Ch 14 Part 1 -- Urinary System -- VTPP 435

Ch 14 Part 1 -- Urinary System -- VTPP 435

Kidney

-bean-shaped pair
-located behind abdominal cavity in front of back muscles
-act directly on plasma to filter 20% of it
-right kidney on top of liver
-left kidney on top of spleen

Renal Artery and Renal Vein

-enter and leave kidneys at medial indentation
-supply blood to kidney

Renal Pelvis

-where urine drains into after being formed
-central collecting cavity at medial inner core of each kidney just before ureter

Ureter

-where urine is channeled into after renal pelvis
-a duct that exits at medial border close to renal artery & vein
-each kidney has one
-carry urine to bladder

Urinary Bladder

-temporarily stores urine
-hollow, distensible
-smooth muscle-walled sac
-has dual innervation

Urethra

-tube that empties urine from bladder due to bladder constriction
-for females: short straight length from bladder to outside
-for males: long and curved length from bladder thru prostate and penis to outside

Nephron

-functional unit of kidney
-bound together by connective tissue
-has "vascular component" and a "tubular component"

Renal Cortex

-granular, outer kidney region layer

Renal Medulla

-inner region made of the renal pyramids
-renal pyramids -- striated triangles

Renal Capsule

-strong fibrous proteins of collagen and elastin
-covers renal cortex as the very outer layer of kidney

Glomerulus

-dominant part of vascular component
-filters water and solutes
-filters a protein free plasma into the tubular component
-ball-like tuft of capillaries

Afferent Arteriole

-carries blood to glomerulus
-small vessels that divided from renal artery to supply one to each nephron

Efferent Arteriole

-carries blood from glomerulus that was not filtered into tubular component
-formed from glomerular capillaries rejoining
-subdivides into peritubular capillaries

Peritubular Capillaries

-supply renal tissue
-help with exchanges with fluid in tubular lumen during conversion of filtered fluid into urine
-intertwined around tubular system
-rejoin to form venules that drain into renal vein for blood to leave kidneys

Bowman's Capsule

-an expanded, double walled cup
-surrounds glomerulus to collect fluid filtered from glomerular capillaries
-then sends fluid to proximal tubule

Proximal Tubule

-uncontrolled reabsorption & secretion of selected substances occur here
-lies in renal cortex
-is highly coiled or convolved

Loop of Henle

-establishes an osmotic gradient in renal medulla
-osmotic gradient needed for kidney to produce varying urine concentration
-forms sharp U-shaped or hair pin loop that dips into renal medulla
-helps reabsorb water and sodium from filtrate

Juxtaglomerular Apparatus

-formed from specialized vascular and tubular cells
-produces substances needed in control of kidney function
-lies next to glomerulus

Distal Tubule & Collecting Duct

-controlled reabsorption of Na+ and water and secretion of K+ and H+
-fluid that leaves is urine and enters renal pelvis
-distal tubule entirely in renal cortex and empties into collecting duct
-collecting duct -- each one drains fluid from up to 8 separate nephrons and plunges down through renal medulla to empty fluid into renal pelvis

Cortical Nephrons

-80% of nephrons
-glomeruli lie in outer layer of renal cortex
-short loops of Henle
-mainly excretory and regulatory functions
-filter & exchange water and solutes with 2 sets of blood vessels and tissue fluid in kidneys

Juxtamedullary Nephrons

-20% of nephrons
-glomeruli lie in innery layer of renal cortex next to renal medulla
-loops of Henle are long into medulla
-Vasa Recta -- supply blood to medulla
-help develop osmotic gradient to concentrate urine

Glomerular Filtration

-nondiscriminant filtration of a protein free plasma from glomerulus into Bowman's capsule
-filters about 20% of plasma that enters glomerulus

Tubular Reabsorption

-selective movement of filtered substances from tubular lumen into peritubular capillaries plasma
-reabsorbed substances carried by peritubular capillaries to venous system --> heart to be recirculated
-over 90% of filtered plasma is reabsorbed the rest is urinated

Tubular Secretion

-selective movement of non filtered substances from peritubular capillaries into tubular lumen
-helps filter 80% of the unfiltered plasma in peritubular capillaries into tubule