healthy bodies

• Cells


  • Humans have an estimated 100,000 billion cells
  • All living things are composed of cells whose details are visible only through a microscope
  • Different body tissues and organs are made up of different kinds of cells
  • All vital functions of an organism occur within cells
  • All cells contain hereditary information for regulating cell functions & for transmitting information to the next generation of cells
  • Cells are referred to as BUILDING BLOCKS of the body
• Cell membrane


  The basic function of the cell membrane is to protect the cell from its surroundings
• Cell nucleus


  The cell nucleus contains the majority of the cell's genetic material in the form of multiple linear DNA molecules organized into structures called chromosomes
• DNA


  Deoxyribonucleic acid is a molecule that carries most of the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms
• Smooth Endoplasmic Reticulum


  Performs functions in several metabolic processes, including synthesis of steroids, lipids and phospholipids, as well as the metabolism of carbohydrates, elimination of drugs from the system and attachment of receptors to cell membrane proteins
• Cytoplasm


  Thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins
• Ribosome


  Are a cell structure that makes protein
• Mitochondria


  Takes in nutrients, breaks them down, and creates energy rich molecules for the cell
• Golgi


  • Modifying, sorting and packaging of proteins for secretion
  • Involved in the transport of lipids around the cell, and the creation of lysosomes
• Each Cell looks after itself. It can: take in nutrients, convert nutrients into energy, carry out specialised functions, reproduce itself
• Each cell has a set of instructions for carrying out these activities
• Types of cells


  • Cells live alone (unicellular) or in groups (multicellular). THE HUMAN ORGANISM is multicellular with 220 different types of cells and tissues
• Components of cells


  • Cell membrane
  • DNA
  • Nucleus
• Osteoblasts


  • Osteoblasts are the major cellular component of bone
• Osteoclasts


  • The bone reabsorbing cells
• Cellular metabolism


  • Cells need energy to do their work - conduction by nerve cells & contraction by muscle cells etc.
  • Cells must be able to 'capture' and store energy & then release that energy when needed
  • An important source of energy for cells is glucose
• DNA (deoxyribonucleic acid)


  • All cells possess DNA, the hereditary material of genes
  • Genes are units of stored information (the recipe for that cell)
  • Genes are massed together in chromosomes
  • There are 46 chromosomes in each cell
  • ONE cell is less than a millimetre long but contains two metres of DNA!

  
• If you unravelled all your chromosomes from all the cells of your body, then laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times
• A Gene


  • A gene is a region of DNA that controls a hereditary characteristic
  • Genes are made up of DNA
  • A gene carries biological information in a form that must be copied and transmitted from each cell to all its new cells
  • Chromosomes contain several hundred genes
  • As of 2001, humans are thought to have between 30,000 and 40,000 genes

  
• Making new cells


  1. CELL DIVISION (mitosis) involves a single cell (called a mother cell) dividing into two daughter cells

  2. Every time a cell divides, each chromosome must be carefully copied and then distributed to assure that each daughter cell gets a complete and accurate set of information
• Chromosome Replication and Division
• Cell division - Mitosis


  • Cell division allows worn or damaged cells to be replaced
  • Division of a single cell dividing into 2 daughter cells
  • Body cells, such as those that make up skin, hair, and muscle, are duplicated by mitosis
  • If cellular reproduction becomes uncontrolled, tumours and cancers can develop
• Cell division - Meiosis


  • The chromosomes are re-arranged during meiosis to form new combinations of genes
  • Reproductive cell division – results in half the number of diploid cells
  • This is vitally important for genetic variation
  • The sex cells, sperm and ova, are produced by meiosis
• Stem cells


  • Stem cells are very early stage cells that have the ability to turn into other specialised types of cells
  • For example a stem cell can turn into liver cells, skin cells, nerve cells etc.
  • A newly fertilised egg produces 8 identical cells that form a clump of cells that can potentially produce other types of cells
• 3 types of stem cells


  • Embryonic stem cells
  • Adult stem cells
  • Umbilical cord stem cells
• Many cells form tissues. Tissues are a group of cells that perform a specific function. The basic types of tissues in the human body include epithelial, muscle, nervous, and connective tissues.

  
• Systems


  Body systems are made up of small units serving specific purposes: 1. The smallest units are cells 2. Cells together form tissues (bones, muscle etc) 3. Different tissues working together form organs 4. Different organs (eg.heart, lungs etc) working together form Body Systems (digestive, nervous etc).
• Epithelial tissue


  • Epithelial tissue helps to keep the body's organs separate, in place and protected
  • Membranous tissue covering internal organs and other internal surfaces of the body protect the tissues that lie beneath it from radiation, desiccation, toxins, invasion by pathogens, and physical trauma
  • Some examples of epithelial tissue are the outer layer of the skin, the inside of the mouth and stomach, and the tissue surrounding internal organs
• Types of tissues in the human body


  • Epithelial
  • Muscle
  • Nervous
  • Connective

  
• Body systems


  1. Cells

  2. Tissues

  3. Organs

  4. Body Systems
• Epithelial tissue


  • Helps to keep the body's organs separate, in place and protected
  • Membranous tissue covering internal organs and other internal surfaces of the body protect the tissues that lie beneath it from radiation, desiccation, toxins, invasion by pathogens, and physical trauma
• Examples of epithelial tissue


  • Outer layer of the skin
  • Inside of the mouth and stomach
  • Tissue surrounding the body's organs

  
• Connective tissue


  • Adds support and structure to the body
  • Most types contain fibrous strands of the protein collagen that add strength
• Examples of connective tissue


  • Inner layers of skin
  • Tendons
  • Ligaments
  • Cartilage
  • Bone
• Tendons


  Connective tissue joining muscle to bone, capable of resisting high tensile forces while transmitting forces from muscle to bone
• Cartilage


  Function is to connect bones together
• Muscle tissue


  • Specialised tissue that can contract
  • Contains specialised proteins that slide past one another and allow movement
• Examples of muscle tissue


  • Muscles throughout your body
• Muscle fibre


  Long, multi-nucleated muscle cells, or myofibers, that make up skeletal muscle
• Nerve tissue


  • Has the ability to generate and conduct electrical signals in the body
  • Electrical messages are managed by nerve tissue in the brain and transmitted down the spinal cord to the body