Urinary System Anatomy and Physiology

Urinary System Anatomy and Physiology

Medical Terminology

I.  Purpose of Urinary System

A. Removes wastes and excess water from the body

B. Maintains body’s acid-base balance

II.  Anatomy of Urinary System

A. 2 Kidneys

B. 2 Ureters

C. 1 Bladder

D. 1 Urethra

III.  Kidneys

A. 2 bean-shaped organs

B. Located on either side of the vertebral column

C. Protected by ribs and heavy cushion of fat

D. 2 Main sections of kidneys

1.  Cortex – outer section which contains most of the nephrons

2.  Medulla – inner section which contains collecting tubules

E. Hilum

1. Notched or indented area on medial border of each kidney

2. Area where ureter, nerves, blood vessels, and lymph vessels

enter and leave the kidney

IV.  Nephrons

A. Microscopic filtering units

B. > one million per kidney

C. Parts of the nephron

1.  Glomerulus

2.  Bowman’s Capsule

3.  Convoluted Tubules

4.  Collecting Duct

V.  Physiology of the Urinary System

A. Renal artery carries blood to the kidneys

B. Branches of renal artery pass through the medulla to the cortex

C. Blood enters glomerulus of the nephron

D. Water, salt, sugar, metabolic products and other substances are filtered out in the glomerulus

E. Red blood cells and proteins are not filtered out

F.  Filtered blood goes to renal vein and out of kidney to travel back to the heart and lungs to be reoxygenated

G.  Filtered substances enter Bowman’s Capsule and then go to convoluted tubules

H.  Most salts, sugars, and water are reabsorbed while in tubules, BUT excess sugar, salts, water, and wastes (uric acid) stay in tubule

I.  Substances remaining in tubule become concentrated liquid called urine

J.  Urine then enters collecting ducts in medulla

VI.  Urters

A. 2 muscular tubes

B. One extends from each kidney to bladder

C. 10 to 12 inches in length

D. Urine passes from kidney through ureter to bladder through peristalsis which is a rhythmic wavelike motion of involuntary muscle

VII.  Bladder

A. Hollow muscular sac

B. Stores urine

C. Feel urge to urinate when about 1 cup of urine is in bladder; although it can hold much more

D. Circular sphincter muscles control opening to bladder

E. Bladder full – receptors in bladder send out reflex action opening these muscles

VIII.  Urethra

A. Tube that carries urine from bladder to outside

B. Urinary Meatus – external opening in urethra

C. Urethra in Females

1.  1 ½ inches in length

2.  Opens in front of vagina

3.  Carries only urine

D. Urethra in Males

1.  8 inches in length

2.  Passes through prostate gland and through penis

3.  Carries both urine and seman