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| 31. | juxtamedullary nephrons | nephrons adjacent to the border of the cortex and medulla with loops of Henle that extend into the renal medulla |
| 32. | leaky tight junctions | tight junctions in which the sealing strands of proteins between the membranes of adjacent cells are fewer in number and incomplete; allows limited intercellular movement of solvent and solutes |
| 33. | leukocyte esterase | enzyme produced by leukocytes that can be detected in the urine and that serves as an indirect indicator of urinary tract infection |
| 34. | loop of Henle | descending and ascending portions between the proximal and distal convoluted tubules; those of cortical nephrons do not extend into the medulla, whereas those of juxtamedullary nephrons do extend into the medulla |
| 35. | macula densa | cells found in the part of the DCT forming the JGA; sense Na+ concentration in the forming urine |
| 36. | medulla | inner region of kidney containing the renal pyramids |
| 37. | mesangial | contractile cells found in the glomerulus; can contract or relax to regulate filtration rate |
| 38. | micturition | also called urination or voiding |
| 39. | myogenic mechanism | mechanism by which smooth muscle responds to stretch by contracting; an increase in blood pressure causes vasoconstriction and a decrease in blood pressure causes vasodilation so that blood flow downstream remains steady |
| 40. | nephrons | functional units of the kidney that carry out all filtration and modification to produce urine; consist of renal corpuscles, proximal and distal convoluted tubules, and descending and ascending loops of Henle; drain into collecting ducts |
| 41. | net filtration pressure | (NFP) pressure of fluid across the glomerulus; calculated by taking the hydrostatic pressure of the capillary and subtracting the colloid osmotic pressure of the blood and the hydrostatic pressure of Bowman's capsule |
| 42. | oliguria | below normal urine production of 400-500 mL/day |
| 43. | osteomalacia | softening of bones due to a lack of mineralization with calcium and phosphate; most often due to lack of vitamin D; in children, osteomalacia is termed rickets; not to be confused with osteoporosis |
| 44. | pedicels | finger-like projections of podocytes surrounding glomerular capillaries; interdigitate to form a filtration membrane |
| 45. | peritubular capillaries | second capillary bed of the renal portal system; surround the proximal and distal convoluted tubules; associated with the vasa recta |
| 46. | physiological sphincter | sphincter consisting of circular smooth muscle indistinguishable from adjacent muscle but possessing differential innervations, permitting its function as a sphincter; structurally weak |
| 47. | podocytes | cells forming finger-like processes; form the visceral layer of Bowman's capsule; pedicels of the podocytes interdigitate to form a filtration membrane |
| 48. | polyuria | urine production in excess of 2.5 L/day; may be caused by diabetes insipidus, diabetes mellitus, or excessive use of diuretics |
| 49. | principal cell | found in collecting ducts and possess channels for the recovery or loss of sodium and potassium; under the control of aldosterone; also have aquaporin channels under ADH control to regulate recovery of water |
| 50. | proximal convoluted tubules | (PCTs) tortuous tubules receiving filtrate from Bowman's capsule; most active part of the nephron in reabsorption and secretion |
| 51. | renal columns | extensions of the renal cortex into the renal medulla; separates the renal pyramids; contains blood vessels and connective tissues |
| 52. | renal corpuscle | consists of the glomerulus and Bowman's capsule |
| 53. | renal cortex | outer part of kidney containing all of the nephrons; some nephrons have loops of Henle extending into the medulla |
| 54. | renal fat pad | adipose tissue between the renal fascia and the renal capsule that provides protective cushioning to the kidney |
| 55. | renal hilum | recessed medial area of the kidney through which the renal artery, renal vein, ureters, lymphatics, and nerves pass |
| 56. | renal papillae | medullary area of the renal pyramids where collecting ducts empty urine into the minor calyces |
| 57. | renal pyramids | six to eight cone-shaped tissues in the medulla of the kidney containing collecting ducts and the loops of Henle of juxtamedullary nephrons |
| 58. | renin | enzyme produced by juxtaglomerular cells in response to decreased blood pressure or sympathetic nervous activity; catalyzes the conversion of angiotensinogen into angiotensin I |
| 59. | retroperitoneal | outside the peritoneal cavity; in the case of the kidney and ureters, between the parietal peritoneum and the abdominal wall |
| 60. | sacral micturition center | group of neurons in the sacral region of the spinal cord that controls urination; acts reflexively unless its action is modified by higher brain centers to allow voluntary urination |
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