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7/27/2019 Histo Urinary System
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ANATOMY EVALS 8: Urinary System
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TOPIC: Histology Urinary SystemLECTURER: Dr. Ed Gonzales
DATE: December 2012
TRANSCRIBED BY: MAE PANTOLLA
BATCH 2016
Component Organs
A. Kidneys- performs all functions of systemB. Ureters- passageways for urineC. urinary bladder- temporary storage of urineD. urethra- passageway for urine.A. Kidney
a. Functions- homeostasis
o maintainance of normal composition and volume of body fluidso by eliminating metabolic waste products from body via urine
- production of hormones and other biologically active substanceso renino erythropoietin,o thrombopoietino kininso calcitrol (1, 25-dihydroxycholecalciferol).
b. Hilus- fissure on medial surface- entry for renal artery- exit for renal vein- exit for renal pelvis
c. Renal Sinus- hilus leads to it- 2.5 cm deep space within kidney- fat-filled- contains renal blood vessels, nerves and renal pelvis and calyces.
d. Capsule-
thin but tough (fibrous); easily stripped off from organ- at hilus,i. lines renal sinusii. becomes continuous with walls of calyces.
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e. Region on longitudinal section:
1. medulla inner portion striated
2. cortex outer portion reddish and granular
(note: arcuate vessels demarcate junction of cortex and medulla).
MEDULLA CORTEX
1. renal pyramids 10-15 conical structures that
make up medulla
renal papilla- apex ofpyramid
2. renal columns (of Bertin) inward extension of cortex
that separate pyramids.
- medullary rays (of Ferrein)o grossly:
longitudinal streaks from base of pyramids
o microscopically: collecting tubules segments of the loop of Henle
f. lobe renal pyramid
cortex that overlies base of pyramid corresponding cortical tissue in renal column (of Bertin)
g. lobule1. cortex
medullary ray (of Ferrein)- center of lobule
nephrons that drain into collecting tubules in medullary ray blood vessels, CT, nerves
2. medulla terminal segments of collecting tubule papillary ducts segments of loop of Henle that dip into medulla blood vessels, nerves, CT
h. blood vessells average blood flow to kidneys = 1.2 liters per minute
renal artery - from abdominal aorta
Interlobar arteries - enters renal sinus- traverses medulla and proceeds to cortex
Arcuate arteries - at corticomedullary junction- no anastomoses between arcuate arteries
Interlobular arteries
RENAL ARTERY INTERLOBAR ARTERY ARCUATE ARTERY INTERLOBULAR ARTERY
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Efferent arterioles
peritubular capillary network vasa recta
- supplies tubules around glomerulus- supply medulla
INTERLOBULAR ARTERIES AFFERENT ARTERIOLE GLOMERULAR CAPILLARIES EFFERENT ARTERIOLE
SUPERFICIAL AND
DEEP CORTICAL VEINSTELLATE VEINS INTERLOBULAR VEIN MEDULLARY VEIN ARCUATE VEIN
INTERLOBAR
VEIN
i. Uriniferous tubule1. Nephron2. intrarenal ducts
a. collecting tubulesb. papillary ducts.
Interlobular arteries
- straight branches of arcuate- located between renal lobules- form outer boundaries of lobules- terminally, supplies capsule.
Afferent arterioles - supply lobules
Glomerular capillaries - each has 20-50 loops
Efferent arterioles - drains glomerulus- then breaks up two ways:
superficial cortical veins - drain outer cortex and capsuledeep cortical veins - drain rest of cortexmedullary veins - a.k.a ascending segment of vasa rectae
- drain medulla
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NEPHRON INTRARENAL DUCTS
- functional unit of kidney- 1 to 1.5 million per kidney.Parts:
a. Renal corpuscle1. glomerulus
a) glomerular capillariesb) mesangeal matrix (mesangium)c) glomerular mesangeal cells
2. Bowmans capsule (glomerular capsule)a) Parietal layerb) Visceral layer
b. Renal tubule.segments:
1. proximal convoluted tubule2. Henles loop
a) thick descending limbb) thin limbc) thick ascending limb
3. distal convoluted tubule- juxtaglomerular complex
a. juxtaglomerular cellsb. macula densac. extraglomerular mesangial cells
a. collecting tubulessegments:
- arched collecting tubules- straight collecting tubules - main components of
medullary rays
b. papillary ducts- a.k.a. papillary duct (of Bellini)- formed by convergence of straight collecting
tubules- empties into a minor calyx; about 25 papillary
ducts/ minor calyx
- lined by tall columnar epithelium- functions of both:
o serve as conduits for urineo secrete potassium and acidify urine
(collecting tubules)
- epithelium : simple cuboidal but progressivelybecomes taller
a. Renal corpuscle- a.k.a. Malpighian corpuscle- located in cortex- forms proximal end of nephron.- vascular pole: entry point of afferent arteriole to, and exit of efferent arteriole- urinary pole: area where renal tubule begins.Parts:
1. glomerulus2. Bowmans capsule (glomerular capsule)
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1. GLOMERULUSa) glomerular capillariesb) mesangeal matrix (mesangium)c) glomerular mesangeal cells
GLOMERULAR CAPILLARIES MESANGEAL MATRIX
(MESANGIUM)
GLOMERULAR MESANGIAL CELLS
- result from break up of anafferent arteriole
- 20-50 highly convoluted loops- drain into a single efferent
arteriole.
- fenestrated-
not covered by a diaphragm- but very thick basal lamina
- amorphousmaterial similar to
basement
membrane
- between glomerular capillaries- stellate-shaped cells similar to pericytes.- cytoplasmic processes in between endothelial
cells to reach the capillary lumen
- produce mesangial matrix- contractile and can influence luminal diameter
of capillaries- phagocytickeeps glomerular filtration barrierfree of debris
2. BOWMANS CAPSULE
double-walled structure (each a single layer of epithelial cells)PARIETAL LAYER VISCERAL LAYER
outer wall simple squamous epithelium continuous with visceral layer at vascular pole continuous with epithelium of renal tubule at urinary pole.
covers glomerulus intimately epithelial cells are modified (podocytes).
capsular space (Bowmans space; subcapsular space; urinary space)- between visceral and parietal layers.
Vascular pole
urinary pole
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Podocytes
- modified simple squamous epithelial cells- associated intimately with glomerular capillaries- provided with processes
o major processes vary in shape & size
o minor processes (foot processes or pedicels) given off by major processes wrap around capillary walls interdigitate with pedicels of neighbors.
- subpodocytic spaceso spaces between processes of podocytes and capillaries
- filtration slitso narrow slits between the closely packed pedicelso covered by a thin electron-dense membrane (slit membrane or slit diaphragm).
Glomerular Filtration Barrier
- separates blood in glomerular capillaries from Bowmans capsular space- components
1. endothelium of glomerular capillaries2. basal lamina where endothelial cells and pedicels rest3. slit membrane of filtration slits.
- glomerular filtrationo
filtration barrier acts as sieve to allow ultrafiltrate ofblood (glomerular filtrate) to seep to Bowmans space
- glomerular filtrateo product of glomerular filtrationo flows from Bowmans space into renal tubule.
b. RENAL TUBULE- functions:
o tubular reabsorption - reabsorption of some water and solutes from glomerular filtrateo tubular secretion- addition of some solutes to glomerular filtrate.
- segments:1. proximal convoluted tubule2. Henles loop
a) thick descending limbb) thin limbc) thick ascending limb
3. distal convoluted tubule.PROXIMAL CONVOLUTED TUBULE HENLES LOOP DISTAL CONVOLUTED TUBULE
- direct continuation of Bowmanscapsule
- longest segment of nephron- functions:
o reabsorbs 70%-80% ofwater and sodium ions
present in glomerular
filtrate.o reabsorbs other
substances notably
glucose, amino acidsand chloride ions.
- simple cuboidal epitheliumcomprises entire wall
- cells with microvilli (brush border)- nucleus centrally located- lateral cell boundaries indistinct- basal striations (infolding of cell
membrane filled with
mitochondria)
- dips into medulla, makes hairpinturn, then returns to cortex
- types of nephrons based onlength of loop:
1. short-looped (cortical)nephrons
great majority renal corpuscles in
outer portions of cortex
loops form part ofmedullary rays butbarely make it to
medulla
2. long-looped(juxtamedullary) nephrons
1/7thof nephrons in cortex but near
corticomedullary
junction
loops go deep intomedulla.
- Subsegmenta) thick descending limbb) thin limbc) thick ascending limb
- starts at point of contact ofascending thick limb of loop of
Henle with vascular pole of renal
corpuscle
- functions: reabsorbs a little
amount of water and
sodium ions from
glomerular filtrate secretes potassium and
hydrogen ions intoglomerular filtrate.
- shorter, less convoluted andbigger lumen than proximal
convoluted tubule
- cuboidal epithelial cells have nobrush borders
- distinct cell boundaries
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Henles loop
- Subsegments:THICK DESCENDING LIMB THIN LIMB THICK ASCENDING LIMB
a.k.a. descending straighttubule; proximal straight
tubule
partly in cortex; partly inmedulla
same structure andfunction as proximal
convoluted tubule.
diameter = 15m (descending straight=60m)
lined by simple squamous epithelium further concentrates glomerular filtrate
morphologically identicalwith distal convoluted
tubule.
JUXTAGLOMERULAR COMPLEX
- a.k.a.: JG complex; Jg apparatus- Three (3) atypical cells associated with each
other in vascular pole of renal corpuscle
a. juxtaglomerular cellsb. macula densac.
extraglomerular mesangial cells
JUXTAGLOMERULAR (JG)
CELLSMACULA DENSA
EXTRAGLOMERULAR MESANGIAL
CELLS
- in tunica media ofafferent arteriole before
arteriole enters vascular
pole
- polyhedral cells that arelarger than ordinary
smooth muscle cells
- produce renin andpossibly, erythropoietin
and thrombopoietin.
- modified epithelial cells of tubule- at start of distal convoluted tubule that is in
contact with vascular pole of parent renal
corpuscle
- cellso crowded and narrowero nuclei appear intensely stainingo intimately close to JG cells of afferent
arterioleo sensitive to ion content and volume of
fluid in convoluted distal tubule
o generate molecular signals that promoterenin secretion by JG cells
- a.k.a. pole-cushion cells;lacis cells; Goormaghtigh
cells; polkissen
- light-staining cells betweenmacula densa and afferentarteriole
- probably involved in signaltransmission between
macula densa and
glomerular mesangial cells
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2. intrarenal ductsa. collecting tubulesb. papillary ducts- functions of both:
o serve as conduits for urineo secrete potassium and acidify urine (collecting tubules)
collecting tubules
- segments:- arched collecting tubules- straight collecting tubules - main components of medullary rays
- epithelium : simple cuboidal but progressively becomes taller
papillary ducts
- a.k.a. papillary duct (of Bellini)- formed by convergence of straight collecting tubules- empties into a minor calyx; about 25 papillary ducts/
minor calyx
- lined by tall columnar epithelium
j. Interstitium- refers to scanty connective tissue in peritubular and periarterial spaces
o extracellular substance glycosaminoglycan-rich ground substance collagenous fibers
o cellular elements fibroblasts mononuclear cells: probably belonging to mononuclear phagocyte system interstitial cells
fibroblast-like cells but processes thinner
some say they produce prostaglandins while others say they secrete ahormone whose effects are opposite those of renin.
k. Intrarenal urinary passages- histology similar to ureter and urinary bladder- minor calyx : receives urine from papillary ducts- major calyx: union of several minor calyces- renal pelvis: union of major calyces
B. URETER, URINARY BLADDER AND URINARY PASSAGEIN KIDNEY
histologic layers1. mucosa2. muscularis3. adventitia/serosa
(note: no distinct submucosa).
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MUCOSA MUSCULARIS ADVENTITIA/ SEROSA
- epithelium :o transitional
- lamina propria:o devoid of glands except for mucus
glands near internal sphinter of
urinary bladder
- poorly defined- outer layer - mostly circularly-arranged- inner layer - mostly longitudinally-arranged- in urinary bladder, well-developed
o three indistinct but definite layerso middle layer contains the
circularly-arranged muscles
- adventitiaexcept for
upper part of
bladder which is
serosa.
C. URETHRAMALE FEMALE
segments:
1. prostatico proximal segment, 3-4 cm longo traverses prostate gland
2. membranouso second segment, about 1 cm longo traverses sphincter urethrae muscle
3. spongy (penile urethra; cavernous urethra)o third and longest segment, about 15 cm
long
o traverses peniso terminates in external urethral orifice
(meatus).
- much shorter than male; only 4 cm long- also penetrates sphincter urethra muscle- mucosa
o epithelium is transitional in initial segment butnonkeratinized stratified squamous
epithelium in rest.
o many small, mucus-secreting urethral glandsthat open into lumen
- muscular coat like in male- distal segment surrounded by circularly-arranged
striated (voluntary) muscle fibers that belong to
sphincter urethrae muscle (external sphincter of
urethra).
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MALE URETHRA FEMALE URETHRA
Male urethra segments:
PROSTATIC MEMBRANOUS SPONGY (PENILE URETHRA; CAVERNOUS
URETHRA)- contains opening of prostate gland
and ejaculatory duct (common
passageway for sperms and secretions
of seminal vesicle)
- transitional epithelium- lamina propria
o small urethral glands of (Littre) branched, tubuloalveolar,
mucus-secreting glands (also
present in other segments of
male urethra)
- external to lamina propria are smoothmuscle fibers - form internal urethral
sphincter.
- structurally similar toprostatic urethra
- but epithelium ispseudostratified columnar
- surrounded by circularly-arranged striated
(voluntary) muscle fibers
that belong to the
sphincter urethrae muscle
(the external sphincter of
the urethra)
- pseudostratified columnarepithelium except at external
urethral meatus where epithelium
becomes stratified squamous,
nonkeratinized
- receives ducts of bulbourethralglands (of Cowper)
- pair of glands; 1 cm in diametereach
- embedded in sphincter urethraemuscle on either side of
membranous urethra.
SPONGY (PENILE URETHRA; CAVERNOUS URETHRA)