Chapter #13 - Excretion & Homeostasis Flashcards
Excretion
The removal of waste products of metabolism.
=> all living cells carry out metabolic reactions, which also produce waste products. Some may be toxic so the organism removes them.
What do animals do wth the biproductucts of respiration?
Animal cells need energy and can use the water. However, CO2 is not needed nd is toxic to cells.
=> it diffuses into the blood and out the lungs (it is excreted).
Do plants excrete?
At night, when plants cannot photosynthesize, they use respiration more as a source of energy (although animals are respiring all the time just not as much).
What is urea?
Waste product produced in the liver.
Where does urea come from?
Comes from the breakdown of excess proteins and amino acids.
What happens when you have a lot of urea?
Too much urea in the blood is toxic.
What do the kidneys do when they filter blood?
Ther remove:
* urea
* excess water and ions
… to produce urine (a solution of waste products including urea, produced by the kidneys)
What happens to exces proteins/amino acids?
They are brokeb down into:
1. Carbohydrates (used to create energy, stored in the liver for later)
2. Compounds containing nitrogen (this is then converted into urea)
Deamination
The removal of the part of amino acids containing nitrogen, to form urea.
How is urine disposed of?
The urine flows down the uretters and into the bladder where it is stored. When the sphincter muscle relaxes, urine flows out of the body through the urethra.
Describe step-by-step how urea is produced.
- Protein in food is taken into alimentary canal.
- Proteins are broken down to amino acids during digestion.
- Amino acids are absorbed into the blood and taken to the liver in hepatic portal vein (alimentary canal to liver).
- Amino acids that are needed are made into proteins in liver or released into blood to be assimilated by body cells.
- Amino acids that are not needed are deaminated to carbohydrates and nitrogen-containing compund.
- Carbohydrates are used or stored in liver.
- Nitrogen-containig compund is converted into urea.
- Urea to be excreted and amino acids to be used by the body are taken away by the blood.
What happens to proteins once they are broken down to for amino acids?
Amino acids are absorbed into the blood and taken to the liver in hepatic portal vein (alimentary canal to liver).
What happens to amino acids once they are in the liver?
- Amino acids that are needed are made into proteins in liver or released into blood to be assimilated by body cells.
- amino acids that are not needed are deaminated to carbohydrates and nitrogen-containing compund.
=> Carbohydrates are used or stored in liver.
=> Nitrogen-containig compund is converted into urea.
What is the function of the kidneys?
The kidneys constantly remove urea from the blood and excrete it as urine.
