Homeostasis Flashcards
What is homeostasis?
the maintenance of a constant internal environment in the body
controlled by the nervous system and hormones
What are the parts of the body control systems?
receptors - detect a stimulus (change in the environment), such as temperature change
coordination centres - in the brain, spinal cord and pancreas
they receive information from the receptors, process the information, and instigate a response
effectors - such as muscles or glands create the reponse
glands often release a hormone, which restores the optimum condition
osmoregulation
- controls how much water is lost in urine
- controls amount of water in the body
- stops animal cells from shrinking or swelling by osmosis if the water content of the body changes
Describe the negative feedback loop for osmoregulation
-normal water content in body
-body gains water from food and drink:
too much water in body
-brain detects change and causes more water to be excreted in urine
lots of watery urine:
-normal water content in body
-body loses water when breathing out/ sweat/ urine:
too little water in body
-brain detects change and causes less water loss in urine
small amount of concentrated urine
-normal water content in body
thermoregulation
controls core body temperature
37 degres celsius (36 - 37.5)
What is thermoregulation controlled by?
hypothalamus - triggers changes in skin and muscles
thermoregulatory centre in the hypothalamus monitors/controls core temperature
temperature is detected by the temperature of the blood flowing through it
receptors in the dermis (skin) also detect temperature
What does negative feedback do?
responds to a change in a condition to bring it back to the normal level
Describe what happens if the core body temperature is too hot
- body temp rises due to hot environment or exercise
- hypothalamus detecrts rise and causes body responses
-changes triggered in blood flow so more blood flows near skin surface
(VASODILATION)
-sweat glands release more sweat onto skin surface to evaporate along with heat energy
-sebaceous glands produce oil that helps sweat spread out over skin
-transfer of energy to surroundings is increased
Which type of gland produces oil when the body sweats?
sebaceous gland
Describe what happens if the core body temperature is too low
- body temp falls due to cold environment
- hypothalamus detects change and causes body responses
-changes triggered in blood flow so less blood flows near skin surface
(VASOCONSTRICTION)
-sweat glands stop producing sweat
-body hairs raised by erector muscles in skin, causing goosebumps
-muscles quickly contract and relax in succession - shivering
-reduces transfer of energy to surroundings
Explain two changes that occur in the body if core temperature is too low
-blood vessels that supply skin capillaries constrict, reducing blood flow through the capillaries near the skin surface
this means less heat is transferred to the environment
-muscles quickly contract and relax in succession (causing shivering) releasing energy from increased respiration to warm the body
Explain why it is important for the enzymes in our bodies that our internal temperature is fairly constant
enzymes work fastest/are most active at a particular temperature
at lower/higher temps, they are not as active, so chemical reactions are not carried out as quickly
this could cause harm to the body
Describe osmoregulation in terms of a negative feedback system
if there is too much water in the body more water will be excreted in urine, returning the levels to normal
if there is not enough water then less water is excreted in urine, helping to increase water levels
this is an example of negative feedback because the body works to restore the balance
