1. The Urinary System

2. Urinary or Excretory System
Functions:
Removes certain wastes and excess water from the body
Maintains the acid-base balance of the body

3. Parts include two kidneys, 2 ureters, the bladder, and the urethra

4. Kidneys Two bean-shaped organs
Located on either side of the vertebral column behind the upper part of the abdominal cavity and separated from this cavity by the peritoneum
Protected by the ribs and a heavy cushion of fat
Connective tissue helps hold the kidneys in position
Each kidney is enclosed in a mass of fatty tissue called the adipose capsule
Cover externally by a tough, fibrous tissue called the renal fascia or fibrous capsule

5. Kidney Sections: Cortex Medulla (1) Outer section of the kidney
(2) Contains most of the nephrons that aid in the production of urine
Medulla
(1) Inner section of the kidney
(2) Contains most of the collecting tubules that carry the urine from the nephrons on through the kidney

6. Hilum of Kidney: Notched or indented area on each kidney
Area where ureter, nerves, blood vessels, and lymph vessels enter and leave the kidney

7. Nephrons Microscopic filtering units located in the kidney
Over one million per kidney
Each nephron consists of a glomerulus, Bowman’s capsule, a proximal and distal convoluted tubule, and a collecting duct (tubule)

8. Renal arteries carry blood to the kidney
Branches of the renal artery pass through the medulla to the cortex where the blood enters the first part of the nephron, the glomerulus

9. Glomerulus of the Nephron:
(1) Cluster of capillaries
(2) As blood passes through water, mineral salts, sugar, metabolic products and other substances are filtered out of the blood
(3) Red blood cells and proteins are not filtered out

10. Glomerulus continued:
Filtered blood leaves the glomerulus and eventually is carried to the renal vein, which carries it away from the kidney
Substances filtered out in the glomerulus enter the next section of the nephron, Bowman’s capsule

11. Bowman’s Capsule: (1) C-shaped structure that surrounds the glomerulus
(2) It is the start of the convoluted tubule
(3) Picks up the materials filtered from the blood in the glomerulus
(4)Passes the materials into the convoluted tubule

12. Convoluted Tubules:
As these materials pass through the various sections of the tubule, substances needed by the body are reabsorbed and returned to blood capillaries
At the end, most of the water, sugar, vitamins, and mineral salts have been reabsorbed
Excess sugar and salts, some water, and wastes, including urea, uric acid, and creatinine, remain in the tubules and become known as the concentrated liquid called urine

13. Collecting Ducts:
Urine now enters collecting ducts or tubules located in the medulla
Collecting tubules empty into a funnel-shaped structure, the renal basin or pelvis, which is the first section of the ureter

14. Ureters Two muscular tubes about 10 to 12 inches long
One extends from the renal pelvis of each kidney to bladder
Peristalsis, a rhythmic wavelike motion of the involuntary muscle, moves the urine through the ureter from the kidney to the bladder

15. Bladder Hollow muscular sac
Lies behind the symphysis pubis at the midline of the pelvic cavity
Has lining of mucous membrane
Arranged in a series of folds called rugae
Rugae disappear as muscles of the bladder allow it to expand and fill with urine
Three layers of visceral (smooth) muscle form the walls

16. Bladder Functions: Receives the urine from the ureters
Stores the urine until it is eliminated from the body
Urge to void (urinate or micturate) occurs when the bladder contains about 250 cc (1 cup) of urine, but bladder can hold much more urine

17. Circular Sphincter Muscles:
Control the bladder opening to prevent emptying
When bladder is full, receptors in the bladder will send out a signal for a reflex that will open the muscle
Reflex action cannot be controlled by infants, but as children get older, they learn to control this reflex

18. Urethra: Tube that carries the urine from bladder to the outside
External opening is called the urinary meatus
Different in females than males

19. Urethra cont. Females Tube about 1 ½ inches (3.75cm) long
Opens in front of the vagina
Carries only urine to the outside

20. Urethra cont: Males S-shaped tube about 8 inches (20 cm) long
Passes through the prostate gland and out through the penis
Carries both urine from the urinary system and semen from the reproductive system

21. Urine 1. Liquid waste product produced by the urinary system
2. About 95 percent water
3. Waste products dissolved in this water are urea, uric acid, creatinine, mineral salts, and various pigments
4. Excess useful products, such as sugar, can also be found in urine but their presence usually indicates disease
5. About 1,500 to 2,000 cc (1½ to 2 quarts) of urine are produced daily from the approximately 150 quarts of liquid that is filtered through the kidneys

22. Conditions affecting urination
1. Polyuria: excessive urination
2. Oliguria: below normal amounts of urination
3. Anuria: absence of urination
4. Hematuria: blood in the urine
5. Pyuria: pus in the urine
6. Nocturia: urination at night
7. Dysuria: painful urination
8. Retention: inability to empty the bladder
9. Incontinence: involuntary urination