Tissue: The Living Fabric:

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Tissue The Living Fabric
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Types of Primary Tissues

• Epithelial tissue
• Covers
• Connective tissue
• Supports
• Muscle tissue
• Produces movement
• Nerve tissue
• Controls

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Figure 4.1 Overview of four basic tissue types
epithelial, connective, muscle, and nervous
tissues.
Nervous tissue Internal communication
Brain Spinal cord 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
Lining of digestive tract organs and other
hollow organs Skin surface (epidermis)
Connective tissue Supports, protects, binds
other tissues together
Bones Tendons Fat and other soft padding
tissue
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Epithelial Tissue (Epithelium)

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

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Characteristics of Epithelial Tissue

• Cells have polarityapical (upper, free) and
  basal (lower, attached) surfaces
• Are composed of closely packed cells
• Supported by a connective tissue reticular lamina
  (under the basal lamina)
• Avascular but innervated
• High rate of regeneration

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Classification of Epithelia

• Ask two questions
• How many layers?
• 1 simple epithelium
• gt1 stratified epithelium
• 2. What is the shape of the cell
• Squamous
• Cuboidal
• Columnar

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Figure 4.2a Classification of epithelia.
Apical surface
Basal surface
Simple
Apical surface
Basal surface
Stratified
Classification based on number of cell layers.
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Cells of Epithelial Tissues

• Squamous cells
• Cuboidal cells
• Columnar cells
• (If stratified, name according to apical layer of
  cells)

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Figure 4.2b Classification of epithelia.
Squamous
Cuboidal
Columnar
Classification based on cell shape.
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Overview of Epithelial Tissues

• For each of the following types of epithelia,
  note
• Description
• Function
• Location

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Figure 4.3a Epithelial tissues.
Simple squamous epithelium
Description Single layer of flattened cells with
disc-shaped central nuclei and sparse cytoplasm
the simplest of the epithelia.
Air sacs of lung tissue
Nuclei of squamous epithelial cells
Function Allows materials to pass by diffusion
and filtration in sites where protection is not
important secretes lubricating substances in
serosae.
Location Kidney glomeruli air sacs of lungs
lining of heart, blood vessels, and lymphatic
vessels lining of ventral body cavity (serosae).
Photomicrograph Simple squamous epithelium
forming part of the alveolar (air sac) walls
(140x).
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Simple Squamous Epithelium

• Two other locations
• Endothelium
• The lining of lymphatic vessels, blood vessels,
  and heart
• Mesothelium
• The epithelium of serous membranes in the ventral
  body cavity

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Figure 4.3c Epithelial tissues.
Simple columnar epithelium
Description Single layer of tall cells with
round to oval nuclei some cells bear cilia
layer may contain mucus-secreting unicellular
glands (goblet cells).
Microvilli
Simple columnar epithelial cell
Function Absorption secretion of mucus,
enzymes, and other substances ciliated type
propels mucus (or reproductive cells) by ciliary
action.
Mucus of goblet cell
Location Nonciliated type lines most of the
digestive tract (stomach to rectum), gallbladder,
and excretory ducts of some glands ciliated
variety lines small bronchi, uterine tubes, and
some regions of the uterus.
Basement membrane
Photomicrograph Simple columnarepithelium of
the small intestine mucosa (660x).
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Figure 4.3d Epithelial tissues.
Pseudostratified columnar epithelium
Description Single layer of cells of differing
heights, some not reaching the free surface
nuclei seen at different levels may contain
mucus-secreting cells and bear cilia.
Cilia
Pseudo-stratified epithelial layer
Function Secrete substances, particularly mucus
propulsion of mucus by ciliary action.
Location Nonciliated type in males
sperm-carrying ducts and ducts of large glands
ciliated variety lines the trachea, most of the
upper respiratory tract.
Basement membrane
Photomicrograph Pseudostratified ciliated
columnar epithelium lining the human trachea
(800x).
Trachea
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Figure 4.3e Epithelial tissues.
Stratified squamous epithelium
Description Thick membrane composed of several
cell layers basal cells are cuboidal or columnar
and metabolically active surface cells are
flattened (squamous) in the keratinized type,
the surface cells are full of keratin and dead
basal cells are active in mitosis and produce the
cells of the more superficial layers.
Stratified squamous epithelium
Function Protects underlying tissues in areas
subjected to abrasion.
Nuclei
Basement membrane
Location Nonkeratinized type forms the moist
linings of the esophagus, mouth, and vagina
keratinized variety forms the epidermis of the
skin, a dry membrane.
Connective tissue
Photomicrograph Stratified squamous epithelium
lining the esophagus (285x).
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Connective Tissue

• Most abundant and widely distributed of primary
  tissues
• Four main classes
• Connective tissue proper
• Cartilage
• Bone
• Blood

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Table 4.1 Comparison of Classes of Connective
Tissues (1 of 2)
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Table 4.1 Comparison of Classes of Connective
Tissues (2 of 2)
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Major Functions of Connective Tissue

• Binding and support
• Protecting
• Insulating
• Storing reserve fuel
• Transporting substances (blood)

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Characteristics of Connective Tissue

• Three characteristics make connective tissues
  different from other primary tissues
• Have mesenchyme (an embryonic tissue) as their
  common tissue of origin
• Have varying degrees of vascularity (blood
  vessels)
• Have extracellular matrix
• Connective tissue not composed mainly of cells
• Largely nonliving extracellular matrix separates
  cells
• So can bear weight, withstand tension, endure
  abuse

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Connective Tissue Fibers

• Three types of fibers provide support
• Collagen
• Elastic fibers
• Reticular

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Cells

• "Blasts" cells
• Immature forum mitotically active secrete
  ground substance and fibers
• Fibroblasts in connective tissue proper
• Chondroblasts in cartilage
• Osteoblasts in bone
• Hematopoietic stem cells in bone marrow
• "Cyte" cells
• Mature form maintain matrix
• Chondrocytes in cartilage
• Osteocytes in bone

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Other Cell Types in Connective Tissues

• Fat cells
• Store nutrients
• White blood cells
• Neutrophils, eosinophils, lymphocytes
• Tissue response to injury
• Mast cells
• Initiate local inflammatory response against
  foreign microorganisms they detect
• Macrophages
• Phagocytic cells that "eat" dead cells,
  microorganisms function in immune system

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Figure 4.7 Areolar connective tissue A
prototype (model) connective tissue.
Extracellular matrix
Cell types
Ground substance
Fibers
Macrophage
Collagen fiber
Elastic fiber
Reticular fiber
Fibroblast
Lymphocyte
Fat cell
Mast cell
Neutrophil
Capillary
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Figure 4.8b Connective tissues.
Connective tissue proper loose connective
tissue, adipose
Description Matrix as in areolar, but very
sparse closely packed adipocytes, or fat cells,
have nucleus pushed to the side by large fat
droplet.
Nucleus of adipose(fat) cell
Function Provides reserve food fuel insulates
against heat loss supports and protects organs.
Location Under skin in subcutaneous tissue
around kidneys and eyeballs within abdomen in
breasts.
Fat droplet
Adipose tissue
Photomicrograph Adipose tissue fromthe
subcutaneous layer under the skin (350x).
Mammary glands
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Figure 4.8g Connective tissues.
Cartilage hyaline
Description Amorphous but firm matrix collagen
fibers form an imperceptible network chondroblast
s produce the matrix and when mature
(chondrocytes) lie in lacunae.
Function Supports and reinforces serves as
resilient cushion resists compressive stress.
Chondrocyte in lacuna
Location Forms most of the embryonic skeleton
covers the ends of long bones in joint
cavities forms costal cartilages of the
ribs cartilages of the nose, trachea, and larynx.
Matrix
Costal cartilages
Photomicrograph Hyaline cartilage from a costal
cartilage of a rib (470x).
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Figure 4.8h Connective tissues.
Cartilage elastic
Description Similar to hyaline cartilage, but
more elastic fibers in matrix.
Function Maintains the shape of a structure
while allowing great flexibility.
Chondrocyte in lacuna
Matrix
Location Supports the external ear (pinna)
epiglottis.
Photomicrograph Elastic cartilage from the human
ear pinna forms the flexible skeleton of the ear
(800x).
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Figure 4.8i Connective tissues.
Cartilage fibrocartilage
Description Matrix similar to but less firm
than that in hyaline cartilage thick collagen
fibers predominate.
Function Tensile strength allows it to absorb
compressive shock.
Location Intervertebral discs pubic symphysis
discs of knee joint.
Chondrocytes in lacunae
Intervertebral discs
Collagen fiber
Photomicrograph Fibrocartilage of
an intervertebral disc (125x). Special
staining produced the blue color seen.
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Figure 4.8j Connective tissues.
Others bone (osseous tissue)
Description Hard, calcified matrix containing
many collagen fibers osteocytes lie in
lacunae. Very well vascularized.
Central canal
Function Supports and protects (by enclosing)
provides levers for the muscles to act on
stores calcium and other minerals and fat marrow
inside bones is the site for blood cell
formation (hematopoiesis).
Lacunae
Lamella
Location Bones
Photomicrograph Cross-sectional view of bone
(125x).
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Figure 4.8k Connective tissues.
Connective tissue blood
Description Red and white blood cells in a fluid
matrix (plasma).
Red blood cells (erythrocytes)
Function Transport respiratory gases, nutrients,
wastes, and other substances.
White blood cells Lymphocyte Neutrophil
Location Contained within blood vessels.
Plasma
Photomicrograph Smear of human blood (1670x)
shows two white blood cells surrounded by red
blood cells.
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Figure 4.9a Muscle tissues.
Skeletal muscle
Description Long, cylindrical, multinucleate
cells obvious striations.
Part of muscle fiber (cell)
Function Voluntary movement locomotion
manipulation of the environment facial
expression voluntary control.
Nuclei
Location In skeletal muscles attached to bones
or occasionally to skin.
Striations
Photomicrograph Skeletal muscle (approx. 440x).
Notice the obvious banding pattern and the fact
that these large cells are multinucleate.
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Figure 4.9b Muscle tissues.
Cardiac muscle
Description Branching, striated, generally
uninucleate cells that interdigitate at
specialized junctions (intercalated discs).
Intercalated discs
Function As it contracts, it propels blood into
the circulation involuntary control.
Striations
Location The walls of the heart.
Nucleus
Photomicrograph Cardiac muscle (900x) notice
the striations, branching of cells, and the
intercalated discs.
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Figure 4.9c Muscle tissues.
Smooth muscle
Description Spindle-shaped cells with central
nuclei no striations cells arranged closely to
form sheets.
Function Propels substances or objects
(foodstuffs, urine, a baby) along internal
passageways involuntary control.
Nuclei
Location Mostly in the walls of hollow organs.
Smooth muscle cell
Photomicrograph Sheet of smooth muscle (720x).
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Nervous Tissue

• Main component of nervous system
• Brain, spinal cord, nerves
• Regulates and controls body functions
• Neurons
• Specialized nerve cells that generate and conduct
  nerve impulses
• Neuroglia
• Supporting cells that support, insulate, and
  protect neurons

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Figure 4.10 Nervous tissues.
Nervous tissue
Description Neurons are branching cells cell
processes that may be quite long extend from the
nucleus-containing cell body also contributing
to nervous tissue are nonexcitable supporting
cells.
Nuclei of supporting cells
Neuron processes
Cell body
Axon Dendrites
Cell body of a neuron
Function Neurons transmit electrical signals
from sensory receptors and to effectors
(muscles and glands) which control
their activity supporting cells support and
protect neurons.
Neuron processes
Location Brain, spinal cord, and nerves.
Photomicrograph Neurons (350x).