Module 4: Urinary System Flashcards

1
Q

Role of kidneys?

A

Filter blood and produce urine

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2
Q

Role of ureters?

A

Receive urine from kidneys and carry urine down to bladder via gravity and peristalsis

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3
Q

Role of bladder?

A

Receives and stores urine; micturition

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4
Q

Role of urethra?

A

Carries urine from bladder to external environment

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5
Q

Functions of urinary system?

A
  • Filters blood plasma
  • Prevents nutrient loss, regulates blood volume, pressure, pH, glucose levels
  • Releases hormones
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6
Q

Location of kidneys?

A

Retroperitoneal paired organs sitting either side of vertebral column; left kidney slightly superior to right because of liver positioning

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7
Q

What is the periotoneum?

A

Abdominal sac around intestines

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8
Q

What structures protect the kidneys?

A

11th and 12th ribs, visceral organs, fat, and connective tissue layers

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9
Q

What is the hilum?

A

Entry/exit point for renal artery, renal nerves, renal vein, and ureter

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10
Q

Function of renal artery?

A

Supplies kidney with approximately 20% of resting cardiac output, from the abdominal aorta, to be filtered

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11
Q

Function of renal vein?

A

Takes blood out of kidney to inferior vena cavae

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12
Q

What is the fibrous capsule?

A

Innermost CT layer of kidney; surrounds entire kidney, comprised of collagen fibres

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13
Q

What is the perinephric/perirenal fat?

A

Middle CT layer of kidney; thick, cushioning layer of adipose tissue

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14
Q

What is the renal fascia?

A

Outermost CT layer of kidney; dense, fibrous layer anchoring kidney to surrounding structures

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15
Q

Where is the renal cortex?

A

Outermost ~1cm of kidney

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16
Q

Role of renal cortex?

A

Where filtration and reabsorption - namely, waste products/water removed form blood, glucose/proteins/AAs reabsorbed from filtrate into blood - occurs

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17
Q

Where is the renal medulla?

A

~2-3cm region below renal cortex

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18
Q

Role of renal medulla?

A

Regulates concentration of urine

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19
Q

Where is the renal sinus? What comprises it?

A

Central cavity of kidney; renal pelvis, renal calyces, blood vessels, fat

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20
Q

Where are the renal pyramids?

A

Conical structures extending from cortex to sinus

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21
Q

How many renal pyramids per kidney?

A

8-18 per kidney

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22
Q

Role of renal pyramids?

A

Transport urine from the renal cortex to the renal sinus

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23
Q

What is a renal papilla?

A

Apex of a renal pyramid (facing sinus) which projects into the lumen of a kidney calyx and through which collecting ducts discharge urine

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24
Q

What are renal columns?

A

Bands of tissue separating adjacent renal pyramids

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25
Q

What comprises kidney lobes?

A

Renal pyramid + overlying renal cortex + adjacent tissues of renal columns

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26
Q

Role of kidney lobes?

A

Functional units where urine is produced

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27
Q

Role of minor calyces?

A

Collect urine produced by a single kidney lobe

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28
Q

What are major calyces?

A

Fusion of 4-5 minor calyces

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29
Q

Role of major calyces?

A

Collect urine from minor calyces

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30
Q

What is the renal pelvis?

A

Large funnel-shaped chamber which is continuous with ureter

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31
Q

How frequently do ureters drain urine from the kidney and transport it to the bladder?

A

Every ~30 seconds

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32
Q

What are the ureters?

A

Pair of retroperitoneal muscular tubes extending from kidneys to urinary bladder, firmly attached to posterior abdominal wall, ~25-30cm long

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33
Q

Describe the mucosa of the ureters.

A

Transitional epithelium (stratified cuboidal/squamous), allowing for expansion of ureter diameter

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34
Q

Describe the muscularis externa of ureters.

A

Layer of smooth muscle outside mucosa that facilitates peristalsis

  • Upper two-thirds: 2 layers (inner longitudinal, outer circular)
  • Lower one-third: 3 layers (inner longitudinal, middle circular, outer longitudinal)
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35
Q

Describe the mucosa of the bladder.

A

Transitional epithelium (stratified cuboidal/squamous), with rugae

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36
Q

Describe the muscularis externa of the bladder.

A

Layer of smooth muscle outside mucosa that facilitates expulsion of urine; 3 layers (inner longitudinal, middle circular, middle longitudinal), with sphincters

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37
Q

What are sphincters of the bladder?

A

Bands of skeletal muscle that act as valves, controlling urine flow

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38
Q

Different between internal urethral sphincter and external urethral sphincter?

A
  • Internal urethral sphincter = involuntary
  • External urethral sphincter = voluntary
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39
Q

Role and length of urethra in males?

A

~20-25cm in males, transporting urine and semen

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40
Q

Role and length of urethra in females?

A

~4cm in females, transporting urine

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41
Q

Describe the mucosa of the urethra.

A
  • Proximal (near bladder): transitional epithelium
  • Middle: stratified and pseudostratified columnar
  • Distal: stratified squamous
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42
Q

Describe the muscularis externa of the urethra.

A
  • Proximal: 2 layers of smooth muscle (inner longitudinal, outer circular)
  • Distal: some skeletal muscle, associated with external urethral sphincter
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43
Q

What is micturition?

A

Urination; expulsion of urine

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44
Q

When does the urge to urinate occur?

A

When urine in bladder is at ~200mL

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45
Q

What triggers the micturition reflex?

A

Stretch receptors in bladder wall

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46
Q

What occurs if the micturition reflex is ignored?

A

Urine continues to accumulate, and at 500mL, detrusor muscle contractions force internal urethral sphincter open

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47
Q

In what populations does micturition occur involuntarily? Why?

A

If neurological pathway for control of external urethral sphincter is not established (infants), or not powerful enough to prevent (elderly), micturition occurs involuntarily

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48
Q

How nephrons per kidney?

A

~1 million per kidney

49
Q

2 types of nephrons?

A
  • Cortical nephrons (~85%)
  • Juxtamedullary nephrons (~15%)
50
Q

What are cortical nephrons?

A

Short nephron loops, located almost entirely renal cortex, and important for excreting waste products into urine

51
Q

What are juxtamedullary nephrons?

A

Have long nephron loops extending deep into renal medulla, and important for producing concentrated urine

52
Q

3 main components of nephron?

A
  • Renal corpuscle
  • Renal tubule
  • Collecting system
53
Q

What comprises the renal corpuscle structure?

A

Spherical filtration structure consisting of glomerulus and glomerular/Bowman’s capsule

54
Q

Glomerulus structure?

A

Capillary network, with afferent arterioles (going in) and efferent arterioles (going out)

55
Q

What increases glomerular pressure?

A

Smaller diameter of efferent arterioles

56
Q

Role of renal corpuscle?

A

Site of blood filtration via filtration membrane, driven by blood pressure; water and dissolve solutes are pushed out of glomerular capillaries -> capsule space -> renal tube

57
Q

What is Bowman’s capsule?

A

C-shaped structure partially surrounding the glomerulus

58
Q

What is filtration membrane?

A

Porous membrane between the blood and the capsular space

59
Q

Role of filtration membrane?

A

Controls what blood components enter nephron and what remains within vessels and re-enters circulation

60
Q

Layers of the filtration membrane?

A
  • Fenestrated endothelium (stops cells and platelets)
  • Basement membrane (stops large/charged proteins)
  • Slits between pedicels (stops medium-sized proteins)
61
Q

What are pedicels?

A

Foot-like processes extending from each podocyte that wrap around glomerular capillaries

62
Q

What is a podocyte?

A

Epithelial cells surrounding the glomerulus

63
Q

What passes through the filtration of the corpuscle?

A

Water, small proteins, amino acids, glucose, salts

64
Q

Role of renal tubule?

A

Site of filtrate modification, where filtrate components are altered via secretion and absorption

65
Q

3 components of renal tubule?

A
  • Proximal convoluted tubule (PCT)
  • Loop of Henle/nephron loop
  • Distal convoluted tubule (DCT)
66
Q

Function/structure of PCT?

A
  • Beginning of renal tubule
  • Cells have microvilli to aid reabsorption of essential substances from filtrate back into blood
67
Q

Function/structure of Loop of Henle?

A
  • Middle segment of renal tubule
  • Ascending and descending components
  • Descending: reabsorption of water
  • Ascending: impermeable to water reabsorption of Na+ and Cl- from filtrate
68
Q

Function/structure of DCT?

A
  • Last segment of renal tubule
  • Adjusts filtrate composition via reabsorption and secretion (more so secretion)
  • Reabsorption of water, Na+, Ca++ in exchange for secretion of H+, etc.
69
Q

What are the ducts associated with the collecting system?

A
  • Collecting duct
  • Papillary duct
70
Q

Role of collecting system?

A

Tubular fluid (urine) from each nephron empties into collecting system -> minor calyces

71
Q

Role of collecting duct?

A
  • Receives fluid from the DCTs of several nephrons as it passes back into the medulla via the osmotic gradient
  • May/may not reabsorb water, depending on hydration status
72
Q

Role of papillary duct?

A

Collects filtrate from multiple collecting ducts and delivers it to a minor calyx

73
Q

Through what blood vessel does oxygenated blood enter the kidney?

A

Renal artery

74
Q

Into what blood vessels does the renal artery divide into?

A

Divides into segmental arteries in the renal sinus

75
Q

Into what blood vessels do segmental arteries divide into?

A

Interlobar arteries, which run within renal columns

76
Q

Pathway of blood through the kidneys to the glomerulus to out again?

A

Renal artery -> segmental arteries -> interlobar arteries -> further branched arteries -> afferent arterioles -> glomerulus -> efferent arterioles -> peritubular capillaries -> cortical veins -> inferior vena cavae

77
Q

What are peritubular capillaries? Role?

A

Tiny blood vessels that surround the entire renal tubule, allowing reabsorption and secretion between blood and the inner lumen of the nephron

78
Q

3 functions of that regulate composition and volume of blood?

A

Filtration
Reabsorption
Secretion

79
Q

Where does filtration of blood occur?

A

In the renal corpuscle

80
Q

What is reabsorption?

A

Transport of water and solutes:
Tubular fluid -> peritubular fluid -> bloodstream

81
Q

What is secretion?

A

Transport of solutes:
Peritubular fluid -> tubular fluid

82
Q

What is the Glomerular Filtration Rate?

A

Volume of filtrate formed per minute by both kidneys

83
Q

What are diuretics?

A

Chemicals that slow/inhibit water reabsorption in the collecting duct, and so enhance urinary output

e.g. substances that encourage diuresis by inhibiting release of ADH (alcohol), substances that inhibit Na+ reabsorption (caffeine)

84
Q

3 most important metabolic waste products?

A

Urea, creathrine, uric acid

85
Q

What factors enhance filtration?

A

Thinner filtration membrane, large SA of glomerular capillaries, higher glomerular BP

86
Q

What is urea?

A

A chemical that comes from the breakdown of proteins in the liver

87
Q

What is creatinine?

A

Product of muscle breakdown, measurement of kidney function

88
Q

What is uric acid?

A

Product of nucleic acid catabolism

89
Q

What is body fluid?

A

Liquid portion of cells and tissues; 55-60% of body mass

90
Q

What is intracellular fluid?

A

Fluid inside the cell (ICF)

91
Q

What is extracellular fluid?

A

Fluid outside the cell (ECF)

92
Q

Where does exchange between ICF and ECF occur?

A

Cell membrane

93
Q

Where does exchange between ECF and blood plasma occur?

A

Capillary wall

94
Q

What is metabolic water?

A

Water formed by cells as a metabolic, unregulated by-product (about 200mL of water gain)

95
Q

Where is thirst regulated?

A

Hypothalamus

96
Q

What 4 organs are responsible for water loss?

A

Kidneys
Skin
Lungs
GIT

97
Q

What are electrolytes?

A

Charged ions in a solution

98
Q

Functions of electrolytes?

A

Controls osmosis
Maintains acid-base balance
Carries electrical currents

99
Q

What electrolytes do we mainly gain from eating a salty meal?

A

Increase of Na+ and Cl- ions in the blood

100
Q

Response to eating a salty meal?

A

Water moves from ICF -> ECF -> blood plasma, increasing blood volume and urine output

101
Q

What are acids?

A

Substances that release H+ ions, thus lowering pH

102
Q

What are bases?

A

Substances that accept H+ ions, thus raising pH

103
Q

What is acidosis?

A

Blood pH below 7.35; suppresses CNS -> coma

104
Q

What is alkalosis?

A

Blood pH above 7.45; excites CNS -> seizures, spasms, convulsions

105
Q

What is a lower UTI?

A

Infection in bladder, urethra; relatively uncomplicated

106
Q

What is an upper UTI?

A

Infection in ureters, kidney; serious

107
Q

What is the rate of UTIs in men vs women? Why?

A

1 in 20 men, 1 in 2 women; more frequent in women due to shorter urethra

108
Q

What are kidney stones?

A

Crystallisation of minerals and salts in urine, forming hardened lumps of matter, affecting any part of urinary tract (kidney -> bladder)

109
Q

Causes of kidney stones?

A

Dehydration, excess Ca2+

110
Q

What is renal failure?

A

Kidney failure; kidneys unable to filter wastes from blood and homeostasis thus cannot be maintained any longer

111
Q

What is acute renal failure?

A

Sudden, relatively reversible

112
Q

What is chronic renal failure?

A

Gradual, generally irreversible

113
Q

What is caused by renal failure?

A

BP increases
Anaemia develops (decreased EPO production)
CNS problems (sleepy, coma)

114
Q

What is erythropoietin?

A

Hormone secreted by kidneys that stimulates erythropoiesis

115
Q

What is dialysis?

A

Time-consuming procedure that removes waste products and excess fluid - that is, perform purification of blood - upon kidney dysfunction; glomerular membrane replaced with artificial membrane

116
Q

Role of aldosterone?

A

Increases retention of sodium and water, and the excretion of potassium, by the kidneys

117
Q

Role of ANP?

A

Increases glomerular filtration rate (GFR) within the kidney by dilating the afferent arterioles and constricting the efferent arterioles

118
Q

Role of ADH?

A

Causes the kidneys to release less water, decreasing the amount of urine produced (urine output)