Urinary System

Health Science Technology Dr. Halbert

Urinary system = excretory system

Removes some wastes & excess water and maintains pH balance

Consists of 2 kidneys, 2 ureters, bladder and urethra

Kidney

On either side of vertebral column separated from the abdominal cavity by peritoneum

Enclosed in a mass of fatty tissue called adipose capsule

Also covered by tough fibrous tissue called renal fascia or fibrous capsule

Kidney structure 2 main sections

Cortex Medulla

Cortex: outer section, contains most of the nephrons

Medulla: inner section, contains most of the collecting tubules, which carry the urine from the nephrons thru the kidney

Hilum Notched or

indented area of the kidney thru which ureter, blood vessels & lymph vessels enter & leave kidney

Nephron Filtering unit of kidney One million nephrons

per kidney Consists of

Glomerulus Bowman’s capsule Proximal convoluted

tubule Distal convoluted

tubule Collecting duct

Glomerulus First part of nephron Cluster of capillaries As blood passes thru from

renal artery, water, mineral salts, sugar are filtered out of blood

RBCs & proteins are not filtered out

Filtered blood makes its way to renal vein

Bowman’s capsule C-shaped structure

that surrounds the glomerulus & is start of convoluted tubule

Picks up filtered material from glomerulus & passes them to convoluted tubule

Passing through tubules

Substances needed by body are reabsorbed & returned to blood capillaries

Excess sugar, mineral salts; some water; & wastes remain in tubule & become urine

Urine enters collecting ducts located in medulla

Renal Pelvis Collecting ducts

empty into renal pelvis, funnel-shaped structure which is first section of ureter

Ureters Two muscular

tubes About 10-12 inches Peristalsis moves

urine through the ureter to the bladder

Bladder Hollow muscular

sac that lies behind the symphysis pubis & at midline of pelvic cavity

Mucous membrane lining arranged in folds, rugae which disappear as bladder expands with urine

Bladder wall

Formed by three layers of smooth muscle

Bladder stores urine until eliminated Urge to void occurs when bladder

contains 250 cc (1 cup) of urine but bladder can hold much more

Sphincter

Circular muscle controls opening of bladder to prevent emptying

Urethra Tube that

carries urine from the bladder to the outside

External opening is the urinary meatus

Urethra Male vs Female Female

3.75 cm (1½ in) Carries only urine Opens in front of

vagina

Male 20 cm (8 in) Carries urine &

semen Passes through

prostate & out through penis

Urine Liquid waste product

produced by urinary system

95% water Waste products: urea

(major waste product), uric acid, creatinine, mineral salts, pigments

Urochrome: pigment giving urine its yellow color

About 1½ to 2 quarts produced daily from 150 quarts of liquid that is filtered through the kidney

Terms

Polyuria: excessive urinationOliguria: decreased amounts of urineAnuria: absence of urineHematuria: blood in urinePyuria: pus in urineNocturia: urination at nightDysuria: difficult or painful urinationRetention: inability to empty the bladderIncontinence: involuntary urination

Diseases of Urinary System

Cystitis Inflammation of

the bladder Usually caused by

pathogens entering urinary meatus

More common in females

Glomerulonephritis

Inflammation of the glomerulus Acute form: usually follows a

streptococcal infection Chronic form: progressive disease that

causes scarring of the glomeruli leads to kidney failure

Pyelonephritis

Inflammation of kidney tissue & renal pelvis usually caused by bacteria

Renal calculus Kidney stone Calculus is formed

when salts in the urine precipitate

May become lodged in renal pelvis or ureter

Renal failure

When kidneys stop functioning Acute renal failure (ARF): caused by

hemorrhage, shock, poisoning, injury, dehydration

Chronic renal failure (CRF): results from progressive loss of kidney function, caused by hypertension, toxins, endocrine disease, chronic glomerulonephritis

Uremia

Toxic condition that occurs when kidneys fail & waste products are present in blood stream

Urethritis

Inflammation of the urethra usually caused by bacteria, viruses or chemicals

Image Citations

Slide 3: Anatomy of the urinary system, front view, 1/1/07, http://www.health.uab.edu/default.aspx?pid=65499

Slide 5: Illustration of the anatomy of the kidney, 1/1/07, http://www.uchospitals.edu/online-library/content=P01468

Slide 8: Glomerulus, 2/17/07, http://www.aic.cuhk.edu.hk/web8/Hi%20res/Glomerulus.jpg

Slide 13: Male Bladder & urethra, 2/17/07, http://www.ivy-rose.co.uk/Topics/Urinary/Bladder_Urethra_Female_cIvyRose.jpg

Slide 18: Urine, 2/17/07, http://www.open2.net/open2static/source/file/root/32/15/132078/urine.jpg

Slide 21: Cystitis, 2/17/07, http://www.pathology.vcu.edu/education/renal/lab2.p.html