B3.2 - The Endocrine System Flashcards
What are hormones?
Chemical messengers made by endocrine glands
Transported via the bloodstream to target organs to cause a response in specific cells
What is thyroxine?
A hormone produced by the thyroid gland
Plays a vital role in regulating the body’s metabolic rate
What is the function of the thyroid gland?
To convert iodine into thyroxine by combining it with tyrosine (an amino acid)
How are thyroxine levels controlled?
The body needs more energy - hypothalamus causes pituitary gland to release TSH (thyroid-stimulating hormone)
TSH stimulates thyroid gland to release thyroxine - increase metabolic rate so cells transfer more energy
Cells have enough energy - hypothalamus inhibits TSH production
Thyroid gland stops releasing thyroxine
What is the function of FSH (follicle-stimulating hormone) ?
Secreted by pituitary gland
Travels to ovaries and causes egg to mature
Stimulates ovaries to produce oestrogen
What is the function of oestrogen?
Made in ovaries
Causes build up of uterus lining
What is the function of LH (luteinising hormone) ?
When levels reach a peak in the middle of the cycle, ovulation is triggered
What is the function of progesterone?
Maintains uterus lining
What are some non-hormonal contraceptive techniques?
Condom
Cervical cap
Intrauterine device
What do condoms do?
Non-hormonal
Short term contraceptive
Prevents sperm entering vagina
Prevents spread of STIs
What do cervical caps do?
Non-hormonal
Removed after 6 hours
Covers cervix to prevent sperm cells from entering vagina
What is an IUD?
Non-hormonal
Remains effective for 5-10 years
Releases copper to prevent sperm surviving in the uterus and fallopian tubes
What are some hormonal contraceptives?
Oestrogen and progesterone pills
Progesterone pills
Intrauterine system
What are oestrogen and progesterone pills?
Hormonal
Taken daily for 21 days of menstrual cycle
Prevents ovulation by thickening mucus in cervix
Stops sperm from reaching ovum and the ovum implanting in the uterus wall
What is a progesterone pill?
Hormonal
Taken daily around the same time
Thickens mucus in cervix
Stops sperm reaching ovum
Thickens uterus lining preventing implantation
Prevents ovulation