organisation of the body from chemical to organismic level

• 4 major elements in the body

  oxygen, carbon, hydrogen, nitrogen
• 9 lesser elements in the body

  calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, iodine, iron
• 13 trace elements in the body

  aluminium, boron, chromium, cobalt, copper, fluorine, manganese, molybdenum, selenium, silicone, tin, vanadium, zinc
• macronutrients


  carbohydrates, proteins, fats
• micronutrients


  vitamins and minerals
• the cell


  smallest structural and functional unit of an organism, 50-60 trillion cells, 200 different cell types in human body, range of sizes/shapes/functions with the same basic function
• nucleus


  contains genetic information, site of initiation of protein synthesis
• nucleolus


  production of ribosomes
• ribosome


  manufactures proteins
• rough ER


  studded with ribosomes, it then becomes the factory of protein synthesis
• smooth ER


  lipid synthesis, metabolises toxins, calcium store
• lysosome


  destruction of debris and waste products
• mitochondria


  provides energy
• golgi complex


  processes newly made proteins and transports them to their destination within the cell
• cytoskeleton


  provides strength and rigidity to the cell, transport and mobility
• membrane


  encloses the cell
• plasma membrane - protein

  act as channels, transporters, receptors, enzymes or cytoskeleton anchors

  1. integral proteins - create channels
  2. peripheral or semi-integral proteins - loosely attached to the surfaces
• plasma membrane - lipids

  1. phospholipids - 75%, head is hydrophilic and tail is hydrophobic, tail to tail makes it impermeable to most water-soluble molecules
  2. glycolipids - helps in cell communication, growth development and detects harmful foreign cells
  3. cholesterol - 40%, only found in mammalian cells and help to strengthen the membrane, makes the membrane less deformable and less permeable to small water-soluble molecules
• diffusion


  substances move from areas of high concentration to an area of low concentration e.g. oxygen, carbon dioxide, nitrogen, steroids, fat-soluble vitamins (ADEK), water, urea, and small alcohols
• osmosis


  diffusion of water through a selectively permeable membrane which only allows water molecules to move across it
• facilitated diffusion


  channel or transporter proteins help molecules across cell membrane, these molecules include urea, glucose, fructose, galactose and certain vitamins
• primary active transport


  uses integral membrane proteins act as pumps to push molecules across the plasma membrane, substances include ions, amino acids, and monosaccharides, it consumes ATP
• tissue level - epithelial

  1. covers body surfaces, lines hollow organs, cavities and ducts, forms glands and therefore functions in secretion
  2. functions - protection (physical, secretion, absorption, filtration, sensation (embedded sensory endings)
• tissue level - connective


  support, bind and protect the body and its organs
• tissue level - nervous

  these are excitable and specialized for rapid signal conduction, initiates and transmits nerve impulses
• tissue level - muscular


  these are excitable and specialized for contraction, provides movement and force
• areolar connective tissue (loose)


  a loose weave of tissue that acts a packing between tissues and functions as support, holding body fluids, defense (against infection via white cells and macrophages) and storing nutrients
• adipose connective tissue (loose)


  closely packed adipocytes or fat cells that insulates, protects organs and acts as a reserve fuel supply
• dense connective tissue

  • parallel arrangement of collagen fibers with few elastin fibers so resist force in one direction
  • forms tendons to attach muscle to bone and ligaments that attach bone to bone
• specialist types


  cartilage, bone and blood
• What are the three main components of connective tissue?

  Ground substance, cells, and fibres
• What is the composition of ground substance in connective tissue?

  It is a loose flexible gel that is mainly water and proteoglycans
• What is the function of ground substance in connective tissue?

  It allows diffusion of materials and dissolved substances
• What types of cells are found in connective tissue?

  • Blast cells: fibroblasts, chondroblasts, osteoblasts
  • Clast cells: break down connective tissue
  • Cyte cells: maintain, recycle, and break down ground substance (e.g., chondrocytes in cartilage and osteocytes in bone)
• What is the role of blast cells in connective tissue?

  They are responsible for producing the components of the extracellular matrix
• What do clast cells do in connective tissue?

  They break down connective tissue
• What is the function of cyte cells in connective tissue?

  They maintain, recycle, and break down ground substance
• What are the two main types of fibres found in connective tissue?

  Collagen and elastin
• What is the function of collagen in connective tissue?

  It provides toughness and tensile strength
• What is the role of elastin in connective tissue?

  It is a rubber-like protein that can stretch and recoil