P2 10/11/12 Homeostasis+ response Flashcards
(37 cards)
define homeostasis +what it controls
the regulation of conditions within the body to maintain optimal conditions for enzymes
controls: body temp, blood glucose conc., water levels
3 features of control systems
receptors: specialist cells that detect stimuli (changes in enviro), eg. light receptors in eye
coordination centres: receive info then coordinate any possible response, eg. brain/ spinal cord/ pancreas
effectors: bring a response to restore optimum conditions, eg. muscles/ glands
describe the negative feedback control system for body temp
receptors in skin/brain- detect rise in body temp above 37
control centre (brain)- activates heat loss response
effectors reduce body temp- sweat glands secrete sweat
receptors in skin/brain- detect fall in body temp below 37
control centre (brain)- activates heat retention response
effectors increase body temp- muscles shiver
simple function of human nervous system
enables humans to react to their environment and coordinate behaviour
2 parts to human nervous system
central nervous system: brain+ spinal cord
peripheral nervous system: network of nerves out from CNS to rest of body
how information passes through nervous system (3 neurones)
- network of nerves out from CNS (brain+spinal cord)
- nerves made of nerve cells (neurones)
- these cells carry messages in the form of electrical impulses
-> sensory neurones: from receptors to CNS, detect pain
-> relay neurones: within CNS
-> motor neurones: from CNS to effectors, initiate motor response
describe what reflex actions are +importance
- automatic/involuntary and very quick
- a protective function to prevent injury
- eg. blinking, pupil reflex, breathing, coughing, sneezing
describe role of nerve impulses in a reflex action
- stimulus detected by a receptor - impulses passed via sensory neurones
- impulses reach relay neurones in spinal cord
- impulses passed to effector via motor neurones
-> impulses don’t go through brain as response needs to be quick, but sensation is relayed to brain while reflex is being carried out
how are synapses in neurones adapted to function in a reflex arc
- synapses- junction between neurones, delays transmission of impulses as they are converted into chemical signals
- impulses in reflex arc passed through only 2 synapses (sensory -> relay, relay -> motor) so delay is minimal
-> impulses do not go through brain as response needs to be quick + would take longer to travel through millions of brain synapses
method of calculating human time taken to detect a stimulus RP
- partner holds a ruler above you
- position your hand infront of you so the ruler will sit between your index finger + thumb - top of your finger should be level with 0cm on ruler
- partner drops ruler unexpectedly, catch asap
- measure the point at which you caught the ruler above your thumb
- repeat three times and find a mean reaction time
define endocrine system +hormones
system of glands that secrete hormones into the bloodstream for growth/repair/reproduction
-> hormones - chemical messengers, from source to organ, effect is slower than nervous system but lasts longer+ affects several locations
describe pituitary gland
- underside of brain
- master gland - hormones it releases stimulates other glands to produce their own hormones
-> eg. release of thyroid-stimulating hormone causes thyroid to release thyroxine - releases hormones in response to changes in body condition
- produces FSH and LH in females for menstrual cycle
describe thyroid gland
- in neck, infront of trachea
- releases thyroxine hormone to regulate rate of metabolism in cells
describe adrenal glands
- on top of kidneys
- produce hormones to regulate rate of metabolism in cells + blood pressure
- produce adrenaline for ‘fight or flight’ in response to threat/danger
describe pancreas gland
- behind stomach
- monitors and produces insulin+glucagon hormones to regulate blood sugar levels/ blood glucose concentration
-> negative feedback system
describe ovaries as glands
produce oestrogen+progesterone hormone - regulates monthly menstrual cycle by maintaining the uterus lining for pregnancy
+development of secondary sex characteristics
describe testes as glands
produce testosterone hormone - stimulates sperm production
+ development of secondary sex characteristics
describe body’s response when blood glucose levels are high
- pancreas secretes insulin
- insulin triggers cells to take in glucose from the blood
- glucose is converted into glycogen in the liver+muscles (for storage)
- therefore reducing blood glucose concentration
describe body’s response when blood glucose levels are low
- pancreas secretes glucagon
- glucagon triggers liver+muscles to convert stored glycogen into glucose
- glucose released back into bloodstream
- therefore increasing blood glucose concentration
describe negative feedback
- a biological response of producing negative effects to counteract a change in conditions
- works in a loop
- eg. thyroxine levels, blood glucose levels, body temp
cause+treatment of type 1 diabetes
- pancreas fails to produce sufficient insulin, so blood glucose levels are uncontrollable+too high
- treated with insulin injections, managed by monitoring carbohydrate intake/ regular exercise
cause+treatment of type 2 diabetes
- body cells stop responding to insulin, so stop taking in glucose from blood - blood glucose levels are uncontrollable+too high
- treated with tablets, managed by controlling carbohydrates in diet/ strict regular exercise
what happens at female puberty +why
- oestrogen hormone produced by ovaries - stimulates menstrual cycle + development of secondary sex characteristics (breasts, body hair)
- at puberty, eggs already formed in ovaries begin to mature + one is released around every 28dys (ovulation)
what happens at male puberty +why
- testosterone hormone produced by testes - stimulates sperm production + development of secondary sex characteristics (voice breaking, body hair)
- at puberty, sperm begins developing at a constant rate
