B12 Homeostasis Flashcards
where is the thermoregulatory centre and how does it work
it is in the hypothalamus in the brain and contains receptors that sense changes in the temperature of the blood flowing through the brain
what happens when the internal body temperature needs to cool down
vasodilation- blood vessels that supply your surface skin capillaries open wider and let more blood flow through causing your skin to flush so you transfer more energy by radiation which cools you down
produce more sweat which evaporates and cools you down
what happens when your internal body temperature needs to warm up
vasoconstriction- blood vessels that supply skin capillaries constrict to reduce blood flow to skin to reduce energy being transferred by radiation
sweat production is reduced or stopped
shivering- skeletal muscles contract and relax rapidly which needs a lot of respiration (exothermic process). Energy transferred warms the body up
why does carbon dioxide need to be removed from the body
dissolved co2 produces an acidic solution which affects how enzymes work
how is carbon monoxide removed from the body
diffuses out of the cells into the blood down a concentration gradient. diffuses from the blood into the air in the alveoli of the lungs which is then removed when you exhale
how is urea removed from the body
passes from the liver cells into the blood. filtered out of the blood into the kidneys and then passes out in the urine
what is urea made up of
ammonia which forms from the amino group from the amino acids when the liver removes it (deamination). The amino acids come from excess protein from eating or cells being worn out which can’t be stored
what are 2 ways of uncontrollable water loss
water is lost each time you exhale
lost through the skin in sweat
what is selective reabsorption
the amount of water and dissolved mineral ions reabsorbed depends on what is needed by your body
what is the role of ADH
a hormone that maintains water balance in the blood by changing the amount of water reabsorbed by the kidney tubules
what are the 2 methods of treating kidney failure
dialysis
kidney transplant
what does dialysis do
restores the concentrations of urea and mineral ions in the blood that have built up
what are disadvantages of dialysis
have to follow a strict diet
have to spend regular, long sessions connected to it
feel tired and unwell in between sessions
eventually causes serious damage to the body
much more expensive than the transplant
what is the role of dialysis fluid
contains the same levels of glucose and mineral ions as that of a person without kidney disease which ensures there is no net movement of glucose out of the blood
why is diffusion down a concentration gradient so important in dialysis
excess ions move out of the blood into the dialysis fluid by diffusion leaving blood plasma concentration of mineral ions at a normal level
