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
contents of the urinary system
kidneys, ureters, urinary bladder, urethra
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)
covers outer portion of kidney
helps keep shape
what surrounds the renal capsule?
what does the renal fascia do?
anchors the kidney to ab wall
what is attached to the hilus of the kidney?
the ureter and renal blood vessels
divisions of the kidney
outer renal cortex, central renal medulla,
cortex + pyramids
what are renal columns composed of?
what do renal columns do?
separate adjacent pyramids
what does the renal lobe contain?
1. renal pyramid; 2. overlying area of renal cortex; 3. adjacent tissues of the renal columns
what is the renal sinus continuous with?
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 innervates the kidneys and the ureters?
what does sympathetic activation do to kidneys?
regulates glomerular blood flow and pressure, stimulates renin release, and accelerates sodium ion and water reabsorption
what is the basic functional unit of the kidney?
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
short loops of Henle that dives into r. medulla
long loops of Henle extending deep into medlla
allow kidney to excrete more diluted or concentrated urine
what do the efferent arteriole provide blood to?
the peritubular capillaries
what do peritubular capillaries surround?
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 does the renal corpuscle contain?
capillary knot of the glomerulus and Bowman's capsule
what is another name for Bowman's capsule?
what happens at the glomerulus?
podocytes of visceral epithelium wrap their feet around the capillaries
what are pedicels of the podocytes separated by?
narrow filtration slits
what does the capsular space separate?
the parietal and visceral epithelia
notable characteristic of lamina densa of basal lamina?
it is unusually thick
how does blood arrive at the vascular pole of the renal corpuscle?
via the afferent arteriole
how does blood depart from the vascular pole of the renal corpuscle?
in the efferent arteriole
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
which convoluted tubule contains the most microvilli
proximal convoluted tubule (PCT)
function of PCT
actively reabsorbs nutrients, ions, plasma proteins, and electrolytes from the tubular fluid
what do the limbs of loop of Henle contain?
thick segment and thin segment
what does the loop of Henle's descending limb do?
delivers fluid to the distal convoluted tubule (DCT)
what is passively transported out of the ascending limb of the loop of Henle?
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
what does juxtaglomerular apparatus secrete?
the hormones renin and erythropoietin
what does the DCT open into?
the collecting system
what does the collecting system consist of?
connecting tubules, collecting ducts, papillary ducts
functions of collecting system?
1. transports fluid from the nephron to the renal pelvis; 2. adjusts the osmotic concentrations and volume