Homeostasis Flashcards
What is homeostasis?
Maintaining a stable internal environment
How does the body maintain homeostasis?
Negative feedback mechanisms
Examples of homeostasis?
Temperature, blood glucose, hormones
Cold temperature outside?
Thermoreceptors detect body temperature is too cold
Thermoregulatory centre
effects:
Hair goes up to trap warm air
surface blood vessels vasoconstrict so that the blood is closer to your body
excessive rapid muscle contractions to keep warm
Warm temperature outside?
Thermoreceptors detect body temperature is too hot
Thermoregulatory centre
effects:
surface blood vessels vasodilator so that the blood is closer to your surroundings so that heat can escape from radiation
you sweat which takes heat by evaporation
Ideal core body temperature
37 degrees
What is a hormone?
Chemical molecule released into the blood
produced by glands
part of the endocrine system
What makes up the endocrine system?
Pituitary gland thyroid adrenal gland pancreas ovaries/testes
Action of nerves?
Fast
short acting
precise area
Action of hormones?
slower
longer acting time
general area
High blood glucose?
insulin released
glucose moves into muscles and liver
stored in liver as glycogen
decrease in blood glucose
Low blood glucose?
glucagon released
liver breaks down glycogen
increase in blood glucose
What is type 1 diabetes?
Genetic
body doesn’t make insulin
What is type 2 diabetes?
obesity
body doesn’t respond to insulin anymore
What are the kidneys?
Part of the endocrine system
filter the blood
produces urine
What is urea?
excess amino acids are converted into fats and carbohydrates in the liver
ammonia is produced as a waste product
ammonia is converted to urea by liver
urea transported to kidney to be filtered by the nephrons
Why change ammonia to urea?
Ammonia is toxic
Why change excess amino acids to fats and carbohydrates?
So you can store them
What is selective reabsorption?
When your body chooses what to absorb again e.g. water, glucose, ions or salts
what substances are removed by the kidney?
urea, excess salts, water
What controls urine concentration?
antidiuretic hormone
where does antidiuretic hormone come from?
pituitary gland
when is ADH release?
when the water in your blood is reduced It makes you wee less
what happens in kidney failure?
build up of waste products in blood
what is dialysis?
a machine that filters the blood
how does a dialysis machine work?
blood flows between partially permeable membrane surrounded by dialysis fluid
waste moves out into the dialysis fluid
useful substances can’t pass out into fluid
how many times do you need dialysis?
2-3 times a week
what is the other option for kidney failure other than dialysis?
Kidney transplant
types of kidney transplant?
dead and alive
alive is better
risks of kidney transplant
body can reject it so you have to take immunosuppressants which increases risk of infection or illnesses
advantage of transplant
cheaper than dialysis
more freedom
can be taken from a family member with the same blood type
