Transcript Chapter 3

Chapter 3
Body Tissues
Body Tissues
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Human body starts out as one cell
Cell division occurs to create millions of cells
Cellular Specialization results
Anytime you have a group of cells working
together for the same purpose TISSUES result.
Four Main Tissue Types
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2.
3.
4.
Connective- Support
Nervous- Control
Muscle- Movement
Epithelium- Covering
Tissues
• Most organs are composed of several tissue
types.
• The Type of tissue will determine the function
of the organ.
Epithelial Tissue
• The lining, covering, and glandular tissue of
the body.
• Covers all free body surfaces and contains
versatile cells.
• Nearly all substances given off or received by
the body must pass through the epithelium.
Epithelial Functions
1. Protection
2. Absorption
3. Filtration
4. Secretion
Examples: Epithelium of the skin-protects
against bacterial and chemical damage.
-Epithelium that lines the digestive tract absorbs
food into the body.
Characteristics of Epithelium
• Cells fit closely together and form continuous
sheets.
• The membranes always have one free
(unattached) surface or edge. This Apical
Surface is exposed to the body’s exterior or
tot eh cavity of an internal organ
Characteristics Cont.
• The lower surface rest on a basement
membrane
• Epithelial tissues have no blood supply of their
own(avascular) and depend on diffusion from
capillaries to provide oxygen and food.
• If well nourished, epithelial cells will
regenerate easily.
Classification of Epithelium
• Given two names: the 1st= number of cell
layers, 2nd= shape of the cells
Number of cells
1) Simple= one layer of cells
2) Stratified= more than one cell layer
Classification Cont.
Shapes of Cells
1. Squamous- flattened like fish scales
2. Cuboidal- cube shaped like dice
3. Columnar- cells shaped like columns
* The terms describing the shape and the
arrangement are then combined to describe
the epithelium completely.
Simple Epithelia
• The simple epithelia are most concerned with;
-absorption
- secretion
- filtration
**because they are thin protection is not a
function**
Simple Squamous Epithelium
• A single layer of thin squamous cells.
• Cells fit closely together
• Forms membranes where filtration or
exchange of substances by rapid diffusion
occurs.
• Found in the following areas:
-air sacs of the lungs, forms walls of
capillaries, forms serous membranes
Simple Cuboidal Epithelium
• One layer of cuboidal cells
• Forms:
- glands and their ducts(salivary glands and
the pancreas), walls of kidney tubules, covers
the surface of the ovaries,
Simple Columnar Epithelium
• Made up of a single layer of tall cells that fit
closely together.
• Forms;
- Goblet Cells(produce lubricating mucus),
lines the entire length of the digestive system
Pseudostratified Columnar Epithelium
• Pseudo=false or fake
• The appearance of the cells arrangement
leads to the look of multiple layers when in
fact there is only one.
• Function; absorption and secretion
• Ciliated version lines the respiratory tract,
goblet cells produce mucus to trap dust and
debris while the cilia push the mucus away
from the lungs
Stratified Epithelium
• Consists of two or more cell layers
• Considerably more durable then simple
epithelia
• Functions to Protect
Stratified Squamous Epithelium
• Most common stratified epithelium in the
body.
• Consists of several layers
• Found in sites that receive a good amount of
abuse or friction like the esophagus, the
mouth, and the outer portion of the skin
Stratified Cuboidal Epithelium
• Two layers with the cells being cuboidal in
shape
• Very rare along with stratified columnar
epithelium
Stratified Columnar Epithelium
• Very rare found only in the ducts of large
glands
Transitional Epithelium
• Highly modified, stratified squamous
epithelium that forms the lining of only a few
organs- the urinary bladder, the ureters, and
the urethra.
• All of these organs are a part of the urinary
system and subject to considerable stretching.
• The ability of transitional cells to slide past
one another and to change shape allows for
the urinary system to function properly
Glandular Epithelium
• A gland consists of one or more cells that
make and secrete a particular product.
• This product is called an secretion.
• Two major types of glands are formed from
epithelial sheets.
1. Endocrine Glands
2. Exocrine Glands
Endocrine Glands
• Lose their connection to the duct
• Their secretions(all hormones) diffuse directly
onto the blood vessels that weave through the
gland.
• Examples include; thyroid, adrenals, and
pituitary
Exocrine Glands
• Retain their ducts
• Secretions empty through the ducts to the
epithelial surface
• Include; sweat and oil glands, liver and
pancreas
Connective Tissue
• Connects body parts
• Found everywhere in the body
• It is the most abundant and widely distributed
of the tissue types.
Common Characteristics of Connective
Tissue
• Variations in blood supply (well vascularized)
Exceptions: tendons and ligaments poor
blood supply, cartilages are avascular.
• Extracellular Matrix-made up of many types of
cells and a non-living substance found outside
those cells
Extracellular Matrix
• Makes connective tissue different then all
other tissues.
• The matrix is produced by the connective
tissue cells and secreted to there exterior.
• Matrix may be liquid, semi-solid, gel-like, or
very hard
Extracellular Matrix
• Because of the matrix, connective tissue can
bear weight, withstand stretching, and other
abuses that no other tissue could withstand.
• One extreme-fat with lots of cells and a soft
matrix
• Another extreme-bone with few cells and hard
matrix
Extracellular Matrix
• Various types and amounts of fibers are
deposited in and form a part of the matrix.
– Examples: Collagen Fibers ( white)
– Elastic Fibers (yellow)
– Reticular Fibers ( Fine collagen)
Connective Tissue Functions
• Protecting, Supporting, and Binding together
other body tissues.
Types of Connective Tissues
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Bone
Cartilage (3)
Dense connective tissue (2)
Loose connective tissue (2)
Adipose tissue
Reticular connective tissue
Blood
Muscle Tissue
• Highly specialized to CONTRACT AND
SHORTEN.
Types of Muscle Tissue
• Skeletal Muscle
• Cardiac Muscle
• Smooth Muscle
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
Nervous Tissue
• Composed of cells called neurons
• All neurons receive and conduct
electrochemical impulses from one part of the
body to another
Nervous Tissue Function
• Irritability and conductivity are two major
functions of nervous tissue.
Neuron Structure
• Very unique
• Cytoplasm stretches out into long extensions
that can carry impulses over large areas in the
body.
• Work with a group of supporting cells that:
– Insulate
– Support
– Protect the delicate structures of the neurons
Tissue Repair
• The body has many protective features put
into place to help prevent damage or injury.
• When injury does occur, it stimulates the
body’s inflammatory and immune responses
and the healing immediately begins.
Inflammation
• A nonspecific response to try and prevent
further injury.
Immune Response
• An extremely specific response that mounts a
vigorous attack against a recognized invader.
2 Major Ways That Tissue Repair
Occurs
1. Regeneration-the replacement of destroyed
tissue by the same kind of cell
2. Fibrosis- repair by dense connective tissue or
the formation of scar tissue
Tissue Repair
• The type of tissue repair depends on:
1. The type of tissue damaged
2. The severity of the injury
**Clean cuts(incisions) heal more quickly than
ragged tears(lacerations).
Tissue Injury Events
1. Capillaries become very permeable which
allows fluids rich in clotting proteins to seep
into the injured area.
2. A clot is constructed which stops the
bleeding and holds the edges of the wound
together.
Events
3. Clot walls off the injured area preventing
bacteria and other harmful substances from
getting into the tissue.
4. The clot that is exposed to air will dry and
form a scab.
5. Granulation Tissue Forms
Events
6. Granulation tissue is a delicate pink tissue
composed largely of capillaries that grow into
the damaged area from surrounding healthy
blood vessels.
7. The clot is disposed of and the connective
tissue synthesizes collagen fibers(scar tissue)
to form
Events
8. Surface epithelium begins to regenerate.
9. Surface epithelium will cover the scar.
**the ability for different tissues to regenerate
varies widely**
Regeneration
• Easily: skin epidermis and mucous
membranes, fibrous connective tissue, and
bone
• Poorly: skeletal muscle
• Not at all: cardiac muscle and nervous tissuereplaced only by scar tissue
Developmental Aspects of Cells and
Tissues
Developmental
• Neoplasm- an abnormal mass of proliferating
cells .
– Benign
– Malignant
Developmental
• Hyperplasia-occurs when certain body tissues
enlarge because there is some local irritant or
condition that stimulates cells
Developmental
• Atrophy-decrease in size- can occur in a
certain organ or body area that loses its
normal stimulation