Unit 2 - Cells and Tissues

• General Anatomy of a Human Cell

  • roughly 37 trillion cells in the adult human body
  • organelles of a cell are similar to organs of our body
• Genetics


  is what makes us what we are
• All of our chromosomes are stores in the nucleus
• Humans have 46 chromosomes - 23 pairs (22), last one is sex chromosome (X,Y), 23 chromosomes from dad, 23 chromosomes from mom
• Genes


  Short segments of DNA found throughout our chromosomes, genes are blueprints for proteins

  
• Stem cell


  type of cell that does not have a specific function other than divide (blank cell)
• Stem cells mature or differentiate into a very specific cell type
• Primary Tissue Types

  1. Epithelial tissue
  2. Connective Tissue
  3. Muscle tissue
  4. Nerve tissue
• Morphological Classification of Epithelial Tissues

  • Shape
  • Layers
  • Ciliation
• squamous


  flat, squashed
• cuboidal


  cube
• columnar


  tall, skinny
• Transitional Epithelium

  stratified cuboidal, stratified squamous
• simple


  one cell thick
• stratified

  more than one layer; deepest layer is attached to the basement membrane
• pseudostratified

  look stratified but all cells are attached to basement membrane
• Classification by Ciliation


  Ciliated tissues have cilia on their free surface - non-ciliated, ciliated, Cilia facilitates movement (not the cell itself but the material around the cell)
• Connective Tissue

  • protects, supports, transports, stores energy and binds tissue
  • cells separated by extracellular matrix - a collection of protein fibers (collagen, elastic) and ground substance (water, assortment of large proteins and sugars)
  • structure varies greatly
  • most types are highly vascularized
• Epithelial Tissue

  • found in linings, coverings and glandular tissues
  • covers all free surfaces of the body

  Functions:

  • protect
  • absorb
  • filter
  • secrete

  Characteristics:

  • Cells tightly packed
  • one apical (unattached) surface, one basal surface attached to basement membrane
  • Cells reproduce rapidly
  • Not vascularized (no blood vessels)
• Types of Connective Tissue

  dense connective tissue, loose connective, bone, cartilage, blood and lymph
• dense connective tissue


  strong durable ex. tendon/ligament, tissue with a lot of fibroblasts (collagen)
• loose connective tissue

  between organs/tissues ex. adipose tissue, fat), more cells, loosely arranged, semi-fluid matrix, fat filled cells (adipocytes), little extracellular material
• bone

  bone cells (osteocytes) are surrounded by hard matrix of calcium and other minerals
• cartilage

  more flexible, but still supportive, cells (chondrocytes) surrounded by variable matrix
• blood and lymph


  transports gases, nutrients, fights infections
• Muscle Tissue

  has the ability to contract (shorten), which is used to provide
• Different Types of Muscle

  skeletal, cardiac, smooth
• Nervous Tissue

  • neuron conducts electrical impulses
  • long processes (axons) allow impulse to travel distances
  • support cells (glia) lubricate and protect neurons
• Integumentary System

  • cutaneous membrane , skin
  • covers outer surface of body
  • a pliable layer of epithelial tissue that covers and line the body - “epithelial membrane”
  • Considered simple “organ” since it contains more than one tissue type - epithelial sheets, underlining connective tissue, some muscle and nervous tissue as well

  Functions:

  • protects (physical, chemical, biological)
  • water conservation
  • temp. regulation (hair, sweat, layers)
  • excretion (oil, sweat)
  • synthesizes vitamin D
  • sensory (pressure, temp. pain)
  • cushions
  • appearance
• epidermis

  (epithelial tissue)
first layer of skin, outer keratinized epithelial layer, epi = on top
• dermis

  dense connective tissue
• hypodermis

  • adipose tissue
  • below dermis
  • not considered part of the skin
  • subcutaneous adipose tissue (fat)
  • insulates temp, absorbs shock
• stratum corneum


  five thin layers of (strata) epithelial cells is avascular (no direct blood supply), continuously shed, protects underlying tissues from light, heat, water, chemicals, bacteria
• stratum basale


  deepest layer, closest to blood supply, has melanocytes and keratinocytes
• melanocytes


  produce melanin
• jaundice


  occurs when a bile pigment accumulates throughout the body including skin because liver function is insufficient
• Exocrine glands


  release products through ducts
• Sebaceous Glands


  produce sebum (oil), keeps skin and hair soft, not found in palms or soles, bactericidal effect
• Sweat glands


  (sudoriferous), low pH (acidic) inhibits bacteria, aids in the heat response to cool the body