Homeostasis and Response Flashcards
why is homeostasis important
cells need the right conditions to function properly, also for enzyme action
what is homeostasis
regulation of conditions inside the body to maintain a stable environment in response to changes
give examples of control systems
temperature, water content, blood glucose
give the components that work together in homeostasis
effectors, receptors and coordination centres
what is negative feedback
bringing the level of something back to normal
what is a stimulus
change in environment
what is the process for when something is too high/low
- receptor detects stimulus is too high/low
- coordination centre processes information and organises a response
- effector produces a response that counteracts the change
what does the nervous system mean
humans can react and coordinate behaviour
what is the difference between prokaryote nervous systems and eukaryote nervous systems
prokaryotes have reflexes and eukaryotes have nervous systems
what is the CNS
brain, spinal chord, sensory and motor neurones
what are sensory neurones
carry info as electrical impulses from receptors to CNS
what are motor neurones
carry info as electrical impulses from CNS to effectors
what are effectors
all muscles and glands that respond to nervous impulses
what is a synapse
connection between two neurones
how does a neurone transfer to another neurone
nerve signal transferred by chemicals diffuse across gap sets off electrical signal in next neurone
what are reflexes?
rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain - they can reduce the chance of being injured
what is an example of a reflex?
if a bright light is in your eye, your pupils get smaller so that less light gets in the eye to stop it getting damaged.
what are the 6 steps to a reflex arc?
- stimulation of pain receptors
- impulses travel along sensory neurone
- impulse pass along relay neurone through a synapse
- impulse travels along a motor neurone via synapse
- impulse reaches muscle and muscle contracts
how do you do the ruler drop test in 6 steps?
- person rests their arm on the edge of a table
- hold a ruler above their hand and let go without any warning
- person should try to catch the ruler to measure reaction time
- write down the measurement of them catching it
- repeat the test several times and calculate the mean
- repeat but give the person caffeine
what are hormones 5
- chemical molecules released into the blood
- only affect target organs
- long lasting effects
- control things that need constant adjustment
- controlled and secreted endocrine glands that make up your endocrine system
what is the pituitary gland?
- in your brain, looks like an egg
- regulate body conditions
- master gland
what is the thyroid?
- in your throat, looks like a butterfly
- produces thyroxine
- regulates metabolism, heart rate and temperature
what is the adrenal gland?
- looks like a cupcake, in your stomach
- produces adrenaline
- fight or flight
what is the pancreas?
- in your stomach, looks like a rat
- produces insulin
- regulates blood glucose
what are ovaries?
- in uterus, looks like two eggs
- produces oestrogen
- menstrual cycle
what are testes?
- balls, two eggs
- produces testosterone
- puberty and sperm production
what does eating foods containing carbohydrates do?
puts glucose into the blood from the gut
how do you remove glucose from the blood?
- exercise
- metabolism of cells
- insulin
where is excess glucose stored?
insulin turns glucose into glycogen in the liver and muscles
what happens when blood glucose is too high?
- insulin (pancreas)
- liver turns glucose into glycogen
- glucose goes into liver and muscle cells
what happens when blood glucose is too low?
- glucagon (pancreas)
- glucagon makes liver turn glycogen into glucose
- glucose goes into blood
what is diabetes?
condition that affects your ability to control your blood sugar level
what is type 1 diabetes?
- pancreas produces little/ no insulin
what do people with type 1 diabetes do to treat it?
insulin injections at mealtimes to make sure glucose is removed from the body once food has been digested to stop the level getting too high
what does the amount of insulin depend on?
- persons activeness
- persons diet
how should people with type 1 diabetes think about their intake?
limiting intake of food rich in carbohydrates
what is type 2 diabetes?
when a person becomes resistant to their own insulin
what increases your chance of getting type 2 diabetes?
being overweight
how can type 2 diabetes be controlled?
- carbohydrate controlled diet
- regular exercise
what happens in stage 1 (day 1 - day 4) in the menstrual cycle?
lining of the uterus breaks down
what happens in stage 2 (day 4 - day 14) in the menstrual cycle?
lining of the uterus builds up
what happens in stage 3 (day 14) in the menstrual cycle?
ovulation
what happens in stage 4 (day 14 - day 28) in the menstrual cycle?
lining of uterus maintained
what fsh?
- pituitary gland
- egg matures in one of the ovaries in follicle
- stimulates ovaries to produce oestrogen
what is oestrogen?
- ovaries
- lining of uterus to grow
- stimulates the release of LH and inhibits FSH
what is LH?
- pituitary gland
- stimulates ovulation
what is progesterone?
- ovaries by remains of follicle after ovulation
- maintains lining of uterus
- inhibits LH FSH
how can oestrogen be a contraceptive?
- taken everyday to keep level of it high, inhibits production of FSH
- egg development and production stop
how can progesterone be a contraceptive?
stimulates thick mucus that prevents any sperm reaching the egg
what is a side effect of an oestrogen pill?
- nausea
- headaches
- doesn’t protect against STDs
what are other forms of contraception using oestrogen and progesterone? (5)
- contraceptive patch stuck on the skin, lasts a week
- contraceptive implant releases continuous progesterone, lasts three years
- contraceptive injection, 3 months
- plastic IUD kills sperm and release progesterone
- copper IUD kills sperm and prevent sperm from surviving
what are non-hormonal forms of contraception?
- condoms stop sperm from entering and prevent STDs
- diaphragm is a cup that fits over the cervix that uses spermicide
what are other ways to avoid pregnancy?
- abstinence
- ‘natural methods’ menstrual cycle
- sterilisation: cutting/tying fallopian tubes or sperm duct (permanent)
how can hormones be used to increase fertility?
women that have low levels of FSH cause their eggs to mature: no eggs are released. FSH and LH stimulate ovulation
what is a side effect of using hormones to increase fertility?
- expensive
- too many eggs stimulated can result in twins/triplets
what is IVF? (4)
- collecting eggs and fertilising them using a lab and sperm
- if the man has a low sperm count, they inject it into the egg
- embryo grows in an incubator, then is transferred to a woman’s uterus
- FSH and LH are given before egg collection
what is a downside of IVF? (4)
- multiple births
- success rate is low (26%)
- stressful
- abdominal pain, nausea, vomiting and dehydration
how has technology improved IVF? (3)
- microscopes improve technique and success
- micro-tools used on egg and sperm
- time-lapse imaging: growth can be monitored
why are some people against IVF?
- embryos can be destroyed and people think it’s unethical as it is a potential human life
- genetic testing could lead to preferred characteristics which people find unethical
