Download Anatomy Chapter 3

Anatomy Chapter 3
Part II: Body Tissues
Part II: Body Tissues
• The human body starts out as a single cell, a fertilized egg,
then divides repeatedly.
• There is a division of labor in the body (cell differentiation), as certain groups
of specialized cells perform functions that benefit the organism as a whole.
• Specialization carries hazards – small groups of cells become indispensible,
loss could disable or destroy the body (heart, brain).
• Groups of cells with similar structure and function makeup tissues.
• Four primary tissue types: epithelium (covering), connective (support),
nervous (control), and muscle (movement).
• Most organs contain several tissue types; arrangement determines the organs
structure and function.
I. Epithelial tissue
Epithelial tissue or epithelium – lining,
covering, and glandular tissue
 Covering and lining epithelium cover all free body surfaces,
lines body cavities, forms boundaries from outside; nearly
all substances given off or received must pass through
epithelium (bacteria)
 Epithelial functions include protection, absorption,
filtration, and secretion
 Glandular epithelium forms various glands in the body
(perspiration, oil, digestive enzymes, mucus)
Special characteristics:
 Apical surface – free surface or edge
 Basement membrane – lower surface, epithelium rests on
 Avascular – no blood supply: diffusion
Classification of Epithelium:
 Simple epithelia – one layer thick; absorption,
secretion, filtration
Simple squamous
epithelium:
rapid diffusion
Air sacs
Walls of capillaries
Basale layer of skin
 Simple cuboidal epithelia – glands and their ducts
Salivary glands
Pancreas
Kidney tubules
Surface of ovaries
 Simple columnar epithelia – single layer of tall cells that fit closely
together. Mucous membranes or mucosa if lining opens to the outside of
the body.
Lining of digestive
tract and
Respiratory tract
Pseudostratified
columnar epithelia–
nuclei appear at
different heights above
basement membrane,
giving a false stratified
look.
Tissue lines the respiratory
tract. Mucous is produced
by Goblet cells to trap dust
and debris, cilia propel
upward and out from the
lungs.
• Stratified epithelia – consists of two or more cell layers, durable, function
primarily to protect.
Stratified squamous epithelium – most common
stratified epithelium; several layers of cells; found at
sites that receive abuse or friction: skin.
Transitional epithelia – modified to line a few organs; urinary bladder,
ureters, part of urethra. Subject to considerable stretching.
Classification of Connective Tissue
 Connective tissue connects body parts – found every where in the body;
most abundant and widely distributed of tissue types; function in
protection, supporting, binding together body tissues
 Most are vascularized – have a good blood supply; tendons and ligaments have poor
blood supply and cartilage is avascular causing these tissue to heal very slowly when
injured
 Extracellular matrix – outside the cell, produced by the cells and secreted; structureless
ground substance (water, adhesion proteins {glue}, large charged polysaccharide
molecules {trap water – reservoir} and fibers (collagen {white}, elastic {yellow}, reticular
fibers
 Forms soft packing tissue around organs, bear weight, withstand
stretching and other abuses (abrasions)
Bone – osseous tissue; cavities called lacunae are
surrounded by a hard matrix; protect and support
Cartilage – less hard, more flexible, found in few places in the body; most
abundant is hyaline cartilage
Hyaline cartilage – larynx (voice box),
attach ribs to breastbone, covers ends of
bones that form joints, makes up fetal
skeleton
Fibrocartilage – cushion disks between
vertebrae of spinal column
Elastic cartilage – supports external ear
Dense connective tissue – collagen fibers are main matrix; form strong,
ropelike structures such as tendons (attach skeletal muscles to bones) and
ligaments (connect bones to bones at joints); makes up lower layers of skin (dermis)
arranged in sheets
Loose connective tissue – softer, have more cells, fewer fibers
Areolar tissue – most widely distributed connective tissue, soft pliable; cushions and protects
organs; universal packing tissue – helps hold internal organs together. Reservoir of water and salts
for surrounding tissue.
Edema – areolar tissue soaks up
excess fluid and area swells and
becomes puffy; phagocytes enter
swollen area.
Adipose tissue – fat, droplet of stored oil
occupies most of fat cell’s volume; forms
subcutaneous tissue beneath skin, insulates body,
protects it from extremes of heat and cold; protects
some organs; fat deposits in hips, breasts; stored
fuel
Blood or vascular tissue – considered connective tissue because it consists of blood
cells, surrounded by nonliving, fluid matrix called blood plasma
Blood is atypical. Blood
is a transport vehicle for
the cardiovascular
system, carrying
nutrients, wastes, and
other substances
Muscle Tissue
• Tissues highly
specialized to
contract, or
shorten, to
produce
movement. Three
types of muscle
tissue: skeletal,
cardiac, and
smooth muscle.
Skeletal muscle tissue – attached to skeleton, controlled voluntarily, form
flesh of the body, called the muscular system. Cells are long, cylindrical,
multinucleate, with obvious striations (stripes). Cells often called muscle fibers.
Cardiac muscle tissue– found only in the heart; contracts to propel blood through the
blood vessels. Has striations, is uninucleate, relatively short, branching cells fit tightly
together at junctions called intercalated disks. Involuntary control.
Smooth muscle tissue – no striations, single nucleus, spindle-shaped. Found in
walls of hollow organs (stomach, bladder, uterus, blood vessels). Can enlarge or
contract cavity of organ as things are propelled through a specific pathway.
Involuntary.
Peristalsis – wavelike motion that keeps food moving through digestive tract.
Nervous Tissue
Neurons – receive and conduct electrochemical impulses from one part of the
body to another. Two major functional characteristics: irritability and conductivity.
Axons are long processes of the cell that conduct impulses over long distances in
the body. Supporting cells insulate, support, and protect neurons.
Brain
Spinal cord
Nerves
Tissue Repair
 Tissue injury stimulates body’s inflammatory and immune response and
the healing process begins.
 Repair occurs in two major ways:
 Regeneration – replacement of destroyed tissue by the same kind of cells
 Fibrosis – repair by dense connective tissue, by formation of scar tissue
 Injury sets series of events into motion:
 The capillaries become very permeable
 Granulation tissue forms
 The surface epithelium regenerates
 Regeneration differs in tissue type: epithelial tissue and mucous membranes
regenerate easily; as do fibrous connective tissue and bone; skeletal tissue
regenerates poorly if at all, cardiac and nervous tissue is replaced largely by scar
tissue.
Developmental Aspects of Cells and Tissues
 Cell division is critical during growth periods
 Amitotic cells have become handicapped by injury and cannot be replaced
by the same type of cells (heart muscle – myocardial infarction)
 Neoplasm is a failure of cells to follow the normal controls of cell division;
causes tumors.
 Benign tumors are usually not harmful, not invasive
 Malignant tumors are cancerous, invasive, tissue destroying
 Hyperplasia is the result of certain body tissues (organs) enlarging
because of a local irritant or condition that stimulates cells
 Atrophy is a decrease in size or an organ of body area that loses its normal
stimulation (sessile people – couch potatoes, aged people)