1. 4
Tissue: The Living Fabric:

2. Types of Primary Tissues
Epithelial tissue
Covers
Connective tissue
Supports
Muscle tissue
Produces movement
Nerve tissue
Controls
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3. Nervous tissue: Internal communication • Brain • Spinal cord • Nerves
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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4. 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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5. Characteristics of Epithelial Tissue
Cells have polarity—apical (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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6. Classification of Epithelia
Ask two questions:
How many layers?
1 = simple epithelium
>1 = stratified epithelium
2. What is the shape of the cell
Squamous
Cuboidal
Columnar
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7. 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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8. Cells of Epithelial Tissues
Squamous cells
Cuboidal cells
Columnar cells
(If stratified, name according to apical layer of cells)
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9. Figure 4.2b Classification of epithelia.
Squamous
Cuboidal
Columnar
Classification based on cell shape.
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10. Overview of Epithelial Tissues
For each of the following types of epithelia, note:
Description
Function
Location
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11. 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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12. 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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13. 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 columnar epithelium of the small intestine mucosa (660x).
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14. 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 male’s 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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15. 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
Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane.
Basement membrane
Connective tissue
Photomicrograph: Stratified squamous epithelium lining the esophagus (285x).
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16. Most abundant and widely distributed of primary tissues
Connective Tissue
Most abundant and widely distributed of primary tissues
Four main classes
Connective tissue proper
Cartilage
Bone
Blood
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17. Table 4.1 Comparison of Classes of Connective Tissues (1 of 2)
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18. Table 4.1 Comparison of Classes of Connective Tissues (2 of 2)
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19. Major Functions of Connective Tissue
Binding and support
Protecting
Insulating
Storing reserve fuel
Transporting substances (blood)
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20. 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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21. Connective Tissue Fibers
Three types of fibers provide support
Collagen
Elastic fibers
Reticular
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22. Cells "Blasts" cells "Cyte" 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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23. 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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24. Cell types Extracellular matrix Ground substance Macrophage Fibers
Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue.
Cell types
Extracellular matrix
Ground substance
Macrophage
Fibers
• Collagen fiber
• Elastic fiber
• Reticular fiber
Fibroblast
Lymphocyte
Fat cell
Mast cell
Neutrophil
Capillary
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25. 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.
Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs.
Nucleus of adipose (fat) cell
Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts.
Fat droplet
Adipose tissue
Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x).
Mammary glands
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26. Figure 4.8g Connective tissues.
Cartilage: hyaline
Description: Amorphous but firm
matrix; collagen fibers form an
imperceptible network;
chondroblasts 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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27. 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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28. 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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29. Figure 4.8j Connective tissues.
Others: bone (osseous tissue)
Description: Hard, calcified
matrix containing many collagen
fibers; osteocytes lie in lacunae.
Very well vascularized.
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).
Central
canal
Lacunae
Lamella
Location: Bones
Photomicrograph: Cross-sectional view
of bone (125x).
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30. 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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31. 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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32. 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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33. 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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34. Nervous Tissue Main component of nervous system Neurons Neuroglia
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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35. Figure 4.10 Nervous tissues.
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).
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