histology of the renal system

Question 1

functions of the urinary tract?

Answer 1

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

Question 2

gross structure of the kidney?

Answer 2

Bean shaped organ (10-12cm long X 5-6cm wide X ~3cm thick) in the upper retroperitoneal area.

Question 3

what is the kidney covered in?

Answer 3

Organ is covered by a thin but strong capsule of dense collagen fibres.

Question 4

what is the hilum?

Answer 4

site of entry of renal artery and exit of renal vein and ureter.

Question 5

what are the parts of the kidney from kidney to ureter?

Answer 5

renal pelvis, major calyces (singular calyx), minor calyces.

Question 6

what are the layers of the kidney?

Answer 6

Has a cortex and a medulla with the medulla further subdivided into layers.

Question 7

the medulla is further divided into?

Answer 7

Medulla divided into medullary pyramids (8-18 per kidney), with apices pointing toward the hilum (called the papillae) ending on the minor calyces.

Question 8

each medullary pyramid

Answer 8

Each medullary pyramid and its associated cortical tissue is considered a lobe of the kidney.

Question 9

what are the renal columns?

Answer 9

doesn’t anchor the cortex down

provides a conduit for the incoming blood supply

Question 10

fat pads of the kidney?

Answer 10

renal sinus

Question 11

renal capsule

Answer 11

The kidney is covered by a fibrous capsule. The capsule is continuous with the connective tissue that lines the renal sinus.

Question 12

what is the basic functional unit of the kidney?

Answer 12

the nephron

Question 13

what is the nephron composed of?

Answer 13

renal corpuscle and renal tubules

Question 14

how many nephrons does each human kidney contain?

Answer 14

600,000-1 million nephrons

Question 15

what is the total length of a nephron?

Answer 15

Total length of a nephron is approximately 45-65mm

Question 16

what is the function of the renal corpuscle?

Answer 16

production and collection of glomerular filtrate

Question 17

what is the renal corpuscle formed from?

Answer 17

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).

Question 18

what is the supply of the tuft of capillaries?

Answer 18

The tuft of capillaries is supplied by an afferent arteriole and drained by an efferent arteriole.

Question 19

what are the two cell layers that separate the blood from the glomerular filtrate?

Answer 19

the capillary endothelium and a specialised epithelium which lies on top of the glomerular capillaries

Question 20

what are the epithelial cells called?

Answer 20

podocytes, outer layer of cells

Question 21

the endothelium is fenestrated with?

Answer 21

pores 70-90nm in diameter, and the podocytes have interdicting cell processes forming filtration slits about 25nm wide

Question 22

what is present between the two layers in the renal corpuscle?

Answer 22

Between these two layers is a thicker than usual (0.3µm rather than 0.05µm) basal lamina, made up of a feltwork of GAGs.

Question 23

what produces the connective tissue in the renal corpuscle?

Answer 23

Scattered mesangial cells produce a connective tissue core called the mesangium. These cells have several functions, including support and removal of debris.