Homeostatis, Thermoregulation + Osmoregulation Flashcards
what is homeostasis?
the maintenance of a constant internal environment e.g. body water content, body temperature and blood sugar level
what does the hypothalamus do?
- it monitors the temperature of the blood
- if it detects a change in the temperature of the blood flowing through it, it signals via neurones to other organs of the body
- which will bring the temperature of the blood back to its normal level
which ways does the body maintain temperature?
- sweating
- shivering
- controlling heat loss by controlling the amount of blood which flows near the surface of the skin
why do our hairs stand on end during thermoregulation?
explanation = the hair traps a layer of air which provides insulation for conduction of heat
effect = less heat loss
why do we release less sweat during thermoregulation?
explanation = less sweat is released therefore
effect = less heat loss
why does vasoconstriction happen during thermoregulation?
explanation = arterioles supplying the capillaries near the surface of the skin get narrower - they constrict. less blood will flow through capillaries near the surface of the skin, therefore less heat will be lost by radiation
effect = less heat loss
why do our hairs lie flat during thermoregulation?
explanation = hairs lie flat and therefore an insulating layer of air is not formed
effect = more heat lost
why is more sweat released during thermoregulation?
explanation = sweat isn’t cold - the sweat is secreted at normal body temperature. when the sweat evaporates, heat energy is taken away from the skin as evaporation of water requires energy
effect = more heat loss
why does vasodilation happen during thermoregulation?
explanation = arterioles supplying the capillaries near the surface of the skin get wider - they dilate. more blood will flow through capillaries near the surface of the skin, therefore more heat will be lost by radiation
what is osmoregulation?
the regulation of water levels within the body to keep it from rising or falling too much
how can water levels be changed within the body during osmoregulation?
by adjusting the permeability of the collecting duct in the nephron (in the kidney)
what is the process of osmoregulation?
- at different times your body will need to reabsorb different amounts of water - for instance after exercise your body will want to retain as much water as possible because you will have released a large amount through sweat. your body controls this using a hormone called anti-diuretic hormone (ADH)
- an area in your brain called the hypothalamus monitors the level of water in your blood - if you need to reabsorb more it tells the pituitary gland to release more ADH
- as ADH is a hormone it is carried in the blood - the collecting duct is surrounded by capillaries. the ADH diffuses out of the blood and binds with receptors on the surface of the collecting duct cells. if ADH binds this triggers the wall of the collecting duct to become more permeable to water. therefore, more water is reabsorbed into blood - less urine is produced; it is more concentrated and darker coloured
