TISSUES

• Epithelial Tissue 

  • Tightly-joined and closely-packed cells
  • Composed mostly of the cells
  • Covers the outside of the body and lines the internal organs ex: skin and digestive tract
  • Makes up glandular tissue such as sweat glands and pancreas
  • Provides surface for absorption, excretion, and transport of molecules
• Simple Squamous Epithelium (one)

  • Composed of thin, flat cells that lie on the basement membrane like floor tiles.
  • Location : air sacs of the lungs and lining of blood vessels
  • Function : allows passage of filtration and diffusion
  • The endothelium is the epithelial tissue that lines vessels of the lymphatic and cardiovascular system, and it is made up of a single layer of squamous cells.
  • The mesothelium is a simple squamous epithelium that forms the surface layer of the serous membrane that lines body cavities and internal organs.
• Simple Cuboidal Epithelium

  • Cube like or wedge-shaped cells
  • Lines tubules and found in kidney tubules, ducts, and surface of the ovary.
  • Function : Absorption and Secretion
• Simple Columnar Epithelium

  • Resembles tall columns
  • This can be ciliated on the apical surface or have microvilli (tiny hairlike structures)
  • Location : Lines digestive tract and gallbladder
  • Function : Absorption and enzyme secretion.
• Pseudostratified Columnar Epithelium

  •  (pseudo- = “false”) describes tissue with a single layer of irregularly shaped
  • cells that give the appearance of more than one layer.
  • Function:  Responsible for protecting foreign particles ; Filter and carry or transport mucus and filtered particles away from the respiratory organs;
  • Secretion of mucus and absorption of excess fluid.
  • Location : Regions of uterus, lines the bronchi
• Stratified Squamous Epithelium (more than one)

  • Covers the outermost layer of the skin
  • Keratinized (tough protein that hardens cells) variety lines the surface of the skin
  • Protects underlying tissues in areas subject to abrasion
• Transitional Epithelium 

  • Made up of several layers of cells
  • Unusual in the way that it has some remarkable stretching capabilities 
  • Lines urinary bladder, ureter, and allows the bladder to expand.
• Connective Tissues

  • Binds structure together, form a framework and support organs and body as a whole. Store fat, transport substances, and protect against disease.
  • Help repair tissue damage
  • Occur throughout the body
  • Usually Matrix - consists of fibers and fluids, gel, or solid ground substance.
• Connective Tissue Proper - loose and dense connective tissue

  Supporting Connective Tissue - Cartilage and Bone

  Fluid Connective Tissue - Blood
• Areolar (Loose Connective Tissue)

  • It contains all three types of fibers (collagen, elastin, and reticular) with much ground substance and fibroblasts.
  • widely distributed under the epithelia of the body
  • Function : Packing material or meshwork ; wraps and cushion organs 
• Adipose Tissue

  • Consists of fat cells with little extracellular matrix. It stores fat for energy and provides insulation.
  • Provides reserve fuel (lipid), insulates against heat loss, supports and protects organs.
  • Around kidneys, under the skin, in bones, within abdomen, and in breasts,
• Reticular Tissue

  • Has fibroblasts and fibrocytes. This is made up of fine strands of collagen 
  • Found in soft internal organs, such as the liver, spleen, and lymph nodes.
  • It provides an internal framework for these organs. 
• Dense regular connective tissue 

  • consists of collagenous fibers packed into parallel bundles.
  • Found in tendons and ligaments.
• Dense irregular connective tissue

  •  consists of collagenous fibers interwoven into a mesh-like network.
  • Found in deep layers of the skin and the white part of the eye.
• Cartilage 

  • is a connective tissue consisting of collagenous fibers embedded in a firm matrix of chondroitin sulfates.
• Hyaline cartilage 

  • Provides support with some flexibility.
  • Found in the apex of the nose, covering the ends of most long bones at joints.
  • The cells that occur in hyaline cartilage are chondrocytes and the fibers are collagenous fibers
• Fibrocartilage

  • Provides some compressibility and can absorb pressure
  • Found in intervertebral discs
• Elastic Cartilage

  • Provides firm but elastic support.
  • Flexible
  • Found in the external ear and in part of the larynx called the epiglottis
• Blood

  • is a fluid connective tissue containing erythrocytes and various types of leukocytes that circulate in a liquid extracellular matrix. 
• Muscle Tissue

  • Is characterized by properties that allow movement.
  •  They are contractile, meaning they can shorten and generate a pulling force. When attached between two movable objects, in other words, bones, contractions of the muscles cause the bones to move.
• Skeletal Muscle - Striated and Voluntary

  Cardiac Muscle - Striated and Involuntary

  Smooth Muscle - Nonstriated and Involuntary
• Nervous tissue

  • Is found in the brain, spinal cord, ganglia, and peripheral nerves in the body.
  • Is characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information. 
  • Two main classes of cells make up nervous tissue: the neuron and neuroglia 
• Neuroglia

  • Play an essential role in supporting neurons and modulating their information propagation.
• Neuron 

  • Is the conductive cell of the tissue
• Three major regions of neuron : Dendrites, Axon, and Nerve cell body.
• Dense Connective Tissue

  • Cells: fibroblasts
  • Fibers: collagen fibers heavily packed in the ECM either in parallel order (dense regular),

  or randomly interlaced (dense irregular)
• Loose Connective Tissue

  • Cells: fibroblasts
  • Fibers: collagen fibers loosely scattered in the ECM
• Reticular Connective Tissue

  • Cells: reticular cells
  • Fibers: reticular fibers organized in delicate networks
• Cartilage

  • Cells: chondrocytes
  • ECM: collagen II (hyaline cartilage), elastic fibers (elastic cartilage), collagen I (fibrocartilage)
• Bone

  • Cells: osteoblasts, osteocytes, osteoclasts
  • ECM: calcified lamellae
• Blood

  • Cells: erythrocytes, leukocytes, platelet
  • ECM: blood plasma
• Adipose tissue

  • Cells: white and brown adipocytes
  • ECM: no ECM
• Embryonic connective tissue

  • Mesenchyme: mesenchymal cells in reticular fibers rich ECM
  • Mucoid tissue: mesenchymal cells in collagen rich ECM