Bio p2 menstrual cycle

• Egg development


  1. Stage 3

  2. Stage 4
• The wall is then maintained for about 28 days
• Menstrual cycle


  1. Egg implants in uterus wall by day 28

  2. Spongy lining starts to break down

  3. Whole cycle starts again
• Hormones controlling menstrual cycle

  • Oestrogen
  • Progesterone
  • LH
  • FSH
• Oestrogen


  Produced in the ovaries
• Oestrogen


  • Causes the lining of the uterus to grow
  • Stimulates the release of LH and inhibits release of FSH
• Progesterone


  Produced in the ovaries by the remains of the follicle after ovulation
• Progesterone


  • Maintains the lining of the uterus during the second half of the cycle
  • When the level falls, the lining breaks down
  • Inhibits the release of LH and FSH
• FSH (Follicle-Stimulating Hormone)


  • Produced in the pituitary gland
  • Causes an egg to mature in one of the ovaries in a structure called a follicle
  • Stimulates the ovaries to produce oestrogen
• LH (Luteinising Hormone)


  • Produced by the pituitary gland
  • Stimulates the release of an egg at day 14 (ovulation)
• Adrenaline is a hormone released by the adrenal glands, which are just above the kidneys
• Adrenaline


  • Released in response to stressful or scary situations
  • Gets the body ready for 'fight or flight' by triggering mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles
  • Increases heart rate
• Negative feedback


  Body can control the levels of hormones (and other substances) in the blood by triggering a response to bring the level back to normal
• Thyroxine


  • Hormone released by the thyroid gland
  • Plays an important role in regulating the basal metabolic rate
  • Important for processes like stimulating protein synthesis for growth and development
• Thyroxine regulation


  1. Released in response to thyroid stimulating hormone (TSH) from the pituitary gland

  2. Negative feedback system keeps the amount of thyroxine in the blood at the right level
• Synapses are the connections between neurons
• Signals are transferred across synapses by chemicals
• Reflex


  Automatic response to certain stimuli that don't involve the brain
• Reflex arc


  1. Receptors detect stimulus

  2. Sensory neuron sends signal to relay in central nervous system

  3. Relay neuron sends signal to motor neuron

  4. Motor neuron sends signal to effector (muscle)
• Reaction time


  Time taken to respond to a stimulus
• Measuring reaction time


  1. Person holds ruler vertically

  2. Person drops ruler and other person catches it as quickly as possible

  3. Measure distance ruler fell to get reaction time
• Caffeine can improve reaction time
• Reaction time can be affected by factors like age, fatigue, and drugs