Human biology

• The cell theory states

  1. All living things are made up of cells

  2. All cells come from other cells

  3. Information is passed from parent to daughter cells

  4. All activities occur within cells
• Cell membrane


  Selectively semipermeable phospholipid membrane that controls what enters and leaves the cell
• Nucleus


  Controls activities of the cell surrounded by a nuclear membrane containing nuclear pores
• Nucleolus


  Manufactures and stores ribosomal RNA (non membrane bound organelle)
• Lysosomes


  Destroy ingested foreign material. Can also self destruct (store digestive enzymes)
• Nuclear membrane


  Allows some substances in and out of the nucleus
• Centrioles


  tubular structures that're involved in cell diffusion
• Mitochondria


  Where cell respiration takes place (produces ATP energy)
• Golgi apparatus


  Modify and package proteins and lipids and forms vesicles
• SER


  Manufactures lipids (no dots)
• RER


  Transport protein through the cell (contain dots)
• Cytoskeleton


  Maintain cells shape and allow movement (microtubules and microfilaments) e.g. flagella, cillia and centrioles
• Ribosomes


  Where protein synthesis takes place
• Vacuoles


  Membrane bound organelles that help store waste products, water, hormones and neurotransmitters
• Cillia


  Numerous short cell extensions that move substances across their surface e.g. lining the trachea
• Flagella


  One long extension that moves the whole cell e.g. sperm cell
• 4 types of tissue

  1. Connective

  2. Nervous

  3. Muscular

  4. Epithelium
• Connective T


  cells and their surrounding matrix that join strictures together e.g. blood, tendons, ligaments
• Nervous T


  Cells that pass messages through our body e.g. neurons and their supporting cells
• Epithelium T


  Sheets of cells that line organs and opening e.g. skin, lining of the mouth, rectum
• Muscular T


  Cells that contract to allow movement e.g. heart, skeletal muscles, diaphragm
• How are cells able to function properly?

  Must be in a stable environment (homeostasis)
• Intercellular or Interstitial fluid

  Thin film fluid that surrounds every cell

  Cells receive their requirements, from and remove waste and products into interstitial fluid to maintain functioning
• Intracellular fluid (cytoplasm)


  Inside the cells
• Extracellular fluid


  fluid outside the cell
• What does the cell membrane do?

  Keeps the cells contents separate from the outside environment of the cell and determines which substances can enter or leave that cell
• semi permeable


  membranes that allow some substances through but not others
• What two substances is the cell membrane composed of?

  Lipids (fat) and protein
• Lipids


  Contain phosphate group = phospholipids

  arranged in two layers forming bi layer
• Hydrophilic


  Water soluble e.g. phosphate heads
• Hydrophobic


  Fat soluble e.g. lipid tails
• protein molecules


  scattered throughout bilayer and carry most of cell membrane functions e.g. transporting substance through cell membrane, acting as receptors
• Chloesterol


  Reduce fluidity and increase stability of the cell membrane
• Fluid mosaic model


  Fluid - phospolipids of cell membrane move within cm

  Mosaic - cm is made up of a number of different components e.g. proteins, lipids and cholesterol
• Kinetic theory of matter

  all particles move
• Diffusion


  net movement of particles from an area of higher concentration to an area of lower concentration without use of energy

  
  

  process will continue with solutes moving in 1 direction until zones are equilibrium (concentration level equal)

  
  

  Occurs across a diffusion gradient, the steeper the gradient, the faster the net diffusion
• How do we speed up diffusion

  Temp is increased

  Distance something has to travel is reduced

  diffusion gradient is larger
• Osmosis


  movement of water molecules (solvents) from area of high water concentration to an area of low concentration without use of energy.

  
  

  Concentration solution determined by amount of solute dissolved

  
  

  lower the concentration of solvent, higher osmotic pressure)
• Osmotic pressue


  ability of a solution to draw water to itself
• Surface area to volume ratio

  if size of an object influences sa to vr and we hypothesize that size will increase, sa to vr will decrease

  
  

  As size of cube increases, sa to vr ratio decreases

  
  

  All cells must be small in order to survive