histology of the renal system Flashcards
functions of the urinary tract?
Maintain water and electrolyte homeostasis, body fluid osmolarity and acid-base balance.
Excrete toxic metabolic waste products (mainly urea and creatinine).
Act as an endocrine gland, producing renin (enzyme) and erythropoietin (maintenance of RBC production)
The UT accomplishes 1 and 2 by the production, storage and voiding of urine
gross structure of the kidney?
Bean shaped organ (10-12cm long X 5-6cm wide X ~3cm thick) in the upper retroperitoneal area.
what is the kidney covered in?
Organ is covered by a thin but strong capsule of dense collagen fibres.
what is the hilum?
site of entry of renal artery and exit of renal vein and ureter.
what are the parts of the kidney from kidney to ureter?
renal pelvis, major calyces (singular calyx), minor calyces.
what are the layers of the kidney?
Has a cortex and a medulla with the medulla further subdivided into layers.
the medulla is further divided into?
Medulla divided into medullary pyramids (8-18 per kidney), with apices pointing toward the hilum (called the papillae) ending on the minor calyces.
each medullary pyramid
Each medullary pyramid and its associated cortical tissue is considered a lobe of the kidney.
what are the renal columns?
doesn’t anchor the cortex down
provides a conduit for the incoming blood supply
fat pads of the kidney?
renal sinus
renal capsule
The kidney is covered by a fibrous capsule. The capsule is continuous with the connective tissue that lines the renal sinus.
what is the basic functional unit of the kidney?
the nephron
what is the nephron composed of?
renal corpuscle and renal tubules
how many nephrons does each human kidney contain?
600,000-1 million nephrons
what is the total length of a nephron?
Total length of a nephron is approximately 45-65mm
what is the function of the renal corpuscle?
production and collection of glomerular filtrate
what is the renal corpuscle formed from?
Formed from a tuft of capillaries called the glomerulus and the cup of simple squamous epithelium at the blind end of the nephron which the capillaries invaginate into (called Bowman’s capsule).
what is the supply of the tuft of capillaries?
The tuft of capillaries is supplied by an afferent arteriole and drained by an efferent arteriole.
what are the two cell layers that separate the blood from the glomerular filtrate?
the capillary endothelium and a specialised epithelium which lies on top of the glomerular capillaries
what are the epithelial cells called?
podocytes, outer layer of cells
the endothelium is fenestrated with?
pores 70-90nm in diameter, and the podocytes have interdicting cell processes forming filtration slits about 25nm wide
what is present between the two layers in the renal corpuscle?
Between these two layers is a thicker than usual (0.3µm rather than 0.05µm) basal lamina, made up of a feltwork of GAGs.
what produces the connective tissue in the renal corpuscle?
Scattered mesangial cells produce a connective tissue core called the mesangium. These cells have several functions, including support and removal of debris.
