Tissues
 Tissue: Group of cells with the same function. Types of tissue:
Epithelial, connective, muscle and nervous
 Cells vary in size, arrangement, shape and function but those of a
tissue are similar.
 Classification of tissue is done by 2 general characteristics
 Arrangement of cells
 One layer of cells is called simple
 More than one layer is called stratified
 2.. Type of cells: squamous, cuboidal. and columnar
 Squamous: looks like a fried egg, or fish scale, unicellular
 Cuboidal: looks like a dice, unicellular
 Columnar: looks like a column on a basement membrane
Epithelial Tissue
 Epithelial tissue functions:
 Cover organs
 Forms inner lining of body cavities
 Lines hollow organs
 The underside of tissue is anchored to connective tissue by a
basement membrane.
 Generally, they lack of blood vessels.
 The cells are going through mitosis constantly because skin and
cells of stomach are constantly being damaged
 The cells are tightly packaged, with little intercellular material
 Desmosomes sometimes attach cells in this tissue
Types of Epithelial Tissue
 The types of epithelial tissue are classified according to cell shape
and layers.
 Simple Cuboidal Epithelium.
 They have a central located nucleus
 Covers ovaries and kidney tubules
 Simple Columnar Epithelium;
 Single layer of elongated cells with nucleus close to the basement.
 They can be ciliated or non ciliated.
 They can move the egg of the female ovaries
 Specialized for absorption
 Gladular cells that are called goblet cells, secrete protective mucous
 Simple Squamous Epithelium:
 Single layer of thin, flattened cells and fit tightly together.
 Substances pass easily
 Characteristic of alveolis and kidneys
Types of Epithelial Tissues
 Pseudostratified Columnar Epithelium;
 Columnar epithelium that appears stratified but it is not,
appears stratified because cell nucleus is located at different
positions.
 The cells are generally ciliated
 The cells secreat mucous
 Lines the passages of respiratory system
Types of Epithelium
 Stratified Squamous Epithelium:
 Contain many layers making the tissue thick
 Cells nearest surface are flattened, deeper layers where cell division occurs
are cuboidal or columnar.
 Newest cells, push old one upper.
 Older cells accumulate keratin, protective rough material .
 Lines oral cavities, throat, esophagus, vagina…
 Stratified Cuboidal Epithelium:
 Two or three layers of cuboidal cells
 Lining of lumen
 Located in sweat glands, salivary glands, mammary glands and pancreas.
 Stratified Columnar Epithelium:
 Several layers of cells
 The superficial cells are elongated, whereas the basal layers a cube shaped.
 Located in vans deferens, urethra and pharynx
Types of Epithelial Cells
 Gladular Epithelium:
 Composed of cells that secrete substances in body or outside body.
 Cells are found within columnar or cuboidal epithelium and one or
more cells constitute a gland.
 Two types of glands:






Exocrine: Glands that secrete their products into ducts, onto some
internal or external surface
Endocrine: Glands that secrete their products into tissue fluid or blood.
A simple gland (single epithelial cell) communicates with surface by
unbranched duct
A compound gland (multicellular gland) communicates by branched ducts
Tubular glands have epithelial lined tubes
Alveolar glands have saclike dilatation tubes
Epithelial Tissue Glands
 Exocrine glands are also classified according to the ways they
secrete their products:
 Merocrine glands: release products by exocytosis
 Serous cells: high concentration of enzymes
 Mucous cells: thicker fluid mucus, rich in mucin (glycoprotein)
 Apocrine glands: Lose small portions of glandular cells bodies
 Holocrine glands: release entire body
Epithelial Tissue- Transitional
 Specialized to change in response to pressure.
 Inner part of urinary bladder
 Several layers of cuboidal cells.
Connective Tissue
 Much of body weight.
 Most abundant
 Provide support and protection and framework
 Fill spaces, store fat, produce blood cells, prevent against diseases





and help to repair tissue damage.
The cells are farther apart than epithelial cells.
They have abundant intercellular material or matrix.
This matrix consist of fibers or ground substances that varies from
solid to semiliqid.
Cells can divide
Vascular
Types of Connective Cells
 Fixed cells- they are present in stable numbers (present in
stable numbers)
 Fibroblasts- large and star shaped, produce fibers by secreting
fibrin
 Wandering cells- they appear in tissues temporarily(
macrophages)
 Macrophages or histiocytes, they are white cells, specialized in
phagocytosis, clear blood from pathogens
 Mast cells –widely distributed, located near blood vessels and
release heparin and histamine.(inflammation)
Connective Tissue Fibers
 Collagenous Fibers: thick threads of protein collagen, major
structural protein in the body. They are long, parallel
bundles, they are flexible but partially elastic, lots of tensil
strength. Hold structures together(ligaments)
Elastin Fibers: Bundles of microfibrils embedded in a protein
called elastin, weaker than collagen but very elastic, branched
in networks.
 Reticular Fibers: thin collagenous fibers, highly branched,
they form supporting networks.
Types of Connective Tissue
 Two categories:
 Connective tissue proper includes loosed connective tissue,
adipose tissue , reticular tissue, dense connective tissue and
elastic connective tissue
 Specialized Connective tissue: includes cartilage, bone and
blood
Types of Connective Tissue
 Loose Connective Tissue or Areolar Tissue
 Delicate thin membranes throughout the body.
 Cells are mainly fibroblasts, separated by gel like ground
substance with lots of collagen.
 Adipose Tissue or fat.
 Store fat in droplets within connective tissue, at first they
resemble fibroblasts, they enlarge when they accumulate fat,
and push their nuclei to a side.
 This tissue lies beneath the skin, in spaces between muscles,
around kidneys, behind eyes and in abdominal membranes,
around joints and in the surface of heart.
Types of Connective Tissue
 Dense Connective Tissue: many closely packed, thick, collagenous
fibers, fine network of elastic fibers, and a few cells mostly
fibroblasts. Subclasses are regular or irregular, according to
organization.
 Fibers of regular dense connective tissue are very strong, and binds
together, poor blood supply, slow tissue repair (ligament)
 Fibers of irregular dense connective tissue are thicker, interwoven and
more randomly organized.Found in dermis, inside layers.
 Elastic Connective Tissue: Consist of yellow, elastic fibers in
parallel strands or in branching networks. Collagenous fibers and
fibroblasts. Attachments of vertebrae, lining of arteries.
Cartilage
 Cartilage is a rigid connective tissue.
 Provides support, framework, attachments and protects underlying






tissues, and forms structural models for developing bones.
Cartilage matrix is abundant and composed of collagenous fibers
embedded in gel like ground substance.
Ground substance is rich in protein-polysaccharide substance and
contains a large amount of water.
Cartilage cells or chondrocytes occupy small chambers called lacunae
and lie completely in matrix
Connective tissue is covered by perichondrium, a cartilaginous
structure.
Lack of blood supply
Get nutrients by diffusion aided by water in matrix
Types of Cartilage
 Three types of cartilage distinguished by the type of intercellular
material
 Fibrocartilage:
 Contains many large collagen fibers in matrix
 Tough tissue, shock absorber for structures subject to pressure
 Found in pads of intervertebral discs, cushion knee and pelvic girdle.
 Elastic Cartilage:
 Contains dense network of collagen fibers in matrix
 Flexibel because contains elastic fibers
 Found in ears and larynx
 Hyaline cartilage;
 it has fine collagen fibers in matrix
 Most common
 Looks like white glass
 Found in bones, nose in embryos skeleton.
Bone
 It is the most rigid connective tissue
 Its hardness is due to mineral salts, such calcium phosphate






and calcium carbonate in its matrix
The intercellular material contains a large amount of
collagen.
Internally supports structures, and protects cranial and
thoracic cavities
Attachment for muscles
Contains red bone marrow
Stores and releases inorganic salts
Bone matrix is deposited by bone cell, osteocytes.
Bone
 Bone matrix is deposited by osteocytes in thin layers called lamellae,






which form concentric patterns around capillaries.
These capillaries are located in longitudinal tubes called central, or
Harvesian canals.
Osteocytes are located in lacunae in the lamellae, and also form
concentric circles.
The osteocytes and layers of intercellular materials are around a central
canal called osteon or Harvesian system.
Each central canal contains a blood vessel, cytoplasmic processes that
extend outward and pass through minute tubes in the matrix called
canaliculi.
Gap junctions attach these cellular processes.
Materials move rapidly between blood vessels, injured bone heals faster
than injured cartilage.
Blood
 It is a connective tissue which cells are suspended in a gluid






intercellular matrix called plasma.
These cells include, white cells, red cells, and cellular fragments
called plasma.
Red blood cells transport gases
White blood cells fight infections
Platelets are involved in blood clotting.
Most blood cells form in special tissues in red marrow in the
hollow parts of bones.
Only red blood cells function within blood vessels, white blood
cells migrate from blood to capillary walls and reside in there until
they die.
Muscle Tissue
 The cells are called muscle fibers because they are elongated.
 Cells are contractile, they can shorten and thicken.
 Three types: skeletal, smooth and cardiac
 Skeletal:
 Attach bones
 Conscious- voluntary
 Long cells
 Striated
 Multinucleated
 Move head, trunk, facial expressions…
Types of Muscle Tissue
 Cardiac Muscle
 Involuntary
 Striated
 The cells are intercalated by special intercellular junction
(intercalated discs) only in cardiac muscle
 Found in heart.
 Smooth Muscle Tissue





No striations
Involuntary
Shorter than skeletal, spindle shaped
Mononuclei
Found in stomach, intestines, bladder, uterus, blood vessels.
Nervous Tissue
 Its cells are called neurons
 Found in brain, spinal cord and peripheral nerves.
 The neurons are highly specialized
 The neurons cordianate, regulate and integrate body
functions.
 Neuroglial cells or supporting cells , carry on phagocytosis
and help supply blood vessels.
Types of Membranes
 Two or more types of tissues together and performing the same
function is called organ.
 Epithelial membranes are thin, sheetlike structures that are
composed of epithelial and underlying connective tissue and
covers body surface and lining cavities.
 There major types
 Synovial: composed of connective tissue
 Serous membranes: line up cavities that lack openings to the outside
and reduce friction. Composed of one simple squamous layer and
one cuboidal layer. They produce serous fluid. Line thorax and
abdomen
 Mucous membranes: line cavities and open to the outside of
body.One epithelium layer over a layer of connective tissue. Line
respiratory, urinary and reproductive system.