Anatomy

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Anatomy Physiology

• Tissue The Living Fabric

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Anatomy Physiology

• Tissue The Living Fabric

• Objectives
• Identify and describe the functions of the 4 main
  types of body tissues
• Describe the various types and functions of
  epithelia
• Explain the properties and functions of different
  types of connective tissue
• Identify the major types of muscle tissue
• Describe the basic types and functions of nerve
  tissue

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Tissues

• Groups of cells similar in structure and function
• Types of tissues
• Epithelial tissue
• Connective tissue
• Muscle tissue
• Nerve tissue

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Nervous tissue Internal communication Brain,
spinal cord, and nerves
Muscle tissue Contracts to cause movement
Muscles attached to bones (skeletal) Muscles of
heart (cardiac) Muscles of walls of hollow
organs (smooth)
Epithelial tissue Forms boundaries between
different environments, protects, secretes,
absorbs, filters Skin surface (epidermis)
Lining of GI tract organs and other hollow organs
Connective tissue Supports, protects,
binds other tissues together Bones Tendons
Fat and other soft padding tissue
Intro to tissues
Figure 4.1
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Epithelial Tissue (Epithelium)

• Two main types (by location)
• Covering and lining epithelia
• On external and internal surfaces
• Glandular epithelia
• Secretory tissue in glands

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Functions of Epithelial Tissue

• 6 main functions of epithelium
• Protection (skin)
• Absorption (digestive tract, kidneys)
• Filtration (digestive tract, kidneys)
• Excretion (digestive tract, kidneys)
• Secretion (glands, kidneys)
• Sensory reception (skin)

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Homeostatic Imbalance

• Epithelial Tissue
• An important characteristic of cancerous
  epithelial cells is their failure to respect the
  basement membrane boundary. (85 out of 100
  cancers are of epithelial cells)
• They penetrate it and invade the tissues beneath.

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Characteristics of Epithelial Tissue

• Cells have polarity- apical (upper, free) and
  basal (lower, attached) surfaces- cell regions
  near the apical surface differ in structure and
  function from cell regions in the basal surface.
• Apical surfaces may have
• Microvilli finger-like extensions of the plasma
  membrane that increase surface area.
• Lining of the intestine
• Cilia tiny hair like projections that propel
  substances along their free surface.
• Lining of the trachea

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Characteristics of Epithelial Tissue

• Are composed of closely packed cells to form
  continuous sheets.
• Supported by a connective tissue reticular lamina
  (under the basal lamina)
• A layer of extracellular material containing a
  fine network of collagen and protein fibers.
• Avascular (contains no blood vessels) but
  innervated (supplied by nerve fibers).
• Epithelial cells are nourished by substances
  diffusing from blood vessels in the underlying
  connective tissue.
• High rate of regeneration
• Reproduce rapidly to replace lost cells due to
  hostile substances in the external environment.

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Classification of Epithelia

• Ask two questions
• How many layers?
• 1 layer
• simple epithelium
• Very thin most concerned with absorption,
  secretion, and filtration.
• 2 or more layers stratified epithelium
• More durable, major role is protection.

Figure 4.2a
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Classification of Epithelia

• What type of cell?
• Squamous
• Flattened and scale-like
• Cuboidal
• Box-like, tall as they are wide
• Columnar
• Tall and column shaped
• (If stratified, name according to apical (top)
  layer of cells)

Figure 4.2b
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Epithelia Simple Squamous

• Thin, often permeable cells
• Found where filtration and exchange of substances
  by rapid diffusion is a priority
• Kidneys
• Lungs
• Blood vessels

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Epithelia Simple Squamous

• Two noteworthy names
• Endothelium innercovering slick-friction
  reducing lining
• The lining of lymphatic vessels, blood vessels,
  and heart
• Mesothelium middlecovering
• The epithelium of serous membranes in the ventral
  body cavity

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Figure 4.3a
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Figure 4.3b
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Figure 4.3c
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Figure 4.3d
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Figure 4.3e
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Epithelia Stratified Cuboidal

• Quite rare in body
• Found in some sweat and mammary glands
• Typically two cell layers thick

Sweat Duct
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Epithelia Stratified Columnar

• Limited distribution in body
• Small amounts in pharynx, male urethra, and
  lining some glandular ducts
• Also occurs at transition areas between two other
  types of epithelia

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(f) Transitional epithelium
Description Resembles both stratified squamous
and stratified cuboidal basal cells cuboidal or
columnar surface cells dome shaped or
squamouslike, depending on degree of organ
stretch.
Transitional epithelium
Function Stretches readily and permits
distension of urinary organ by contained urine.
Location Lines the ureters, urinary bladder,
and part of the urethra.
Basement membrane
Connective tissue
Photomicrograph Transitional epithelium lining
the urinary bladder, relaxed state (360X) note
the bulbous, or rounded, appearance of the cells
at the surface these cells flatten and become
elongated when the bladder is filled with urine.
Figure 4.3f
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Answer the following questions and turn in!! ?

• Explain what is meant by epithelial tissue being
  avascular but innervated.

• What structure can be noted on the apical surface
  of the cells in this image?
• What is the name of this tissue type?
• A multilayered epithelium with cuboidal basal
  cells and flat cells at its surface would be
  classified as ________?

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Answer the following questions and turn in!! ?

• Explain what is meant by epithelial cells having
  polarity

• What is significant about the cells closes to the
  basement membrane of this tissue type?
• What is the name of this tissue type?
• A multilayered epithelium with cuboidal basal
  cells and columnar cells at its surface would be
  classified as ________?
• What types of organs would you find transitional
  epithelium in?

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Glandular Epithelia

• Objectives
• Define gland
• Differentiate between exocrine and endocrine
  glands, and differentiate between multicellular
  and unicellular glands
• Describe how multicellular exocrine glands are
  classified structurally and functionally

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Glandular Epithelia

• A gland is one or more cells that makes and
  secretes an aqueous fluid.
• Glandular cells obtain needed substances from
  blood and transform them chemically into a
  product that is then released from the cell.
• Classified by
• Site of product releaseendocrine (internally
  secreting) or exocrine (externally secreting)
• Relative number of cells forming the
  glandunicellular (e.g., goblet cells) or
  multicellular (typically ducted)

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Endocrine Glands

• Ductless glands
• Secrete hormones that travel through lymph or
  blood to target organs

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Exocrine Glands

• More numerous than endocrine glands
• Secrete products into ducts
• Secretions released onto body surfaces (skin) or
  into body cavities
• Examples include mucous, sweat, oil, and salivary
  glands

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Unicellular Exocrine Glands
Goblet Cell

• The only important unicellular gland are mucous
  cells and goblet cells. (scattered)
• Goblet cells- look like a glass with a stem due
  to the accumulation of mucin at the top of the
  cell.
• Both produce mucin that dissolves in water when
  secreted and forms mucous- a slimy protective and
  lubricating coating found within the human body.

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Multicellular Exocrine Glands

• Multicellular exocrine glands are composed of a
  duct and a secretory unit
• Classified according to
• Duct type
• Simple unbranched duct
• Compound branched duct
• Structure of their secretory units
• Tubular secretory cells form tubes.
• Alveolar (acinar) secretory cells form small
  sacs.
• Tubuloalveolar have both types of secretory
  units.

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Figure 4.5
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Modes of Secretion

• Merocrine
• Products are secreted by exocytosis
• Examples pancreas, sweat and salivary glands.

• Holocrine
• Products are secreted by rupture of gland cells
• Example sebaceous glands

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Answer the following questions and turn in!! ?

• What is a gland?

• Explain the difference between endocrine and
  exocrine glands and provide an example of each
• What type of an exocrine gland is a goblet cell
  and what does it produce?
• Draw and label the various structural
  presentations for multicellular exocrine glands.
• What is the primary difference between the way
  merocrine and halocrine glands secrete their
  products?

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Connective Tissue

• Objectives
• Identify common characteristics of connective
  tissue, and list and describe its common
  structural elements
• Describe the common types of connective tissue
  found in the body and indicated their particular
  functions

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Connective Tissue

• Most abundant and widely distributed tissue type
• Four classes
• Connective tissue proper
• Cartilage
• Bone tissue
• Blood

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Major Functions of Connective Tissue

• Binding and support
• Protection
• Insulation
• Transportation (blood)

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Characteristics of Connective Tissue

• Connective tissues have
• Mesenchyme (embryonic tissue) as their common
  tissue of origin
• Varying degrees of vascularity (supply of blood
  vessels)
• Cells separated by nonliving extracellular matrix
  (ground substance and fibers)
• This is what enables the connective tissue to
  bear weight, withstand great tension, and endure
  physical trauma.

Mesenchymal Cells
Areolar Connective Tissue
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Structural Elements of Connective Tissue

• Ground substance
• Unstructured material that fills the space
  between the cells and contains the fibers
• Functions as a molecular sieve through which
  nutrients and other dissolved substances diffuse
  between blood capillaries and cells.
• Components
• Interstitial fluid
• Adhesion proteins (glue)
• Proteoglycans
• Protein core large polysaccharides
  (chrondroitin sulfate and hyaluronic acid)
• Trap water in varying amounts, affecting the
  thickness of the ground substance

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Structural Elements of Connective Tissue

• Fibers provide support.
• Three types of fibers
• Collagen (white fibers)
• Strongest and most abundant type
• Provides high tensile strength
• Elastic
• Networks of long, thin, elastin fibers that allow
  for stretch
• Reticular
• Short, fine, highly branched collagenous fibers

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Structural Elements of Connective Tissue

• Cells
• Mitotically active and secretory cells blasts
• Mature cells cytes
• Fibroblasts in connective tissue proper
• Chondroblasts and chondrocytes in cartilage
• Osteoblasts and osteocytes in bone
• Hematopoietic stem cells in bone marrow
• Fat cells, white blood cells, mast cells, and
  macrophages

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Connective Tissue Embryonic

• Mesenchymeembryonic connective tissue
• Gives rise to all other connective tissues
• Gel-like ground substance with fibers and
  star-shaped mesenchymal cells

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Answer the following questions and turn in!! ?

• What are the 4 classes of connective tissue?

• What 3 types of fibers provide support for
  connective tissue?
• What are 4 functions of connective tissue?
• What function(s) does adipose serve?

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Connective Tissue Proper
The name connective tissue proper is used to
designate the connective tissue that fills
interstitial spaces as opposed to the specialized
connective tissues (blood, bones, cartilage,
etc).

• Types
• Loose connective tissue
• Areolar
• Adipose
• Reticular

• Dense connective tissue
• Dense regular
• Dense irregular
• Elastic

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Figure 4.8a
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Figure 4.8b
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Figure 4.8c
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Figure 4.8d
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Figure 4.8e
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Figure 4.8f
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Connective Tissue Cartilage

• Three types of cartilage
• Hyaline cartilage
• Elastic cartilage
• Fibrocartilage

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Homeostatic Imbalance

• Cartilage
• Aging cartilage cells lose their ability to
  divide ? injure cartilages heal slowly.
• During later life cartilages tend to calcify or
  ossify (become bony).

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Figure 4.8g
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Figure 4.8h
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Figure 4.8i
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Other tissues
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Figure 4.8j
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(k) Others blood
Description Red and white blood cells in a fluid
matrix (plasma).
Plasma
Function Transport of respiratory gases,
nutrients, wastes, and other substances.
Neutrophil
Location Contained within blood vessels.
Red blood cells
Lymphocyte
Photomicrograph Smear of human blood (1860x)
two white blood cells (neutrophil in upper left
and lymphocyte in lower right) are seen
surrounded by red blood cells.
Figure 4.8k
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Nervous Tissue

• Nervous system

Figure 4.9
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Muscle Tissue
Figure 4.10a
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Muscle Tissue
Figure 4.10b
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Muscle Tissue
Figure 4.10c
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Epithelial Membranes

• Cutaneous membrane (skin)
• Consists of keratinized stratified squamous
  epithelium (epidermis) firmly attached to a thick
  layer of dense irregular connective tissue
  (dermis)

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Epithelial Membranes

• Mucous membranes
• Mucosae
• Line body cavities open to the exterior (e.g.,
  digestive and respiratory tracts)

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Epithelial Membranes

• Serous Membranes
• Serosaemembranes (mesothelium areolar tissue)
  in a closed ventral body cavity
• Parietal serosae line internal body walls
• Visceral serosae cover internal organs

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Steps in Tissue Repair
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Steps in Tissue Repair
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Steps in Tissue Repair
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Homeostatic Imbalance

• Scar Tissue
• Scar tissue that forms in any muscular organ-
  heart or urinary bladder can severely impair the
  function of that organ.
• Scars reduce the internal volume of the organ and
  block movement of substances through the hollow
  organ.
• Can hamper the muscles ability to contract.
• Heart progressive heart failure.
• Visceral organs adhesions connect organs
  together and prevent normal shifting about ? ex.
  Intestines adhesions obstruct the flow of
  foodstuffs.
• Tissue Damage-Snake Bite

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The End! ?
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Developmental Aspects

• Primary germ layers ectoderm, mesoderm, and
  endoderm
• Formed early in embryonic development
• Specialize to form the four primary tissues
• Nerve tissue arises from ectoderm
• Muscle and connective tissues arise from mesoderm
• Epithelial tissues arise from all three germ
  layers