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