Urinary or Excretory System Functions: Removes certain wastes and excess water from the body...
-
Upload
ethelbert-obrien -
Category
Documents
-
view
237 -
download
0
Transcript of Urinary or Excretory System Functions: Removes certain wastes and excess water from the body...
Urinary or Excretory SystemFunctions:
Removes certain wastes and excess water from the body
Maintains the acid-base balance of the body
KidneysTwo 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
Kidney Sections:Cortex(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
Hilum of Kidney:Notched or indented area on each kidney
Area where ureter, nerves, blood vessels, and lymph vessels enter and leave the kidney
NephronsMicroscopic 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)
Renal arteries carry blood to the kidneyBranches of the renal artery pass
through the medulla to the cortex where the blood enters the first part of the nephron, the glomerulus
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
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
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
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
Convoluted Tubules:
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
UretersTwo muscular tubes about 10
to 12 inches longOne 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
BladderHollow muscular sacLies 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
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
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
Urethra:Tube that carries the urine from bladder to the outside
External opening is called the urinary meatus
Different in females than males
Urethra cont.FemalesTube about 1 ½ inches
(3.75cm) longOpens in front of the
vaginaCarries only urine to
the outside
Urethra cont:MalesS-shaped tube about 8
inches (20 cm) longPasses through the
prostate gland and out through the penis
Carries both urine from the urinary system and semen from the reproductive system
Urine1. Liquid waste product produced by the urinary
system2. About 95 percent water3. 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
Conditions affecting urination
1. Polyuria: excessive urination2. Oliguria: below normal amounts of
urination3. Anuria: absence of urination4. Hematuria: blood in the urine5. Pyuria: pus in the urine6. Nocturia: urination at night7. Dysuria: painful urination8. Retention: inability to empty the bladder9. Incontinence: involuntary urination
http://www.youtube.com/watch?v=aQZaNXNroVY