Chapter 6 Histology

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Chapter 6Histology
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What is Histology

• Histology is the study of tissues and how they
  are arranged into organs.
• histo- tissue ology- study of
• Objectives Name, draw, recognize and
  differentiate the function of the four primary
  classes and their subcategories which adult
  tissues are classified.

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Chapter 6 Histology

• Introduction -tissues
• a) multicullar structure tissues contain cells
  of similar type. The cells work together to
  perform a specific function.
• b)cells and matrix
• 1) matrix- extracellular material containing
  protein and mineral salts.
• 2) fluid surrounding cells is the interstitial
  fluid (Inter - between cells vs. Intra inside a
  cell)

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Chapter 6 Histology

• 2) Embryonic tissues- tissues from which all
  other tissues will arise. Starts with fertilized
  egg. Forms 3 layers (strata) called the primary
  germ layers.
• a) ectoderm (outer) -forms epidermis nervous
  system
• b) endoderm (inner)-forms mucous membrane lining
  GI tract respiratory system and digestive
  glands
• c) mesoderm (middle)-forms mesenchyme that gives
  rise to muscle, bone, blood and other connective
  tissues

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Chapter 6 Histology

• 3) 4 basic tissue types (adult)
• a) epithelial
• 1) one or more cell layers thick, free surface
  
• 2) simple or stratified
• 3) coverings protection, secretion absorption

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Chapter 6 Histology

• 3) 4 basic tissue types (adult)
• b) connective
• 1) extensive extracellular matrix collagen
  (flexible but strong), elastin (elastic
  qualities)
• 2) support, binding, protective
• 3) Connective tissue proper- Loose (adipose
  (fat)) tissue, Areolar (loosely binds epithelial
  cells to deeper tissue, and Reticular
  (supportive framework for lymphatic organs.

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Epithelial Tissue

• There are two major categories of epithelial
  tissue membranous and glandular.
• Membranous The outer layer of skin, inner
  lining of cavities and lumina and coverings of
  visceral (internal-especially the heart, lungs,
  liver, pancreas or intestines) organs.
• Glandular specialized tissue that form
  secretory portions of glands.

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Membranous- Simple Epithelia

• Simple Epithelial Tissue single layer thick and
  is located where diffusion, absorption,
  filtration and secretion are principle functions.
  
• Some cells contain cilia that move materials
  across cell surfaces.
• Other cells contain microvilli that increase
  surface area for absorption.

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Membranous- Simple Epithelia

• Simple Squamous Epithelium Flattened ,
  irregularly shaped cells with an oval centrally
  located nucleus. Write down three places in the
  body where each type of epithelial cell can be
  found.

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Membranous- Simple Epithelia

• Simple Columnar Epithelium Tall, columnar cells
  with a single nucleus located near the basement
  membrane. Specialized unicellular glands called
  Goblet cells are scattered through this tissue.
  Goblet cells secrete a lubricative and protective
  mucus. Write locations.

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Membranous- Simple Epithelia

• Simple Cuboidal Epithelium Tightly fitted cube
  shaped cells found lining the lumina of small
  ducts and tubules that have excretory, secretory
  and absorptive functions.
• Write locations.

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Membranous- Simple Epithelia

• Simple Ciliated Columnar Epithelium Similar to
  columnar cells but with cilia along the free
  surface. Cilia do what? Where are they located?

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Membranous- Simple Epithelia

• Pseudostratified Ciliated Columnar Epithelium
  Ciliated columnar epithelium that appears to be
  layered- but each cell is anchored to the
  basement membrane. Write location.

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Membranous- Stratified Epithelia

• Stratified Epithelia Tissue consisting of two
  or more layers. This tissue is primarily
  protective and enhanced by rapid cell divisions.
  Stratified epithelia are classified according to
  the shape of the surface layer of cells.
• Why is this tissue not well suited for
  absorption and secretion?

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Membranous- Stratified Epithelia

• Stratified Squamous Epithelium Composed of a
  variable number of cell layers that are flattest
  at the surface. Mitosis occurs at only at the
  deepest layers.
• Keratinized Contains keratin (strengthening
  protein)
• Nonkeratinized No keratin, called mucosa
• Where are they located?

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Membranous- Stratified Epithelia

• Stratified Cuboidal Epithelium Consists of two
  or three layers of cuboidal cells where
  stratification provides a more robust lining.
  What location?

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Membranous- Stratified Epithelia

• Transitional Epithelium similar to
  nonkeratinized stratified squamous epithelium.
  Where is this located and what is the specific
  function?

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Chapter 6 Histology

• Body Membranes Thin layers of epithelial tissue
  that cover, support and protect visceral organs
  and line body cavities.
• Mucous Membrane secrete thick mucus to
  lubricate and protect associated organs. Oral and
  nasal cavities, respiratory, reproductive,
  urinary and digestive system.
• Serous Membrane secrete serous fluid to help
  protect. Pleurae (lungs), Pericardial (heart),
  Peritoneal (adominopelvic)

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Glandular Epithelia

• Glandular Epithelia Tiny invaginations
  (infoldings) of membranous epithelia that give
  rise to specialized secretory structures called
  exocrine glands.
• Unicellular Single cells (Example ?)
• Multicellular These can be simple or compound
  and are composed of both secretory cells and
  cells that form the walls of ducts.

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Membranous- Stratified Epithelia

• Multicellular Exocrine Glands Are organized the
  way they release their product.
• Merocrine- exocytosis through cell membrane
• Apocrine- secretion accumulates near surface of
  the cell and then is released with a portion of
  the cell.
• Holocrine- the entire secretory cell is
  discharged along with secretory product.

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Multicellular exocrine glands
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Chapter 6 Histology

• 3) Connective cont. Dense regular (tendons and
  ligaments), Dense irregular (dermis- forms
  protective coverings around organs, bones, nerves
  and most cartilages), Elastic (large arteries,
  lower respiratory tract, between arches of
  vertebrae)

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Chapter 6 Histology

• Connective continued
• Cartilage- consisting of chondrocytes, provides
  support along with elastic/flexible properties.
• Bone- comprised of spongy bone and compact or
  dense bone
• Blood- fluid connective tissue

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Cartilage

• Hyaline cartilage eases joint movement, holds
  airway open during respiration, growth zones of
  long bones in children.

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Cartilage

• Elastic cartilage Abundant elastic fibers that
  provide flexibility. Found in framework of outer
  ear, auditory canal and portions of larynx.

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Cartilage

• Fibrocartilage Abundant collagenous fibers that
  withstand compression. Found in the symphysis
  pubis, intervertebral discs, and knee joint.

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Bone

• Bone The most rigid connective tissue. Unlike
  cartilage, bone has a rich vascular supply and is
  the site of metabolic activity. Bones density is
  due mostly to inorganic calcium phosphate
  (calcium hydroxyapatite).
• Spongy (porous) (think Spongebob) or Compact
  (dense)

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Blood

• Blood vascular tissue or fluid connective tissue
  that helps to maintain homeostasis. Contains
  plasma, erythrocytes (red blood cells),
  leukocytes (white blood cells), and thrombocytes
  (platelets).

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Question Review

• Why do some injuries to tendons and ligaments
  require more time to heal than a broken bone.
  Use your book and notes to formulate a reasonable
  answer- you may use smart phones at this time.
  (10 minutes)

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Chapter 6 Histology

• 3) 4 basic tissue types (adult)
• c) muscle
• 1) skeletal, cardiac, smooth
• 2) contractile
• 3)excitable membrane potential
  electrical charge

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Skeletal Muscle

• Skeletal muscle attaches to bone and allows
  voluntary movement. Muscle cells are
  multinucleated, striated, cylindrical fibers.

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Cardiac Muscle

• Cardiac muscle branched, striated fiber with a
  single nucleus and intercalated discs (gap
  junctions).

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Smooth Muscle

• Smooth muscle Elongated, spindle fibers with a
  single nucleus. Involuntary movement of internal
  organs.

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Review Question

• Why are skeletal muscle cells multinucleated and
  why does cardiac muscle have intercalated disks?
  Use your book and notes to formulate a reasonable
  answer- you may use smart phones at this time.
  (10 minutes)

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Chapter 6 Histology

• 3) 4 basic tissue types (adult)
• d) nervous
• 1) Consits of neurons and neuroglia (or glial
  cells)
• 2) glia provide protection for neurons
• neurons nerve cells
• 3) Rapid signaling
• 4) Highly excitable membrane potential

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Chapter 6 Histology

• Tissue growth and repair
• a) embryonic tissue differentiates into adult
  tissue types.
• b) growth
• 1) hyperplasia incr. cell .
• 2) hypertrophy - incr. cell size.
• c) shrinkage /death
• 1) atrophy- decr. in cell size
• 2) necrosis premature tissue death
• 3) infarction sudden death to interrupted
  blood supply.
• a) cell rupture, stimulated inflammation.
• 4) apoptosis programmed cell death
• a) cell shrinks, phagocytized.