TISSUES
Tissues
• 4 main types of tissue in body:
– Epithelial
– Connective
– Muscle
– Nervous
Epithelial Tissue
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Covers body and body parts
Lines many parts of body
Cells are packed close together
Form continuous sheets that contain no blood
vessels
Shape of Epithelial Tissue Cells
• Classified according to shape:
– Squamous (flat and scalelike)
– Cuboidal (cube shaped)
– Columnar (higher than they are wide)
– Transitional (varying shapes that can stretch)
Arrangement of Cells
• Can also be categorized
according to arrangement of
cells”
– Simple- single layer of same
shaped cells
– Stratified- many layers of cells
• Named for the shape of cells in
the outer layer
Simple Squamous Epithelium
• Single layer of thin irregular shapes
• Allows for substances to readily pass through
• Function: diffusion of 02 between alveoli and
blood; filtration and osmosis
• Location: Alveoli in lungs
– Lining of blood and
lymph vessels
Example of Simple Squamous
Epithelium
Stratified Squamous Epithelium
• Many layers; outer layer are flattened cells
• Function: specialize in protection
– Protect body against invading microorganisms
• Location: lining of mouth and esophagus,
epidermis
• This is why cracks or cuts in skin can lead to
infection
– The barrier is compromised
Stratified Squamous Epithelium
Simple Columnar Epithelium
• Single layer of tall, narrow cells
– Nucleus located at bottom of each cell
– Goblet cells- open spaces among cells the produce
mucus
• Function: protection, secretion, transportation
and absorption
• Location: lining inner surface of stomach,
intestines, reproductive and respiratory tracts
• See pg. 121 in textbook for figures
Simple Columnar Epithelium
Stratified Transitional Epithelium
• Many layers of varying shapes
• Function: protection, ability to stretch!
– Cell shape can change from cuboidal to sqaumous
when stretched
– Keeps organs from tearing under pressure of
stretching
• Location: walls of bladder
Pseudostratified Epithelium
• Appears multilayered, but isn’t- pseudo (false)
– Each cell is anchored to the basement membrane
• Cilia found at end
– Can move in unision
– Move mucus along trachea to get rid of foreign
particles
• Function: protection
• Location: surface lining of trachea
Very Cool Pic of
Pseudostratified Epithelium
Simple Cuboidal Epithelium
• Single layers of cube shaped cells
• Function: Secretion, absorption
– Form tubules to create glands
• Exocrine- release secretion through a duct
• Endocrine- release secretion directly into bloodstream
• Location: Glands, kidney tubules
Name That Epithelium!
Glandular Epithelia
• Glands secrete aqueous fluids
• Main Types:
– Endocrine – ductless
• Produce hormones
• Secrete directly into bloodstream
– Exocrine – have ducts
• Secrete products onto body surface or
into body cavities
• Ex: mucous, sweat, oil & salivary glands
Introduction to Connective Tissue
• Most abundant and widely distributed in body
• Many varied types
– Thin and web-like to give flexible shape
– Strong, tough cords to give rigid structure to bone
• Found in skin, membranes, muscles, bones,
nerves, organs and blood
• Main function: supporting framework
The Matrix
• Matrix- intercellular material found between
cells
• The structural quality and appearance of the
matrix depends on type of connective tissue
– Ex:
– Matrix of blood is liquid
– Matrix of bone is hard and rigid
–“
“ tendons is strong and flexible
Major Types of Connective Tissues
• Loose Connective
– Areolar
– Adipose
– Reticular
• Dense Connective
– Regular
– Irregular
– Elastic
• Bone
• Cartilage
• Blood
Areolar Tissue
• Most widely distributed of all connective
tissue
• Function: “Glue” that gives form to internal
organs
• Loose arrangement of fibers and cells
• Location: area between organs and other
tissues
Adipose Tissue
• Store lipids (fats)
• Found in areas under skin where fat deposits
can accumulate
• Function: protection, insulation, nutrient
reserve
Reticular
• Similar to areolar but fibers of matrix are
reticular fibers
• Forms delicate network
• Found in spleen & bone marrow
– Act as soft skeleton to support WMC
Dense Regular
• Made of bundles of collagen- strong white
fibers arranged in parallel rows
• Tendons, ligaments are made of this
– Help anchor muscles to bone, bone to bone
• Function: flexible but strong connection
Dense Irregular
• Similar to dense regular but collagen bundles
are thicker & arranged irregularly
• Found in dermis and covering of some organs
– i.e. kidneys, bones, nerves
Elastic Connective Tissue
• Extremely elastic dense irregular tissue
– Allows for extreme elastic recoil
• Found in vertebrae & aorta
Bone
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Hard, calcified matrix
Made of osteons- structural building blocks
Circular arrangement of calcified matrix
Storage area for calcium
Function: Support and protection
Cartilage
• Hard, flexible matrix
• Chondrocytes- cartilage cells
– Found in tiny spaces throughout matrix
• Function: Firm, flexible support
• Found in nose, ears, vertebral disks, surfaces
of bones
Blood
• Liquid matrix containing red and white blood
cells
• Found in blood vessels
• Function: transportation
Hematopoietic Tissue
• Liquid matrix with dense arrangement of
blood cell producing cells
• Found in red bone marrow
• Function: make new blood cells
Name that Connective Tissue!
Introduction to Muscle Tissue
• Movement specialists of body
• Ability to contract and expand more than any
other tissue
• Can be slow healing
– Scar tissue can form instead
• 3 main types:
– Skeletal
– Cardiac
– Smooth
Skeletal Muscle Tissue
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Striated
Voluntary- controlled by will
Has many cross striations
Many nuclei per cell
Attached to bone to cause movement when
contracted
Cardiac Muscle Tissue
• Striated
– Faint cross striations
• Involuntary- contract without conscience
effort
– Heart beat
• Muscle fibers branch to form interlocking
mass of contracting tissue
Smooth Muscle Tissue
• Not striated
– Long smooth shape
– Only 1 nucleus per cell
• Involuntary
• Form walls of blood vessels and organs in
digestive tract
• Also found in eye, arrector muscles on hairs
Nervous Tissue
• Function: rapid communication between body
structures and control of body functions
• Consists of 2 types of cells:
– Neurons- functional units of the system
– Glia- connecting and supporting cells
Nerve Cell Shape
• Cell body – main part of neuron
• Axon- long and slender, transmits a nerve
impulse
• Dendrites- branching part that transmits
impulses
Covering and Lining Membranes
• Cutaneaous- skin
– Keratinized stratified squamous epithelium attached
to dense irregular connective tissue
• Mucous- line body cavities that open to exterior
– ‘Wet’ membranes→bathed by mucous
– GI, respiratory, urogenital tracts
• Serous- Moist membranes that line cavities in
closed ventral cavity
– Secrete serous fluid that lubricates
– Ex: pleura, pericardium, peritoneum
3 Types of Epithelial Tissue
Membranes
• Cutaneous
• Sereous
• Mucous
Mucocutaneous Junction
• Transitional area where skin and mucous membrane
meet
• Lack accessory organs such as hair or sweat glands
• Moistened by mucous glands within body orifices
• Examples: eyelids, nasal openings and anus
– Can become sites of infection or irritation
Name that Membrane!
Tearin’ Tissue
• Tissues eventually get damaged and injured
• They are usually replaced by scars
• Epithelial and connective tissues regenerate
the best
– If cut, cells quickly divided to form new daughter
cells that fill the wound
Tearin’ Tissue
• Muscle tissues has harder time healing
– Fibrous tissue usually replaces damaged
tissue
– Can cause organs to lose ability to function
– Heart
• Nerve tissue also has limited ability to
regenerate
– Neurons outside brain and in spinal cord
can sometimes regenerate slowly
– In normal adult brain once neuron is
damaged it will not grow back
Process of Tissue Repair
• Phagocytes eat dead or injured cells
• Gaps are filled in by regeneration- new tissue
growth
• Collagen fibers form dense mass to cover injury
• If small injury this will be replaced by normal
tissue later
• If large area of damage the dense fiber remains
as a scar
– Fibrosis-proliferation of fibrous tissue resulting in scar
tissue