animal hormones

• What is a hormone?

  A chemical substance produced by a gland
• How do hormones affect target organs?

  They alter the activity of specific target organs
• What hormone is produced by the thyroid gland?

  Thyroxine
• What hormone is produced by the pancreas?

  Insulin
• What hormone is produced by the adrenal glands?

  Adrenaline
• What hormone is produced by the testes?

  Testosterone
• What hormone is produced by the ovaries?

  Oestrogen
• What are the main components of the nervous and endocrine systems?

  • Nervous system: nerves (neurones), brain, spinal cord
  • Endocrine system: glands
• What type of message does the nervous system use?

  Electrical impulses
• What type of message does the endocrine system use?

  Chemical hormones
• How fast is the transmission speed of the nervous system?

  Very fast
• How fast is the transmission speed of the endocrine system?

  Slower
• What is the length of effect for nervous system messages?

  Short - until nerve impulses stop
• What is the length of effect for endocrine system messages?

  Longer - until hormone is broken down
• What hormone regulates thyroxine levels?

  TSH (thyroid-stimulating hormone)
• Where is thyroxine secreted from?

  The thyroid gland
• What does thyroxine stimulate?

  The metabolic rate at rest
• What happens if thyroxine levels are too high?

  TSH release is inhibited
• What happens if thyroxine levels fall below normal?

  TSH release is increased
• What are the effects of adrenaline?

  Increases blood glucose concentration
• How does adrenaline affect heart rate?

  It increases heart rate
• What does adrenaline do to blood flow?

  Diverts blood flow towards muscles
• What does adrenaline do to pupils?

  Dilates pupils for more light
• What does adrenaline do to glycogen in the liver?

  Breaks down glycogen to glucose
• What does testosterone stimulate?

  Sperm production
• What physical changes does oestrogen cause?

  Breast development
• What is the role of progesterone?

  Maintains the lining of the uterus
• What does FSH do?

  Stimulates maturation of an egg
• What does LH do?

  Stimulates ovulation of eggs
• What are the stages of the menstrual cycle?

  1. Menstruation lasts 5-7 days
  2. Thickening of the uterus lining
  3. Ovulation occurs around day 14
  4. Egg travels to the uterus
  5. Maintenance of the uterus lining
• What hormone causes the egg to mature in the ovary?

  FSH
• What hormone stimulates ovulation?

  LH
• What hormone is involved in building up the lining of the uterus?

  Oestrogen
• What hormone is required to maintain the lining of the uterus?

  Progesterone
• What happens if the egg is not fertilised?

  • Corpus luteum breaks down
  • Progesterone levels drop
  • Menstruation occurs
• What happens if fertilisation occurs?

  • Corpus luteum continues producing progesterone
  • Prevents breakdown of the uterus lining
  • Placenta secretes progesterone during pregnancy
• What does the Combined Pill contain?

  Oestrogen and progesterone
• How effective is the Combined Pill at preventing pregnancy?

  Over 99% effective
• How does high oestrogen affect FSH production?

  Inhibits FSH production
• What role does progesterone play in the Combined Pill?

  Inhibits release of mature eggs