Waste Removal Noadswood Science, 2012

Waste Removal  To understand how waste products are removed from the body Thursday, September 17, 2015

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 CO 2 (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 ProductWhy Is It Produced?How Is It Removed? CO 2 Product of aerobic respiration Through the lungs when we exhale Urea 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

CO 2  The job of the lungs is to transfer oxygen into the blood, and the waste carbon dioxide out of it

CO 2  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)