CELL TYPES

• Levels of Cellular Org. (5)

  Organism > Organ system > Organ > Tissue > Cell

  
• Tissue


  Group of cells that carry out specific functions that work together.
• 3 embryonic tissues called germ layer:

  – Endoderm (innermost)

  – Mesoderm (middle)

  – Ectoderm (outermost)

  
• Epithelial tissues


  covers the body and lines body cavities. it protects organs, absorbs and secretes materials. present in gastrointestinal tract (mouth, pharynx (throat), esophagus, stomach, small intestine, large intestine, rectum, and anus.)
• Connective tissue


  give support and structure, to bind together, and to protect tissues and organs of the body. it's dispersed in a matrix.
• Muscle Tissue

  enables movement by contracting in response to stimuli. Muscle cells are long and thin, known as muscle fibers, and can be voluntary (skeletal) or involuntary (cardiac & smooth).
• Nervous Tissue


  is specialized for generating and transmitting electrical impulses throughout the body.
• 4 Main Types of Tissues

  • Epithelial tissue
  • Connective tissue
  • Muscle tissue
  • Nervous tissue
• 3 types of Covering and Lining Epithelium

  • Simple Epithelium
  • Pseudostratified Columnar Epithelium
  • Stratified Epithelium
• Simple Epithelia 


  consists of a single layer which facilitates absorption, secretion, and filtration processes.
• Simple squamous epithelium


  have scale-like appearance

  
• Simple cuboidal epithelium


  box-like cell

  
• Simple columnar epithelium


  column like cell

  
• 3 types of SIMPLE EPITHELIA

  • Simple squamous epithelium
  • Simple cuboidal epithelium
  • Simple columnar epithelium
• Pseudostratified Columnar Epithelium

  appears stratified due to varying cell sizes but is a SINGLE LAYER. It is found in the respiratory tract, often with cilia that move mucus and trapped particles out of the airways.
• Stratified Epithelium

  consists of several stacked layers of cells. This functions as protection against physical and chemical wear and tear.
• Stratified squamous epithelium


  most common type of stratified epithelium in the human body.

  
• Stratified cuboidal epithelium


  functions as protective tissue. Can be found in sweat glands, salivary glands, and mammary glands.
• Stratified columnar epithelium

  functions for secretion and protection. found at the male urethra and the ducts and some glands.
• Transitional Epithelium

  kind of stratified epithelium that has gradual changes in shape of the apical cells as the bladder fills with urine. allows the urinary organs to expand and stretch. found in the urinary system (bladder, urethra, and the ureters).
• 4 types of Stratified Epithelium

  • Stratified squamous epithelium
  • Stratified cuboidal epithelium
  • Stratified columnar epithelium
  • Transitional epithelium
• Glandular Epithelium

  makes up the glands such as thyroid gland, sweat glands, digestive glands, and adrenal glands that are responsible for secretion of chemical substances.
• Endocrine Glands


  a ductless gland that release secretion into the surrounding tissues and fluids.
• Exocrine Glands


  secretion leaves through a duct that leads to epithelial surface.
• Endocrine and Exocrine 


  Types of Glands
• Proper


  Type of connective tissue in which fibroblasts are present
• Loose Connective Tissue


  functions for both shock absorption and binding tissue. allow nutrients to diffuse through cells
• Adipose tissue


  Stores fat for energy, insulation, and protection.
• Areolar tissue

  contains all cell types and fibers and is distributed in a random, web-like fashion.
• Reticular tissue

  Forms a mesh-like framework for soft organs such as the spleen and liver.
• Dense Connective Tissue

  Contains more collagen for greater strength and resistance to stretching.
• Dense regular CT

  found in tendons and ligaments, providing tensile strength.
• Dense irregular CT

  found in the skin’s dermis, providing strength in multiple directions.
• Specialized connective tissues


  provide support and hold the body tissues together
• Cartilage


  a type of specialized connective tissue that provides support.
• Hyaline cartilage

  provides strong support while providing pads for shock

  absorption.
• Elastic Cartilage

  maintain the shape of the structure while allowing flexibility. It is found in the external ear or also known as the auricle and in the epiglottis.
• Fibrocartilage

  thick bundles of collagen fibers dispersed through the matrix. Examples of these include the knee and jaw joints and the intervertebral discs.
• 3 types of Cartilage

  • Hyaline Cartilage
  • Elastic Cartilage
  • Fibrocartilage
• Bone (Osteo)


  known as the hardest connective tissue. The main function of bones is to provide protection to delicate internal organs such as the brain and support the body.