b3

• stimulus


  change in the environment
• receptors


  detect the stimulus
• cns (central nervous system)


  process information and coordinates a response
• effectors


  carries out a respond always through a muscle r gland
• sensory neurones


  carries electrical impulses from receptor to CNS
• relay neurones


  carry electrical impulses from sensory neurones to motor neurone
• motor neutrones


  carries electrical impulses from CNS to effectors, which carried out a response
• steps of a neurone response

  1. stimulus 2. receptor 3. sensory neurone

  4. relay neuron 5. CNS (brain + spinal cord)

  6. motor neurone 7. effector 8. response
• reflex arc


  where impulses travel through a set pathway, bypassing the brain to increase survival
• simple reflex


  fast and involuntary (carried out w/o thinking)
• hormones


  - chemical messengers, made in the glands, travel in the blood and work in target organs
• homeostasis


  keeping internal conditions constant
• nervous system


  involves neurones, travels through electrical impulses, fast and targets precise areas
• endocrine system


  involves hormones (chemical messengers), travel in the blood, slow and targets larger areas
• thyroxine


  hormones produced by the thyroid gland and controls metabolic rate
• metabolic rate


  how much energy is available to cells
• negative feedback


  a change in conditions results in an action that will reverse the change
• adrenaline


  made in adrenal gland, which prepares the body for actions and is released when threatened/scared
• factors of adrenaline


  - increases respiration to release more ATP

  - increases breathing to take in more oxygen

  - increases heart rate

  - slows digestion
• menstrual cycle


  lasts around 28 days (day 1 - period starts)
• ovulations

  (on day 14) an egg is released from the ovary
• implantations


  is egg is fertilised, the egg will implant into uterus lining
• FSH (follicle stimulating hormone)


  pituitary gland releases FSH, causing egg to mature and oestrogen to be released
• LH (luteinising hormone)


  pituitary gland releases LH which causes egg release ovulation
• oestrogen


  ovaries release oestrogen which makes the uterus lining thicken

  causes FSH to stop and starts to release LH
• progesterone


  maintains the uterus lining and inhibits LH
• egg not fertilised


  uterus lining sheds and period occurs
• contraception


  methods to prevent pregnancy
• condom


  - non-hormonal

  - effectiveness of 98% (M) and 95% (F)

  - barrier prevent sperm entering vagina

  - protects against STIs
• cervical cup


  - non-hormonal

  - effectiveness of 92%-96%

  - inserted into vagina to prevent sperm entering uterus
• IDU coil


  - non-hormonal

  - effectiveness of over 99%

  - lasts 5-10 years

  - inserted into uterus

  - works by releasing copper
• combined pill (oestrogen and progesterone pill)

  - hormonal

  - effectiveness of over 99%

  - prevent ovulation and implantation

  - thickens mucus from cervix
• progesterone only pill


  - hormonal

  - effectiveness of over 99%

  - prevents implantation

  - thickens mucus from cervix
• IUS (hormonal coil)

  - hormonal

  - effectiveness of over 99%

  - inserted into uterus

  - lasts 3-5 years
• causes of infertility

  - blocked oviducts

  - lack of mature eggs

  - not releasing eggs
• fertility treatment


  conditions treated using hormones
• IVF (in vitro fertilisation)

  1. collect eggs from mother

  2. fertilise with sperm from father outside body

  3. place one or two embryos into womb
• IVF pros


  helps couple who can't have babies
• IVF cons


  - not reliable

  - expensive

  - unethical (embryos destroyed if not used)
• insulin

  hormone which controls blood sugar level