Download CLASS NOTES

CLASS NOTES
EXCRETORY SYSTEM
FUNCTION
1. Eliminates non-solid wastes through sweat, urine and exhalation to
maintain homeostasis
2. Waste products include toxic materials, excess water, salts, carbon
dioxide, urea, minerals and vitamins
ORGANS
1. skin
 sweat glands release excess water and salt
 sweating maintains body temperature
2. lungs
 exhalation removes excess water and carbon dioxide
3. kidneys
 two bean shaped organs located in the lower back
 eliminates wastes by filtering and cleaning the blood to
produce urine
4. ureters
 tubes that connect the kidneys to the urinary bladder
5. urinary bladder
 sac-like organ that can store up to half a liter of urine
6. urethra
 tube through which urine is eliminated from the body
KIDNEY STRUCTURE
1. Kidneys are the main organs responsible for maintaining fluid and chemical
balance in your body.
2. One-fourth of your blood supply flows through your kidneys each minute.
3. nephron – the structural unit of the kidney
4. each kidney contains about 1 million nephrons
KIDNEY FUNCTION
1. Filtration
 Glomerulus – mass of arterioles, venule, and capillaries that enters
the kidney
 Bowman’s capsule – cup-shaped structure that contains the
glomerulus
 Blood entering the kidney goes through the glomerulus where small
molecules such as water, amino acids, salts, glucose, electrolytes, and
urea are pushed out of the capillaries into the Bowman’s capsule
 Urea – a waste product produced when proteins break down
 Large molecules such as blood cells stay in the blood
2. Reabsorption
 filtrate – the material that enters Bowman’s capsule
 Nephrons process 48 gallons of filtrate each day but only 1% is
processed as urine
 Most of the filtrate is reabsorbed by the capillaries and returns to the
body
 The reabsorption of water and sodium maintains fluid balance
3. Excretion
 Products that are not re-absorbed are excreted in urine
 Urine is made of water, urea, excess salt and other material that
remains in the filtrate
 Filtrate leaves the Bowman’s capsule and enters the loop of Henle
 Loop of Henle – part of the nephron where excess water is absorbed
and the urine is concentrated
 Filtrate then enters the collecting duct and go to the ureters, then
urinary bladder
 Urine is eliminated through the urethra
URINE TESTING
1. Normal urine is clear, pale yellow and composed of 95% water
2. The presence of blood, protein or sugar in urine may be due to injury or
infections
3. Drugs are broken down by the liver, filtered by the kidneys and detected in
urine
KIDNEY INJURY & DISEASE
1. Kidney damage can be due to accidents, hypertension (high blood pressure),
infection or diabetes.
2. It is possible to live with only one kidney
3. Treatment for kidney disease is a kidney transplant or dialysis
4. dialysis – process by which a patient’s blood is cleaned and chemically
balanced through a mechanical process
 dialysis machine – blood from the patient goes through a filter in the
machine which removes waste products. Blood is returned to the
patient. The process takes 3-5 hours and is done 3 times a week.
 peritoneal dialysis – dialysis fluid is pumped into the abdomen and
the waste products and excess fluid move from the bloodstream into
the dialysis fluid. The fluid is then removed from the abdomen