Urology & Renal Flashcards

1
Q

What is the urinary system composed of?

A

Kidneys, ureters, bladder, and the urethra

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2
Q

What are the main functions of the kidney?

A

Excretion of metabolic products such as urea, uric acid, creatinine
Excretion of foreign substances
Homeostasis of bodily fluids, electrolytes, and acid-base balance
Regulates blood pressure
Secretes hormones such as erythropoietin and renin

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3
Q

What are the anatomical structures of the kidney?

A

Cortex, medulla, minor calyx, major calyx, ureter, renal artery, and renal vein

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4
Q

Where does the urine once formed, travel through in the kidney?

A

Minor calyx to the Major calyx and then through the ureter

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5
Q

What are the functions of the peritubular capillaries?

A

Provide oxygen and nutrients to the nephron to allow them to perform their functions
Help in reabsorption of different substances along the nephron and then take it away to the circulatory system
Help in secretion of different substances into the tubular fluid

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6
Q

What is the function of the detrusor muscle?

A

Contracts to build pressure in the urinary bladder to support urination

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7
Q

What does stretching of the trigone to its limit lead to?

A

Signals sent to the brain about the need for urination

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8
Q

Is it the internal or external sphincter that gives involuntary control to prevent urination?

A

Internal sphincter - must be relaxed for urination to proceed
External sphincter gives voluntary control to prevent urination

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9
Q

What is the function of the bulbourethral gland?

A

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

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10
Q

What are the 2 different cell type classes in the collecting duct and describe their mitochondria density?

A

Principal cells - Low density of mitochondria

Intercalated cells - High density of mitochondria

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11
Q

What are the anatomical differences between the juxtamedullary and superficial nephrons?

A

The glomerulus of the superficial nephron is in the upper cortex of the kidney, whereas the juxtamedullary nephron has its glomerulus closer to the medullary border
The Loop of Henle in the superficial nephron only extends to the outer medulla, whereas the one in the juxtamedullary nephron extends into the inner medulla

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12
Q

Why does the cortex have a granular appearance, whereas the medulla has a striated appearance?

A

The loop of Henle extending through the medulla gives it its striated appearance

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13
Q

What are the 3 cell types making up the juxtamedullary apparatus?

A

Extraglomerular mesangial cells, macula densa (distal convoluted tubule), and juxtaglomerular cells (afferent arteriole).

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14
Q

What are the main functions of the juxtaglomerular apparatus?

A

GFR regulation through tubular-glomerular feedback mechanism

Renin secretion for regulating blood pressure

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15
Q

What are the 4 main renal processes?

A

Glomerular filtration
Reabsorption
Secretion
Excretion

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16
Q

Is glomerular filtration a passive or active process?

A

Passive

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17
Q

Describe the permeability of the filtration barrier

A

Highly permeable to fluids and small solutes

Impermeable to cells and proteins

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18
Q

What is the name of the spaces between capillary endothelium and how big are they?

A

Fenestrae

70nm in diameter

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19
Q

What substances can pass through fenestrae?

A

Water, ions, and small proteins

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20
Q

What substances can pass through the slit diaphragm of the glomerular basement membrane?

A

Water and small solutes only

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21
Q

What are podocytes?

A

Highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule

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22
Q

What is the name of the ‘pulling’ pressure exerted by the solutes?

A

Oncotic pressure - fluid molecules are drawn in across a semipermeable membrane

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23
Q

What is the name of the force that causes the glomerular filtration from the glomerulus into the Bowman’s capsule?

A

Hydrostatic pressure from glomerular capillaries

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24
Q

How do you calculate the net ultrafiltration pressure?

A

Puf = HPgc - HPbw - πgc
Puf - Net ultrafiltration pressure
HPgc - hydrostatic pressure in glomerular capillaries
HPbw - hydrostatic pressure in bowman’s capsule
πgc - Oncotic pressure of plasma proteins in glomerular capillaries

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25
Q

What is meant by the glomerular filtration rate and how do you calculate it?

A

Amount of fluid filtered from the glomeruli into the Bowman’s capsule per unit time (ml/min)

GFR = Puf x Kf
Kf - ultrafiltration coefficient (membrane and surface area available for filtration)

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26
Q

What is the GFR for a healthy male and female respectively?

A

Male -> 90-140ml/min

Female -> 80-125ml/min

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27
Q

What does a fall in GFR show about the excretory products in the plasma?

A

That there is an increase in the excretory products in the plasma

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28
Q

Describe the myogenic mechanism used to regulate the GFR when arterial pressure is high

A
Arterial pressure increases
Afferent arteriole stretches
Arteriole contracts
Vessel resistance rises
Blood flow reduces
GFR stays the same
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29
Q

Describe the tubuloglomerular feedback mechanism used to regulate the GFR

A

Increase/Decrease in GFR
Increased/Decreased NaCl in Loop of Henle
Change is detected by macula densa
Increased/Decreased ATP and adenosine discharged
Afferent arteriole constricts/dilates
Blood flow decreases/increases
GFR stabilizes

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30
Q

What is meant by renal clearance?

A

Number of liters of plasma that are completely cleared of the substance per unit time
Therefore it is only concerned with the excretory role of the kidneys

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31
Q

How would you calculate renal clearance?

A
C x P = U x V     therefore        C = (U x V)/P ml/min
C = Renal Clearance
U = Concentration of substance in urine
V - Rate of urine production
P = Concentration of substance in plasma
32
Q

If a substance is only filtered in the kidneys and not reabsorbed or secreted, then what value is the GFR the same as?

A

Renal clearance

33
Q

Give an example of a molecule that is only filtered and so it follows this principle?

A

Inulin

34
Q

Since inulin is not found in mammals, what must be done?

A

Transfuse it

35
Q

How can creatinine be used to assess renal function?

A

If renal function is stable, the creatinine amount in urine is stable
Low creatinine clearance or high plasma creatinine may indicate renal failure

36
Q

Why is creatinine not the ideal molecule like inulin and why is it still commonly used despite this?

A

It is secreted in small amounts into the nephron

However, the process for estimating creatinine in the blood and urine can account for that to allow for GFR calculations

37
Q

What is the renal plasma flow?

A

The volume of plasma that reaches the kidney (afferent arteriole) per unit of time.
If the total amount of a molecule entering the kidney equals the amount excreted, then the renal clearance of this molecule is the same as the renal plasma flow

38
Q

What molecule is used to measure the renal plasma flow?

A

Para aminohippurate (PAH) - all of it is removed from the plasma passing through the kidney through filtration and secretion

39
Q

What is meant by the filtration fraction and how is this calculated?

A

The ratio of the amount of filtered plasma that arrives via the afferent arteriole.
FF = GFR/RPF
e.g - a value of 0.15 implies that 15% of the plasma has been filtered

40
Q

What is the difference between primary and secondary active transport?

A

Primary - Uses ATP directly to transport molecules in and out of the cell
Secondary - Movement of one solute along its electrochemical gradient provides energy for the other solute to move against its own electrochemical gradient

41
Q

Is endocytosis a primary or secondary active transport mechanism?

A

Primary - small proteins are reabsorbed in the PCT using an ATP molecule

42
Q

Explain how the Na+-Glucose symporter works

A

Na+ moves down its electrochemical gradient into the cell
This provides the energy to transport glucose against its electrochemical gradient into the cell
Na+ and glucose move in the same direction

43
Q

Explain how the Na+/H+ antiporter works

A

Na+ moves down its electrochemical gradient into the cell
This provides energy to actively transport H+ against its electrochemical gradient out of the cell
Na+ and H+ move in opposite directions

44
Q

In the epithelial cell layer of the renal tubules, how does water follow the transcellular pathway (substances move through the cells from the basolateral side to the apical side and vice-versa)?

A

It is transported from tubular fluid → Epithelial cells → blood via aquaporins in the epithelial cells

45
Q

How does transcellular Na+ reabsorption occur in the renal tubules?

A

3Na+ is transported from epithelial cells into the blood via Na+/K+ ATPase
This creates a concentration gradient for Na+ as it is lower in the epithelial cell so Na+ from the tubular fluid diffuses into the cell
2 K+ is transported from the blood into epithelial cells via Na+/K+ ATPase so this is an active transport as ATP is used

46
Q

What is meant by the paracellular pathway in the renal tubules?

A

Substances such as water, Ca2+, K+, Cl- and urea are transported through the tight junctions between the epithelial cells

47
Q

How does Na+ and Bicarbonate reabsorption occur in the early proximal convoluted tubule?

A

Na+/K+ ATPase creates a low Na+ concentration in the epithelial cell
CO2 enters the epithelial cell by diffusion and binds to H20, catalyzed by carbonic anhydrase to form bicarbonate and H+
Na+/H+ antiporter then transports Na+ down its concentration gradient into the cell from tubular fluid and H+ out into the tubular fluid against its concentration gradient using the energy from the transportation of Na+
Na+/HCO3- symporter transports Na+ down its concentration gradient into the blood and bicarbonate is transported into the blood against its concentration gradient using energy from the transportation of Na+

48
Q

How does Angiotensin II regulate the Na+ reabsorbed?

A

By increasing the number of Na+/H+ antiporters

49
Q

How does glucose reabsorption occur in the early proximal convoluted tubule?

A
Na+/K+ ATPase creates a concentration gradient with less Na+ in the epithelial cell
Na+/Glucose symporter (SGLT2) transports Na+ from the tubular fluid into epithelial cells and this provides energy to transport glucose against its concentration gradient from the tubular fluid into the epithelial cell
Glucose transporter (GLUT2) transports glucose into the blood from the epithelial cell via facilitated diffusion
50
Q

Explain the general processes of reabsorption involving the Loop of Henle

A

Na+ and Cl- passively leave the thin ascending limb into the medulla and leaves actively from the thick ascending limb actively
This creates a low water potential in the medulla and so water leaves through the descending limb passively

51
Q

Describe and explain the osmolarity of the tubular fluid in the different parts of the loop of Henle

A

At the point where the descending limb enters the ascending limb, the tubular fluid is hyperosmolar as water has been passively reabsorbed from the descending limb but since it is impermeable to Na+ and Cl-.
At the tip of the thick ascending limb, the tubular fluid is hypoosmolar as the salt has been reabsorbed far more

52
Q

How does Na+ and Cl- reabsorption in the thick ascending limb of the Loop of Henle occur?

A

Na+/K+ ATPase creates a concentration gradient with a low concentration in the epithelial cell
Na+/K+/2Cl- symporter transports these ions from the tubular fluid into the epithelial cell
K+ is recycled back out into the tubular fluid
K+/Cl- symporter allows reabsorption of these ions from the epithelial cell into the blood

53
Q

How does Na+ and Cl- reabsorption occur in the early distal convoluted tubule?

A

Na+/K+ ATPase creates a concentration gradient with a low concentration in the epithelial cell
Na+/Cl- symporter transports Na+ and Cl- into the epithelial cell from the tubular fluid into the epithelial cell
K+/Cl- symporter then transports the K+ and Cl- from the epithelial cell into the blood

54
Q

Is the early distal convoluted tubule permeable to water?

A

No

55
Q

How does active Ca2+ reabsorption occur in the early distal convoluted tubule?

A

Na+/K+ ATPase creates a concentration gradient with low concentration in the epithelial cell
Na+/Ca2+ antiporter transports Na+ into epithelial cell from the blood and Ca2+ is transported from the epithelial cell into the blood against its concentration gradient
Ca2+ ATPase pump transports Ca2+ against its concentration gradient as well into the blood from the epithelial cell

56
Q

How do the principal cells work to correct hyperkalemia?

A

By transporting the K+ out of the epithelial cells and into the tubular fluid

57
Q

Is the later part of the distal convoluted tubule permeable to water?

A

Yes, it has aquaporins

58
Q

How does aldosterone increase Na+ reabsorption?

A

By increasing the apical Na+ channels and basolateral Na+/K+ ATPase pumps

59
Q

How does ADH increase water reabsorption?

A

Increases the apical aquaporins

Basolateral aquaporins are almost always present

60
Q

How do Na+ reabsorption and K+ secretion occur in the principal cells of the distal convoluted tubule and collecting duct?

A

Na+/K+ ATPase creates a concentration gradient with low concentration in the epithelial cell so that Na+ is reabsorbed
K+ is transported into the epithelial cell from the blood and so it is secreted actively

61
Q

How do the alpha and beta intercalated cells of the distal convoluted tubule and collecting duct maintain an acid-base balance?

A

The alpha intercalated cells facilitate HCO3- reabsorption and H+ secretion, whereas the beta intercalated cells facilitate HCO3- secretion and H+ reabsorption
Alpha intercalated cells have Cl-/HCO3- antiporters on the basolateral side, whereas beta intercalated cell have them on the apical side
Then the H+ ATPase pump is on the apical side on the alpha intercalated cells and on the basolateral side on the beta intercalated cells
These two cell types work together to act as a buffer to changes in pH

62
Q

What are the consequences of kidney failure?

A

Filtration failure
Unwell with an accumulation of waste substance
Haematuria and proteinuria, low serum protein,
including albumin in the blood
Hypertension, water retention
Metabolic acidosis
Anemia - lack of erythropoietin production
Vitamin D deficiency and secondary hyperparathyroidism

63
Q

What is inflammation of the bladder called?

A

Cystitis

64
Q

What are some of the non-infective causes of inflammatory urinary disorders?

A
Metabolic
     Diabetic nephropathy
Immunological
     Nephritic syndrome
     Nephrotic syndrome
65
Q

What are the different types of urological disorders?

A
Inflammatory
     Infective
     Non-infective
Obstructive
Neoplastic
Developmental/genetic
66
Q

What are some of the causes of obstructive urinary disorders?

A

Stones

Benign prostatic hypertrophy

67
Q

What are some examples of neoplastic urinary disorders?

A

Kidney, bladder, prostatic or testicular cancer

68
Q

What are some developmental or genetic urinary disorders?

A

Polycystic kidneys, horseshoe kidney

69
Q

What are some of the potential mechanisms that immune system damage to the kidney might occur?

A

Through antibodies or inflammatory cells (neutrophils, monocytes, macrophages, or T cells)

70
Q

What is glomerulonephritis?

A

The inflammation of the microscopic filtering units of the kidney

71
Q

What are some of the clinical presentations of immunological disorders?

A

Nephritic syndrome
Proteinuria
Nephrotic syndrome
Damage to other organs may also be present

72
Q

How might you go about diagnosing immunological causes of the inflammatory urological disorder?

A

History and physical examination
Urine Test (urine dipstick, microscopy, and protein:creatinine ratio)
Blood Test (kidney function and immunology tests)
Imaging (start with an ultrasound)
Kidney biopsy

73
Q

What is a horseshoe kidney?

A

When 2 kidneys fuse together at the bottom

74
Q

When does horseshoe kidney occur?

A

When a baby is growing in the womb as the baby’s kidneys move into place

75
Q

How may we know if a patient has horseshoe kidney?

A

Imaging of the abdomen or pelvis

76
Q

What are the consequences of horseshoe kidneys?

A

Increased risk of obstruction, stones, and infection