CH 26 The Urinary System

The medulla contains:

*6-18 renal pyramids, whose tips (renal papillae) project into the renal sinus.

Urine is produced by the kidneys..

-It is a fluid waste product containing water, ions, and soluble compounds

Structures/organs of the urinary system include:

-Pair of kidneys -Pair of ureters -Urinary bladder -Urethra

the glomerular filtrate (or simply filtrate) is subdivided into:

-Proximal convoluted tubule (PCT) -Nepheron loop (loop of Henle) -Distal convoluted tubule (DCT)

what is the diagnostic test for kidney stones called?

-Pylogram -an image obtained by taking an X-ray of the kidneys after a radiopaque compound has been administered.

Three concentric layers of connective tissue in the kidneys:

-Renal capsule: (fibrous) covers the outer surface of the organ -Adipose capsule: (perinephric fat) surrounds the renal capsule -Renal fascia : collagen fibers anchors the kidneys to surrounding structures

Urination (micturition)

-Urine is forced out of the body from the urinary bladder through the urethra.

the loop of Henle includes

-a descending limb -a ascending limb *each contains a thick segment & a thin segment.

the female urethral lining is usually

-a transitional epithelium near the urinary bladder * the rest is usually a stratified squamous epithelium

Reabsorption in the PCT and the loop of Henle reclaims:

-all of the organic nutrients -85% of the water -more than 90% of the Na and Cl ions.

distal convoluted tubule

-an important site for the active secretion of ions, acids, and other materials -the reabsorption of sodium ions and adjusting osmotic concentration and balance

the wall of each ureter consist of

-an inner mucosal layer -a middle muscular layer -an outer connective tissue layer (adventitia)

The loops of Henle (nepheron loop)

-are short -the efferent arteriole provides blood to the peritubular capillaries that surrounds the renal tubules

nepheron

-basic functional unit of the kidney

juxtamedullary nepherons

-closer to the medulla -with their loops of Henle extending deep into the renal pyramids

the collecting system consists of

-connecting tubules -collecting ducts -papillary ducts

The proximal convoluted tubule (PCT)

-containing mostly dense microvilli -actively reabsorbs nutrients, ions, plasma proteins, and electrolytes from the tubular fluid.

renal lobe

-contains a renal pyramid -the overlying area of renal cortex -adjacent tissues of the renal columns

minor calyces

-continuous with the major calyces -receive urine from the collecting tubules of the renal pyramids and convey it to the major calyces

roughly 85% of the nepherons are:

-cortical nepherons -found within the cortex

Renal capsule (fibrous capsule)

-covers the outer surface of the organ. -layer of collagen fibers

renal corpuscle

-cup shaped chamber. -contains glomerulus (capillary network)

renal tubule

-empties into the collecting system and renal corpuscle -long, tubular portion of a nephron that produces and takes urine to the renal pelvis of a kidney

the male urethral lining caries :

-from a transitional epithelium at the urinary bladder -to a stratified columnar or a pseudostratified epithelium -then to stratified squamous epthelium near the external urethral orifice.

sympathetic activation regulates

-glomerular blood flow and pressure, stimulates renin release, and accelerates sodium ion and water reabsorption -renal nerves stimulate this in kidneys

The renal corpuscle contains the capillary knot of the:

-glomerulus & Bowman's capsule (glomerular capsule)

Urinary bladder

-hollow muscular organ -serves as a storage reservoir for urine

from the nepherons, blood flows into the (4 veins):

-interlobular vein -arcuate vein -interlobar vein -renal vein

the urinary bladder is STABILIZED by the

-median umbilical ligament (urachus) -lateral umbilical ligaments.

the process of urination is cooridinated by the:

-micturition reflex, which is initiated by stretch receptors in the bladder wall

rugae

-mucosal lining of the urinary bladder

the interior of the kidney is divided into:

-outer renal cortex -central renal medulla -inner renal sinus

At the glomerulus:

-podocytes of the visceral epithelium wrap their 'feet' around the capillaries.

Nepherons are responsible for:

-production of filtrate -reabsorption of organic nutrients -water -ions

The arteries (vasculature) of the kidneys includes:

-renal artery -segmental artery -interlobar artery -arcuate artery -interlobular artery (cortical radiate arteries) *these go to the afferent atrioles that supply nepherons

the juxtaglomerular apparatus secretes the hormones:

-renin -erythropoietin

Calculi

-solid structures formed from calcium deposits, magnesium, or crystals of uric acid in the kidneys.

Adipose capsule (perinephric fat)

-surrounds the renal capsule -thick layer

blood arrives at the vascular pole of the renal corpuscle via:

-the afferent arteriole and departs in the efferent arteriole.

DCT opens into

-the collecting system

the ascending limb delivers fluid to:

-the distal convoluted tubule (DCT) -sodium ions are passively transported out of the ascending limb.

The ureter and renal blood vessels are attached to:

-the hilus of the kidney.

tubular fluid modification and urine production END when the fluid ENTERS

-the minor calyx in the renal sinus

the ureters, urinary bladder, and urethra are responsible for

-transporting, storing, eliminating the urine.

the internal features of the urinary bladder include:

-trigone -neck -internal urethral sphincter

juxtaglomerular apparatus (15% of nephrons)

Composed of: -macula densa -juxtaglomerular cells -extraglomerular mesangial cells

from the efferent arteriole

blood enters the peritubular capillaries and the vesa recta that follow the loops of Henle in the medulla

papillary duct

drains into the renal pelvis

renal nerves

part of sympathetic autonomic nervous system which causes vasoconstriction/dilation to regulate blood flow

the kidneys and ureters are intervated by:

renal nerves

incontinence

An inability to control urination voluntarily

Renal fascia

anchors the kidney to surrounding structures

The functions of the urinary system include:

1. Regulating plasma concentrations of ions. 2. Regulating blood volume and pressure by adjusting the volume of water lost & releasing erythropoitin and renin 3. Helping stabilize blood pH 4. Conserving nutrients 5. Eliminating organic wastes 6. Synthesizing calcitriol

Age-related changes in the urinary system include:

1. declining number of functional nepherons 2. reduced glomerular filtration 3. reduced sensitivity to ADH 4. problems with micurition reflex (urinary retention may develop in men whose prostate glands are enlarged)

The position of the kidneys in the abdominal cavity is maintained by:

1. overlying peritoneum 2. contact with adjacent visceral organs 3. supporting connective tissues

renal sinus

A cavity within the kidney is formed from the hilus and is where blood vessels, nerves, lymphatic, and ureter pass

Prostatitis

A chronic or acute irritation of the prostate gland

Automatic bladder

A condition in which the micturition reflex remains intact, but the person cannot prevent the reflexive emptying of the bladder.

dysuria

A condition of pain upon urination

nephrolithiasis

A condition where kidney stones are present in the kidneys

tubular fluid

The fluid from the proximal convoluted tubule through the distal convoluted tubule. *It starts as a renal ultrafiltrate in the glomerulus, changes composition through the nephron, and ends up as urine leaving through the ureters.

renal pyramid

The triangular structures of the renal medulla in each kidney; approx 6-18 in each kidney

Podocytes

These cells support Bowman's capsule and provide half of the glomerular membrane

hemodialysis

a technique in which an artificial membrane regulates the composition of the blood

Voluntary urination involves

coupling the micturition reflex with the voluntary relaxation of the external urethral sphincter compressing bladder.

what is usually associated with aging?

increased kidney problems

Cystitis

inflammation of the lining of the urinary bladder

Urethritis

inflammation of the urethral wall

The pedicels of the podocytes are separated by

narrow filtration slits

the lamina densa of the basal lamina

is usually thick

The inner layer of the renal capsule

lines the renal sinus

major calyces

receives urine from the minor calyces to convey to the renal pelvis

capsular space

separates the parietal and visceral epithelia

the ureters extend from

the renal pelvis to the urinary bladder *are responsible for transporting urine to the bladder

both the minor and major calyces lead into

the renal sinus, which is continuous with the ureter.

renal papillae

the tips of the renal Pyramid

from the renal corpuscle, the tubular fluid

travels through the proximal convoluted tubule (PCT), the loop of Henle (nepheron loop), and the distal convoluted tubule (DCT). It then flows through the connected tubule, collecting duct, and papillary duct to reach the renal minor calyx.

ureter

tube that carries urine from the kidney to the urinary bladder

Vesa recta

veil of capillaries formed by the efferent arteriole that surrounds entire nephron