Biology 2

• Peer review


  Published into the scientific literature and checked by other scientific teams
• Homeostasis


  Regulating the internal conditions of the body (temperature, water levels, blood glucose)
• Central nervous system


  Made up of brain and spinal cord
• Endocrine system


  Hormonal system-involves glands, hormones and blood vessels
• Hormones


  Chemical messengers released by glands that travel in bloodstream
• Synapse


  Gap between 2 neurons. Signal passes between 2 neurons chemically.
• Nervous and endocrine systems

  Fast response that protects us from harm
• Reflex response


  Stimulus, receptor, sensory neuron, relay neuron, motor neuron, effector, response
• Receptors


  • Eyes (light), skin (temperature and pressure), ears (sound), nose (smell), tongue (taste)
• Effectors


  • Muscles (contract) or gland (releases chemical)
• Menstruation


  Uterus lining sheds
• Menstrual cycle


  Type 1 diabetes: Pancreas fails to produce enough insulin, treated with insulin injections

  Type 2 diabetes: Cells can no longer respond to insulin, treated with carbohydrate controlled diet and exercise
• Major glands in body

  • Thyroid, adrenal, testes (males), pituitary (master gland), pancreas, ovaries (females)
• Insulin


  Causes uptake of glucose by cells that convert glucose to glycogen in liver and muscles
• Glucagon


  Causes glycogen to be converted into glucose when blood glucose level is too low
• Hormonal contraceptives


  • Oral contraceptive (contains oestrogen to inhibit FSH and stop egg maturing)

  Skin patch, injection, implant (contains progesterone to inhibit maturation and release of egg for several months/years)
• Non-hormonal contraceptives


  • Barrier methods (condom/diaphragm), abstaining from intercourse when egg may be in oviduct, surgical methods (sterilisation), spermicidal agents, intrauterine device
• Ovulation


  Egg is released from ovary
• Fertilisation


  Egg and sperm join
• Fertility treatment


  • FSH/LH given to mature and release more eggs, fertility drug given, collected and fertilised artificially, fertilised eggs develop into embryos implanted into mother's uterus
• Thyroxine


  Stimulates the basal metabolic rate. Plays an important role in growth and development
• Adrenaline


  Produced in times of fear or stress. Increases the heart rate (more O2 and glucose delivery to brain and muscles). Prepares you for fight or flight
• Sexual reproduction


  2 parents, genetic variation in offspring
• Mitosis


  Produces all body cells (except gametes). Cell divides into two genetically identical daughter cells. Same number of chromosomes as parent cell.
• Meiosis


  Produces gametes only. The cell divides twice to form four daughter cells, each with half the chromosomes of the parent cell.
• DNA


  Polymer, made up of two strands forming a double helix
• Gene


  Small section of DNA on a chromosome, that code for a particular protein
• Genome


  Entire genetic material of an organism
• Chromosomes


  Humans have 46 chromosomes in each cell, except gametes which have 23 (half)
• Sex chromosomes


  Females-XX, males-XY
• Dominant


  Only 1 copy of allele is needed for condition to be expressed (e.g. DD or Dd)
• Recessive


  2 copies of the allele are needed for condition to be expressed (e.g. ff)
• Homozygous


  Same alleles present (e.g. FF or ff)
• Heterozygous


  Different alleles present (e.g. Ff)
• Phenotype


  The characteristic expressed
• Genotype


  The combination of alleles
• Polydactyl


  Condition where individual has extra fingers and toes-caused by a dominant allele
• Cystic fibrosis


  Disorder of cell membranes-caused by recessive allele
• Causes of variation


  • Genetics (inherited e.g. eye colour), environment (developed characteristics e.g. scar), combination (both e.g. weight)
• Evolution


  Theory of Charles Darwin. Caused by natural selection. All organisms have evolved from simple life forms. Started billions of years ago