Histology of the Renal System Flashcards
Functions of the kidney and the urinary tract
- Maintain water and electrolyte homeostasis, body fluid osmolarity and acid base balance
- Excretion of toxic metabolic waste products (mainly urea and creatinine)
- Acts as an endocrine gland to produce renin and erythropoietin
the urinary tract establishes functions 1. and 2 by
production storage and voiding of urine
gross structure of the kidney
- 10-12cm long, 5-6cm wide, 3cm thick
- located in the retro-peritoneum
- covered by a thin but strong capsule of dense collagen fibres
- renal hilum= site of entry of the renal artery, vein and ureters
urine drains from
minor calyx into major calyx into renal pelvis and into the ureter
kidney has an
outer renal cortex and an inner renal medulla
renal medulla is divided into
medullary pyramids with apices pointing towards the hilum called the papillae and ending on the minor calyxes
nephron is composed of the
renal corpuscle and the renal tubule
renal corpuscle is
the glomerulus and the renal tubule
nephron is
the basic functional unit of the kidney and is composed of the renal corpuscle
renal corpuscle
formed from a tuft of capillaries called the glomerulus and the cup of simple squamous epithelium at the blind end of the nephron into which the capillaries invaginate called bowmans capsule
the tuft of capillaries is supplied by
the afferent arteriole and drains via the efferent arteriole
2 layers seperate the blood from the glomerual filtrate
the capillary endothelium and a specialised epithelium which lies on top of the glomerular capillaries which contains epithelial cells called Podocytes
between the 2 layers
is the basal lamina
mesangial cells produce
a connective tissue core called the mesangium which functions include the support and removal of debris
the loop of henle in the medulla is
the thin limb of the loop of henle has a thin, squamous lining in which the nuclei protrude into the tubular lumen, there is a transition into the thick ascending limb which is lined by simple cuboidal epithelial cells with abundant mitochondria
vasa recta
thin walled blood vessels dip into the medulla from above and then climb back up to the cortex these loops of blood vessels are collectively called the vasa recta
the distal convoluted tubules are found in the
renal cortex and are lined with simple cuboidal epithelium however, unlike the proximal convoluted tubule those of the distal convoluted tubule lack a brush border of extensive microvilli
in the renal cortex
the collecting ducts along the straight segments of the proximal and distal tubular are gathered in perpendicular bundles to the surface the kidney called MEDULLARY RAYS
in the medulla the collecting ducts appear
alongside the loop of henle and the vasa recta,
the lining of the collecting ducts is
simple columnar epithelium
the juxtaglomerular apparatus
specialised region formed at the site where the distal convoluted tubule passes adjacent to the vascular pole of the same renal corpuscle that forms part of its very own nephron
the juxtaglomerular apparatus is made of 3 components
- Macula densa
- Juxtaglomerular cells
- extra-glomerular mesangial cells (lacis cells)
macula densa
on the side of the distal consorted tubule nearest the afferent arteriole, the cells of the DCT are called,crowded together and there nuclei are intensely stained, the macula densas function is t send the ion composition of the distal convoluted tubule
junta-glomerular cells
modified smooth muscle cells in the wall of the afferent arteriole these cells contain and secrete renin
