excretion in humans Flashcards
provide some examples of metabolic waste products
1) carbon dioxide: produced of aerobic respiration
2) urea
- absorbed amino acids are transported to the liver, distributed round the body and then assimilated (liver is involved and it uses amino acids to synthesise the proteins found in blood plasma
- urea is a waste product formed from the the breakdown of proteins (abnormally high urea concentration in blood may cause abdominal pain, vomiting or nausea)
3) mineral salts/ions
- deficiency of certain irons may result in deficiency diseases (eg. lack of calcium can result in weakening of bones)
- excess salts/ions in the body can be harmful : lower the water potential in blood plasma, making it more concentrated - water may pass out of the tissue cells into the blood via osmosis and the cells may become dehydrated
- kidneys help to remove the excess salts
4) water: product of aerobic respiration
- excess water in the body will increase the water potential in the blood plasma, by osmosis, water will enter the tissue cells (as a result, tissue cells may swell and burst)
what is excretion and why is it necessary
> excretion is the process of removing metabolic waste products, toxic substances and excess substances from the body
it is important that harmful substances do not build up in the body
metabolic activities occurs while carrying out life processes to sustain life:
1) the body produces harmful/toxic substances (not needed by the body)
2) metabolic waste products/excretory products need to be removed
human urinary system & its parts (functions)
1) kidneys are bean-shaped organs that are embedded in a mass of fat in the abdominal cavity
> function: (main) excrete urea and excess salt and water as urine
2) ureter is a narrow-tube that connects the kidney to the urinary bladder
> function: urine from each kidney passes through the ureter to the urinary bladder
3) urinary bladder is an elastic muscular bag located in front of the rectum
> function: stores urine
4) urethra is the duct through which:
> function: urine passes from bladder to outside of the body
