B3 - Removal of Waste and Water Control Flashcards
Where is carbon dioxide produced?
Carbon Dioxide is produced by respiration and must leave the body by the bloodstream.
Explain the formation of urea.
Urea is formed up of proteins in the diet. These are then turned into amino acids by the protease enzymes during digestion. Some of the amino acids go on for growth and repair uses whilst the excess gets sent to the liver where it gets converted into urea.
How is the carbon dioxide removed from the body?
When the cells respire they produce carbon dioxide. This then diffuses into the blood and is breathed out of the body.
What is the function of the kidneys?
To filter the blood of
urea
excess water
excess ions/salts (from salty foods)
‘the homeostasis of the blood’
How does urea leave the body?
It is sent to the nephrons in the kidneys. These remove urea as it is poisonous.
What enters the body when we eat and drink?
Water and ions enter the body when we eat and drink.
How do the kidneys produce urine?
The kidney has many nephrons in it. The nephrons have a filters in with sieve like holes. Water, glucose, ions and urea are all absorbed from the blood. Some water, some ions and ALL the glucose is reabsorbed back into the blood. The excess ions and water go on to make urine.
What actions will the kidney take to produce urine on hot and cold days?
Hot days: small volume of urine, concentrated urine, yellow (little water and ions are sent as they are needed by the body)
Cold days: clear, dilute urine is produced in greater quantities.
How can the kidney be damaged?
Kidney trauma/injury
Inherited kidney problems
Alcohol and drugs
Kidney infections (both bladder and viral)
What can be done?
Dialysis which is where the blood is cleaned outside the body using a machine to restore the concentration of dissolved substances to normal levels. This process has to be carried out regularly.
A kidney transplant where the old one is left in but a new one from a donor is inserted so you have two functioning kidneys.
What are the advantages and disadvantages of dialysis and kidney transplants?
Dialysis.
Advantages:
No drugs need to be taken
No wait for a compatible donor
Prolongs Life
Disadvantages:
Restricted diet
Hard to work as it needs to be done regularly
Restrictions on holidays
Takes a long time for the blood to be filtered
Not a long term solution.
Organ Transplants
Advantages:
Give a more normal lifestyle
They give a less restricted diet
Disadvantages:
Doesn’t last forever (around 10 years)
Have to take drugs
There aren’t many donors so there is often a long wait.
Why would a replacement kidney be rejected?
On the surface of the kidney there are antigens which will be different from your own. This means the kidney could be rejected by your immune system as it creates antibodies to destroy the new organ.
How can the risk of rejection be reduced?
Tissue Typing: Close family members, identical twins and even clones of yourself can be researched and would prove good matches for kidney transplants as they have the same tissue type and similar antigens as the recipient so the white blood cells would not try and mount a response.
Anti Rejection Drugs: These prevent the immune system mounting a response and creating antibodies to damage the transplanted kidney. This does however mean patients are susceptible to other infections.
How does a dialysis machine work?
The dialysis machine passes the blood between partially permeable membranes. This allows unwanted substances such as urea and excess salts to diffuse through the membrane into the dialysis fluid. The dialysis fluid contains no urea or salts so there is a steep concentration gradient for them to diffuse down. The dialysis fluid does however contain all the useful substances such as glucose in it so that there is no concentration gradient for the glucose and useful substances to diffuse down so there is no net movement of these useful substances.
