Download The Excretory System - Westgate Mennonite Collegiate

16.1 INTRO TO THE
EXCRETORY SYSTEM
Systems

The excretory system includes:
 Respiratory
system (already studied)
 Circulatory system (already studies)
 Urinary system (focus of this unit)
 Integumentary (skin) system (brief intro in this unit)
Main Functions of Urinary System

To maintain homeostasis by:
 Removing
metabolic waste products, notably
nitrogenous waste from breakdown of amino acids:
 Urea
 Creatine
 Uric
acid
 Maintaining
 Kidneys
water-salt balance
perform this function
 Blood volume and blood pressure are closely connected
 More salts = more blood volume = higher blood pressure
Main Functions of Urinary System
 Maintaining
acid-base balance
 Kidneys
perform this function
 Monitor and maintain blood pH at 7.4
 Excrete H+ ions and reabsorb HCO3- ions as needed
 Secretion
 Kidneys
of hormones
excrete renin (hormone) that stimulates the excretion
of aldersterone.
 Aldersterone promotes the reabsorption of Na+ ions in the
kidneys
 Kidneys secrete eruthropoietin, which stimulates red blood
cell production
Organs of Urinary System
A. Kidney
1. Bean-shaped
2. Located between peritoneum and the back muscles
3. Renal pelvis – funnel-shaped structure at the
beginning of the ureter
4. Medulla
a, Inner, striated layer
b. Striated cones are renal pyramids
c. Base of pyramids empty into cuplike cavities
called calyces
5. Cortex – composed of millions of microscopic
nephrons
Organs of Urinary System
B. Nephron – functional unit of kidney
1. Bowman’s capsule
2. Glomerulus
3. Proximal convoluted tubule
4. Loop of Henle
5. Distal convoluted tubule
6. Collecting tubule
C. Ureters
1. One from each kidney
2. Smooth muscle tube with mucous membrane lining
Organs of Urinary System
D. Urinary bladder
1. Hollow, muscular organ
2. Made of elastic fibers and involuntary muscle
3. Stores urine – about 500 cc
E. Urethra
1. Connects bladder with urinary meatus
2. Urinary meatus is opening to body