GCSE edexcel biology : topic 7

What hormone(s) does the pituitary gland produce?

•Follicle-stimulating hormone (FSH) •Luteinising hormone (LH) •Anti-diuretic hormone (ADH)

What hormone(s) does the thyroid gland produce?

thyroxine

What hormone(s) does the adrenal gland produce?

adrenalin

What hormone(s) does the pancreas produce?

insulin

What hormone(s) does the ovaries produce?

oestrogen

What hormone(s) does the testes produce?

testosterone

Where is the pituitary gland located?

in the brain

where is the thyroid gland located?

in the neck (thyroid)

where is the adrenal gland located?

just above the kidneys

where is the pancreas located?

near the kidneys

where are the ovaries located?

just below the hip

where are the testes located?

just below the hip

how does adrenalin affect heart rate?

•adrenalin increases heart rate because it increases pressure in the coronary arteries. • increased pressure in the coronary arteries leads to increased heart rate because the more frequently the heart beats, the higher the blood pressure as more blood is being pumped through the arteries. • additionally, adrenaline affects the relaxation and contraction of the muscles in the heart, this results in the heart contracting more frequently and therefore heart rate increases.

how does adrenaline affect blood flow?

•adrenaline increases blood flow by increasing the pressure in the coronary artery which leads to increased heart rate. Therefore blood flow increases as the heart contracts to pump blood through the arteries. • blood flow will increase as blood pressure and heart rate increase as all of the factors are linked and correlate. •as the heart rate increases, more blood is pumped around the body more quickly, blood pressure increases resulting in the blood having to flow more quickly, however, exceedingly increased blood pressure decreases the blood flow due to the blood pressure making it more difficult for the blood to flow quickly and easily (efficiently.)

how does adrenaline affect blood pressure?

•adrenaline increases blood pressure as adrenaline increases heart rate. The increased heart rate forces blood to flow more quickly through narrow arteries, resulting in increased blood pressure. •adrenaline also narrows arteries which increases blood pressure as the blood has less area to flow through - much like when cholesterol prevents blood from flowing as quickly - increasing blood pressure.

how does adrenaline affect blood sugar levels?

•as well as binding to specific receptors in the heart to increase heart rate, adrenaline binds to receptors in the liver which causes the liver to release glucose (by breaking down its glycogen stores as in homeostasis). •the glucose is added to the blood and therefore blood sugar levels increase. •adrenaline stimulates the liver to release glucose so that there is enough energy available for the "fight or flight" response which adrenaline prepares the body for.

What mechanism controls thyroxine levels to maintain metabolic rate?

the negative feedback mechanism

what happens when thyroxine levels are too high?

•the hypothalamus is stimulated to inhibit the release of the thyrotropin releasing hormone (TRH) • reduced Thyrotropin releasing hormone (TRH) reduces the production of thyroid stimulating hormone (TSH) in the pituitary gland. • reduced thyroid stimulating hormone (TSH) reduces the production of thyroxine in the thyroid gland. •the thyroxine level decreases/reduces. •the thyroxine levels return to normal.

what happens when thyroxine levels are too low?

•the hypothalamus is stimulated to release thyrotropin releasing hormone (TRH) •thyrotropin releasing hormone (TRH) stimulates the pituitary gland to release thyroid stimulating hormone (TSH) •thyroid stimulating hormone (TSH) stimulates the thyroid gland to release thyroxine. •the thyroxine level increases • the thyroxine levels return to normal

how many stages are there to the menstrual cycle?

there are 4 stages to the menstrual cycle

what happens during the first stage of the menstrual cycle?

•during days 1-7 menstruation begins. •the lining of the uterus breaks down and is released. •FSH (follicle stimulating hormone) is released by the pituitary gland and causes a follicle (an egg and its surrounding cells) to mature in one of the ovaries. •the FSH production stimulates oestrogen production.

what happens during stage 2 of the menstrual cycle?

•oestrogen production is stimulated by FSH production and is released by the ovaries. •the uterus lining (the endometrium) is repaired from day 4 to day 14 as oestrogen causes the endometrium to thicken and grow. •the endometrium become a thick spongy layer of blood vessels in preparation for a fertilised egg to implant there. •a high level, of oestrogen stimulates a surge in LH (luteinising hormone) production.

what happens during stage 3 of the menstrual cycle?

•at day 14 LH is released by the pituitary gland and stimulates ovulation. • the follicle ruptures and the egg is released from ovary, this is ovulation. •LH stimulates the remains of the follicle to develop into a structure called the corpus luteum. •the corpus luteum secretes progesterone.

what happens during stage 4 of the menstrual cycle?

•progesterone is released by the corpus luteum following ovulation. •progesterone maintains the endometrium and inhibits the production of LH and FSH. •if fertilisation has not taken place then the corpus luteum fades away. as the corpus luteum secrets progesterone the progesterone level will decrease. •when the levels of progesterone decrease and there is a low oestrogen level, the endometrium breaks down. •the uterine lining detaches at around day 28, •the low progesterone level allows FSH to increase so the menstrual cycle starts again.

what is the endometrium?

the uterus lining

what does FSH stand for?

Follicle stimulating hormone

what does LH stand for?

luteinizing hormone

where is FSH released from?

the pituitary gland

where is oestrogen released from?

ovaries

where is LH released from?

pituitary gland

where is progesterone released from?

corpus luteum

what is the function of FSH?

FSH stimulates oestrogen production and causes a follicle to mature in one of the ovaries. a follicle is an egg and it's surrounding cells.

what is the function of oestrogen?

oestrogen causes the lining of the uterus to thicken and grow. The uterus lining (the endometrium) thickens until day 14 when ovulation begins. Following ovulation oestrogen production decreases if the egg is not fertilised.

what is the function of LH?

A high level of oestrogen stimulates an LH surge. The LH surge stimulates ovulation (at day 14).

what is the function of progesterone?

•Progesterone is released after ovulation. •Progesterone maintains the lining of uterus and inhibits the release of FSH and LH. •The uterus lining (the endometrium) breaks down if there is a low oestrogen level and a low progesterone level. •The low progesterone level allows FSH to increase and then the menstrual cycle begins again. •If the egg is not fertilised then the level of progesterone will decrease, therefore the menstrual cycle begins again if the egg is not fertilised.

why are men who have had their testes removed at Moore risk of developing brittle bones?

they are more at risk because testosterone leads to denser bones in males compared to females. As the testes are glands which produce testosterone, if the testes are removed then less testosterone will be produced so there is an increased risk of brittle bones.

What are the methods of contraception?

• the diaphragm •female condom •the male condom •IUD •Combined pill •mini pill •combined patch

what are the barrier methods of contraception?

•diaphragm •female condom •male condom

what are the hormonal methods of contraception?

•IUD •combined pill •mini pill •combined patch

how does the diaphragm work as a method of contraception?

•inserted into the vagina before sexual intercourse •it blocks the cervix •it has to be used with a spermicide to be effective • it stops the sperm from reaching the egg and the spermicide kills the sperm and the cap stops the sperm. •it has to stay in the vagina for at least 6 hours after sex for prevention of pregnancy

what are the advantages of the diaphragm as a method of contraception?

•doesn't have to be used all the time •no associated health risks •can add extra spermicide •suitable for unplanned sex •reusable •has no effect on periods •fertility returns to normal afterwards

what are the disadvantages of the diaphragm as a method of contraception?

•not as effective as other types of contraception •only provides limited protection against STIs •cystitis can be a problem for some women •latex and spermicide can cause irritations for some women and their partners

how does the female condom work?

•it is worn inside the vagina •it stops sperm getting into the uterus

what are the advantages of using a female condom as a method of contraception?

•protects against STIs and pregnancies •no medical side effects •can be inserted up to 8 hours before sex •protects both partners •made from polyurethane so can be used for people allergic to latex

what are the disadvantages of using a female condom as a method of contraception?

•aren't reusable •can split or tear if not used correctly •not as widely available as other contraception

how does the male condom work?

•worn over the penis •stops sperm getting into the uterus

what are the advantages of using a male condom as a method of contraception?

•protects against STIs and pregnancies •no medical side effects •protects both partners •can be made of materials other than latex

what are the disadvantages of using a male condom as a method of contraception?

•aren't reusable •can split or tear is not used correctly •not reusable

what does IUD stand for?

Intra uterine device

how does IUD work as a method of contraception?

•releases copper to change fluids in the womb and fallopian tubes so stops sperm from surviving. •can also stop fertilised eggs from implanting in the womb.

What are the advantages of using IUD as a method of contraception?

•most women can use an IUD •It works straight away once fitted •It lasts for up to 10 years (or until removed) •normal fertility returns to normal as soon as it is taken out •it is not affected by other medicines •can be used by breastfeeding mothers

What are the disadvantages of using IUD as a method of contraception?

•periods may last longer, become heavier, or more painful •Doesn't protect against STIs •can lead to pelvic infections if an STI is contracted while using it

How does the combined pill work as a method of contraception?

•contains oestrogen and progesterone •the progesterone stimulates the production of thick cervical mucus in the cervix so it is harder for sperm to reach eggs in the uterus •the combination of both hormones thins the lining of the womb so there is less chance of a fertilised egg implanting or being able to grow.

How does the mini pill work as a method of contraception?

•contains progesterone •produces thick cervical mucus in the cervix so it's harder for sperm to penetrate the uterus and reach eggs to fertilise them •prevents ovulation

what is the difference between IUD and IUS?

IUD is hormone free and IUS is hormonal

How does the combined patch work as a method of contraception?

•delivers oestrogen and progesterone through the skin •prevents ovulation •progesterone produces thick cervical mucus in the cervix so it's harder for sperm to reach eggs in the uterus •combination of both hormones thins the lining of the uterus so there is less chance of a fertilised egg implanting or being able to grow •works the same as the combined pill but in patch form.

What does ART stand for?

Assisted Reproductive Technology

What is ART?

•ART includes all fertility treatments which involve handling eggs or embryos outside of the body. •The techniques involve treatments which deal with both the female's eggs and the male's sperm. •It works by removing eggs from a woman's body and mixing them with sperm to make zygotes. Finally, the zygotes are put back into the female's body. •procedures are usually used with fertility drugs to increase success rates

What does IVF stand for?

in vitro fertilisation

What is IVF?

When drugs, hormones and medicines are used for ART. IVF is carried out using the female's eggs and the male's sperm and/or sperm from donors.

describe the process of IVF.

•The woman's natural menstrual cycle is suppressed with medication •FSH and LH are used to stimulate the ovaries to produce more eggs than normal •the eggs are monitored and hormones are used to help them mature •the eggs are collected •the eggs are out in contact with the sperm and left for a few days to fertilise •one or two embryos are placed into the womb

How are hormones used in IVF?

FSH and LH are used to stimulate egg production so that more than one egg can be collected for IVF

What is clomifene therapy?

Clomifene therapy is a drug treatment to stimulate ovulation.

How does clomifene therapy work?

•Clomifene is a drug which blocks the effect of oestrogen, this makes the body increase the amounts of the two hormones essential for ovulation: FSH and LH. •FSH causes the eggs to mature in the ovaries and LH triggers the release of one or more mature eggs from the ovaries (ovulation) •by knowing when the woman will be ovulating the couple can have intercourse during this time to increase the chance of becoming pregnant.

What is the target organ for insulin?

The liver or a muscle

When insulin is present which substance is formed from glucose in the target cells?

glycogen

Why must blood glucose concentration be controlled?

To maintain a constant internal environment for the body's enzymes to function correctly. Too little or too much glucose can damage organs, resulting in unconsciousness or death.

What is the cause of type 1 diabetes?

the person's insulin-producing cells have been destroyed, so they do not release insulin.

what are hormones?

hormones are chemicals released directly into the blood, which affect target cells. Hormones control 'things' in organs and cells that need constant regulation and adjustment.

what glands make up the endocrine system?

endocrine glands

what are endocrine glands?

where hormones are produced

what are the target organs for the pituitary gland?

the ovaries, the kidney

what are the endocrine glands that you need to know?

•the pituitary gland •the thyroid gland •the ovaries •the testes •the adrenal glands •the pancreas

what are the differences between neurones and hormones?

neurones: fast action, act for a short amount of time, act in a precise area. hormones: slower action, act for a long amount of time, act in a more general way.

why are neurone responses quick? why can't hormones be used for these types of responses?

the information needs to be passed to the effectors really quickly, for example, pain signals or warnings from your eyes, hormones can't be used for these types of responses because the hormones are too slow to carry the information quickly.

what response does adrenalin prepare the body for?

fight-or-flight response

describe the process in which adrenalin prepares the body for a fight-or-flight response.

•adrenalin binds to specific receptors in the heart which causes the heart muscle to contract more frequently and more forcefully so heart rate and blood pressure. •this increases blood flow to the muscles so the cells receive more oxygen and glucose for increased respiration •adrenalin binds to receptors in the liver to cause the liver to break down its glycogen stores to release glucose. •this increases blood glucose level so there's more glucose in the blood to be transported to cells. overall, heart rate increases, blood pressure increases, blood flow increases, blood glucose levels increases, and respiration increases in cells for more energy in the fight-or-flight response.

what system controls the levels of hormones in the blood?

the negative feedback system

what can an underactive thyroid gland cause?

weight gain because less thyroxine means that the metabolic rate decreases, this results in less of the glucose which is taken into the body being broken down in respiration and so more is stored as fat.

what is the menstrual cycle?

a monthly sequence of events in which the female body releases an egg and prepares the uterus in case the egg is fertilised.

what is another name for the uterus?

the womb

what is the womb also known as?

the uterus

what happens if a fertilised egg implants in the uterus?

the woman becomes pregnant and the level of progesterone will remain high to maintain the lining of the uterus during pregnancy

what are the main methods an infertile couple could resort to in order to become pregnant?

clomifene therapy and IVF

how does IVF work?

eggs are collected from the female's ovaries and they are fertilised in a lab using the male's sperm. before egg collection FSH and LH are given to stimulate egg production. when the embryos have developed into balls of cells on or two of them are implanted into the uterus to improve the chance of pregnancy.

how can oestrogen be used as a contraceptive?

oestrogen can be used to prevent the release of an egg. although oestrogen is naturally used to stimulate the release of eggs, if it is taken every day to maintain a high level of oestrogen then it inhibits the production of FSH and as a result egg development and egg production stop.

how can progesterone be used as a contraceptive?

progesterone can be used to reduce fertility by stimulating the production of thick cervical mucus, preventing sperm from getting through the cervix and reaching an egg

what is the entrance to the uterus also called?

the cervix

what is the cervix?

the entrance to the uterus

which types of contraceptives are more effective when used correctly?

hormonal contraceptives

what is type 1 diabetes?

a condition when the pancreas produces little to no insulin

how can a person with type 1 diabetes be treated?

with insulin therapy: this usually involves injecting insulin into the blood and is often done at mealtimes so the glucose is removed from the blood quickly once the food has digested.

where is insulin normally injected in people with type 1 diabetes?

in the subcutaneous tissue - the fatty tissue just underneath the skin

what does the amount of insulin someone with type 1 diabetes needs to inject depend on?

the person's diet and how active they are

what do people with type 1 diabetes need to consider apart from insulin therapy?

•limiting their intake of foods rich in simply carbohydrates (sugars) which cause the blood glucose level to rise rapidly. •taking regular exercise which helps to remove excess glucose from the blood

what are the dangers of injecting too much insulin in insulin therapy?

it could result in a dangerously low blood glucose level

what is type 2 diabetes?

a condition when the pancreas doesn't produce enough insulin or when a person becomes resistant to insulin (their body's cells don't respond properly to the hormone)

which type of diabetes correlates with obesity?

type 2

when are people classed as obese?

when they have a BMI over 30

what does BMI stand for?

Body Mass Index