Transcript Waste Removal - Noadswood Science

Waste Removal
Noadswood Science, 2012
Saturday, April 2, 2016
Waste Removal
 To understand how waste products are removed from the body
Waste
 What waste products does the human body produce?
 Faeces
 Urea
 Carbon dioxide
 It is vital that all of these materials are removed from the body to
maintain its healthy functioning…
Homeostasis
 Homeostasis is the maintenance of a constant internal environment
 There are six different bodily levels which must all be controlled:  Removal of CO2 (waste product)
 Removal of urea (waste product)
 Ion content (must remain at correct level)
 Water content (must remain at correct level)
 Sugar content (must remain at correct level)
 Temperature (must remain at correct level)
Waste
 The conditions inside the body must be controlled within narrow
limits – homeostasis
 Waste products must be removed from the body – if they are not,
they will increase in concentration and may interfere with chemical
reactions or damage cells
 Waste products that must be removed include carbon dioxide and
urea…
Waste
Waste Product
Why Is It Produced?
How Is It Removed?
CO2
Product of aerobic respiration
Through the lungs when
we exhale
Produced in the liver when excess
amino acids are broken down
Kidneys remove it from
the blood making urine,
which is temporarily
stored in the bladder
Urea
CO2
 The job of the lungs is to transfer oxygen into the blood, and the
waste carbon dioxide out of it
CO2
 The job of the lungs is to transfer oxygen into the blood, and the
waste carbon dioxide out of it
Urea
 Urea is produced in the liver
 Proteins cannot be stored by the body so excess amino acids are
broken down by the liver into fats and carbohydrates
 The waste product is urea which is passed into the blood to be
filtered out by the kidneys (urea is also lost partly in sweat)
Urea
 Water enters the body through
food and drink as well as being
a product of aerobic
respiration in cells
 If the amount of water in the
body is wrong, cells can be
damaged because too much
water enters or leaves them
Kidneys
 The kidneys perform three main roles: 1.
Removal of urea (from the blood)
2.
Adjustment of ions (in the blood)
3.
Adjustment of water content (in the blood)
Removal Of Urea
 Proteins cannot be stored by the body, so excess amino acids are
converted to fats and carbohydrates – this occurs in the liver
 As a waste product of this, urea is produced (it is poisonous, so the
kidneys filter it out of the blood and temporarily store it in the
bladder in the form of urine)
Adjustment Of Ions
 Ions such as sodium and potassium are taken into the body in food
and absorbed into the blood – if the ion / water concentration
changes osmosis can be affected so excess ions are removed by the
kidneys when needed
Adjustment Of Water
 Water is taken into the body (food / drink) and removed in urine,
sweat and when we breathe out
 Kidneys can allow more / less water to pass out (affecting the colour
of urine) depending on how much water the body needs to keep /
pass out
Nephrons
 Nephrons are filtration units in the kidneys – under high pressure
water, urea, ions and sugar are squeezed out of the blood and into
the Bowman’s capsule
 The membrane between the
blood vessels and the
Bowman’s capsule acts like a
filter, allowing only smaller
molecules through (and bigger
molecules such as proteins and
blood cells are retained)
Nephrons
Reabsorption & Release
 As the liquid flows along the nephron useful substances are
reabsorbed (such as sugar, ions and water) – this process occurs via
active transport against a concentration gradient
 The remaining substances (including urea) then continue out of the
nephron into the ureter and down into the bladder (as urine)