Transcript Excretory System basic

The Human Excretory System
The function of the
excretory system is
the excrete (get rid
of) wastes that are
not helpful to the
body.
EXCRETION
Excretion is:
• removal of metabolic wastes
• removal of excess heat
Main Excretory organs involved are:
• kidneys
• liver
• lungs
• skin
A Note About Metabolism
• Metabolism
• This is the series of activities that cells do in
order to keep the organism alive.
• Cellular activities usually involve chemical
reactions that produce products necessary for
life and bi-products (wastes) that are often
toxic to cells.
• Example: Cellular Respiration produces ATP
energy for the cells but it also produces
Carbon Dioxide, which is very harmful to the
cells.
Cellular Waste
• Wastes that are removed
include carbon dioxide,
water, salt, urea and uric
acid.
• All excreted wastes travel at
some time in the blood.
Major Metabolic wastes:
• carbon dioxide, water
– CO2 and H2O are from cellular respiration
• certain nitrogen compounds
– Breakdown of amino acids from proteins produces
nitrogen compounds
• Urea
• Ammonia
• Uric acid
• Mineral salts from metabolism
– Sodium chloride (NaCl)
– Potassium sulfate K2SO4
Structures of the Excretory System
1.
2.
3.
4.
5.
Skin
Lungs
Liver
Urinary System
Large Intestine
Can you guess how these
structures are a part of
the excretory system?
What makes the Large
Intestine different from
the rest?
Large Intestine
• The large intestine
removes solid,
undigested food from the
body after it passes
through the digestive
system.
• Waste is stored in rectum
until it is excreted from
the body as solid waste.
NOTE: This is NOT waste
produced by the cells
(cellular waste) as a part
of your metabolism!!!!!
Skin
Wastes such as excess
water, salt, urea and uric
acid are removed from
the body in sweat.
Skin
2.
Excretion– Small amounts of urea and salts in sweat
– Removal of excess heat (Major Function)
• Blood vessels dilate bringing more warm blood to skin
surface
• Sweat is produced by sweat glands
• Sweat absorbs body heat and evaporates to water
vapor and body heat leaves the body in the water
vapor
• Body cools as a result of the evaporation
Lungs
Excess carbon dioxide
waste is removed
from the body when
we exhale.
CO2
Liver
The liver is a part
of what other
system?
The digestive
system
Liver
The liver has many functions,
including (but not limited to):
1. to produce substances that break down fats
2. produce urea (the main substance of urine)
3. make certain amino acids (the building blocks
of proteins)
4. filter harmful substances from the blood
(such as alcohol)
5. The liver is also responsible for producing
cholesterol. It produces about 80% of the
cholesterol in your body.
The Liver and Waste
• The liver produces
urea and uric acid
as a by-product of
the breakdown of
proteins
• Urea and uric acid
are sent to the
kidneys to be
processed
Liver
Formation of Urea in Liver:
• Amino acids are broken down.
1) amino group, NH2→
changed to
ammonia, NH3 → changed to urea (less
poisonous)
• Finally: Urea diffuses back into bloodstream
and is filtered out by the kidneys.
Human Excretion
• Liver’s role
–Detoxification• changes harmful substances into inactive
or less poisonous substances
• These inactive substances are returned to
blood and are filtered by kidneys.
The urinary system
• The kidneys filter the
blood to form urine,
which is excess water,
salt, urea and uric
acid
Urinary System
Kidneys-> ureter-> urinary bladder-> urethra
Kidneys
2 main functions
1. Remove wastes from cellular metabolism
2. Regulate the concentrations of substances
found in the body fluids
*****If kidneys cannot perform these functions
a person will die.*****
Kidney structure
3 layers of the kidney
• Cortex- outer layer blood is filtered to remove
waste and excess substances
• Medulla- middle layer made up of tubes
called collecting ducts that carry the filtered
substances (filtrate) to the innermost layer of
the kidney
• Pelvis- cavity that collects the filtrate and
connects the kidney to the ureter which exits
the kidney
Nephron
Nephron- waste filtering unit of the kidney found
in the cortex and the medulla
• 1.25 million nephrons in each kidney
Filtration in Nephron
1. Blood enters kidney through renal artery,
2. Small substances (water, salts and minerals)
and wastes (urea) diffuse from the capillaries
into the nephron of the kidneys.
3. Urea, excess water and excess substances
travel to the renal pelvis to form urine.
4. Water and some dissolved substances are
reabsorbed into the blood through the
capillaries.
5. Clean blood leaves the kidney through the
renal vein.
Urine- final waste fluid excreted
• Made up of water, urea and various salts.
• 1-1.5 liters of urine are produced every 24
hours
Structures Involved in Getting Rid of Urine!
Ureter- tube connects kidney to urinary bladder
•Function –conducts urine from kidney to bladder
Urinary Bladder- collects and stores urine for
Excretion
Urethra- during urination urine travels from the bladder to the
outside of the body