Flashcards in kidney histology Deck (16):
Are the kidneys intra or retroperitoneal
1. Describe the major anatomical regions of the kidney including the renal artery and vein, major and minor calyces, medulla, cortex, renal pyramids and regions containing collecting ducts
2. Outline the flow of blood into and within the kidney finishing with its exit in the renal vein
Abdominal aorta > renal artery > anterior and posterior segments > interlobar arteries (btw medullary pyramids) > Arcuate arteries (medullary-cortical junction) > interlobular arteries (cortex) > afferent arterioles (supply glomeruli in cortex) > efferent arterioles >vasa recta (capillary plexus in cortex) or interlobular veins (medulla) > arcuate veins > interlobar vins > renal vein
Which parts of the nephron are responsible for blood filtrtion and selective resorption?
Blood filtration: renal corpuscle. Resorption: renal tubules
Location of renal corpuscles
Structure of renal corpuscle
It consists of a condensed capillary network (the glomerulus) surrounded by an epithelial capsule (Bowman’s capsule).
Structure of glomerulus
In the interior of the capillary bed is the connective tissue of the mesangium containing mesangial cells. On the outside of the capillaries is a special layer of cells called podocytes, which comprise the visceral epithelium of Bowman’s capsule.Between the endothelial cell of the capillary and the podocytes is a basal lamina called the filtration barrier that selectively filters the blood.
Bowmans capsule structure
Podocytes on the outside of capillaries form the visceral epithelium. The parietal epithelium is a simple squamous epithelium that is continuous with the visceral epithelium and it also turns into the wall of the proximal convoluted tubule
Describe the thickness of the glomerular basal lamina in disease
The thickness of the lamina is markedly increased in certain diseases such as diabetes mellitus, and autoimmune
disorders such as lupus.
Role of mesangial cells
Mesangial cells secrete the matrix that is continuous with the basal lamina in the inner part of the glomerulus where the mesangium meets the endothelial cells of the capillaries. The mesangial cells are phagocytic and are thought to play a role in maintenance of the filtration lamina in the inner portion of the glomeruli. These cells are also contractile.
Structure of proximal tubule
Cuboidal epithelium with microvilli in lumen and tight junctios near luminal surface. Na-K pumps on basolateral side drives uptake of sodium, glucose and amino acids by facilitated diffusion on lumen side. Absorbs 75-85% volume of filtrate
Loop of Henle structure
Cells in the thin loops are simple squamous epithelium, with the thin descending and thin ascending portions having different permeabilites to NaCl and water. Cells of the thick ascending loop are cuboidal and active transporters of sodium
Distal tubule structure and function
In the cortex. Cells are cuboidal, with short microvilli
on the luminal side which are not as abundant as in proximal tubule cells. Acid- base balance, responds to aldosterone and ADH. Na-K pumps in basolateral side drive transport of sodium.
Structure of collecting tubules/ducts
Principal (clear) cells and intercalated cells (dark). Cells are cuboidal with short microvilli and become more columnar towards the collecting duct. Principal cells are active transporters, and couple sodium uptake to potassium secretion into the lumen of the tubules. Intercalated cells secrete H+ and reabsorb bicarbonate. ADH increases water resorption
Juxtaglomerular complex structure/function
specialization of cells located at the vascular pole of the renal corpuscle. The macula densa connects the distal convoluted tubule to afferent/efferent arteriole region. Juxtaglomerular cells are smooth muscle cells in afferent arteriole wall that secrete renin. Lacis cells directly contact macula densa and juxtaglomerular cells