Chapter 5 - Tissues

• Tissues - groups of cells that work together to carry out a particular specialised function
• 4 major types of tissue:

  • epithelial - form protective coverings and function in secretion and absorption
  • connective - support soft body parts and bind structures together
  • muscle - produce body movements
  • nervous - conduct impulses that help control and coordinate all body activities
• Epithelial tissue:

  • function - protection, secretion, absorption, excretion
  • location - cover body surface, cover and line internal organs, compose glands
  • characteristics - lack blood vessels, readily divide, cells are tightly packed together
• Connective tissue:

  • function - bind, support, protect, fill spaces, store fat, produce blood cells
  • location - widely distributed throughout body
  • characteristics - mostly have rich blood supply, have at least 2 distinct cell types, cells are further apart than epithelial with extracellular matrix in between
• Muscle tissue:

  • function - movement
  • location - attach to bones, in walls of hollow internal organs, heart
  • characteristics - able to generate forces in respinse to specific stimuli
• Nervous tissue:

  • fucntion - conduct impulses for coordination, regulation, integration and sensory reception
  • location - brain, spinal cord, nerves
  • characteristsics - cells communicate with each other and other body parts by recieving and sending stimuli
• Micrographs:

  • they are thin slices of prepared tissue specimens
  • advantage is tha they are thin so light passes through them readily

  A) longitudinal

  B) oblique

  C) oblique

  D) longitudinal

  
• Types of epithelium

  A) squamous

  B) cuboidal

  C) columnar

  D) stratified

  E) columnar

  F) transitional

  
• Simple squamous epithelium:

  • Single layer of thin flattened cells
  • cells fit lightly together & nuclei are usually broad and thin
  • function - filtration, diffusion, osmosis, covering of surfaces
  • E.g. Line the air sacs (alveoli), walls of capillaries, lining of blood and lymph vessels, etc
• Simple cuboidal epithelium:

  • single layer of cube-shaped cells
  • Cells usually have centrally located, spherical nuclei
  • function - protection and secretion
  • E.g. covers the ovaries, lines kidney's, line certain ducts of glands

  
• Simple columnar epithelium:

  • Single layer of cells with elongated nuclei located at about the same level
  • Cells are taller than they are wide and can be ciliated or non-ciliated
  • function - protection, secretion, absorption
  • e.g. goblet cells, lining of uterus, stomach and intestines

  
• Stratified squamous epithelium:

  • Many cell layers, making this tissue relatively thick
  • Cells divide in the deeper layers, newer cells push older ones further outward where they flatten
  • function - protection
  • E.g. epidermis (superficial layer of skin), lining of throat, oral cavity, etc

  
• Stratified cuboidal epithelium:

  • 2 or 3 layers of cuboidal cells that form the lining of the lumen and provide more protection
  • function - protection
  • e.g. lines ducts of mammary glands

  
• Pseudostratified columnar epithelium:

  • appear to be stratified or layered but are not (because nuclei lie at two or more levels in the row)
  • Cells commonly have cilia
  • function - protection, secretion, movement of mucus
  • E.g. lines passage of the respiratory system

  
• Transitional epithelium:

  • Specialised to change in response to increased tension
  • function - stretchability, protection
  • e.g. forms inner lining of urinary bladder

  
• Glands:

  • made of epithelial tissues
  • exocrine = secrete product into a duct or onto an outside body surface
  • endocrine = secretes hormones into the bloodstream
  • types of glands:
  • merocrine = fluid product released through cell membrane via exocytosis (e.g salivary or sweat glands)
  • apocrine = cellular product and portions of cells pinch off during secretion (e.g. mammary glands)
  • holocrine = secretion contains entire secretory cells (e.g. sebaceous glands of the skin)

  
• Connective tissue:

  • most abundant and widely distributed
  • Bind structures, provide support and protection, store fat, fill spaces, produce blood cells, protect against infections, repair tissue damage
  • Cells are spread apart with an abundance of extracellular matrix lying between them
  • some are quite rigid some are flexible
• Types of connective tissue:

  A) specialised

  B) loose

  C) areolar

  D) fibrocartilage

  E) dense

  F) elastic

  
• Major cell types of connective tissue:

  • fibroblasts
  • produce protein fibres in connective tissues
  • most common type of fixed cells
  • macrophages
  • large phagocytic cell
  • specialised to carry on phagocytosis
  • mast cells
  • cells that antibodies are formed in response to allergens attach, which cause the cells to release allergy mediators that cause symptoms
  • they are usually near blood vessels

  A) fibroblasts

  B) macrophages

  C) mast cell