functions of the urinary system
1. regulating plasma concentrations of ions;
2. regulating blood volume and pressure by adjusting the volume of water los and releasing erythropoietin and renin;
3. helping stabilize blood ph;
4. conserving nutrients;
5. eliminating organic wastes;
6. synthesizing calcitriol
how is the position of the kidneys maintained in the abdominal cavity?
1. overlying peritoneum; (but is retroperitoneal organ)
2. contact with adjacent visceral organs;
3. supporting connective tissues
three concentric layers of connective tissue in the kidneys?
renal capsule, adipose capsule, renal fascia (most outer)
what does the renal lobe contain?
1. renal pyramid; 2. overlying area of renal cortex; 3. adjacent tissues of the renal columns
what does the vasculature of the kidneys include?
renal, segmental, interlobar, arcuate, and interlobular arteries to the afferent arteries that supply the nephrons
how does the blood flow in the kidneys?
from the nephron, into the interlobular, arcuate, interlobar, and renal veins
what does sympathetic activation do to kidneys?
regulates glomerular blood flow and pressure, stimulates renin release, and accelerates sodium ion and water reabsorption
what does the nephron consist of?
1. renal corpuscle - plasma filtered via glomerulus and Bowman's capsule
2. renal tubule - prox convoluted tubule, loop of Henle, distal convoluted tubule
where does tubular fluid travel from the renal corpuscle?
through the proximal convoluted tubule (PCT), the loop of Henle (nephron loop) and the distal convoluted tubule (DCT) then through the connecting tubule, collecting duct, and papillary duct to reach the renal minor calyx
long loops of Henle extending deep into medlla
allow kidney to excrete more diluted or concentrated urine
what are nephrons responsible for?
1. Glomerular filtration (filtrate to cappillaries in g. capsule to renel tubule
2. Tubular reabsorption of organic nutrients, water, ions
3. Tubular Secretion
what happens at the glomerulus?
podocytes of visceral epithelium wrap their feet around the capillaries
where does blood go from the efferent arteriole?
enters the peritubular capillaries and the vesa recta that follow the loops of Henle in the medulla
function of PCT
actively reabsorbs nutrients, ions, plasma proteins, and electrolytes from the tubular fluid
what does the loop of Henle's descending limb do?
delivers fluid to the distal convoluted tubule (DCT)
what does reabsorption in the PCT and loop of Henle reclaim?
all of the organic nutrients, 85% of the water, and more than 90% of the Na and Cl ions
distal convoluted tubule is an important site for what?
1. active secretion of ions, acids, and other materials;
2. reabsorption of sodium ions;
3. adjusting osmotic concentration and balance
what is juxtaglomerular appartaus composed of?
macula densa, juxtaglomerular cells, extraglomerular mesangial cells