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Waste Removal
Noadswood Science, 2012
Waste Removal
To understand how waste products are removed from the body
Friday, April 21, 2023
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 respirationThrough the lungs when we exhale
UreaProduced 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
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)