Excretion in Humans Flashcards
What are the organs that form the excretory system?
- Lungs
- Liver
- Kidneys
- Bladder
- Skin
What do kidneys mainly excrete?
Excess water, salts and urea
Def. Excretion
The process that eliminates waste or excess material from metabolic reactions in an organism
Why is it important to remove waste material in the body?
To prevent build up of toxins and accumulation of ions (taking up space)
What is the kidney?
Two bean shaped organs that filter the blood
What is the ureter?
The tube that connects the bladder to the kidneys, transporting waste and excess substances
What is the bladder?
An organ that stores urine (excess water, salts and urea) as it is being produced by the kidneys
What is the urethra?
The tube that connects the bladder to the exterior of the body, where urine is then released
What are the two functions of the kidney?
- They regulate the water and ion content of the blood
- They excrete the toxic waste products of metabolism (such as urea) and substances in excess of requirements (such as salts)
Where and why is urea produced?
And what is first removed from the amino acid
Produced by the liver due to the deamination of excess amino acids
This means that any amino acids not used for protein production get sent to the liver to be assimilated (converted) into urea, meaning the Nitrogen/Amine group is removed, as it is toxic to cells, and is absorbed in the blood to be sent to the Kidneys. The rest is reused for other processes
What is removed from amino acids before deamination
The Nitrogen group – amine group (NH2) is first removed from the amino acids (deamination)
(This group is toxic to cells in the body)
Where are kidneys found?
In the top of the abdominal cavity, underneath the diaphragm
What is the renal vein?
A vessel that takes filtered blood away from the kidneys
What is the renal artery?
The vessel that brings blood, with waste inside it, to the kidneys
Name the parts of a kidney
- Pelvis
- Ureter
- Medulla
- Cortex
How is blood filtered in the kidney?
- Blood flows into the glomerulus under a high-pressure
- Small particles (e.g. Sugar, Salt, Water & Urea) are forced into the bowman’s capsule (Ultrafiltration)
- Useful molecules are reabsorbed into the blood, including glucose, some salt and some water (Selective Reabsorbtion)
How and where is the amount of water absorbed controlled?
Controlled by a hormone called ADH (released by the pituary gland)
What happens when there is not enough/too much water in the blood stream?
I there is too much, water will not be reabsorbed in large quantities, and instead added to urine
Otherwise, if the body is dehydrated, the water will be reabsorbed into the bloodstream, meaning less water is in the urine and it becomes more yellow
What are the parts of a nephron?
- Glomerulus
- Bowman’s capsule
- Tubule (Consists of first coiled tubule and Loop of Henle)
- Collecting duct
What is the part of the Kidney that filters blood?
Nephrons
What process occurs when small substances are forced out of the glomerulus into the bowman’s capsule?
Ultrafiltration
What process occurs when the necessary sunstances such as glucose, some water and some salts, reenter the bloodstream?
Selective Reabsorbtion
Why is Urea removed from the body?
It is a toxic substance
Explain what happens in a nephron
- Blood passes through Glomerelus at high pressure
- Small particles such as water, salts, glucose and urea are forced out into the Bowmans Capsule
- These particles flow through the Tubule which in entwined with capillaries
- The particles are selectively reabsorbed into the body, depending on what it needs
This takes part in Homeostasis
What is the function of the liver in excretion?
- Separation of toxic amine/nitrogen group
- This is absorbed into the blood as urea
- Toxic substances and worn red blood cells are broken down
- Excretory substances such as chloresterol are used in bile
- All of this is called deamination
