Endocrine System
The endocrine system is a group of endocrine glands which release hormones to control your body
What does the blood do with hormones?
The blood carries the hormone to a target organ where it produces an effect
Compare the endocrine system with the nervous system
Endocrine system is slower but acts for longer
Describe the pituitary gland in the brain
A ‘master gland’ which secretes several hormones into the blood in response to body conditions. These hormones in turn act on other glands to stimulate other hormones to be released.
Describe how reproductive hormones cause secondary sex characteristics to develop at puberty
Testosterone
– a hormone produced by the testes which controls the development of male secondary sexual characteristics
Oestrogen
– a hormone produced by the ovaries which controls the development of female secondary sexual characteristics, for example breast development
Testosterone
Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production.
Describe how the menstrual cycle is regulated by four hormones
- Follicle stimulating hormone
(FSH) causes the maturation of an egg in the ovary - Luteinising hormone
(LH) stimulates the release of the egg - Oestrogen is involved in repairing and thickening the uterus lining, progesterone maintains the uterine lining
- Progesterone maintains the lining of the uterus during the latter part of the menstrual cycle and during pregnancy
State where the menstrual cycle hormones are produced
- FSH - Pituitary
- Oestrogen - Ovaries
- LH - Pituitary
- Progesterone - Ovaries
Name the menstrual cycle hormones
- FSH (Follicle Stimulating Hormone)
- Oestrogen
- LH (Luteinising Hormone)
- Progesterone
Explain the interactions of hormones in the control of the menstrual cycle
LH and FSH promote ovulation and stimulate the ovaries to produce oestrogen and progesterone
Describe and evaluate the different hormonal and non-hormonal methods of contraception
- barrier methods such as condoms and diaphragms which prevent the sperm reaching an egg
- intrauterine devices which prevent the implantation of an embryo or release a hormone
- surgical methods of male and female sterilisation.
- spermicidal agents which kill or disable sperm
- abstaining from intercourse when an egg may be in the oviduct
- oral contraceptives that contain hormones to inhibit FSH production so that no eggs mature
- injection, implant or skin patch of slow release progesterone to inhibit the maturation and release of eggs for a number of months or years.
Explain the use of hormones in modern reproductive technologies to treat infertility
This includes giving FSH and LH in a ‘fertility drug’ to a woman. She may then become pregnant in the normal way
Describe In Vitro Fertilisation (IVF) treatment
- IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
- The eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
- The fertilised eggs develop into embryos.
- At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb).
Evaluate IVF and understand social and ethical issues associated with IVF treatments
Although fertility treatment gives a woman the chance to have a baby of her own:
* It is very emotionally and physically stressful
* The success rates are not high
* It can lead to multiple births which are a risk to both the babies and the mother.
Explain the roles of thyroxine and adrenaline in the body
- Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
- Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development
Plants - hormones
Plants produce hormones to coordinate and control growth and responses to light (phototropism) and gravity (gravitropism or geotropism)
Describe and explain how unequal distributions of auxin cause unequal growth rates in shoot tips and roots
Auxins change the rates of elongation in plant cells and control growth of stems and roots.
Stems and roots respond differently to high concentrations of auxins:
- cells in stems grow more
- cells in roots grow less
Describe the commercial uses of plant hormones. They are used in both agriculture and horticulture
- Gibberellins are important in initiating seed germination.
- Gibberellins can be used to:
- end seed dormancy
- promote flowering
- increase fruit size
- Ethene controls cell division and ripening of fruits. It is used in the food industry to control ripening of fruit during storage and transport.
- Auxins are used:
- as weed killers
- as rooting powders
- for promoting growth in tissue culture
