B12 Homeostasis In Action Flashcards
Describe what happens to excess amino acids in the body?
They’re sent to the liver and converted into Ammonia. Since ammonia is very toxic the liver immediately converts it to Urea, which can be safely excreted by the kidneys
What is Deamination?
The process of excess amino acids being converted into Ammonia in the liver
What part of the body regulates body temperature?
The thermoregulatory centre
Where is the thermoregulatory centre located?
In the hypothalamus
Explain 2 ways the body cools itself down
- Blood vessels supplying the surface skin capillaries
dilate (Vasodilation), allowing more blood to flow
through the capillaries, transferring energy through
radiation through the skin and out of the body, cooling
it down - The body produces sweat, which transfers energy off
of the body when it evaporates, cooling it down
What are the 3 ways that the body loses water?
- Sweating
- Exhaling
- Urinating
Describe how the body produces urine
Blood enters the kidney through an artery, and the kidney filters out urea, excess ions and excess water. Theses leave the kidney as urine and are stored in the bladder. Blood now leaves the kidney through a vein.
Describe the process of selective reabsorption
Blood passes into the kidney, where small molecules are filtered out of the blood, including urea, ions, water and glucose. Then all of the glucose, some of the ions, and some of the water is reabsorbed back into the blood
What does ADH do?
Causes the kidney to reabsorb more water, and less urine is produced`
Where is ADH produced?
In the pituitary gland
Describe how the kidneys maintain water levels
If the blood has become too concentrated after losing water (e.g. sweating during exercise), the pituitary gland releases the hormone ADH into the bloodstream, which travels to the kidneys, and makes the kidney tubules to be more permeable to water, and more water is reabsorbed into the blood, so less urine is produced, returning blood water levels to normal, and the pituitary gland stops releasing ADH. The opposite happens when the blood is too dilute.
(Negative feedback cycle)
How does kidney Dialysis maintain the body’s water levels?
When a person has faulty kidneys, they will have a greater than normal concentration of water, urea and ions in their bloodstream. In dialysis, the patient’s blood passes over a semi permeable membrane, allowing urea, ions and water through, but not larger molecules (e.g. proteins and blood cells) through. On the other side of the membrane contains dialysis fluid, which has the normal concentrations of water and ions, but no urea. This is to ensure that all the urea flows from the blood into the dialysis fluid, down the concentration gradient. The dialysis fluid is constantly replenished to maintain the concentration gradient for urea. Excess water and ions will diffuse from the blood into the fluid, returning the concentrations to normal
What kind of molecules aren’t absorbed by the kidneys?
Large molecules e.g. proteins and red blood cells
What is dialysis fluid?
A fluid containing the normal concentrations of water and ions, but no urea
What are the inconveniences of dialysis?
- Patients must visit the hospital frequently
- Patients also have to eat a controlled diet so they
don’t produce too much urea - It is more expensive than other options
