B 3.2 Endocrine System Flashcards
What are hormones
Where are they made, where secreted
Where do they cause a response?
Big question is how do hormones travel and cause an effect?
Hormones are CHEMICAL MESSENGERS. They are made in ENDOCRINE GLANDS and secreted in blood, where they travel in plasma and travel all around the body. However they only cause a response in Target hormones by binding the specific receptors for the hormone, found in the membrane / cytoplasm of the cells in the target hormone. These cells are the TARGET CELLS. Once binded with these cells, a response is stimulated…
What is homeostasis ?
Maintaining of internal environment / conditions in body
Where are the various glands found
Thyroxine , testosterone, progesterone oestrogen, insulin, others
Hypothalamus and Pituitary gland, the hormonal centre, produces hormones that REGULATE THE PRODUCTION OF OTHER HORMONES.
- Thyroid gland in neck produces thyroxine (actually takes amino acid tyrosine, which combines with iodine, to make thyroxine )
- pancreas produce insulin, and adrenal glands (ABOVE KIDNEY) produce adrenaline
- ovaries produce oestrogen progesterone
Testes testosterone
So what is the endocrine system then?
Collective term for all the glands and hormones they produce , which in turn coordinates body processes with the nervous system.
Similarity and differences between hormones and nerves?
4 differences need to know
Similar
- both send messages around the body to stimulate a response about changes in internal/ external environment
Differences
- speed, how they transmitted, duration of response, area targeted
- nerves communicate very fast, hormones slow
- nerves act very fast, hormones can act fast ish but mostly slow (think puberty)
- nerves messages are transmitted across an electrical impulse of the axon of neurone, hormone does their hormone secreted in blood
- nerves target a specific area, but hormones a more wide range
- finally nerve do ELECTRICAL signals, Hormone CHEMICAL
What is a negative feedback loop? Example
Negative feedback loop is when a change from conditions of the set point is detected by receptor cells and this is corrected by a mechanism. Once the change is corrected, the mechanism is switch off, like heating system. Things like thermoregulation and water balance are used with negative feedback loops.
What is thyroxine used for , how is negative feedback loop control levels of thryroxine in body?
Thyroxine is used to control the metabolic rate- the rate at which energy is transferred from food to chemical in our body,
When the HYPOTHALAMUS detects energy is needed, the hypothalamus CAUSES the Pituitary gland to release hormone TSH (thyroxine stimulating hormone). This stimulates the thyroid gland to produce and release thyroxine, which increases the metabolic rate, allowing cells to transfer more energy. Once the hypothalamus detects the cells have enough energy, it stops the pituitary gland from producing more tsh which in turn stops the thyroid gland from producing thyroxine.
However when too much energy being produced- it stops.
What does the hormone adrenaline do and how is that controlled?
Adrenaline prepares you for fight or flight response. This is detected by stress levels.
When hypothalamus detects stress levels are high, it sends signals to the adrenal glands to produce adrenaline, which does a range of things:
- it increases the rate of respiration, which allows you to transfer ATP more. (Bunds to liver cells, which stimulates it to break down glycogen to glucose with glucagon …)
- it increases rate of breathing and heart rate to cope with the increase of respiration (binds to receptor cells in heart)
- diverts blood away from not vital organs (like digestive system) to vital organs and mainly MUSCLES.
when hypothalamus detects that stress levels are normal again, it stops sending signals for the adrenal gland to produce adrenaline, and so the body systems return to previous state.
Not necessarily a negative feedback loop
What is normal body temperature, what happens if it goes below 35 or above 42?
37
Below 35 causes hypothermia, causing enzyme reactions to happen too slowly and so enough energy is not produced, and cells begin to die.
Above 42 is HYPERTHERMIA (more movement= hyper). Amino acids in chain in enzymes begin unravel, changing shape of active siege causing enzymes to denature. Reactions stop happening, and you die.
How is temperature controlled (in terms of receptor cells etc)
The thermoreguslotry centre in YOUR BRAIN, is responsible for regulation.
- it relies on receptor cells in skin and internal receptor cells in blood to determine what is happening, monitoring external and internal temps.
Change is detected, body fix, mechanism removed, negative feedback, maintains homeostasis…
Hypothalamus btw
What happen if body too cold
4 things
- Body stops sweating (so no more energy can be transferred from Body to surroundings when sweat evaporates)
- hairs on skin raise- all the hairs raise which traps a layer of air between them, insulating the body -making you warm
- vasoconstriction happens- blood vessels SUPPLYING CAPILLARIES near the skin constrict ( marrow) , REDUCING BLOOD FLOW AND So less heat is lost to surroundings.
- Shivering takes place: this is when muscles contract and relax really quickly, making your cells respire more for energy to do so, and since respiration exothermic reaction - it transfers energy by heating .
What happens if body too warm?
3 things, reverse of cold.
- sweat glands produce sweat (mixture if water urea salts). When this gets evaporated, what is transferred from body to surrounding schooling you down
- Hairs lower, so insulating layer of air goes away
- vasodilation : when blood vessels supplying capillaries widen, increasing blood flow, and therefore more heat is lost by RADIATION.
- shivering stops
Hormones for reproduction and what do they do?
Testosterone for males, stimulates speem production and importwnt for development of male reproductive system such as enlargement of penis, growth etc
Oestrogen for females, involved in menstrual cycle and involved similarly for growth of female characteristics, such as breast development
Menstrual cycle
How does it work simply 4 stages
What is OVULATION, when does this happen
How long is the menstrual cycle?
1) menstrual cycle is 28 days. Day1 when it starts, 1-4 the uterus lining breaks down and is released
2) Uterus lining thickens in anticipation if a fertilised egg. At the same time, an egg begins to mature in the ovaries. Day 4-14
3) the egg is fully matured and released into the uterus at 14 days. This is ovulation
4) if the egg is fertilised until day 28, then women is pregnant. The egg is protected and treated with oxygen and nutrients
If the egg is not fertilised, then the uterus lining breaks down , and exits with the egg… day 1 starts again….
How do hormones control the mesnrtual cycle (full)
So what happens at the end, how does the cycle restart? (What hormone)
1) FSH (secreted by pituitary gland- all stimulating ones in there). Is secreted. This causes a follicle (egg) to start maturing. FSH ALSO stimulates the production of oestrogen .
2) Oestrogen (made and secreted in ovaries) causes the uterus lining to thicken and grow. It also stimulates (pituitary to ) production of Luteinising hormone , but INHIBITS production of FSH- so only one egg is released per cycle.
3) LH stimulates ovulation at day 14. Basically once LH levels hit a peak in the middle of the cycle, this happens, LH also therefore indirectly stimulates progesterone production, because after the egg is released, Progesteron there to keep the uterus lining…
4) Progesterone (made and secreted by ovaries) maintains uterus lining for the remainder 14 days. It also inhibits production if LH and FSH. The progesterone comes from the empty folicile, and this follicle gets released because if a peak of LH, this is why LH indirectly stimulates progesterone production.
5) IF FERTILISED EGG, PROGESTERONE LEVELS REMAIN HIGH TO MAINTAIN UTERUS LINING. ONCE PROGESTERONE LEVELS DROP WHEN UTERUS EXITS, FSH COMES BACK, RESTARTING THE WHOLE CYCLE AGAIN.
Explain the graph for the cycle
1) uterus lining break in stage 1, but then till day 14 it grows and until day 28 after that it maintains , to which it breaks down again.
2) FSH levels rise, causing oestrogen levels to rise too. This also therefore causes LH to rise. However as soon as oestrogen goes up, FSH goes down for one egg.
4) once lH hits peak, egg released, and LH levels completely drop as progesterone causes LH and FSH just in case to be inhibited. Meanwhile, oestrogen has no use, so its LEVElS go down too.
5) finally when uterus lining and egg leaves , progesterone levels drop, which allows for FSH levels to rise again, starting it all over again…
What are barrier vs non barrier contraception’s?
Barrier contraception’s prevent the sperm from reaching the egg like barrier, this could be just a barrier but also PHYSICAL devices that say release chemicals that kill sperm (spermicides), or just doesn’t let it implant in the uterus.
Non barrier contraception is using hormones to disrupt the female reproductive cycle to stop pregnancy
Barrier contraception’s (3) how they work, what are they
3 main, 2 meh
How effective and what important info about them
1) condom : this is place over the penis or inside the vagina, preventing sperm from reaching vagina. 95% effective for female 98% effective for male. ADAVATAGE= STOPS SPREAD OF STI/ STUs
2) diaphragm / cervical cap: this is inserted into the vagina cover cervix, preventing sperm from entering the uterus. It MUST BE USED with a spermicide, because even after removal sperm can still fertilise. Also, removed after 6 hours after intercourse,
3) intrauterine devices (IUD): inserted In to the uterus, and have copper which PREVENTS them from surviving. Also CHANGES LINING OF WOMB SO FERTILISED EGGS STILK CSN’T IMPLANT . Effective for ten years , and 99% effective
4) ‘natural ‘ ways, such as withdrawal, (removing penis before emasculating- risky relies on timing not effective’
5) sterilisation. This SURGICAL PROCEDURE, that for women stops eggs completely going from ovaries to uterus. For men, it stops them from ejaculating completely. Over 99% effective but permanent .
Non barrier contraception’s (3)
First progesterone pill
How long should you take it?
1) progesterone pill: this does a few things that keep coming
- stimulates thick mucus production at cervix, preventing sperm from entering (less likely
- thins the uterus lining that oestrogen builds- this reduces a chance of a fertilised egg from implanting
- also prevents ovulation to a certain extent, as progesterone inhibits FSH and LH production ( not always though)
- HAS TO BE TAKEN EVERY DAY SAME TIME, OR NO WORK
WOMEN TAKE IT BECAUSE THEY MAY HAVE NAGTIVE EFFEVTS TO OESTROGEN
2) oestrogen and progesterone pill (combined)
How long must it be taken? (Less then progesterone)
Does everything progesterone pill does (thick mucus, thin lining prevent implantation )
But also stops ovulation from happening more then just progesterone pill as oestrogen inhibits FSH…
- this one can be taken for 21 days per cycle though ,
3) intrauterine system (NOT DEVICE - THIS IS BARRIER)
What key key difference is it from the progesterone versions
Intrauterine device is the exact same as progesterone only pill
- thinnuterus lining stop Chance of implantation
- thick mucus lower chance of sperm
- can prevent ovulation
HOWEVER IT LASTS 3-5 YEARS LONG
What are the effectiveness again of these contraception’s ?
1) condom = male= 98, female = 95
2) cervical cap / DIAPHRAGM = 92-96
3) everything else, from intrauterine device to three hormones (intrauterine system, combined and progesterone only pill) are 99% effective, provided they used properly though (miss a day, brüh)
Important part:
What are advantages and disadvantages to contraceptive methods?
- Hormonal methods have UNPLEASANT side effects like irregular periods,ACNE HEADACHES MOOD SWinGs.
- might mess up , such as condom splits, or if woman takes hormone incorrectly- ruins everything
- methods some times include going to doctor and getting them to fit something inside, some people may feel UNPLEASANT.
Advantage
- some contraception, such as intrauterine system, last 3-5 years, which is better as you don’t have to do something each time
- some like cndoms prevent exchange of STis - Safe and only method to guarantee this protection…
What is fertility treatment, why do couples need it?
How can it be treated??
Fertility treatment is like using hormones to treat being able to have a baby
1) this could be because
- a lack of mature eggs being produced in ovaries
- women inability to release eggs into uterus
- blocked sperm ducts, Fallopian tubes
- not enough sperm being produced.
2) with hormones . For example FSH given, which stimulates an egg to mature, and triggers oestrogen , which also then stimulates LH production and causes eggs to be released.
FSH and LH can be given to increase the chance of this happening all together - causing an egg to mature and ovulation to happen and increasing chance of theses getting released
