1. Chapter 26 Urinary System1 1

2. Organs of the Urinary System
Kidneys (2)
Ureters (2)
Urinary bladder (1)
Urethra (1)

3. Functions of the Kidney
Filters blood plasma-removes waste products, toxins, H+, drugs, hormones, water, urea
Produces urine
Regulate blood volume and pressure through secretions of:
Enzyme renin controls blood pressure and electrolyte balance
Hormone erythropoietin stimulates production of RBC cells
Regulate the osmolarity of the body fluids
Collaborate with lungs to regulate/buffer PCO2 and acid-base balance (pH) - loss of hydrogen ions and bicarbonate ions in urine
Regulates plasma ion concentrations
Sodium, potassium, and chloride ions controlling urine loss
Calcium ion levels through synthesis of calcitriol-Vitamin D helps to regulate calcium homeostasis
Gluconeogenesis from amino acids in extreme starvation 3

4. KIDNEYS 3 layers of CT tissue:
Renal fascia: dense, fibrous outer layer binds kidney to abdominal wall
Perirenal fat capsule: thick layer of adipose tissue cushions/holds in place
Renal/fibrous capsule: layer of collagen fibers encloses the kidney. On top of kidney

5. Anatomy of the Kidney Cortex: outer layer of the kidney
Medulla: middle layer composed pyramids and renal columns.
Pyramids: collecting ducts/ loops of Henle, lower portion of the nephrons.
Renal columns –extension of cortex
Renal sinus: internal cavity within kidney; stabilizes positions of ureter, renal blood vessels, and nerves
The papilla of each pyramid projects into the calyx.
Calyces collect the urine released from the papillae and allow it to drain into an enlarged collection
minor calyx – drains papilla
major calyces – drains minor calyx
renal pelvis -connected to ureter, which drains kidney
Lobe of the kidney = 1 pyramid and overlying cortex; produces urine
Hilum - entry for renal artery and renal nerves; exit for renal vein and ureter

9. The Nephron Functional unit of the kidney Renal corpuscle
Glomerular capsule (Bowman’s capsule)
Capillary network (glomerulus)
Renal tubule
Begins at renal corpuscle
Located in cortex
Proximal convoluted tubule (PCT)
Loop of Henle
U-shaped tube
Extends partially into medulla
Distal convoluted tubule (DCT)

10. Blood Access to the Nephron
The nephron receives blood from the afferent arteriole.
The afferent arteriole supplies the glomerulus
From the glomerulus blood flows into the efferent arteriole.
The efferent arteriole flows into more capillaries, the peritubular capillaries, and, in juxtamedullary nephrons, the vasa recta.
Peritubular capillaries and vasa recta lead to the venous drainage of the kidney.

11. Types of Nephrons Cortical nephrons 85% of all nephrons
short nephron loops
efferent arterioles branch into peritubular capillaries around PCT and DCT
Juxtamedullary nephrons
15% of all nephrons
very long nephron loops, maintain salinity gradient in the medulla and helps conserve water
efferent arterioles branch into vasa recta around long nephron loop

13. Renal Corpuscle
Bowman’s capsule and glomerulus. Filtration unit of the nephron
The outer (parietal) layer of Bowman's capsule consists of simple squamous epithelial cells with tight junctions and serves to contain the filtrate in the capsular space.
The visceral epithelium of the Bowman's capsule consists of large cells called podocytes with complex processes or “feet” (pedicels) that wrap around specialized dense layer of glomerular capillaries to produce openings called filtration slits.
The glomerulus is a condensed mass of capillaries which allows substances to escape by filtration.

14. synthesize, store, and secrete the enzyme renin
Macula densa Cells epithelial cells of DCT
Increase/decrease GFR by dilating or constricting the afferent arteriole
Juxtaglomerular cells (granular) (JG) - modified smooth muscle cells in the walls of the afferent arteriole
synthesize, store, and secrete the enzyme renin

15. pedicels

17. Ureter, Urinary Bladder, Micturition Reflex
From the collecting ducts urine passes through the papillary ducts, the minor calyces, the major calyces, and the renal pelvis.
The ureters are connected to the renal pelvis and carry urine to the urinary bladder.
Ureters have TWO layers of smooth muscle: a longitudinal layer (outermost) and a circular layer (innermost).
Urine is stored in the bladder
Micturition (urination) occurs when sphincters of the urethra open to allow urine to flow out of the body.

18. http://high-blood-pressure-symptoms. com/wp-content/uploads/2011/12/17
Ureters

19. Urinary Bladder
Hollow muscular elastic organ stores urine in lower pelvic cavity. Contains. 3 layers:
Mucosa transitional epithelium that can be stretched
Epithelial secretes mucus
Rugae allow bladder to expand
Detrusor muscle = 2 layers of longitudinal smooth muscle and a middle circular layer.
Can spasm during infection
The internal urethral sphincter (involuntary)
The external urethral sphincter (voluntary)
The fibrous adventitia covers the bladder attaches to the visceral peritoneum.
Opening of the two ureters and urethra mark a smooth surfaced triangular area called the TRIGONE on the bladder floor.

21. Male and Female Urethra
Urethra is a tubular organ that allows for drainage of the urinary bladder.
Females - short, external orifice is located within the vulva.
Males subdivided into 3 regions: prostatic, membranous, and spongy

22. Disorders Urinary Tract Infection (UTI)
cystitis – infection of the urinary bladder
common in females due to short urethra
frequently triggered by sexual intercourse
can spread up the ureter causing pyelitis
pyelitis – infection of the renal pelvis from blood borne agents such as bacteria. Can also arise from cystitis.
pyelonephritis –kidney infection
Generally results from blood-borne bacteria or virus
Escherichia coli (e-coli) is often the bacteria associated with infection
Kidney stones form in renal pelvis
hard granule of calcium phosphate, calcium oxalate, uric acid, or a magnesium salt
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