Introduction
• Tissue – cells organized into groups that are
specialized to carry out a specific function
• Four major tissue types (table 5.1)
– Epithelial
– Connective
– Muscular
– Nervous
Epithelial Tissue
• Covers organs, forms inner lining of body
cavities, and lines hollow organs
• Underside anchored to connective tissue by
a thin, nonliving layer called the basement
membrane
• Lack blood vessels, readily divides and is
tightly packed
• Carcinomas pp. 101
Epithelial Tissue
• Classified according to shape and number
of layers of cells
– Squamous – thin, flattened cells
– Cuboidal – cube-shaped cells
– Columnar – tall, elongated cells
– Simple – single layer of cells
– Stratified – two or more layers of cells
– Psuedostratified – falsely stratified
Epithelial Tissue
• Simple Squamous Epithelium
– Single layer of thin flattened cells
– Fit together like floor tiles
– Common at sites of diffusion and filtration
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Lines air sacs (alveoli) of the lungs
Forms walls of capillaries
Lines the inside of blood and lymph vessels
Covers membranes that line body cavities
Epithelial Tissue
Simple Squamous Epithelium
Epithelial Tissue
• Simple Cuboidal Epithelium
– Single layer of cube-shaped cells
– Common at sites of secretion and absorption
• Covers the ovaries
• Lines the kidney tubules
• Lines the ducts of the salivary glands, thyroid gland,
pancreas and liver
Epithelial Tissue
Simple Cuboidal Epithelium
Epithelial Tissue
• Simple Columnar Epithelium
– Single layer of elongated cells
– May be ciliated (microvilli)
• Increase surface area
– Common at sites of secretion and absorption
• Lines uterus and most organs of the digestive tract
• Goblet Cells – flask shaped cells imbedded in simple
columnar epithelium that secrete protective mucous
on the free surface of the tissue
Epithelial Tissue
Simple Columnar Epithelium
Epithelial Tissue
• Psuedostratified Columnar Epithelium
– Only appears layered
– Contain cilia and goblet cells
– Lines the passageways of the respiratory system
Epithelial Tissue
Psuedostratified Columnar
Epithelium
Epithelial Tissue
• Stratified Squamous Epithelium
– Relatively thick
– Forms outer layer of the epidermis
• As skin cells age the accumulate keratin, harden and
die
• Prevents water and nutrient loss, and damage from
chemicals and microorganisms
– Lines the oral cavity, esophagus, vagina, and
anal canal
• Not keratinized
Epithelial Tissue
Stratified Squamous
Epithelial Tissue
• Stratified Cuboidal
– Two or three layers of cuboidal cells that form
the lining of a lumen
– Lines the large ducts of the mammary glands,
sweat glands, salivary glands, and pancreas
Epithelial Tissue
Stratified Cuboidal Epithelium
Epithelial Tissue
• Stratified Columnar Epithelium
– Consists of several layers of columnar cells
– Found in the male urethra, ductus deferens and
in parts of the pharynx
Epithelial Tissue
Stratified Columnar Epithelium
Epithelial Tissue
• Transitional Epithelium
– Specialized to change in response to increase
tension
– Forms the inner lining of the urinary bladder
and lines the ureters
Epithelial Tissue
Transitional Epithelium
Connective Tissue
• Functions
– Binds structures
– Provides support and protection
– Serves as framework
– Fill spaces
– Stores fat
– Produces blood cells
– Protects against infections
– Helps repair tissue damage
Connective Tissue
• Contain extracellular matrix
– Consistency varies from fluid to solid
• Most contain good supply of blood vessels
and are well nourished
• May be rigid or flexible
• Contain a variety of cells and fibers
Connective Tissue
• Major Cell Types
– Fibroblasts – most common type of “fixed cell” in
connective tissue
• Produce fibers by secreting proteins into the extracellular
matrix
– Macrophages – originate as white blood cells
• Specialized to carry on phagocytosis
– Mast Cells – release heparin, which prevents blood
clotting and histamine, which promotes reactions
associated with inflammation and allergies
Connective Tissue
• Connective Tissue Fibers
– Collagenous Fibers
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Thick threads of the protein collagen
Flexible but only slightly elastic
Posses great tensile strength
Important components of ligaments and tendons
– Elastic Fibers
• Composed of the protein elastin
• Stretch easily
• Common in areas that are routinely stretched
Connective Tissue
• Connective Tissue Fibers
– Reticular Fibers
• Very thin collagenous fibers
• Highly branched
• Form delicate supporting networks in a variety of
tissues
Connective Tissue
• Loose Connective Tissue
– Areolar Tissue – forms delicate, thin
membranes throughout the body
• Found beneath most layers of epithelium
• Nourishes nearby epithelium cells
Connective Tissue
• Loose Connective Tissue
• Adipose Tissue – (fat) lies beneath the skin, in spaces
b/w muscles, around the kidneys, behind the eyeballs,
in certain abdominal membranes, on the surface of the
heart, and around certain joints
– Cushion joints, insulates and stores energy
Connective Tissue
• Loose Connective Tissue
– Reticular Connective Tissue
• Composed of thin collagenous fibers in a threedimensional network
• Provides framework for the liver and spleen
• Dense Connective Tissue
– Fibers are very strong enabling the tissue to
withstand pulling forces
– Poor blood supply
– Forms parts of tendons and ligaments
Connective Tissue
Dense Connective Tissue
Connective Tissue
• Cartilage
– Rigid connective tissue that provides support,
frameworks, attachments, protects underlying
tissues, and forms structural models for
developing bones
• Chondrocytes – (cartilage cells) occupy small
chambers called lacunae and lie completely with the
extracellular matrix
– Three types of cartilage recognized based on
their extracellular matrix
Connective Tissue
• Cartilage
– Hyaline Cartilage
• Found on the ends of bones in many joints,
in the soft part of the nose, and in the
supporting rings of the respiratory passages
Connective Tissue
• Cartilage
– Elastic Cartilage
• Provides framework for the external
ear and larynx
Connective Tissue
• Cartilage
– Fibrocartilage
• Shock absorber for structures that are subjected to
pressure
• Forms pads b/w discs of the spinal column and
cushions bones of the knee
Connective Tissue
• Bone
– Most rigid connective tissue (CaCO3 CaPO4)
– Supports body structures, protects vital parts of
cranial and thoracic body cavities, and is an
attachment for muscles
– Osteocytes – bone cells embedded in lacunae
– Osteocytes form hollow cylinder-shaped tubes
called osteons within bone tissue
Connective Tissue
• Bone
– Canaliculi – cytoplasmic process that extend
outward and pass through very small tubes in
the extracellular matrix
– Injured bone is thus highly vascularized and
heals more rapidly than injured cartilage
Connective Tissue
Bone
Connective Tissue
• Blood
– Transports a variety of materials b/w interior
body cells and those that exchange substances
with the external environment
– Composed of formed elements suspended in a
extracellular matrix called blood plasma
• Formed elements include RBC’s WBC’s and platelets
– Most blood forms in red marrow within the
hollow parts of long bones
Connective Tissue
Blood
Muscle Tissue
• Skeletal Muscle Tissue
– Found in muscles that attach to bones and is
controlled by conscious effort (voluntary)
– Contain light and dark cross markings called
striations
– Move the head, trunk and limbs
– Enable us to make facial expressions, write,
talk, sing, chew, swallow and breathe
Muscle Tissue
Skeletal Muscle
Muscle Tissue
• Smooth Muscle Tissue
– Involuntary, Do not contain striations
– Comprises the walls of hollow internal organs
• Cardiac Muscle Tissue
– Found only in the heart
– Involuntary, striated
Muscle Tissue
Smooth Muscle Tissue
Muscle Tissue
Cardiac Muscle Tissue
Nervous Tissue
• Found in the brain, spinal cord, and
peripheral nerves
– Neuron – basic nerve cell
• Sense and respond to changes
• Coordinate, regulate and integrate many body
functions
– Neuroglial Cells – support and bind the
components of the nervous tissue, carry on
phagocytosis and help supply nutrients to
neurons by connecting them to blood vessels
Nervous Tissue
Nerve Cell