uriniferous tubule
composed of two embryologically different parts: the nephron and the collecting duct
nephron
arising from metanephric blastema. about 600,000 to 1.4 million in each kidney
ureteric bud
what embryologic structure gives rise to the collecting duct, calyces, renal pelvis, and ureters?
renal corpuscle
location of blood filtering to form the initial filtrate before passing through the loop of Henle
papillary duct (duct of Bellini)
the terminal portion of the collecting duct which opens onto a renal papilla
outer stripe
portion of the outer medulla containing the thick descending limb of the loop of Henle, the thick ascending limb of the loop of Henle, and collecting ducts
inner stripe
portion of the outer medulla containing the thin descending limb of the loop of Henle, the thick ascending limb of loop of Henle, and collecting ducts
renal corpuscle (including Bowman's capsule and the glomerulus)
#1
proximal convoluted tubule
#2
proximal straight tubule
#3
descending thin limb
#4
ascending thin limb
#5
distal straight tubule (aka thick ascending limb)
#6
macula densa
#7
distal convoluted tubule
#8
connecting tubule
#9
connecting tubule of the juxtamedullary nephron (forming an arcade)
#9*
cortical collecting duct
#10
outer medullary collecting duct
#11
inner medullary collecting duct
#12
cortical (subcapsular)
nephrons whose corpuscles lie in the outer cortex
juxtamedullary
nephrons whose corpuscles lie close to the corticomedullary junction
renal lobe
a renal pyramid and parenchyma with associated tubules. 8-18 of these per kidney
medullary rays
groups of straight tubules and collecting ducts in the cortex, appearing to emanate from the medullary pyramids
renal lobule
each medullary ray and the renal cortical structures that feed into it
cortical labyrinth
the tissue between the medullary rays
glomerulus
formed by a cluster of capillaries forming loops that were derived from the afferent arteriole, and which reunite to form the efferent arteriole
vascular pole (of renal corpuscle)
the region where the afferent arteriole enters and the efferent arteriole leaves Bowman's capsule
urinary pole (of renal corpuscle)
the site where the urinary space opens into the lumen of the proximal convoluted tubule
parietal epithelial cells
simple squamous epithelial cells lining the outer surface of Bowman's capsule. at the vascular pole, continuous with the visceral layer of the capsule. at the urinary pole, continuous with the proximal convoluted tubule
podocytes
highly specialized cells within the visceral layer of Bowman's capsule surrounding the glomerulus. cell bodies project into the urinary space. each contains a prominent euchromatic nucleus, a well-developed Golgi apparatus, RER, mitochondria, multivesicul
pedicels (foot processes)
small extensions from secondary processes of podocytes that possess actin filaments and make direct contact with the glomerular basement membrane
filtration slits (slit pores)
spaces between interdigitating pedicels
ultrafiltration
process occurring across the capillary endothelium, filtration slits between podocyte pedicels, and the basement membrane between the endothelium and podocytes
endothelial surface layer (ESL)
the glycocalyx and endothelial cell coat surrounding the glomerular capillary endothelial fenestrations, which fills the fenestrae to form "sieve plugs
glomerular basement membrane (GBM)
a single, shared basal lamina composed of type IV collagen between endothelial cells and podocytes of glomerular capillaries. consists of a lamina rara interna, lamina densa, and lamina rara externa
nephrin
a major component of the slit diaphragm complex of proteins, interacting with actin molecules in the cytoplasm and with similar molecules of the adjacent pedicle in the slit pore
mesangial cells
specialized pedicytes found on the endothelial side of the basement membrane. have a matrix composed of sulfated glycosaminoglycans, fibronectin, laminin, and collagen. functionally, these are phagocytic and can remove substances trapped in the GBM and th
PCT (proximal convoluted tubule)
confined to the renal cortex with a simple cuboidal epithelium, with a brush border of microvilli, prominent endocytic apparatus, and basolateral membrane that connects with neighboring cells. involved with most of the reabsorption of components filtered
proximal straight tubule (thick descending limb of loop of Henle)
located in both the cortex and outer stripe of the medulla. contains cells similar to the PCT with a gradual decrease in height of cells and concentration of microvilli in the brush border, prominence of the vacuolar apparatus, interdigitation of the baso
thin limb of loop of Henle
a section composed of both a descending and ascending parts. begins at the boundary between the outer and inner stripes of the outer medulla. lined by simple squamous epithelium. descending portion is highly permeable to water and the ascending portion is
distal tubule (thick ascending limb of loop of Henle)
lined by simple cuboidal epithelium without a brush border. mitochondria line the basolateral infoldings of the basolateral membranes, so they appear striated. functions to pump ions from the urine
connecting tubules
interposed between the distal convoluted tubule and the collecting ducts. tend to be taller than the principal cells of the collecting duct but have fewer mitochondria than the distal tubule cells
collecting ducts
divided into three regions (CCD, OMCD, and IMCD). lined by simple cuboidal epithelium increasing in height proximally to distally. responsive to ADH to increase water permeability, and to aldosterone to promote Na+ reabsorption and K+/H+ secretion
principal cells
most numerous cells in the collecting duct. in response to ADH, a water channel (aquaporin 2) inserts into the apical membrane to allow water to move from the tubule lumen into the interstitium of the medulla
intercalated cells
scattered as single cells in the connecting tubules and collecting ducts. have more surface micropliae, apical vesicles, basal infoldings, and mitochondria than other collecting duct cells. involved in regulating pH by transport of H+ and HCO3- ions into
JGA (juxtaglomerular apparatus)
located at the vascular pole of the glomerulus and consisting of the macula densa cells of the distal tubule, juxtaglomerular granular cells, and extraglomerular mesangial cells. involved in regulating blood flow through the nephron and influencing blood
macula densa
specialized cells in the distal tubule near the junction of the distal straight and distal convoluted tubules. low columnar cells, sense the concentration of NaCl in the distal tubule lumen and transmit this information to the afferent arterioles to influ
juxtaglomerular granular cells
modified smooth muscle cells in the tunica media of the afferent arteriole. synthesize renin. have a prominent RER, Golgi apparatus, and prominent secretory granules
extraglomerular mesangial cells
pale-staining cells between the afferent and efferent arterioles, macula densa, and intraglomerular mesangial cells. likely provide structural stability for the JGA and likely are involved in transmitting the signaling from the macula densa to the juxtagl
renal arteries
one per kidney, branches off the abdominal aorta. found within the perirenal fat and along the side of the renal pelvis, divides to give rise to segmental arteries to give rise to interlobar arteries
interlobar arteries (and veins)
enter the substance of the kidney through the renal columns. at the corticomedullary junction, these divide to give rise to the arcuate arteries
cortical radial arteries
these arise from the arcuate arteries and run perpendicular to them into the cortex. they are located at the boundaries of the renal lobules and give rise to the afferent arterioles
glomerulus (aka glomerular tuft)
loops of capillaries arising from the afferent arteriole with their associated mesangial cells
efferent arteriole
formed by the capillaries of the glomerulus rejoining and leaving the glomerulus
peritubular capillaries
arise from the efferent arterioles of cortical nephrons and form a dense plexus supplying the tubules within the cortex. permit for rapid transport of resorbed substances from the tubules into the blood. can drain into the cortical radial veins or a plexu
vasa recta
arise from the efferent arterioles of juxtamedullar renal corpuscles. thin-walled blood vessels which enter the medulla and run straight towards the apex of the renal pyramid. may form plexuses around Henle's loop. descending structures have a layer of co
renal interstitium
area between various tubules and between tubules and the renal corpuscles. forms a greater proportion of the area in the medulla than in the cortex
fibroblasts
cells in the renal interstitium that act as a scaffold, being physically attached to the basement membranes of tubules and renal corpuscles by adherens. very active physiologically to produce adenosine to help regulate local hypoxia and synthesizing eryth
dendritic cells
cells within the renal interstitium that are mobile antigen-presenting cells
renal capsule
thin, two-layered capsule with the outer layer containing collagen bundles and the inner layer being more cellular. loosely attached to the underlying renal tissue, can be peeled off easily from a healthy kidney
area cribrosa
the region where the large, terminal collecting ducts open. urine leaves the renal papillae to enter the minor/major calyces then to the renal pelvis and ureter
transitional
all urinary passages from the calyces to the bladder are lined by this type of epithelium. the luminal layer has dome (umbrella) cells
uroplakin
glycoproteins that form thickened areas of urothelial cell membrane plaques to result in a scalloped cell surface
tight junctions
these are present between urothelial cells to help prevent permeability to urine constituents
muscularis externa
a layer of smooth muscle surrounding the lamina propria of the ureter and bladder. consists of woven bundles of smooth muscle. thicker in the bladder, and called the detrusor
urethra
fibromuscular tube which conveys urine from the bladder to the outside of the body at the appropriate time. usually lined by transitional epithelium proximally and may be lined by pseudostratified columnar or stratified columnar/cuboidal epithelium distal
urethral glands
outpouchings of the mucosal epithelium lined by mucous secreting cells found irregularly along the length of the urethra