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Block E -- Renal > Histology Lecture 1 -- Kidney and Urinary System > Flashcards

Histology Lecture 1 -- Kidney and Urinary System Flashcards

(128 cards)

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1
Q

Structures that leave or enter the kidney at the hilum

A

Branches of the:

  • Renal arter yand vein
  • Lymph vessels
  • Ureter
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2
Q

Define the renal pelvis

A

Expanded ureter at the level of the hilum of the kidney

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3
Q

What does the kidney parenchyma surround

A

Renal sinus

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4
Q

Describe the appearance of the cortex and medulla of the kidney in fresh tissue

A
  • Cortex = granular and dark brown
  • Medulla = lighter and striated
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5
Q

Components of the medulla

A

6 - 12 pyramid-shaped regions = renal pyramids

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6
Q

Define the renal papilla

A

Apex of each renal pyramid bulging into the renal sinus

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7
Q

What perforated the renal papilla?

A

Approximately 20 openings of the ducts of Bellini (area cribosa)

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8
Q

Define the tissue between the renal pyramids. Are they part of the medulla or the cortex?

A

Cortical columns / Columns of Bertin

Part of the medulla (even though they are extensions of cortical tissue)

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9
Q

What covers each renal papilla

A

Minor calyx

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10
Q

What forms a major calyx?

A

2 to 3 adjacent minor calyces that fuse

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11
Q

Where do major calyces open into?

A

The renal pelvis

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12
Q

3 types of structures that can be observed in the cortex

A
  • Renal corpuscles
  • Convoluted tubules and longitudinal striations
  • Medullary rays
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13
Q

How many lobes in a rat kidney?

A

1

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14
Q

Define a kidney lobe

A

One renal pyramid and its surrounding cortical tissue

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15
Q

Define a kidney lobule

A

One medullary ray and surrounding area of convoluted tubules and renal corpuscles

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16
Q

Define the uriniferous tubule

A

The functional unit of the kidney

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17
Q

2 parts of the uriniferous tubule and how they are differentiated

A
  • Nephron
  • Collecting tubule

Differentiated by different embryological origins

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18
Q

Number of nephrons per kidney

A

1 - 4 million

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19
Q

2 types of nephron

A
  • Cortical
  • Juxtamedullary
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20
Q

3 characteristics of cortical nephrons

A
  • Located in the cortex
  • Short
  • Short loops of Henle
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21
Q

3 characteristics of the juxtamedullary nephron

A
  • Located close to the medulla
  • Very long loops of Henle that penetrate the medulla
  • About 40 mm long
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22
Q

4 components of the nephron

A
  • Renal corpuscle
  • Proximal convoluted tubule
  • Loop of Henle
  • Distal convoluted tubule
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23
Q

Diameter of renal corpuscle

A

200 micrometers

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24
Q

2 components of the renal corpuscle

A
  • Glomerulus
  • Bowman’s capsule
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25
2 epithelial layers of the Bowman's capsule and their cell types
* Visceral = podocytes * Parietal layer = simple squamous
26
Space between the two epithelial layers of the Bowman's capsule
Urinary space / capsular space/ Bowman's space
27
2 poles of the renal corpuscle
* Vascular pole (afferent arteriole enters glomerulus and efferent arteriole leaves) * Urinary [ole (beginning of PCT)
28
Where does the parietal epithelium of the Bowman's capsule change cell type and to what type does it change?
* At the urinary pole * Changes to simple columnar epithelium
29
3 structural components of podocytes
* Cell body * Several primary processes * Abundant secondary processes (pedicels)
30
2 characteristics of pedicels
* Embrace the capillary loops of the glomerulus * Interdigitate with pedicels from adjacent podocytes to form filtration slits
31
Width of filtration slits
25 nm
32
What bridges the filtration slits
A very thin (about 6 nm) diaphragm
33
Only part of the podocyte that touches the basement membrane of the capillaries
Pedicels
34
4 characteristics of podocyte cell bodies
* Numerous free ribosomes * A few cisternae of rER * Prominent Golgi * Very few mitochondria
35
2 characteristics of the processes of podocytes
* Very few organelles * Contains actin filaments for contractility
36
3 characteristics of the epithelial layer of the glomerular capillaries
* Fenestrated * Bigger fenestra (70 - 90 nm in diameter) than in similar capillaries in other organs * No diaphragm (also in contrast to others)
37
Define the filtration barrier separating the blood from the urinary space
Thick basement membrane derived from the fusion of the basal laminas from podocytes and endothelial cells
38
4 components of the glomerular basement membrane
* Type IV collagen * Laminin * Fibronectin * Proteoglycans rich in heparan sulfate
39
2 groups of mesangial cells and their locations
* Extraglomerular mesangial cells (vascular pole) * Intraglomerular cells (in between capillary loops inside the glomerulus)
40
3 functions of the intraglomerular mesangial cells
* Likely phagocytic (involved in digestion of basement membrane) * May be contractile (contribute to reduced blood flow in glomerulus) * Support capillary loops in regions where podocytes are not in contact with them
41
Size of molecules that are trapped by the basement membrane
\> 69 kDa (i.e. albumin)
42
Charge of molecuels prevented from crossing the basement membrane and how
Negatively charged molecules due to anions in the basement membrane
43
Define the glomerular ultrafiltrate
Fluid that enters the capsular (or urinary) space
44
How does the glomerulus prevent the clogging of the basement membrane by large trapped molecules?
* Continuous renewal through phagocytosis by mesangial cells * De novo synthesis by podocytes and endothelial cells
45
Epithelium type of the PCT
* Simple cuboidal to columnar epithelium
46
4 histological characteristics of the PCT
* Highly acidophilic (numerous elongated mitochondria) * Brush border (numerous elongated microvilli) * Cells larger than those of DCT * Indistinct cell membrane limits (extensive interdigitations of membranes)
47
4 ultrastructural characteristics of the PCT
* Numeroud endocytic structures in apical cytoplasm between bases of microvilli * Basal parts have muiltiple membrane invaginations and laterla interdigitations with adjacent cells * Parallel mitochondria to long axis * Na-K-ATPase at basolateral membrane
48
3 parts of the loop of Henle
* Thick straight descending limb * Thin limb * Thick straight ascending limb
49
Type of epithelium at the thin limb
Squamous
50
Importance of juxtamedullary nephrons
Unique capability of contributing (with the blood vessel loops) to the establishment of the gradient of hypertonicity in the medulla required for urine concentration (counter-current exchange system)
51
Part of the loop of henle that is permeable to water
Thin descending limb
52
Part of the loop of henle that is impermeable to water
Entire ascending limb (both thick and thin)
53
Epithelium type of distal convoluted tubule
Simple cuboidal epithelium without microvilli
54
5 differences between the DCT and PCT histologically
* DCT cells are smaller and flatter * DCT lumens are larger and normally appear wide open * DCT has no brush border * DCT cells are less acidophilic * DCT have more cells (more nuclei close to apical border)
55
Define the macula densa
Elongated epithelial cells with crowded nuclei of the DCT where it contacts the vascular pole of the bowman's capsule of its parent nephron
56
Function of PCT
Reabsorption of 85% of water, solutes, and proteins
57
Describe water reabsorption in the PCT
* Apical membrane = passive * Basolateral = active resorption via Na/K/ATPase pump
58
Describe generally how solutes are reabsorbed in the PCT
Isotonically --\> osmotic potential of the fluid leaving the PCT = that of the initial glomerular filtrate
59
Function of DCT
Partly responsible for the regulation of K+, Ca++, Na+ and pH
60
Primary site for the kidney's hormone-based regulation of Ca++
DCT
61
2 carriers in the luminal membrane of the DCT
* Na+/Cl- co-transporter (symporter) * Calcium-selective channel
62
3 carriers in the basolateral membrane of the DCT
* ATP dependent Na+/K+ antiport pump * Active Na+/Ca++ transporter antiport * ATP dependent Ca transporter
63
Describe the function of the DCT's basolateral transporters
* Na+/K+ ATP dependent pump produces Na+ gradient * Na+ absorbed from the apical surface via the Na/Cl symporter * Gradient allows Ca++ to be reclaimed into the blood by the Na/Ca antiport
64
Describe how the DCT regulates pH
* Absorb bicarbonate and secrete protons into the filtrate OR * Absorb protons and secrete bicarbonate into the filtrate
65
Describe how the DCT controls sodium and potassium levels
* K+ secretion * Na+ absorption
66
What mediates sodium absorption by the DCT?
Aldosterone (increases Na+ absorption)
67
What kind of vasopressin receptor is expressed in the DCT and its effect
* Arginine vasopressin receptor 2 * Increases permeability to water in the presence of ADH (normally pretty impermeable) --\> concentration of urine
68
3 components of the juxtaglomerular apparatus
* Macula dense of the DCT * Juxtaglomerular cells of the afferent arteriole * Extraglomerular mesangial cells
69
Define juxtaglomerular cells
Modified smooth muscle cells of the tunica media of the afferent arteriole
70
3 characteristics of the juxtaglomerular cells
* Round nuclei (not elongated) * Cytoplasm rich in granules containing renin * Basal lamina absent at the level of contact with the macula densa
71
4 boundaries of the space that the extraglomerular mesangial cells occupy
* Afferent arteriole * Macula densa * Efferent arteriole * Vascular pole of Bowman's capsule
72
2 hormones secretes by the juxtaglomerular cells
* Renin * Erythropoietin (probably; in response to hypoxia)
73
Functions of the macula densa
* Production of nitric oxide --\> counteract angiotensin II-mediated contraction of the A.A. --\> increase ultrafiltration * Promotion of renin release in response to ionic content and water volume of the tubular fluid
74
Describe the epithelium cell type and diameter of the collecting tubules and ducts
* Small collecting tubuels = cuboidal epithelium (40 - 50 µm diameter) * Collecting ducts = columnar epithelium (increased diameter) * Ducts of Bellini reach 200 µm at the tip of the pyramids
75
3 common features of all collecting tubules and ducts
* Cytoplasm stains weakly in routine preps * No microvilli * Cell limits are easy to see
76
Where in the nephron is creatinine secreted?
Proximal tubule
77
Site of ADH action
Collecting duct
78
Give the order of the vessels of the kidney starting from the renal artery
* Renal artery * Anterior and posterior branches of renal artery * Interlobar arteries * Arcuate arteries * Lobular arteries * Afferent arterioles * Glomerular capillaries * Efferent arteriole * Peritubular capillary network of cortical tubules OR vasa rectae * Stellate veins * Interlobular veins * Arcuate veins (also receive blood from venae rectae) * Interlobar veins * Renal vein
79
Where are the interlobar arteries located?
Renal columns of Bertin
80
Where are arcuate arteries formed?
At the level of the cortico-medullary junction
81
What forms the outer limits of the lobules?
Lobular arteries
82
What hormone is probably produced by the endothelial cells of the peritubular capillary network?
Erythropoietin
83
Purpose of vasa rectae
Essential for the maintenance of the osmotic gradient in the medulla (do not carry away the high osmotic gradient in the interstitium set up by the loop of Henle) --\> countercurrent exchange mechanism
84
What forms the stellate veins
Capillaries of the outer cortex and capsule
85
From where do arcuate veins receive blood?
Interlobular veins Venae rectae
86
What forms interlobar veins?
Arcuate veins
87
3 interstitial elements of the cortex
* Delicate connective tissue elements, mostly associated with basement membranes investing the epithelial elements and their vascular supply * Fibroblasts * Macrophages
88
4 interstitial elements of the medulla
* More connective tissue than cortex (more abundant in the lower medulla) * Fibroblasts * Macrophages * Interstitial cells
89
2 characeristics of interstitial cells
* Lipid droplets in cytoplasm * Hormonal function (produce medullipin I)
90
What is medullipin I
Precursor of a vasodilator
91
Describe the thickness of the wall in the urinary passages approaching the bladder
The calyces, pelvis and ureters' wall thicknesses increase progressivley with proximity to the bladder
92
Where is transitional epithelium found?
* Urinary bladder * Urinary passages * Minor and major calyces * Renal pelvis * Ureter
93
Describe the lamina propria of the urinary bladder and the calyces, pelvis and ureter
Loose to dense connective tissue
94
General layers of the urinary bladder and urinary passages (calyces, pelvis, ureters)
* Mucosa * Transitional epithelium * Lamina propria * Smooth muscle * Adventitia
95
Arrangement of the smooth muscle in the minor calyces
Helical
96
Describe the mucosa of the ureter and how it varies
Mucosa has several folds that project into the lumen when the ureter is empty, but disappear when it is full
97
Describe the lamina propria of the ureters
Dense, irrgular connective tissue
98
Thickness of the transitional epithelium in the ureters
3 - 5 cells thick
99
Describe the muscularis of the ureters
Most of the ureter = 2 layers: * Outer circular * Inner longitudinal Lower third = 3 layers: * Outer longitudinal * Middle circular * Inner longitudinal
100
Function of the bladder
Store the urine until the pressure inside induces the urge to urinate
101
Purpose of the epithelium in the bladder
Osmotic barrier isolating the urine from the wall of the organ
102
Describe the mucosa of the bladder
Numerous folds when the bladder is empty --\> disappear when full Always smooth in the area of the trigone
103
Describe the superficial cells of the transitional epithelium found in the bladder
Large and dome-shaped Become flattened (stretch) during distension
104
Why are the surface transitional cells of the bladder able to change shape during distension?
Unique device in the plasma membrane = mosaic of specialized, rigid, thick plaques in between areas of normal plasma membrane Empty = plaque regions fold into irregular, angular contours Distended = folds disappear
105
Describe the apical cytoplasm of the bladder's epithelial cells
Contains fusiform vesicles with thickened membranes like the plaques
106
Define the trigone
The area in between the openings of the ureter and the urethra
107
Describe the lamina propria of the bladder
Superficial part of dense connective tissue Deeper part of loose connective tissue
108
Where are glands found in the bladder and what kind are they?
Only in the area around the urethra (mucous glands extending into the lamina propria)
109
Describe the muscularis of the bladder
* Smooth muscle fibers running in every direction * Only well-defined layers in the nack of the bladder: * Thick internal sphincter muscle (circular) * Inner and outer longitudinal
110
Describe the outer layer of the bladder
* Adventitia of dense, irregular connective tissue with many elastic fibers * Certain areas covered by serosa * Other regions surrounded by fat
111
Describe the general musculature of the urethra as it pierces the perineum
* Skeletal muscle fibres are organized as the external sphincter of the urethra (voluntary) * Still has an involuntary internal sphincter
112
When does urinary incontinence occur?
Loss of voluntary control over the striated muscle of the urethra
113
Describe 2 general features of the female urethra
* Short * Normally collapsed lumen except during micturition
114
Describe the epithelium of the female urethra
* Transitional epithelium near the bladder * Stratified squamous non-keratinized epithelium along the rest of its length
115
Describe the mucosa of the female urethra
* Elongated folds * Numerous mucous glands of Littré
116
Describe the tissue surrounding the mucosa of the female urethra
Thin, vascular coat of erectile tissue
117
Describe the muscular layer of the female urethra
* Inner longitudinal * Outer circular
118
3 regions of the male urethra
* Prostatic urethra * Membranous urethra * Spongy or cavernous urethra
119
What surrounds the entirety of the prostatic urethra
Prostate gland
120
Describe the epithelium of the prostatic urethra
Transitional epithelium
121
What opens into the prostatic urethra?
* 2 ejaculatory ducts * Multiple excretory ducts of the prostate gland * Prostate utriculus (a rudimentary duct)
122
Where does the membranous urethra occur?
At the level of passage of the perineal membrane
123
Define the epithelium of the membranous urethra
* Stratified columnar * Patches of pseudostratified columnar
124
What does the spongy/cavernoud urethra correspond to?
The part IN the penis --\> terminates at the tip of the glans penis
125
Describe the epithlium of the spongy or cavernous epithelium
* Stratified columnar * Patches of pseudostratified columnar or stratified squamous non-keratinized epithelia
126
Special feature of the spongy or cavernous urethra
Presence of mucous intraepithelial glands and periurethral mucous glands
127
Describe the epithelium of the dilated terminal part in the glans penis (navicular fossa)
Stratified squamous non-keratinized epithelium
128
Describe the lamina propria of the entire male urethra
Loose connective tissue that is highly vascularized

Block E -- Renal (4 decks)

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