Anatomy - Urinary System

two types of nephrons

1. Cortical (in renal cortex) 2. Juxtamedullary (closer to renal medulla)

ADH and permeability of collecting system

Higher levels of ADH ----> high permeability ----> more water reabsorbed out of duct into medulla ----> more concentrated urine

Location of kidneys

Retroperitoneal between last T12 and L3 Right kidney is slightly lower than left (because of liver)

minor calyx

a cup-shaped extension of the pelvis that encircles the apex of a pyramid

innervation of kidneys

both branches of ANS, however, mostly sympathetic postganglionic fibers

urine storage reflex

by spinal reflexes and pontine storage center 1) increase sympathetic activity 2) stimulate contraction of the external urethral sphincter

renal pelvis

connected to the ureter major calyces combine to form it

kidney lobe

contains a renal pyramid, the overlying area of renal cortex

innervation of external urethral sphincter

controlled by branches of the hypogastric plexus along with internal urethral sphincter, voluntary control of ex. by perineal branch of pudendal nerve

renal medulla

deep to the cortex 6-18 distinct triangular structures- renal pyramids The base of each pyramid faces the cortex The tip (renal papilla) projects into the renal sinus Bans of cortical tissue (renal columns) extend into the medulla

renal cortex

deep to the renal capsule granular and reddish-brown color

nephron loop

descending limb and ascending limb thin and thick segments -- height of epithelium

collecting system

each nephron empties into collecting system through connecting tubule to collecting duct ---> leaves cortex ---> papillary duct

major calyx

formed by four or five minor calyces

vasa recta

group of slender capillaries, absorb water and return it to the general circulation

Anterior surface of right kidney is covered by...

liver, right colic (hepatic) flexure, and duodenum

histology of bladder

mucosa - contains prominent rug - is transitional epithelium submucosa - connective tissue outer muscular layer - inner and outer longitudinal layers of smooth muscle, with a layer of smooth muscle sandwiched in between adventitia

urine voiding reflex

occurs by spinal reflexes and pontine micturition center 1) increase parasympathetic activity 2) decrease somatic motor nerve activity

vascular pole

parietal and visceral epithelia are connected here. glomerular capillaries are connected to the afferent and efferent arterioles.

innervation of urinary bladder

postganglionic fibers from ganglia and hypogastric plexus and parasympathetic fibers from intramural ganglia

ascending limb function

pumps sodium and chloride ions out of the tubular fluid.

distal convoluted tubule

smaller in diameter than PCT epithelial cells lack microvilli boundaries between epithelial cells are not easily seen Main Function - Secretion

renal corpuscle

spherical structure consisting of the glomerular capsule and glomerulus

cover anterior surface of left kidney

spleen, stomach, pancreas, jejunum, and left colic (splenic) flexure

proximal convoluted tubule

the first part of the renal tubule. begins at the tubular pole of the renal corpuscle, opposite the vascular pole. lined by simple cuboidal epithelium with microvilli on the apical surface--increase surface area for reabsorption (main function of PCT)

lines minor and major calyces, renal pelvis, ureters, urinary bladder, and proximal portion of urethra

transitional epithelium (tolerates cycles of distension and relaxation)

trigone

triangular area in the urinary bladder in which the ureters enter and the urethra exits

Filtration as BP forces fluid+solutes out of glomerular capillaries and into capsular space

1) endothelial surface layer: luminal surface of endothelial cells of glomerular capillaries --gycocalyx 2) capillary endothelium --fenestrated 3) basement membrane: surrounding glomerular capillary endothelium, thicker than typical capillary basement membrane 4) glomerular epithelium: podocytes have long cellular processes 5) subpodocyte space:

Layer of connective tissue that protect and stabilize each kidney

1) fibrous capsule - covers the outer surface of the entire organ. collagen fibers. 2) perinephric fat or perirenal fat capsule - surround the fibrous capsule 3) renal fascia - anchors the kidney to surrounding structures and attaches to the deep fascia surrounding the muscles of the posterior body wall.

Cells of Juxtaglomerular complex

1) macula densa Tall closely packed epithelial cells. immediately adjacent to afferent arteriole, at the vascular pole of glomerulus 2) juxtaglomerular cells modified smooth muscle cells in the wall of the afferent arteriole that secrete renin 3) extraglomerular mesangial cells located in triangular space between afferent and efferent glomerular arterioles.

subdivisions of male urethra

1) prostatic urethra 2) the membranous urethra 3) spongy urethra

Tubular passageway from renal corpuscle for filtrate

1) proximal convoluted tubule 2) nephron loop, or loop of Henle 3) distal convoluted tubule

Histology of ureters

1)inner mucosa lined bya tansitional epithelium 2) middle muscular layer made up of inner longitudinal and outer circular layers of smooth muscle 3) outer adventitia that is continuous with the fibrous capsule of the kidney and the peritoneum of the abdominal wall

glomerulus

A ball of capillaries surrounded by Bowman's capsule in the nephron and serving as the site of filtration in the vertebrate kidney.