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

  2. Sends nervous and hormonal signals to effectors

  3. Effectors cause body to lose or retain heat
• Endocrine system

  System of glands that produce hormones that travel to effectors via 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 no longer absorb glucose properly
• Dialysis

  Process that does the job of non-functioning kidneys
• 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
  • Avoiding sex after ovulation
• IVF


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


  Hormone that increases heart and breathing rate in stressful situations
• Thyroxin


  Hormone secreted by thyroid that controls metabolic rate
• 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 characteristics
• Nucleotides are the monomers between the two DNA strands, made of a sugar, phosphate, and one of four nitrogenous bases
• 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
• Genotype

  The code stored in your DNA specifically
• Phenotype

  How the genotype is expressed in your characteristics and physiology
• Nucleotides

  The monomers between the two DNA strands, made from a sugar and phosphate group
• There are four types of nucleotides: A, T, C, and G
• A and T always match to each other in the DNA sequence, as do C and G</b>
• Protein synthesis

  1. Three nucleotides form a code for an amino acid

  2. mRNA copies the DNA sequence

  3. mRNA takes the code to a ribosome

  4. Amino acids are connected in the order needed to make a protein