Chapter 24: Urinary System

Renal Pelvis

A flat, funnel-shaped tube that is simply an expanded superior part of the ureter.

Renal Medulla

A frontal section of the kidney deep to the cortex which consists of cone-shaped masses.

Renal Cortex

A frontal section of the kidney that is more superficial, light in color and has a granular appearance.

Filtration Membrane

Actual filter that lies between the blood in the glomerulus and the capsular space consisting of three layers.

Internal Urethral Sphincter

An involuntary smooth muscle that keeps the urethra closed when urine is not being passed and prevents dribbling of urine between voidings.

Major Calices

Branching extensions of the renal pelvis form two or three _____ _______.

Peritubular Capillaries

Capillaries that surround the tubules in the kidney.

Filtration

During this mechanism of urine production, a filtrate of blood leaves the kidney capillaries and enters the renal tubule. It resembles tissue fluid because it contains small molecules of blood plasma.

Reabsorption

During this mechanism of urine production, most of the nurients, water, and essential ions are recovered from the filtrate and returned to the blood of capillaries in surrounding CT.

Visceral Layer

Layer that clings to the glomerulus and consists of unusual, branching epithelial cells called popcytes.

Cortical Nephrons

Represent 85% of nephrons, located mostly within the cortex

Nephron

Smallest functional unit in the kidney; Produces urine.

Macula Densa

Terminal portion of the nephron loop adjacent to the granular cells that consists of tall, packed epithelial cells that act as chemoreceptors for monitoring solute concentrations in filtrate.

Renal Corpuscle

Where filtration occurs in the nephron.

Trigone

A triangular region on the posterior wall of the bladder formed by openings for ureters and the urethra.

Vasa Recta

Capillary-like blood vessels that supply the loops of Henle and collecting ducts in the medulla of the kidney.

Extraglomerular Mesanglial Cells

Cells that interact with cells of the macula densa and granular cells to regulate blood pressure.

Minor Calices

Major Calices divide to form several ______ ______ which are cup shaped tubes that enclose the papillae of the pyramids.

Capsular Space

The hollow interior of the glomerular capsule that accepts large quantities of fluid and small molecules from the capillary blood.

Ureter

Tube that carries urine from the bladder to the exterior.

Proximal Convoluted Tubule

Tubule confined entirely to the renal cortex; is most active in resorption and secretion.

Distal Convoluted Tubule

Tubule confined to the renal cortex that is specialized for the selective secretion and resorption of ions.

Nephron Loop (loop of Henle)

U-shaped loop that consists of a descending limb and an ascending limb.

Micturition

Urination or voiding; emptying the bladder.

Arcuate Vein.

Vein that blood leaving the cortex drains into that drains into the interlobar vein.

Interlobar Vein

Vein that blood leaving the cortex drains into that drains into the renal vein.

Renal Veins

Vein that the blood leaving the cortex drains into and exits the kidney at the hilum and empties the inferior vena cava.

Cortical Radiate Vein

Veins that blood leaving the cortex drains into that are branching along the cortex that drains into the arcuate vein.

Interlobar Arteries

Within the renal sinus, each segmental artery divides into __________ _________ which lie in the renal columns between the renal pyramids.

Renal Columns

Inwards extensions of the renal cortex that separate adjacent pyramids.

Granular Cells

Modified smooth muscle cells with secretory granules containing a hormone called renin.

Podocytes

Octopus shaped epithelial cells that surround the glomerular capillaries; they help produces and maintain the basement membrane (a filtration membrane in the kidney).

Collecting Ducts

Receives urine from several nephrons and runs straight through the cortex into the deep medulla.

Kidneys

Red-brown, bean shaped organs that lie behind the parietal peritoneum in the superior lumbar region of the posterior abdominal wall.

Juxtamedullary Nephrons

Represent 15% of nephrons, their renal corpuscles lie near the cortex-medulla junction.

Glomerular Arterioles

The arteries of the kidney give rise to ____________ _________ which feed into the peritubular capillaries.

Renal Pyramids

The cone shaped masses that make up the renal medulla.

Detrusor

Thick, muscular layer that forms the middle layer of the bladder consisting of smooth muscle fibers; contraction of this muscle squeezes urine from the bladder during urination.

Filtration Slits

Thin clefts between the foot processes.

Urethra

Thin-walled tube that drains urine from the badder and conveys it out of the body.

Renal Arteries

Arteries that branch at right angles from the abdominal aorta to reach the kidney.

Cortical Radiate Arteries

Arteries that radiate outward from the arcuate arteries and supply the cortical tissue.

Segmental Arteries

As each renal artery approaches the kidney, it divides into five _________ ________ that enter the hilum.

Arcuate Arteries

At the medulla-cortex junction, the interlobar arteries branch into _______ _______ which arch over the bases of the renal pyramids.

Parietal Layer

External layer of the glomerular capsule made of simple sqamous epithelium that contributes to the structure of the capsule,

Renal Fascia

External to the perirenal fat capsule is an envelope of ______ ______ which contains an external layer of fat which cushions the kidney against blows and keeps it in place.

Perirenal Fat Capsule

External to the renal capsule is the _______ _______ _______.

Afferent Arteriole

Feed and drain the glomerulus; Arise from the cortical radiate arteries that run through the renal cortex

Efferent Arteriole

Feed and drain the glomerulus; narrower arteriole which results in higher blood pressure and forces the filtrate out of the blood and into the glomerular capsule.

Papillary Ducts

Formed by collecting ducts; empties into the minor calices.

Renin

Hormone released by the kidneys that is involved with raising blood pressure, blood volume, and the sodium concentration in blood.

Tubular Secretion

In this mechanism of urine production, additional undesirable molecules are moved into the tubule from the blood of surrounding capillaries.

Glomerulus

A ball of capillaries forming part the nephron in the kidney; forms a filtrate that will be modified into urine.

Bladder

A collapsible, muscular sac that stores and expels urine.

Glomerular Capsule (Bowman's Capsule)

A cup-shaped hollow capsule that surrounds the glomerulus.

External Urethral Sphincter

A skeletal muscle used to inhibit urination voluntarily until the proper time.

Hilum

A slit on the surface of an organ through which the vessels and nerves enter and leave; organs include spleen, lungs, kidneys, lymph nodes, and ovaries.

Juxtaglomerular Complex (apparatus)

A structure that functions in the regulation of blood pressure; an area of specialized contact between the terminal end of the nephron loop and the afferent arteriole.

Fibrous Capsule

A thin, tough layer of dense CT that adheres directly to the kidney's surface, maintaining its shape and forming a barrier than inhibits the spread of infection from surrounding areas.