bio paper 2

• Homeostasis


  An organism's ability to regulate internal conditions even when external conditions change
• Importance of homeostasis


  • Allows crucial chemical reactions involving enzymes to happen at an Optimum rate
  • Regulates blood glucose concentration, temperature, and water levels
• Nervous system regulation of homeostasis

  1. Receptor detects stimulus

  2. Electrical signal travels to spine through sensory and relay neurons

  3. Signal travels across synapse by neurotransmitter

  4. Signal goes to brain for conscious decision

  5. Signal goes back to effector via relay and motor neurons
• Reflex


  Signal bypasses the brain and goes straight through the spine to the effector
• Effectors


  Glands that produce specific chemicals the body needs
• Investigating reaction time


  1. Hold ruler between finger and thumb, drop without warning

  2. Measure distance fallen before caught

  3. Repeat multiple times, take mean average
• Parts of the brain

  • Cerebral cortex - higher level functions
  • Cerebellum - motor skills, movement, balance, coordination
  • Medulla oblongata - controls unconscious actions
• MRI scans


  Safely see activity in the brain
• Accommodation in the eye

  1. For far objects: Ciliary muscles relax, suspensory ligaments tighten, lens becomes thin

  2. For near objects: Ciliary muscles contract, suspensory ligaments slacken, lens becomes fatter
• Pupil


  Hole in the iris that can change size depending on light intensity
• Cornea


  Transparent outer layer where light enters the eye, has a slight lensing effect
• Retina


  Contains rods and cones that respond to light
• Thermoregulation


  1. Brain senses blood temperature, sends signals to effectors to lose or retain heat

  2. Sweat glands cause evaporation to cool

  3. Blood vessels dilate or constrict to increase or decrease heat loss

  4. Shivering produces heat
• Endocrine system


  System of glands that produce hormones that travel in the blood
• Pituitary gland


  Main or master gland that produces hormones in response to stimuli
• Pancreas


  Produces insulin to regulate blood glucose levels
• Type 1 diabetes


  Pancreas can't produce enough insulin
• Type 2 diabetes


  Cells don't absorb glucose properly
• Urea


  Waste product from excess protein breakdown, filtered by kidneys
• Kidney regulation of water balance

  1. ADH from pituitary causes kidney tubules to reabsorb more water

  2. Less ADH causes more water loss in urine
• Dialysis


  Process that artificially filters blood when kidneys don't work properly
• Menstrual cycle


  1. FSH causes egg maturation and estrogen production

  2. LH causes egg release

  3. Progesterone maintains uterus lining
• Contraception methods


  • Pills that inhibit FSH
  • Progesterone injections
  • Implants
  • Condoms
  • Diaphragms
  • IUDs
  • Sterilization
• IVF


  In vitro fertilization, eggs and sperm fertilized in lab then implanted
• Adrenaline


  Hormone that increases heart and breathing rate in stress
• Thyroxin


  Hormone secreted by thyroid that controls metabolic rate
• Negative feedback in thyroid regulation

  1. Hypothalamus releases TRH

  2. Pituitary releases TSH

  3. Thyroid releases more thyroxin
• Plant hormones


  Gibberellins - seed germination, flowering, fruit growth

  Auxins - control shoot and root growth, phototropism, geotropism

  Ethene - fruit ripening
• Investigating plant tropisms


  Place seeds on damp cotton wool, stand dish on side, turn 90 degrees and observe root growth
• Meiosis


  Process that produces gametes with half the normal number of chromosomes
• Mitosis


  Process of cell division that produces genetically identical daughter cells
• Genome


  All the genetic material in an organism
• Gene


  Section of DNA that codes for a specific protein
• Genotype


  Genetic code stored in DNA
• Phenotype


  How the genetic code is expressed in an organism's characteristics
• Nucleotides are the monomers that make up DNA, consisting of a sugar, phosphate, and nitrogenous base
• Parasite


  Can reproduce on its own without a parent
• DNA


  A two-stranded polymer in a double helix shape
• Gene


  A section of DNA that codes for a specific protein
• The Human Genome Project completed its initial goal in 2003 when scientists mapped out what every gene is responsible for coding