Levels of organisations

• What do cells in the embryo often do as they differentiate?


  They grow together as a tissue.
• What are the main types of mammalian tissues?


  Epithelial, muscular, and connective tissues.
• What is the function of epithelial tissue?


  • Forms a continuous layer covering or lining surfaces
  • Does not contain blood vessels
  • May have nerve endings
  • Made of collagen and protein
  • Varies in shape and function
• What is the simplest form of epithelial tissue?

  Simple cuboidal epithelium.
• Describe the characteristics of simple cuboidal epithelium.


  Cells are cube-shaped and the tissue is one cell thick.
• Where does simple cuboidal epithelium occur in the body?


  In the proximal convoluted tubule of the kidney nephron and the ducts of salivary glands.
• What are the characteristics of ciliated columnar epithelium?


  • Contains elongated cells
  • Lines tubes that substances move through
  • Found in the oviduct (fallopian tube) and trachea
  • Has cilia on the surface
• What is the composition of the skeleton?


  • Bands of connective tissue
  • Also called bones
  • Made up of cartilage and bone
• What is the function of muscle tissue?


  • Bands of contractile tissue
  • Enable movement
• What is the cardiovascular system?


  • System of blood vessels
  • Transports blood throughout the body
• What type of muscle is skeletal muscle?


  Contractile tissue that enables movement.
• What type of muscle is smooth muscle?


  Contractile tissue that enables movement.
• What is the function of smooth muscle?


  Enables movement.
• What is the function of skeletal muscle?


  Enables movement.
• How does the cardiovascular system function?


  It transports blood throughout the body.
• What does squamous epithelium consist of?


  Flattened cells on a basement membrane
• Where is squamous epithelium found in the body?


  It forms the walls of the alveoli and lines the nasal capsule of the necktons
• What are the three main types of muscle tissue?


  • Skeletal muscle
  • Smooth muscle
  • Cardiac muscle
• What is the primary function of skeletal muscle?


  To generate contraction in mammals
• What are the characteristics of skeletal muscle cells?


  They are long cells or fibres that give powerful contraction
• Why are skeletal muscles called voluntary muscles?


  Because you can choose whether or not to contract them
• What is another name for skeletal muscle?


  Striped or striated muscle
• What are the characteristics of smooth muscle?


  It has individual spindle-shaped cells that contract less powerfully
• Where is smooth muscle found in the body?


  In the skin, walls of blood vessels, and digestive and respiratory tracts
• Why are smooth muscles called involuntary muscles?


  Because you cannot control their contractions
• What is another name for smooth muscle?


  Unstriped or unstriated muscle
• What is unique about cardiac muscle?


  It is only found in the heart and contracts rhythmically
• How does cardiac muscle differ from skeletal muscle?


  Cardiac muscle has stripes but lacks long fibres
• How does cardiac muscle contract?


  It contracts rhythmically without stimulation from nerves or hormones
• What is the function of connective tissue?


  To connect, support, and separate tissues and organs
• What does connective tissue contain?

  Elastic and collagen fibres in an extracellular fluid or matrix
• What are adipocytes?


  Fat-storing cells found in connective tissue
• What is the purpose of stretching exercises?


  To lengthen muscles and connective tissue, improving flexibility
• What is an organ?


  An organ is a group of tissues working together to perform a specific function.
• What are organs and their functions in humans and plants?

  • In humans, the eye contains nervous, connective, muscle, epithelial, and sensory tissues and is the organ of sight.
  • In plants, the leaf contains vascular tissues and is the organ of photosynthesis.
• What is an organ system?


  An organ system is a group of organs working together with a particular role.
• How do organ systems contribute to an organism?


  All the systems of the body work together, making an organism a discrete individual.
• What are the key questions related to organs and organ systems?


  • What is an organ?
  • What are organs?
  • What is an organ system?
  • What are organ systems?
• Cell-to-Cell Interaction


  Cells interact through cell junctions, secreted signals, and cell-surface receptors