B3.2 -Endocrine System 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)
- thyroxine plays a vital role in regulating the body’s metabolic rate - the speed at which the body transfers energy from its chemical stores in order to perform its functions
what is the pituitary gland known as?
where is the pituitary gland?
what does the pituitary gland realse (and when)?
what is key about the pituitary gland?
- known as ‘master gland’
- found in brain, linked to hypothalamus
- releases hormones in when changes are detected by hypothalamus
- many hormones trigger other glands to release more hormones
where is the pancreas and what does it do?
- found below rib cage
- produces insulin and glucagon
- 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
- produce 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?
keeping the conditions in your body constant
The maintenance of a constant internal environment in the body.
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 electrical impulses along axon of a 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?
Adrenaline causes the body to respond by:
- respiring more quickly, to increase rate of ATP production
- increasing rate of breathing, to the cope with extra demand of oxygen
- increasing heart rate
- diverting blood away from areas such as the digestive system towards the muscles
describe stages of a negative feedback loop
- conditions in the body change from a set point
- change detected by a receptor
- corrective mechanisms activated by an effector
- conditions returned to set point
- corrective mechanisms switched off
describe stages of a negative feedback loop (in terms of thyroxine)
- hypothalamus detects cells need more energy
- pituitary gland releases TSH
- thyroid produces thyroxine
- hypothalamus detects cells have enough energy
- pituitary gland stops producing TSH
- thyroid stops producing thyroxine
Low thyroxine levels in the bloodstream stimulate the hypothalamus to release TRH (Thyrotropin releasing hormone) and this causes the pituitary to release TSH so the thyroid releases more thyroxine. So blood levels return to normal.
what happens when the stress is removed (adrenaline)?
When stress is removed, the brains signals to the adrenal glands stop —> the glands stop producing adrenaline —> the affected body systems return to their previous state
what are the four key hormones of the menstrual cycle?
- FSH (follicle stimulating hormone)
- Oestrogen
- Luteinising Hormone (LH)
- Progesterone
what is FSH, and what does it do?
- Follicle stimulating hormone
- secreted by the pituitary gland
- travels to the ovaries where it causes an egg to mature
- also stimulates production of oestrogen
what is Oestrogen?
- made and secreted by ovaries
- causes lining of the uterus to build up
- as oestrogen levels rise, they inhibit the production of FSH — usually prevents more than one egg maturing
- also stimulates the pituitary gland to release luteinising hormone
What is LH?
- Luteinising Hormone
- when LH levels reach a peak in the middle of the cycle, ovulation is triggered (egg released, approx 14 days after it starts to mature in one of the ovaries)
what is progesterone?
- produced in ovaries after ovulation
- maintains lining of the uterus during days 14-28
- levels remain high throughout pregnancy
- inhibits the release of LH and FSH.
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?
+ consideration
- thickens mucus in cervix, stopping sperm from reaching an ovum
- also thins lining of uterus, preventing implantation
- and can prevent ovulation
- taken around same time every day
Allegedly:
- fewer side effects than combined pill (but as effective)
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, stopping sperm from reaching an ovum
- prevents implantation of a fertilised egg into the uterus wall
- taken daily for 21 days of menstrual cycle
which two groups are there of contraceptive methods?
- non-hormonal - barrier methods that prevent a sperm contacting the egg or physical devices that’s release chemical compounds, which kill sperm cells (spermicides) or prevent the implantation of fertilised eggs.
- hormonal - disrupt the normal female reproductive cycle
how does condom work?
+adv
- place over penis, or inside vagina
- prevents sperm entering vagina
- can also prevent the spread of STIs
how do diaphragm or cervical cap work?
- nonhormonal
- inserted into vagina to cover the cervix
- prevents sperm cells from entering the uterus
- removed after 6 or more hrs following sexual intercourse
- not effective unless used in combination with a spermicide
what is a intrauterine device (IUD)?
- nonhormal
- inserted into uterus
- releases copper, which prevents sperm surviving in the uterus and fallopian tubes
- can also prevent implantation of fertilised ovum
- remains effective for 5 TO 10 YEARS
how does intrauterine system work?
- hormonal
- inserted into uterus
Same effect on the body as progesterone only pill:
- thickens mucus in cervix, stopping sperm from reaching an ovum
- also thins lining of uterus, preventing implantation
- and can prevent ovulation
- remains effective for 3to5 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
- blocked sperm ducts
- not enough sperm being produced in testes
- lack of mature eggs produced in the ovaries
- failure of the ovaries to release an egg
what happens during ivf? - 5 step process
1) Fertility (FSH - also LH so many collected) drugs are uses to make lots of eggs mature at the same time for collection
2) The eggs are collected and placed in a special solution in a Petri dish
3) A sample of semen is collected and the sperm and eggs are mixed in the Petri dish
4) The eggs are checked to make sure they have been fertilised and that the early embryos are developing properly
5) When the fertilised eggs gave formed tiny balls of cells, 1 or 2 of the tiny embryos are placed in the womb of the mother. Then, if all goes well, at least one baby will grow and develop successfully
what are the downsides of IVF?
- not a natural process
- many result in multiple births - can be dangerous for both mother and unborn babies
- embryo may not develop properly (dies)
- expensive
NOT reliable, may result in
- no pregnancy
- multiple pregnancies
== can be distressing for those undergoing treatment
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)
what is a tropism?
a response to stimuli which involves growth in a particular direction
what is a positive phototropism?
a part of a plant growing towards light
what is positive gravitropism?
growing in the same direction as gravity
growing downwards
what process ensures seeds grow the correct way?
phototropism + gravitropism
what are auxins?
plant hormones that enable 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)
what do auxins do in shoot cells?
stimulates them to grow more
what do auxins do in root cells?
inhibits the growth of root cells
how do plants respond to light? - shoot
- light hits one side of shoot tip
- auxin moves to the other side of the shoot
- concentration of auxin increases on unlit side of the shoot
- increases the length of this side
- shoot bends towards light
how do plants respond to levels of auxins?
in roots, plants grow more to areas with least auxin (elongate less in areas with more auxin, inhibits growth of root cells),
in stems, plants grow more on areas with most auxin / stimulates growth of shoot cells
where is auxin found in a plant stem?
at the tip (meristems)
what does a plant use hormones for? - 5
- Fruit production + Ripening
- Growth
- Move towards the light
- Leaves falling
- Disease resistance
what does the hormone auxin do?
function
- stimulates growth by causing cell elongation
- also help to regulate fruit development - fruits too small without auxin
what does the hormone ethene do?
Function
- causes plant fruits to ripen by stimulating the conversion of starch into sugar
- > this is why a ripe fruit taste sweeter than an unripe one
- only plant hormone that EXISTS AS a GAS
what does the hormone Gibberellins do?
fucntion
- promotes growth, particularly stem elongation)
- also can end the 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, such as grass
- Auxin weed killer makes weeds grow too fast - this rapid uncontrolled growth kills the plant
how do root growth powders work?
- contains auxin
- auxin used to produce identical plants, clones, from cuttings
- cut off a plant shoot, dip it into rooting powder and plant it
- after a few days, new roots develop from the cut stem
- the new roots anchor into the soil and take up water and minerals
How to delay ripening? - fruit trees
- Auxin is sprayed on fruit trees to delay ripening
- this allows a harvester to be collected all at the same time, and can prevent fruit from dropping off trees early
Commercially - how to ripen fruit
- Ethene is sprayed on fruit trees and plants so that their fruits ripen quicker
- this allows fruit to be ready earlier in the growing season
how do you produce seedless fruit?
- use auxins
- (Seeds produced after plant is pollinated by insects or the wind )
- if auxins are applied to unpollinated flowers, the plant produces seedless fruit
How to control dormancy ? + why
- seeds remain dormant until conditions are ideal for growth - this normally prevents them germinating at the end of the summer so they survive the winter
- commercial growers trigger seeds to germinate in the winter by spraying them with gibberellins or auxins in the greenhouse
Explain in detail how plants respond to gravity
1- A normal young bean plant is laid on its side in the dark. Auxin is equally spread through the tissues.
2 - In the root, more auxin gathers on the lower side
- in the shoot, more auxin gathers on the lower side
3 - The root grows more on the side with the least auxin, making it bend and grow down towards the force of gravity. When it has grown down, the auxin becomes evenly spread again.
- The shoot grows more on the side with the most auxin, making it bend and grow up away from the force of gravity. When it has grown up, the auxin becomes evenly spread again.
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.
explain how the body increases the energy available to cels during exercise (and how it returns to normal when extra energy is no longer needed)
- pituitary gland to releases thyroid-stimulating hormone
- TSH stimulates the thyroid gland to release thyroxine.
- This increases the metabolic rate, allowing cells to transfer additional energy.
- When cells are being supplied with the required amount of energy, the hypothalamus inhibits the production of TSH.
- The thyroid gland therefore stops releasing thyroxine (negative feedback).
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)
How does phototropism help?
When a stem grows towards tree light, the plant can photosynthesise more, so more food is produced for the plant, so it can grow faster, which increases the plant’s chances of survival
Non-hormonal contraception definition
Barrier methods that prevent a sperm contacting the egg or physical devices that release chemical compounds
Hormonal contraception definition
Use of hormones to disrupt the normal female reproductive cycle
How does gravitropism help
Roots growing downwards:
Growing deeper into soil provides anchorage, and normally takes roots nearer to water.
Especially Important for germinating seeds which often land the wrong way up, so ensures that grow correctly.
Function - uterus
fetus develops here
Fucntion - ovary
Eggs mature here
Function cervix
Entrance to uterus
Fucntion vagina
Receives sperm from the penis during sexual intercourse
Fucntion Fallopian tube (__)
Fallopian tube (oviduct) - where the egg is fertilised before travelling along the tube to the uterus.
How can FSH be used as an artificial fertility drug?
- when the women takes this drug it stimulates eggs to mature in her ovaries
- it also triggers oestrogen production
- this significantly increases her chance of getting pregnant, as it increases the likelihood of one or more eggs being released
Evaluating infertility treatments – Higher - adv, dis, ethical
Advantages of IVF include:
It allows people to have babies of their own, who otherwise can’t due to a variety of reasons.
It has a safe track record and has been used since 1978. The embryos can be screened for genetic diseases, which is important for families that already have an affected child. Only unaffected embryos are used.
Unused eggs can be used for research or donated to other couples.
Disadvantages of IVF include:
there are side effects from the drugs used, such as hot flushes and severe headaches
there is a possibility of multiple births, which is dangerous for mother and babies
ovarian hyper-stimulation syndrome (OHS), when too many eggs develop in the ovaries
it is very emotionally and physically stressful
the success rates are not high
Ethical concerns
Some people worry about the ethical implications of IVF. They are concerned that couples may want ‘designer babies’ with ‘desirable’ qualities, so may only want certain fertilised eggs. For example, they may want a girl if they have lots of boys in the family.
Also, the embryos that are not used may be destroyed. Some people might view these as new lives, so may consider destroying them to be unethical.
How do plant hormones act in similar ways to animals ones?
They are produced by cells in one area of the plant, and then transported to a different area to produce a response
Question
Describe the relationship between the different hormones in the menstrual cycle during the 28 days.
Days 1 to 12 – oestrogen gradually increases and peaks approximately on the 12th day. Progesterone, LH and FSH stay approximately at the same levels and begin to increase slightly from around day 12.
FSH and LH patterns are very similar and peak during ovulation at approximately 14 days during this cycle. They drop sharply on day 15 and stay constant until day 28.
Oestrogen drops during days 13 and 14, and progesterone continues to gradually increase until about day 21, when it slowly beings to decrease again. Oestrogen mirrors this shape and also has a second lower peak at about day 21.
Changes occur at puberty because of the hormones: (2)
Changes occur at puberty because of the hormones:
testosterone - produced by the testes - controls the development of male secondary sexual characteristics
oestrogen - produced by the ovaries - controls the development of female secondary sexual characteristics
Secondary sexual characteristics - boys only (4)
- voice breaks
- hair grows on face and body
- body becomes more muscular
- testes start to produce sperm cells
Secondary sexual characteristics - boys + girls (3)
- pubic hair grows
- underarm hair grows
- sexual organs grow and develop
Secondary sexual characteristics - girls only (4)
- voice deepens gradually
- hips get widen
- breasts develop
- ovaries start to release egg cells - menstruation starts
