Urinary System Flashcards
1
Q
Organs in the urinary system
A
- kidneys
- ureters
- urinary bladder
- urethra
2
Q
Functions of urinary system
A
- clears the blood of metabolic waste products
- regulates fluid and electrolyte balance
- produces renal erythropoietic factor and renin
- hydroxylates Vit D to an active form (calcitriol) that is involved in calcium balance
3
Q
Kidney Location
A
-situated retroperitoneally on the posterior wall of the abdominal cavity on either side of the vertebral column
4
Q
Kidney Hilus
A
-hilus: concave medial border through which the ureter, nerves, blood and lymphatic vessels pass
5
Q
Renal Sinus
A
- renal sinus: large cavity surrounded by kidney parenchyma
- contains the renal pelvis
- occupied by loose connective tissue, adipose tissue, blood vessels and nerves
6
Q
Renal Pelvis
A
-expansion of the upper end of the ureter that subdivides into major and minor calyces
7
Q
Capsule
A
-consists of dense irregular connective tissue
8
Q
Renal Cortex
A
- darker granular tissue
- broad outer zone
- inward extensions (renal columns of Bertin)
9
Q
Renal Medulla
A
- lighter, striated tissue
- composed of renal pyramids:
1) apices of pyramids (renal papillae) project into minor calyces
2) tip of each papilla is perforated by openings of collecting ducts (are cribrosa)
3) each pyramid together with its surrounding cortical tissue constitutes a renal lobe
4) human kidneys contain from 6-18 lobes - medullary rays: medullary tissue that projects up into the cortex consisting of collecting tubules and their accompanying proximal and distal tubules
10
Q
Renal lobule
A
-a medullary ray and its surrounding cortical tissue
11
Q
Nephron
A
- functional unit of the kidney
- corresponds to secretory elements of other glands
- approximately 2 x 10^6/kidney
- first part (Bowman;s capsule-distal tubule) is concerned with formation of urine
- second part (collecting system) carries out final concentration of urinary solutes
- components of the nephron
12
Q
Bowman’s capsule
A
- thin-walled expansion at proximal end of nephron
- deeply indented by glomerulus
- visceral layer is composed of podocytes and covers glomerular capillaries
- parietal layer is simple squamous epithelium
- urinary (capsular) space exists between visceral and parietal layers (receives glomerular filtrate)
- glomerular filtration barrier: capillary endothelium (fenestrated, no diaphragms), shared basement membrane, filtration slits between secondary processes of podocytes, produces glomerular filtrate
- vascular pole is where afferent arteriole enters and efferent arteriole leaves
- urinary pole is where the proximal tubule begins
- renal corpuscle consists of Bowman’s capsule plus the glomerulus
13
Q
Proximal tubule
A
- consists of a convoluted and a straight portion
- lined by simple cuboidal epithelium with a conspicuous brush border
- eosinophilic cytoplasm
- extensive lateral extensions (cell boundaries are indistinct)
- lumen often contains fine precipitated material
- can be subdivided into 3 segments by electron microscopy
14
Q
Loop of Henle
A
- consists of the descending straight portion of the proximal tubule, the thin segment, and the ascending straight portion of the distal tubule
- located mostly in the medulla
- lining of the descending straight portion of the proximal tubule resembles that of the convoluted portion
- epithelium of the thin segment is simple squamous
15
Q
Distal tubule
A
- consists of an ascending straight portion (part of the loop of Henle), portion adjacent to renal corpuscle, and convoluted part
- located mainly in cortex
- simple cuboidal epithelium that lacks a brush border
- cells are small than cells of the proximal tubule
- apical nuclei
- less eosinophilic than proximal tubule
- extensive lateral interdigitations (cell boundaries are indistinct)
- no precipitate in lumen
16
Q
Collecting tubules and ducts
A
- tubules are found in the cortex, while ducts are located in the medulla
- epithelium increases in height from cuboidal in tubules to columnar in ducts
- cells have clear, pale-staining cytoplasm
- intercellular boundaries are clearly visible
- largest ducts (papillary ducts) communicate with the minor calyx at the area cribosa
17
Q
Types of nephrons
A
- classified according to the position of their renal corpuslces in the cortex
1) superficial (cortical) nephrons have short loops of Henle that extend a short distance into the medulla
2) juxtamedullary nephrons have long loops of Henle that penetrate deep into the medulla (most important in the production of hypertonic urine)
3) intermediate (midcortical) nephrons
18
Q
Juxtaglomerular Apparatus
A
- responsible for the production of renin
- located where distal tubule returns to its renal corpuscle of origin
- components:
1) macula densa located in wall of distal tubule
2) juxtaglomerular cells: modified smooth muscle cells in tunica media of afferent arterioles
3) extraglomerular mesangial cells (lacis cells): pale-staining cells located in the angle between afferent and efferent arterioles
