Chapter 18: Urinary System and Fluid Balance

Created by

Eunice Mallari

Cards (62)

Urinary System 
the major excretory system of the body
Some organs in other systems also eliminate wastes, but they are not able to compensate in the case of kidney failure
Urinary System Functions 
Excretion
Regulation of blood volume and pressure
Regulation of blood solute concentration
Regulation of extracellular fluid pH
Regulation of red blood cell synthesis
Regulation of Vitamin D synthesis
Components of the Urinary System
Two kidneys
Two ureters
One urinary bladder
One urethra
Kidney Characteristics 
Bilateral retroperitoneal organs
bean shaped
weigh 5 ounces (bar of soap or size of fist)
Kidney Location 
between 12th thoracic and 3rd lumbar vertebra
Renal capsule 
connective tissue around each kidney
protects and acts as a barrier
Hilum 
indentation
contains renal artery, veins, nerves, ureter
Renal Sinus 
contains renal pelvis, blood vessels, fat
Renal cortex 
outer portion
Renal medulla 
inner portion
Renal pyramid 
Cone shaped structures in the medulla whose bases project into the cortex
Renal papillae 
tip of pyramids which drain into calyces
Renal pelvis 
where calyces join together
narrows to form ureter
Nephron 
the functional unit of the kidney
Each kidney has over one million nephrons.
Juxtamedullary nephrons 
renal corpuscles are deep in the cortex near the medulla
long loops of Henle extend deep into the medulla
Well adapted for water conservation
About 15% of nephrons
Cortical nephrons 
Renal corpuscles distributed throughout the cortex
Loops of Henle are shorter and closer to the outer edge of the cortex than juxtamedullary nephrons
Renal Corpuscle 
The filtration portion of the nephron
Glomerulus 
A network of capillaries twisted around each other like a ball of yarn
Bowman’s capsule 
enlarged end of nephron surrounds glomerulus
opens into proximal convoluted tubule
contains podocytes (specialized cells around glomerular capillaries)
Podocytes 
specialized cells around glomerular capillaries
found in bowman's capsule
Outer layer of Bowman capsule
simple squamous epithelial cells that become cube-shaped at the beginning of the proximal convoluted tubule
Inner layer of Bowman capsule
cells called podocytes, which wrap around the glomerular capillaries
Porous capillaries 
highly permeable due to the presence of pores. Neither large proteins nor blood cells can fit through them.
Porous inner layer of Bowman capsule 
A basement membrane lies between the endothelial cells of the glomerular capillaries and the podocytes of the Bowman capsule
afferent arteriole 
supplies blood to the glomerulus for filtration
efferent arteriole 
transports the filtered blood away from the glomerulus
Efferent arteriole has smaller diameter than afferent arteriole creating a high pressure in the capillaries
structures in the corpuscle make up the filtration membrane
Filtrate 
is the fluid filtered from the glomerular capillaries. Enters the lumen inside the Bowman capsule
Proximal convoluted tubule 
where filtrate passes first
drains filtrate from Bowman capsule
Loop of Henle 
contains descending and ascending loops
water and solutes pass through thin walls by diffusion
Distal convoluted tubule 
structure between Loop of Henle and collecting duct
Collecting duct 
empties into calyces
carry fluid from cortex through medulla
Flow of Filtrate through Nephron
Renal corpuscle
Proximal convoluted tubule
Descending loop of Henle
Ascending loop of Henle
Distal convoluted tubule
Collecting duct
Papillary duct
Urine formation involves three processes:
Filtration
Tubular Reabsorption
Secretion
Filtration 
occurs in the renal corpuscle, blood plasma leave glomerulus and enters Bowman space
Tubular Reabsorption 
involves removing substances from the filtrate and placing them back into the blood
Secretion 
involves taking substances from the blood at a nephron area other than the renal corpuscle and putting back into the nephron tubule