Chapter 3: Keeping internal conditions constant Flashcards
What is homeostasis?
The art of keeping the environment inside ones body constant.
3 examples of variables that need regulating:
Temperature, waste levels, levels of useful substances
What are the two main poisonous waste products?
Carbon Dioxide and Urea
Why must carbon dioxide be removed?
Because it mixes with fluid inside cells and creates acidic solutions that prevent enzymes from working
Where does urea come from?
Extra amino acids in protein that cannot be used by the body are converted into urea.
What is the function of the kidneys?
To remove waste products, a part of homeostasis.
What can Kidneys filter out if it is needed?
Water and mineral ions
What must Kidneys filter out?
Urea
What are the main ways through which a person looses water?
Through sweat and breathing it out.
Where is urea produced?
The liver
What is a Ureter?
A tube connecting a kidney to the bladder.
What is the Urethra?
The tube connecting the bladder to the sex organs.
How do the kidneys work?
They completely filter the blood of everything, then re absorb everything the body needs.
Why don’t blood cells enter the kidney tubules?
They are too big.
How is sugar re-absorbed back into the bloodstream?
Active transport
What are the two methods of treating kidney failure?
Dialysis (Artificial Kidney), or a Kidney transplant.
What does Dialysis Fluid contain? Why is it important?
The same amount of useful substances as the blood. Therefore no net movement of useful substances occurs out of the blood.
What does Dialysis Fluid not contain? Why is this important?
Urea. There will be a steep concentration gradient of urea between the dialysis fluid and the blood, so urea will diffuse out of the blood.
What are the disadvantages of Dialysis?
You have to follow a very carefully controlled diet, and you have to spend a long time connected to the machine, many times a week.
What is the main problem with transplanting kidneys or other organs?
Rejection as the anti-bodies of the recipient attack the anti-gens on the cells of the donor’s organ
How is rejection combated?
Use of immuno suppressant drugs
What is the disadvantage of using immuno suppressant drugs?
The body is less effective at fighting off diseases.
Why does body temperature need to remain constant?
The function of enzymes and chemical reactions vary depending on it.
How does the thermoregulatory center of the brain work?
It measures the temperature of blood passing through it, and adjusts the body accordingly.
What does the body do to control temperature?
Sweat more/less, expand/contract capillaries and pull hair up or flat (although this does very little in humans) and shivering.
What temperature does the body work at?
37 degrees C.
Why does sweating cool a person?
Heat energy warms the sweat and causes it to evaporate, taking the heat energy with it.
Why does shivering warm a person?
Causes muscles to contract and relax rapidly, releasing more thermal energy due to respiration.
