Bio Paper 2 (2)

• Homeostasis is the maintenance of a constant internal environment and to keep your body functioning properly, we need to control our blood glucose levels, our water levels and our temperature
• Brain


  • Control center, sending signals to various parts of the body
• Parts of the nervous system

  • Brain
  • Spinal cord
  • Neurons
  • Receptors
  • Effectors
• Reflex


  1. Stimulus picked up

  2. Signal travels to spinal cord

  3. Signal travels back to effector
• Synapse


  Where signal transfers from one nerve cell to another, a slow chemical signal
• Parts of the endocrine system

  • Pituitary gland
  • Thyroid
  • Adrenal glands
  • Pancreas
  • Ovaries
  • Testes
• Testosterone


  Produced in testes, has effects of growing muscles, making balls and penis grow, increasing hair growth
• Oestrogen

  Produced in ovaries, responsible for maturation of eggs and menstrual cycle
• Insulin


  Produced in pancreas, important for regulating blood glucose levels
• Adrenalin


  Produced in adrenal glands, important for fight-or-flight response
• Thyroxine


  Produced in thyroid, important in regulating metabolism
• FSH and LH


  FSH - matures the egg, LH - releases the egg .Produced in pituitary gland, important for reproductive functions
• Blood glucose regulation


  1. Glucose levels rise after meal

  2. Pancreas produces insulin

  3. Insulin causes cells to remove glucose from blood

  4. Glucose levels fall

  5. If glucose too low, pancreas produces glucagon

  6. Stored glucose released back into blood
• Glycogen


  Stored form of glucose in liver and muscle cells
• Types of diabetes


  • Type 1
  • Type 2
• Type 1 diabetes


  Pancreas doesn't produce enough insulin
• Type 2 diabetes


  Cells become insensitive to insulin
• Symptoms of diabetes


  • Weight loss
  • Increased urination
  • Thirst
  • Blurry vision
  • Fatigue
  • Hunger
• Treatment for type 1 diabetes

  Insulin injections
• Treatment for type 2 diabetes

  Controlling diet and exercise
• Menstrual cycle (FOLP)


  1. FSH rises, peaks to grow egg

  2. LH rises briefly to release egg

  3. Estrogen builds up

  4. Progesterone builds up.

  5. Progesterone decreases, lining of uterus breaks down
• Contraception methods


  • Hormonal (pill, coil, IUD)
  • Non-hormonal (condom, diaphragm)
  • Sterilization (vasectomy, tubal ligation)
• Condom


  Barrier method that prevents pregnancy and STDs
• Infertility


  Affects about 1 in 6 people, half due to male reasons, half due to female reasons
• IVF


  Involves taking many drugs with side effects, is very expensive, has around 40% success rate
• Mitosis


  Leads to two identical daughter cells
• Meiosis


  Leads to four different daughter cells
• Mitosis


  Used for growth and repair, results in diploid cells
• Meiosis


  Used for sexual reproduction, results in haploid cells
• Gametes


  • Eggs (in women)
  • Sperm (in men)
  • Eggs (in plants)
  • Pollen (in plants)
• Meiosis


  1. Chromosomes line up and divide twice

  2. Crossing over occurs

  3. Results in haploid cells
• Asexual reproduction


  Leads to genetically identical population
• Gene


  Stretch of DNA that codes for a characteristic
• Genome


  All the genes in a body
• Gamete


  Sex cell (sperm or egg)
• Chromosome


  Bundled up DNA
• Allele


  Different versions of a gene
• Dominant


  Only need one gene to express a characteristic
• Recessive


  Need two identical recessive genes to express a characteristic
• Homozygous


  Genes are the same