B3.2 -Endocrine System (use Miss Howard’s for plant hormones, use this for human hormones) Flashcards
state three endocrine glands
- Thyroid gland
- Pituitary Gland
- Pancreas
Where is the thyroid gland and what does it do?
- in the neck, releases thyroxine (increases resting metabolic rate)
- regulates metabolism, heart rate and temperature by
what is the pituitary gland known as?
where is the pituitary gland?
what does the pituitary gland realse (and when)?
- known as ‘master gland’
- found in brain, linked to hypothalamus
- releases hormones when changes are detected by hypothalamus
where is the pancreas and what does it do?
- found below rib cage
- produces insulin and glycogen
- regulates blood glucose level
where are the adrenal glands?
what do they do? (and when do they do so)
- two glands, situated above each kidney
- product adrenaline (when an organism is presented with a dangerous situation)
where are the testes and what do they do?
- producest testosterone (controls puberty and sperm production)
what do ovaries do?
- produce oestrogen
- regulates menstrual system
how do hormones travel around the body?
being secreted in the blood and transported
what is homeostasis?
The maintenance of a constant internal environment
state the function of a hormone
a chemical messenger which regulates the function of many cells and organs
how do hormones produce a response in target cells from the blood?
diffuse out of bloodstream and bind to specific receptors for that hormone (on cytoplasm of cells for target organ)
what is the endocrine system?
name given to all the endocrine glands and the hormones that they produce
state the function of all the endocrine glands
controls and co-ordinates body processes with the nervous system
compare the speed of communication between CNS and endocrine gland?
- endocrine system triggers a slow response
- CNS triggers a fast response
compare the method of transportation between CNS and endocrine gland?
- CNS electrically impulses along a on of neurone
- ES secreted in bloodstream
compare the duration of response between CNS and endocrine gland?
- CNS short acting
- ES longer acting (except hormones like adrenaline)
compare the area targeted between CNS and endocrine gland?
- CNS very precise area
- ES larger area (target organs)
similarities between CNS and endocrine system?
- both follow basic response oder
receptor cell, coordination centre, effector
what it the function of the thyroid gland?
- release thyroxine
- take iodine (from food) and convert it to thyroxine by combining it with the animo acid tyrosine
what does adrenaline prepare the body for?
intensive action
what is an important control in homeostasis?
negative feedback loop
how does adrenaline affect the lungs?
- enlarges air passages (alters metabolism)
- boosts delivery of oxygen and glucose to brain and muscles
how how does adrenaline affect the body?
- respire faster (higher rate of ATP made)
- breathe faster (extra demand of oxygen)
- higher heart rate
- blood away from digestive system and towards muscles
describe stages of a negative feedback loop
- conditions in the body change from a set point
- change detected by a receptor
- corrective mechanism activated by an effector
- conditions returned to set point
- corrective mechanism off
describe stages of a negative feedback loop (in terms of thyroxine)
- hypothalamus detects cells need more energy
- pituitary gland stimulates TSH
- thyroid produces thyroxine
- hypothalamus detects cells have enough energy
- pituitary gland stops producing TSH
- thyroid stops producing thyroxine
what happens when the stress is removed (adrenaline)?
signals to the adrenal glands stop (affected body systems return to original state)
what are the four key hormones of the menstrual cycle?
- FSH (follicle stimulating hormone)
- Oestrogen
- Luteinising Hormone (LH)
- Progesterone
what is FSH, what is it secreted from, what hormone does it stimulate, and what does it do?
- Follicle stimulating hormone
- released by the pituitary gland
- causes egg in ovary to mature
- stimulates production of oestrogen
what is oestrogen, what is it secreted from, what hormone does it stimulate, and what does it do?
- secreted from ovaries
- development of thick uterus lining
- stimulates production of LH
- stops production of FSH
what is LH, what is it secreted from, what hormone does it stimulate, and what does it do?
- Lutenising Hormone
- secreted by pituitary gland
- stimulates release of mature egg on day 14 of cycle (OVULATION)
- doesn’t stop or stimulate any hormones
what is progesterone, what is it secreted from, what hormone does it stimulate, and what does it do?
- produced in ovaries after ovulation (corpus luteum)
- maintain lining of the uterus during days 14-28
- inhibits (stops) the release of LH and FSH.
- if uterus doesn’t receive fertilised egg, then progesterone levels drop (causing FSH levels to increase)
what happens when progesterone levels drop?
- triggers the breakdown of the lining
- marks day 1 of the next menstrual cycle.
what is stage 1 of the menstrual cycle?
- uterus lining breaks down, resulting in period
Stage 2 of menstrual cycle?
-uterus lining starts to build up again into a thick, spongy layer full of blood vessels.
stage 3 of menstrual cycle?
- Ovulation
- an egg is released from one of the ovaries
stage 4 of menstrual cycle?
- uterus lining is maintained, ready for the arrival of a fertilised egg
- if egg not fertilised, uterus lining breaks down, cycle restarts
what does the progesterone only pill do?
- thickens mucus in cervix (sperm no pass)
- thins lining of uterus
- inhibits release or FSH (eggs no mature)
- fewer side effects than combined pill (but as effective)
- same time every day
- can prevent ovulation
what does the combined pill do?
- Contains both oestrogen and progesterone.
- oestrogen builds up in the body (stop FSH, no eggs mature)
(prevents ovulation) - thickens mucus in cervix (sperm cannot pass)
- daily for 21 days of menstrual cycle
which two groups are there of contraceptive methods?
- nonhormonal (barrier method)
- hormonal (disrupt reproductive cycle)
how does condom work?
- place over penis (or inside vagina)
- prevent spread of STIs
- stops sperm entering vagina
how do diaphragm or cervical cap work?
- nonhormonal
- inserted into vagina (cover cervix)
- removed after 6+ hrs after sex
- needs spermicide (or no work)
what is a intrauterine device (IUD)?
- nonhormal
- inserted into uterus (releases copper)
- prevents sperm surviving uterus and fallopian tubes
- prevent implantation of fertilised ovum
- 5 TO 10 YEARS
how does intrauterine system work?
- hormonal
- inserted into uterus
- thickens mucus from cervix
- thins lining of uterus
- prevent ovulation
- 3-5 YEARS
are hormonal or non-hormonal devices more effective?
usually hormonal
explain why blocked fallopian tubes would prevent a successful pregnancy
as the sperm would not be able to meet the egg
state 4 reasons for infertility (2 male 2 female
- blocked sperm ducts
- not enough sperm being produced in testes
- lack of mature eggs produced in the ovaries
- failure of ovaries to release eggs
what happens during ivf?
1) woman given hormones for many eggs to be matured at the same time
2) eggs collected and placed in a Petri dish
3) semen is collected and mixed in Petri dish
4) egg becomes fertilised
5) embryos are placed in the womb
what are the downsides of IVF?
- multiple pregnancies
- embryo may not develop properly (dies)
- expensive
what are the positives of IVF?
- allows homosexual couples to have children
- allows older couples to have children
- allows younger women to focus on their careers (and choose to have a baby later in life)
- lower chance of miscarriage
what is a tropism?
a response to stimuli which involves directional growth
what is a positive phototropism?
a plant growing towards a light source
what is positive gravitropism?
growing in the same direction as gravity
growing downwards
what process ensures seeds grow the correct way?
phototropism + gravitropism
what is auxin?
the hormone that enables plants to grow towards or away from a stimulus
how do responses to a light stimulus occur?
plant growth hormones
- uneven distribution of auxin
- unequal growth rate
- shorts or root to bend (grow more on one side)
how do shoots of plants respond to light?
- light hits one side of shoot tip
- auxin break down/move to the other side of the shoot
- concentration of auxin increases on one side of the shoot
- that side grows more than the other
- shoot bends towards light
how do roots and shoots respond to levels of auxins?
in roots, plants grow more in areas with least auxin, in stems, plants grow more in areas with most auxin
where is auxin found in a plant stem?
at the tip (meristems)
what does a plant use hormones for?
- Fruit production + Ripening
- Growth
- Move towards the light
- Leaves falling
- Disease resistance
what does the hormone auxin do?
commercially
- stimulates growth
- weed killer
- rooting powder
what does the hormone ethene do?
commercially
- causes fruits to ripen (stimulates conversion of starch to sugar)
- > why ripened fruits taste sweeter
- EXISTS AS GAS
what does the hormone Gibberellins do?
commercially
- promotes growth (stem elongation)
- end dormancy period of seeds/buds
- leads to shoots/flowers opening
how do weed killers work?
- contain auxin
- selective herbicides (only kill broad-leaved plants, and not narrow leaved - grass)
- makes weeds grow too fast (uncontrollable growth kills plants)
how do root growth powders work?
- contains auxin
- produce identical plants (clones), from a plantcutting
- cut off a plant shoot and dip into rooting powder
- roots develop from cut stem
what hormone would you spray to prevent fruit from ripening during transportation?
auxins
what hormone is used for ripening fruit
ethene (sprayed on)
how do commercial growers trigger seeds to germinate during winter?
spray them, with Gibberellins or auxins in the greenhouse
explain how plant root hormones produced this response to gravity
- auxins gather on the lower side of the horizontal root
- root grows more on the side with the least auxin
- bending of the root towards gravity
- When the root is pointing downwards the auxin becomes evenly spread throughout the root.
- The root then continues to grow down
describe the function of FSH in the menstrual cycle
- To stimulate one of the eggs in the ovary to mature / oestrogen to be produced
explain how hormones cause only an effect on target cells rather than the whole body
- Hormones bind to specific receptors for that hormone (found
on the membranes or in the cytoplasm of target cells) - Once bound to their receptors the
hormones stimulate the target cells to produce a response.
Why do plants need hormones?
To allow a response to changes in the environment
what is the purpose of a negative feedback loop?
for homeostasis (keeps internal conditions constant)
why is progesterone secreted? (not the purpose, but like what is the cause of it being produced)
-as once ovulation occurs, the follicle becomes corpus lutem and secretes oestrogen and prigesterone
