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)