  1. Arterial Pressure Increase = Higher GFR
  2. Increases afferent arteriolar blood pressure
  3. Increased stretch on Arteriole and artery walls
  4. Detected by myogenic stretch receptors
  5. Increased Ca2+ influx
  6. Results in more contraction of the blood vessels
  7. Increased resistance in the blood vessels
  8. Reduced Flow
  9. GFR is brought back to normal
55
Q

Describe how an increase in GFR is counter-acted by the tubuloglomerular feedback mechanism?

A
  1. Increase in GFR
  2. Increased NaCl in Loop of Henle
  3. Change detected by Macula Densa
  4. Increased ATP and Adenosine discharged
  5. Afferent arteriole contracts
  6. Less Blood Flow
  7. GFR Reduced and therefore brought back to normal
56
Q

What is the definition of renal clearance?

A

The number of litres of plasma that is completely cleared of the substance x per unit of time

57
Q

What is renal clearance only concerned with?

A

The excretory role played by the kidney

58
Q

what is the formula for renal clearance of substance x?

A

Renal Clearance x = (Urine concentration of x * Urine Flow Rate ) / Plasma concentration of x

59
Q

What is meant by freely filtered?

A

The concentration in the plasma is the same as the concentration in the urine

60
Q

What is the ideal molecule for the practical determination of GFR?

A

Inulin

61
Q

What is the most commonly used molecule in the practical determination of GFR?

A

Creatinine

62
Q

Why is inulin not used in practise for the determination of GFR?

A

It is a plant polysaccharide and therefore is not found in mammals and hence has to be infused

63
Q

GFR = Renal Clearance for which molecules?

A

Inulin and Creatinine

64
Q

Why does the renal clearance of inulin = the GFR?

A

Inulin is freely filtered and is neither reabsorbed nor secreted - so the amount filtered = the amount excreted

65
Q

What 5 properties of inulin make it the ideal molecule for GFR determination?

A
  1. Freely filtered
  2. Neither secreted or reabsorbed in the nephron
  3. Non-Toxic
  4. Measureable in Plasma
  5. Measureable in Urine
66
Q

Why is creatinine used instead of inulin?

A

Creatinine is a waste product from creatine in muscle metabolism, and the amount of creatinine released remains fairly stable

67
Q

What are stable levels of creatinine indicative of?

A

Stable renal function

68
Q

What might indicate renal failure?

A

Low creatinine clearance or high plasma creatine may indicate renal failure.

69
Q

why is creatinine not the perfect molecule?

A

It is freely filtered and not reabsorbed but a small amount is secreted into the nephron therefore its not a perfect molecule. However, the process for estimating creatinine in blood and urine can account for that to allow for GFR calculations.

70
Q

What is the renal plasma flow?

A

The volume of urine arriving at the kidneys per unit of time

71
Q

For what molecule does the renal clearance = the renal plasma flow?

A

PAH = Paraaminohippurate

72
Q

What is the formula for Filtration Fraction?

A

FF = GFR / RPF

73
Q

Why is PAH used as a reference molecule for renal plasma flow?

A

As it is completely removed from the plasma passing through the kidney via glomerular filtration and secretion into the tubule

74
Q

What are the units for GFR?

A

ml/Minute

75
Q

If the urine concentration of substance x is high, and therefore plasma conc low, how will this impact the renal clearance of the molecule?

A

This results in a high renal clearance as a lot of plasma is being cleared of the molecule per unit of time - reflected in the high urine conc

76
Q

What can you say about a molecule which has a clearance ratio of 1?

A

Must be freely filteres

77
Q

Renal clearance of PAH = ?

A

Renal Plasma Flow

78
Q

RPF x Plasma Conc of PAH =?

A

Urine conc of PAH x Urine flow rate

79
Q

What is the standard range for the Filtration Fraction?

A

15-20%

80
Q

Why is inulin not useful practically?

A
  • it is time-consuming
  • requires several blood samples
  • because of the short duration over which measurements are usually made requires bladder catheterisation
81
Q

Why is inulin not given orally when measuring inulin clearance?

A

Might be digested as it is a plant polysaccharide