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The Urinary System
UNIT 6.12
Objectives:
Define, pronounce, and spell all key terms.
Label a diagram of the Urinary System.
State the functions of the ureter, bladder, and urethra.
Explain the action of the Nephron. Explain why the urethra is
different in males and females.
Introduction
The parts of the Urinary System are:
2 kidneys 2 ureters 1 bladder 1 urethra
Lets begin! The Urinary System is
also known as the Excretory System.
Function: responsible for removing certain wastes and excess water from the body and for maintaining the body’s acid-base balance.
Controls the volume and pressure of body fluids by eliminating wastes not needed in our body
Filters the blood and maintains balance of pH in the blood
Kidneys
2 bean shaped organs
4-6 ounces each
4 inches long, 2-3 inches wide, 1 inch thick
Left is slightly larger than the right
Protected and enclosed by adipose (fat pads)
Located on each side of the vertebral column, behind the upper part of the abdominal cavity
Kidneys… Divided into 2 main
sections: the cortex and the medulla
Cortex-the outer section that contains most of the nephrons (aids in the production of urine)
Medulla-is the inner section with 12-18 medullary pyramids that contains most of the collecting tubules (which carry the urine from the nephrons through the kidneys)
Kidneys…
Each kidney has a Hilum (hilus)-an indented area where the ureter, nerves, blood vessels such as the renal artery and the renal vein enter and leave the kidney
Renal pelvis-funnel shaped reservoir of the calyces that collect urine and funnel it into the ureter
Kidney-Anatomy Nephrons-is the
functional unit of the kidney.
They are approx 1 million in each kidney
They are microscopic filtering units
Each contain a glomerulus, Bowmans capsule, a proximal tubule, a distal tubule, and a collecting duct (tubule)
Function of the Nephron The renal artery carries
blood to the kidney
Branches of the renal artery pass thru the medulla to the cortex
Blood then enters the first part of the nephron called the glomerulus
Glomerulus-( a cluster of capillaries)as blood enters , water, mineral salts, sugar, metabolic products, and other substances are filtered out of the blood and then leaves the glomerulus.
Nephron function Next!
The now filtered blood enters the renal vein and carries it away from the kidney
The substances that were filtered by the glomerulus enters the Bowmans capsule
The Bowmans’s capsule-is C-shaped, picks up the substances filtered from the blood and glomerulus then passes it to the tubules
Nephron function Now in the tubules-
substances that are needed by the body are reabsorbed and returned to the blood capillaries
The excess substances (including urea, uric acid, and creatine) remain in the tubule and becomes a concentrated liquid called urine!
Ureters 2 muscular tubes Approx 10-12
inches long Extends from the
renal pelvis to the bladder
Peristalsis-rhythmic wave-like motion of muscle that moves the urine through to the bladder
Bladder Receives urine from the ureters
Hollow muscular sac
Surrounded by mucous membranes in folds called rugae
The urge to urinate begins when it holds approx 250 cc of urine (about a cup)
When full, receptors will send out a reflex action which opens the muscle
Infants have no control over this reflex action
Children learn to control the reflex
Urethra Tube that carries the
urine from the bladder to the outside
The external opening is the urinary meatus
Females-the urethra is approx 1 to 1 ½ inches in length that opens in front of the vagina
Males-the urethra is approx 8 inches long, passes thru the prostate gland, and out thru the penis. It carries both urine and semen.
Urine A liquid waste
Approx 95% water
Mostly urea, uric acid, creatine, and mineral salts
Urea is produced as a break down product of protein and creatine is metabolic by product of muscle metabolism
Sugar found in the urine usually indicates disease (diabetes)
Approx 1 ½ - 2 quarts of urine is produced daily
Key Terms
BLADDER
BOWMANS CAPSULE
CORTEX
EXCRETORY SYSTEM
GLOMERULUS
HILUM
KIDNEYS
MEDULLA
NEPHRONS
RENAL PELVIS
URETERS
URETHRA
URINARY MEATUS
URINARY SYSTEM
URINE
You survived again!!!
Good job!!!