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• Tissues


  A group of cells that share morphological features and perform similar functions
• Organs


  A group of tissues that make up a functional unit that is specialized to execute specific functions within the body
• Levels of organization of life

  • Cells
  • Tissues
  • Organs
  • Organ Systems
• Cells make up all living organisms
• Tissues are formed when cells with similar or related features and functions join together
• Organs are made up of different types of tissues that work together
• Organ Systems are made up of different organs that perform coordinated functions
• An organism may have one or more organ systems
• Major types of tissues found in multicellular animals

  • Epithelial
  • Connective
  • Muscle
  • Nervous
• Epithelial tissues


  • Sheets of cells that cover the exterior surface of organs and structures in the body and line the internal cavities and passageways, and form specific glands
  • Can consist of a single layer (simple epithelia) or multiple layers of cells (stratified epithelia)
• Types of epithelial tissues

  • Squamous
  • Cuboidal
  • Columnar
  • Transitional
• Connective tissues


  • Bind the cells and organs of the body together and protect, support, and integrate all parts of the body
  • Consist of extracellular matrix, living cells, and a nonliving material called ground substance
  • Made up primarily of fibroblasts, cells that produce the fibers found in nearly all connective tissues
• Types of connective tissues

  • Loose (or areolar)
  • Fibrous (or dense)
  • Cartilage
  • Bone
  • Adipose (or fat tissue)
  • Blood
• Muscle tissues


  • Respond to stimulation and contract to provide movement
• Bone tissue


  Makes up the internal skeleton of vertebrates, giving structure and attachment points for tendons
• Bone tissue

  • Contains collagen and elastic fibers, which provide flexibility
  • Contains mineral salts like calcium, which give the tissue hardness
• Adipose (or fat) tissue

  Adipocytes collect and store fat
• Adipose tissue


  • Does not contain fibroblasts and only has a few fibers
  • Stores fat as a source of energy, insulation, and cushioning against damage to body organs
• Blood

  Although blood does not contain fibers, it is considered connective tissue because it has a matrix, a fluid called plasma
• Blood


  • Found all over the body and its primary function is to transport materials such as oxygen, nutrients, and waste
• Types of connective tissue

  • Bone tissue
  • Adipose (or fat) tissue
  • Blood
• Muscle tissue


  Muscle tissues respond to stimulation and contract to provide movement
• Types of muscle tissue

  • Skeletal
  • Smooth
  • Cardiac
• Skeletal muscle


  • Striated, under voluntary control, found in muscles that move bones
• Smooth muscle


  • Nonstriated, under involuntary control, a major component of the walls of blood vessels, digestive and reproductive system tubes
• Cardiac muscle


  • Striated, under involuntary control, found only in the heart
• Nervous tissue

  Made up of neurons and glial cells
• Neurons


  • Make up most of nervous tissue, receive and transmit electrical signals, enabling communication between different parts of the body
• Glial cells


  • Do not transmit signals, support the activities of the neurons in various ways
• Types of glial cells

  • Astrocytes
  • Oligodendrocytes
• Vascular plants

  Plants with specialized tissues that transport water and nutrients
• Vascular plant organ systems

  • Root system
  • Shoot system
• Vascular plant organs

  Roots, stems, and leaves
• Vascular plant tissues

  • Dermal
  • Vascular
  • Ground
• Phloem


  Transports sugars from the site of photosynthesis to roots, leaves, and fruits, where they are needed or stored
• Xylem


  Transports water and nutrients from the roots to the shoots
• Sponges and corals are examples of animals that lack organs or even well-defined tissues
• Mosses and liverworts are examples of nonvascular plants, which do not have specialized vascular tissue (xylem or phloem), and as such also lack true leaves, stems, and roots
• Multicellular protists like brown algae also lack true tissues