Histology and Overview of Urinary System Flashcards

1
Q

Label layer of kidney

A

Medulla

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2
Q

Label layer of kidney

A

Cortex

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3
Q

Label layer of kidney

A
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4
Q

Label

A

Renal corpuscle

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5
Q

Organs of the urinary system

A
  • Kidneys
  • Ureters
  • Urinary Bladder
  • Urethra
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6
Q

The kidney is organized into ___,___ and _____.

A

Cortex

Medulla

Renal pelvis

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7
Q

Functions of the kidneys

A
  • Acts as a blood filter
  • Maintains electrolyte, acid-base, and fluid balance of blood
  • Removes nitrogenous wastes
  • Homeostatic organ
  • Releases hormones
    • Calcitriol (Vitamin D)
    • Erythropoietin
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8
Q

Which hormones are released by the kidney?

A
  • Calcitriol (Vitamin D)
  • Erythropoietin
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9
Q

Label the internal anatomy of the kidneys

A
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10
Q

____________ are cup-shaped structures that funnel urine towards the renal pelvis.

A

Calyces

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11
Q

Which part of the kidney functions as a acinus?

A

Renal corpuscle

NOTE: Each corpuscle “secretes” a filtrate of blood plasma which drains into a renal tubule

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12
Q

Which part of the kidney functions as striated ducts?

A

Renal tubules

NOTE: Renal tubules modify the filtrate by reabsorbing everything that is not waste

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13
Q

What are the components of the nephron?

A
  • Renal corpuscle
  • Proximal convulted tubule
  • Loop of Henle
  • Distal convoluted tubule
  • Collecting duct
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14
Q

The renal corpuscles are the sites where the process of __________formation begins with a filtrate of blood plasma.

A

urine

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15
Q

Each renal corpuscle consists of an epithelial cup called __________ enclosing a knot of capillaries and other elements called the __________.

A

Bownman’s capsule; glomerulus

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16
Q

A proximal convoluted tubule drains filtrate _______ (toward/away) from a renal corpuscle.

A

Away

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17
Q

Where does the distal convoluted tubule pass near the original corpuscle?

A

At the juxtaglomerular apparatus

*It then leads to a collecting duct

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18
Q

A collecting duct receives fluid from several distal tubules, then passes through the medulla and drains into the _________.

A

Pelvis

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19
Q

Label

A
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20
Q

________ of blood is filtered by the kidneys.

A

125 ml/min

NOTE: Less than 1% of this filtrate reaches the bladder

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21
Q

Each kidney contains approximately ____________ renal corpuscles and an equal number of nephrons.

A

1,500,000

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22
Q

The kidney filters approximately _____ of cardiac output.

A

20%

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23
Q

Blood flow in the kidneys

A
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24
Q

Capillaries of the kidneys

A

Glomerulus

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25
Q

Which cells are found in the Bowman’s capsule?

A

Podocytes

NOTE: Podocytes are epithelial cells which support the filtration membrane without obstructing the flow of filtrate.

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26
Q

Which cells are found within the glomerulus?

A
  • Mesangial cells
  • Podocytes
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27
Q

What are the components of the renal corpuscle?

A
  • Glomerulus
    • Cluster of blood vessels
  • Bowman’s capsule
    • Double walled envelope
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28
Q

__________ are epithelial cells covering the glomerular capillaries.

A

Podocytes

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29
Q

Immediately adjacent to each glomerular capillary, in between the podcytes and the capillary endothelium, is the ___________.

A

Filtration membrane

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30
Q

Label

A
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31
Q

Label

A
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32
Q

What type of tissue is the capsule made up of?

A

Dense conenctive tissue

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33
Q

Where does the glomerular plasma collect as it leaves the capillaries throught the filtration membrane?

A

In the Bownman’s space

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34
Q

The parietal epithelium of the renal corpuscle is ___________. The visceral epithelium is comprised of ________.

A

Bownman’s capsule; podocytes

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35
Q

In Bownman’s capsule, epithelium is ___________, becoming cuboidal at the _________.

A

Simple squamous; proximal tubule

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36
Q

Each corpuscle is roughly spherical and has two “poles” at opposite ends. What are the two poles and what structures are associated with each?

A
  • Urinary pole
    • Proximal tubule
  • Vascular pole
    • Juxtaglomerular complex
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37
Q

The _________ pole receives the afferent and efferent arterioles, whcih serve the glomerular capillaries.

A

Vascular

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38
Q

Where are mesangial cells located?

A

At the vascular pole of the corpuscle

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39
Q

Label

A
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40
Q

What types of capilleries are found in the glomerulus?

A

Fenestrated

NOTE: Fenestrations are too small to allow blood cells through, but plasma can pass freely out of the holes and into the filtration membrane.

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41
Q

Which type of material can pass through glomerular capillaries?

A
  • Water
  • Mineral ions
  • Small molecules
42
Q

The filtration membrane is a fusion of the ___________ and __________.

A

Endothelial basement membrane; basement membrane of the podocytes

43
Q

The outside of the filtration membrane is supported by _________.

A

Podocytes

44
Q

The filtrate which accumulates in Bowman’s space drains into the __________.

A

Proximal tubule

*The filtrate from here then forms urine.

45
Q

Between adjacent pedicels are gaps called ________ which permit free passage of fluid filtrate into Bowman’s space.

A

Filtration slits.

NOTE: Pedicels are the “foot processes” of podocytes that rest on the filtration membrane.

46
Q

Label

A
47
Q

Label

A
48
Q

Label

A
49
Q

Glomerular mesangial cells are concentrated toward the _________ pole of the glomerulus.

A

Vascular

50
Q

Function of glomerular mesangial cells

A
  • Produce the mesangial matrix and may contribute to maintenance of the filtration membrane
  • Take up glomerular basal lamina material for turnover and phagocytose immunoglobulins trapped in the basal lamina
51
Q

Describe the nuclei of mesangial cells.

A
  • Small
  • Irregularly shaped
  • Heterochromatic nuclei
52
Q

Extra-glomerular mesangial cells occupy the space between the ___________ and _________.

A

Glomerulus; Macula densa of the distal tubule

NOTE: Extra-glomerular mesangial cells are also called lacis cells

53
Q

What are the components of the mesangial matrix?

A
  • Fibronectin
  • Type IV collagen
  • Perlecan
  • Laminin
54
Q

Function of endothelin

A

Causes vasoconstriction of the afferent and efferent glomerular arterioles.

NOTE: Endothelin levels are increased in glomerular diseases

55
Q

What molecules are released by mesangial cells?

A
  • Endothelin
  • Cytokines
  • Angiotensin II
56
Q

Function of angiotensin II

A

Binding to the receptor stimulates mesangial cell contraction

NOTE: Cytoskeletal contractile proteins also contract mesangial cells, which leads to a modification of blood flow through glomerular capillaries

57
Q

In _____________, kidneys may enlarge to 3-4 times normal weight and volume.

A

polycystic kidney disease

58
Q

Function of proximal tubule

A
  • Reabsorbs most minerals and other nutrients from the tubular fluid and passes them to blood in the peritubular capillaries
59
Q

Function of the loop of Henle

A
  • Helps establish the hypertonic environment of medullary interstitial fluid
60
Q

Function of the distal concoluted tubule

A
  • Returns to the juxtaglomerular apparatus of the corpuscle from whcih the tubule arose
  • Reabsorbs most of substances contained in ultrafiltrate especially glucose and amino acids
61
Q

Label as proximal or distal

A

NOTE: Cells comprising the proximal tubules stain more intensely eosinophilic than those comprising distal tubules, and have nuclei spaced somewhat further apart. The lumen of distal tubules commpnly appear more open and clear than those of proximal tubules.

62
Q

The proximal convoluted tubule is lined by ________ epithelium resting on a thin basal lamina.

A

Simple cuboidal

NOTE: Tubule cells have microvilli on their luminal surfaces

63
Q

What cause the proximal convulted tubules to appear striated?

A

Numerous basal infoldings and many mitochondria

64
Q

What are the structural components of a proximal tubule cell? What are the functions of each?

A
  • Simple cuboidal epithelium
  • Long apical microvilli can occlude the lumen
    • Absorb water, sodium, glucose, and amino acids
  • Apical tubulovesicles
    • Capture peptides for degradation in lysosomes
  • Basally located mitochondria
    • Provide energy for transport of sodium and other molecules
65
Q

TEM of proximal tubule cells

A
66
Q

Tubulovesicles capture peptides for degradation in lysosomes. What are these peptides bound to ?

A

A protein called megalin

67
Q

Label

A
68
Q

The descending and ascending thick limbs, of the loop of henle, are lined by __________; the thin segment is lined by _______.

A

Cuboidal cells; squamous cells

69
Q

The loop of henle helps to establish a hypertonic saline environment in the medulla. What is the purpose of this?

A

Allows recovery of water from collecting ducts, this helps to control to osmolarity of urine.

70
Q

_________ is actively transported out of the ascending loop and establishes a concentration gradient in the interstitium.

A

Na+

71
Q

Label

A
72
Q

Reabsorption in the distal convoluted tubule is regulated by which two hormones?

A
  • ADH
  • Aldosterone
73
Q

Distal convoluted tubules are lined by __________.

A

Simple cuboidal epithelium

74
Q

Differentiate proximal and distal convoluted tubule structurally.

A

Proximal tubules

  • Lined by simple cuboidal epithelium
  • Microvilli
  • Striated with basal infoldings, with lots of mitochondria

Distal convoluted tubules

  • Lined by simple cuboidal epithelium
  • Lack microvilli
  • Striated with basal infoldings, with less mitochondria
75
Q

Label

A
76
Q

Function of macula densa

A

Sensor of sodium and/or chloride concentration

77
Q

The juxtaglomerular apparatus is a complex of structures associated with the ____________ pole of each renal corpuscle.

A

vascular

78
Q

What are the two components of juxtaglomerular apparatus?

A
  • Macula densa
  • Juxtaglomerular cells (“J-G cells”)
79
Q

The macula densa is a patch of densely-packed epithelial cell nuclei along the ______________.

A

distal convoluted tubule

80
Q

Which hormone is excreted by juxtaglomerular cells?

A

Renin

81
Q

_______________in the wall of the afferent arteriole are specialized smooth muscle cells containing secretory granules, the source of the hormone renin

A

Juxtaglomerular cells (“J-G cells”)

82
Q

JG Cells are Activated by __________ Cells to Secrete RENIN.

A

Macula

83
Q

Collecting ducts progressively increase in diameter towards the _________.

A

Medulla

84
Q

In deep medulla, collecting ducts unite with other collecting ducts to form large papillary ducts, which open into _________.

A

renal pelvis

85
Q

Collecting ducts are lined by epithelium that have two types of cell type. What are those cells cells and what are their characteristics?

A
  • Collecting duct (principal) cells
    • Cuboidal-In cortical part
    • Columnar- in medullary part
  • Intercalated/ dark cells
    • Resemble those of dense connective tissue but bulge into the lumen of the collecting duct.

NOTE: Both cell types rest on a thin basal membrane and lack basal infoldings

86
Q

Permeability of collecting duct to water and ions is regulated by ________.

A

ADH

87
Q

Label

A
88
Q

Label

A
89
Q

What affect does ADH have on aquaporin-2?

A
  • Alters the distribution and function of aquaporin-2 in cells of collecting ducts
  • Causes aquaporin-2+ vesicles to fuse with the plasma membrane
90
Q

Erythropoietin is produced by __________.

A

Peritubular fibroblasts

NOTE: Erythropoietin production is induced by hypoxia

91
Q

Function of erythropoietin

A

Stimulates the production of red blood cells in bone marrow

NOTE: Erythropoietin can be administered to dialysis patients to improve RBC counts

92
Q

Function of the ureter

A

Conducts urine from kidney to bladder

93
Q

What are the 3 tissue layers of the ureter?

A
  • Mucosa
    • Lined by 5-6 cell layer of transitional epithelium that rests on lamina propria of loose connective tissue having blood vessels, lymphatics, and with tubular mucus glands in the equidae
  • Muscularis
    • Has inner and outer longitudinal and middle layer of smooth muscles
  • Serosa/ adventitia
94
Q

Label

A

Ureter

95
Q

To flatten out, surface cells must acquire more plasma membrane to cover the same amount of cytoplasm with an expanded surface area of membrane. Where does this additional plasma membrane come from?

A

Stretch induces migration of vesicles to the cells surface. These vesicles have extra plasma membrane units.

96
Q

What are the four tissue layers of the urinary bladder?

A
  • Mucosa
    • Lined by up to 14 cell layers of transitional epithelium that rests on lamina propria of loose connective tissue
  • Submucosa
    • Highly vascular and rich in elastic fibers
  • Muscularis
    • Has inner and outer longitudinal and middle layer of smooth muscles (dextruser muscles)
  • Serosa / Adventitia
97
Q

The longi muscles form sphinters at ureterovesicular junction. What is the purpose of this?

A
  • To prevent backflow of urine
  • To regulate urine emptying at the neck of the bladder
98
Q

What are the 4 tissue layers of the urethra?

A
  • Mucosa
    • Transitional but changes to stratified squamous at external urethral orifice
  • Submucosa
    • Has cavernous tissue spaces that are typical of erectile tissue
  • Muscularis
    • Has inner and outer longi and middle layer of smooth muscles as in bladder but towards external urethral orifice, it acquires an external layer of skeletal muscle called striated urethralis muscle
  • Serosa/ adventitia
99
Q

Major characteristic of polycystic kidney disease

A
  • Outgrowths from normal tubules that enlarge into huge, fluid-filled cysts
  • Kiney cells with abnormal or missing cilia appear to become dysfunctional and cause the formation of cysts
100
Q

Polycystic Kidney disease (Causative gene )

A

Polycystin 1 or 2

  • Code for a protein that localizes to single cilia in renal tubule cells