Tissues

Examples of Tissues in the following topics:

• Types of Connective Tissue

  • Connective tissues encompass a diverse array of tissue types that are involved in binding and supporting body structure and tissues.
  • The functions of areolar connective tissue include the support and binding of other tissues.
  • The two types of adipose tissue are white adipose tissue (WAT) and brown adipose tissue (BAT).
  • Bone tissue is also called the osseous tissue.
  • Describe the diverse types of connective tissue (e.g., adipose tissue, cartilage, bone, blood, and lymphatic tissue).

• Characteristics of Connective Tissue

  • Connective tissue (CT) is a one of the four main classes of tissues.
  • Although it is the most abundant and widely distributed of the primary tissues, the amount of connective tissue in a particular organ varies.
  • Connective tissue fibers provide support.
  • Three types of fibers are found in connective tissue:
  • They help the connective tissue to stretch and recoil.

• Characteristics of Epithelial Tissue

  • The human body consists of four types of tissue: epithelial, connective, muscular, and nervous.
  • Epithelial tissue covers the body, lines all cavities, and composes the glands.
  • In its role as an interface tissue, epithelium accomplishes many functions, including:
  • Protection for the underlying tissues from radiation, desiccation, toxins, and physical trauma.
  • Regulation and excretion of chemicals between the underlying tissues and the body cavity.

• Tissues in Levels of Organization

  • Tissues are groups of similar cells that have a common function.
  • The four basic tissue types are epithelial, muscle, connective, and nervous tissue.
  • Each tissue type has a characteristic role in the body:
  • Most organs contain more than one tissue type.
  • Cells form tissues, and tissues form organs.

• Lymphoid Tissue

  • The tissues of lymphoid organs are different than the tissues in most other organ systems because different tissues within the system vary considerably based on cell cycle proliferation of lymphocytes.
  • Secondary lymphoid tissue provides the environment for the antigens to interact with the lymphocytes.
  • Lymphatic tissues begin to develop by the end of the fifth week of embryonic development.
  • Development of lymphatic tissue starts when venous endothelial tissues differentiate into the lymphatic endothelial tissues.
  • The thymus and bone marrow are primary lymphoid tissue, while the lymph nodes, tonsils, and spleen are secondary lymphoid tissue.

• Structural Elements of Connective Tissue

  • Collagen is a group of naturally-occurring proteins found in animals, especially in the flesh and connective tissues of mammals.
  • Collagen fibrils/aggregates are arranged in different combinations and concentrations in various tissues to provide varying tissue properties.
  • Elastic tissue is classified as "connective tissue proper. " The elastic fiber is formed from the elastic microfibril and amorphous elastin.
  • Elastic fibers are found in the skin, lungs, arteries, veins, connective tissue proper, elastic cartilage, periodontal ligament, fetal tissue, and other structures.
  • This network acts as a supporting mesh in soft tissues such as liver, bone marrow, and the tissues and organs of the lymphatic system.

• Levels of Organization

  • In humans, most cells combine to form tissues, but some cells are found independent of solid tissues and have their own functions.
  • Humans have four different types of basic tissues.
  • Connective tissues such as bone tissue are made up of fibrous cells and give shape and structure to organs.
  • Nervous tissue is made of specialized cells that transmit information through electrochemical impulses, such as the tissue of nerves, the spinal cord, and the brain.
  • Most organs contain tissues such as parenchyma (used to perform the organ functions),  stroma (connective tissue specific to organs) and epithelial.

• Tissue Engineering

  • Tissue engineering is the synthesis of surgical grade human tissue or tissue analogue via culture or manufacture.
  • While most definitions of tissue engineering cover a broad range of applications, in practice the term is closely associated with applications that repair or replace portions of or whole tissues (i.e., bone, cartilage, blood vessels, bladder, skin, etc.).
  • Often, the tissues involved require certain mechanical and structural properties for proper functioning.
  • One of the continuing, persistent problems with tissue engineering is mass transport limitations.
  • A bioreactor in tissue engineering, as opposed to industrial bioreactors, is a device that attempts to simulate a physiological environment in order to promote cell or tissue growth in vivo.

• Graft Rejection and Tissue Typing

  • Transplant or graft rejection occurs when a transplanted tissue is rejected by the recipient's immune system.
  • Transplant (or graft) rejection occurs when transplanted tissue is rejected by the recipient's immune system, which destroys the transplanted tissue.
  • Tissue typing is a procedure in which the tissues of a prospective donor and recipient are tested for compatibility prior to transplantation.
  • Different types of transplanted tissues tend to favor different balances of rejection mechanisms.
  • Describe the role of tissue typing and graft rejection in transplantation

• Bursae and Tendon Sheaths

  • Joints are cushioned by small fluid-filled sacs called bursae and stabilized by tough bands of fibrous connective tissue called tendons.
  • Synovial joints are made up of five classes of tissues.
  • These include bone, cartilage, synovium, synovial fluid, and tensile tissues composed of tendons and ligaments.
  • Elsewhere the tendon lies in a bed of loose fibrous tissue.
  • Bursae occur at sites of shearing in subcutaneous tissue or between deeper tissues such as muscle groups and fascia.