B12 - homeostasis in action fact test Flashcards
how is body temperature monitored and controlled
by the thermoregulatory centre in the hypothalamus
where are temperature receptors found
- thermoregulatory centre (contains receptors sensitive to temperature of blood)
- the skin (contains receptors for temperature and sends nervous impulses to the thermoregulatory centre
why is maintaining body temperature important
it’s important to maintain a body temperature of around 37 degrees because it’s the optimum temperature for which enzymes work. if it is any higher, they will denature, resulting in severe illness
what happens when body temperature is too high
- blood vessels dilate (vasodilation) - this allows more blood to flow through the skin and more heat is lost to the environment
- sweat is produced from sweat glands - the sweat evaporates, transferring heat energy from the skin to the environment
- hairs lie flat
what is vasodilation and what happens during the process
vasodilation is a response to being too hot. the process includes the widening of blood vessels at the surface of the skin to increase heat loss through the surface of the skin. increased blood flow causes skin to appear more red in colour
what happens when body temperature is too low
- blood vessels constrict (vasoconstriction) - less blood flows through the skin, so less heat is lost to the environment
- sweating stops
- shiver (skeletal muscles contract) - releases heat, respiration is exothermic
- hairs stand upright - traps a layer of air next to skin to act as insulating layer
what is vasoconstriction and what happens during the process
vasoconstriction is a response to being too cold. the process involves the narrowing of blood vessels at the skin surface to reduce heat loss through the surface of the skin
when is carbon dioxide produced
during respiration
enters blood by diffusing out of cells into blood down a concentration gradient
enters alveoli by diffusing from blood into the air in the alveoli in your lungs
why does carbon dioxide need to be removed and how is it removed
when dissolved, it produces an acidic solution which would affect the working of all the enzymes in your cells
exhaled during respiration
when is urea produced
when you eat more protein than you need or when your tissues are worn out
it is nitrogenous waste produced by the breakdown of excess amino acids in your liver
(produced in the liver)
why does urea need to be removed and how is it removed
needs to be removed because it’s poisonous and if built up, can cause extreme damage to cells
filtered out of the blood by kidneys and passed out of body through urine produced by kidneys
how are water and mineral ions lost through no control
- water leaves lungs every time you exhale
- water, mineral ions and urea are lost through skin in sweat
how are water and mineral ions lost with control
urea, excess water and mineral ions are removed from the body via the kidneys then excreted into urine. this process is tightly regulated to maintain water and mineral ion content of the blood within narrow limits and remove urea
what happens if concentration of water in the blood increases
water moves into cells via osmosis and causes cell to swell
what happens if concentration of water inside the blood decreases
water moves out of cells via osmosis and this causes the cell to shrivel
