Download Connective Tissue

Ch. 3b
TISSUES
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Tissues
• There are four types of tissue in the body
• Epithelial tissue
• Connective tissue
• Muscle tissue
• Nerve tissue
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General Characteristics of Epithelial Tissue
1. Cells have: Polarity— apical (unattached/
free) and basal (attached) surfaces
•
Apical surfaces: May bear microvilli /cilia
•
Basal surface: Supported by a basement
membrane
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Characteristics of Epithelial Tissue
2. Composed of closely packed cells
3. Avascular
4. High rate of regeneration
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Apical surface
Basal surface
Simple
Apical surface
Basal surface
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Stratified
Figure 4.2a
Classification of Epithelia
•
Ask two questions:
1. How many cell layers?
1 = simple epithelium
>1 = stratified epithelium
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Classification of Epithelia
2. What type of cell?
•
Squamous = flat
•
Cuboidal
•
Columnar
•
# of cell layers followed by cell shape =
epithelial classification
•
If E.T. is stratified, name according to the top
layers of cells
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(Simple squamous epithelium
Description:
•Single layer of flat cells
Function:
•Diffusion & Filtration
Location:
•Air sacs of lungs
•Lining of ventral body
cavity
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Figure 4.3a
( Simple Cuboidal epithelium
Description: Single layer
of cubelike cells
Function: Secretion and
absorption.
Location: Glands and
ducts
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(Simple Columnar epithelium
Description: Single
layer of tall cells
•May have goblet cells
Function:
Absorption and
secretion
Location: Lines most
of digestive tract
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Pseudostratified Ciliated Columnar epithelium
Description: Single layer
of cells of differing heights
on same basement
membrane;
• May have goblet cells
Function: Secretion,
propulsion of mucus by
ciliary action.
Location: upper
respiratory tract.
Trachea
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Stratified squamous epithelium
Description: Thick, surface
cells squamous
•Two types:
• Non-Keratinized: alive
• Keratinized: surface cells
dead & full of keratin
Function: Protection in
areas subjected to abrasion.
Location: Nonkeratinized:
Lines cavities which open to
exterior
•Keratinized: forms epidermis
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Transitional epithelium
Description: Basal cells
cuboidal/columnar
•Surface cells dome shaped
or squamous (depends on
degree of stretch)
Function: Stretches readily
Location: Lines hollow
urinary organs
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Figure 4.3f
Characteristics of Connective Tissue
• Connective Tissues are the most abundant
and widely distributed tissue type
• C.T. has varying degrees of vascularity
• C.T. has cells separated by nonliving
extracellular matrix (ground substance and
fibers)
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Components of Extracellular Matrix
• Ground substance
• Interstitial fluid, Adhesion proteins (“glue”),
• Large polysaccharides
• Three Types of Fibers can be found within the ground
substance:
• Collagen
• Strongest, most abundant type; Provides tensile strength; form
thick cables
• Elastic
• Long, thin, fibers; allow for stretch
• Reticular
• Short, fine, branched fibers that form an internal network (mesh)
that is supportive to other cells
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Cells of Connective Tissue
• Cell Types
• “blasts” = Mitotically active and secretory cells
• “cytes” = Mature cells
• Fibroblasts in connective tissue proper
• Chondroblasts and chondrocytes in cartilage
• Osteoblasts and osteocytes in bone
• Hematopoietic stem cells in bone marrow
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Osseous tissue
Description: Hard, calcified
matrix; osteocytes in lacunae;
Function: Support, protection,
attachment site for muscles.
Location: Bones
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Central
canal
Lacunae
Lamella
Figure 4.8j
Connective Tissue: Cartilage
• Three types of cartilage:
• Hyaline cartilage
• Elastic cartilage
• Fibrocartilage
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Cartilage: Hyaline
Description: most abundant of
cartilage types;less hard and
more flexible than bone;
Chondrocytes in lacunae.
Function: Supports,cushions,
resists compressive stress.
Location: Forms most of
embryonic skeleton; articular
cartilage; cartilages of nose,
trachea, larynx.
Chondrocyte
in lacuna
Matrix
Costal
cartilages
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Cartilage: Elastic
Function: Also allows
great flexibility.
Location: Ear, epiglottis.
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Chondrocyte
in lacuna
Matrix
Cartilage: Fibrocartilage
Location: Intervertebral
discs
Intervertebral
discs
Chondrocytes
in lacunae
Collagen
fiber
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Connective tissue proper: Dense regular connective tissue
Description: Parallel
collagen fibers
Function: Withstands tensile
stress when pulling force is
applied in one direction.
Collagen
fibers
Location: Tendons, most
ligaments
Nuclei of
fibroblasts
Shoulder
joint
Ligament
Tendon
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Connective tissue proper: Dense irregular connective tissue
Description: Irregularly
arranged collagen fibers
Function: Withstands
tension exerted in many
directions
Location: Fibrous capsules
of organs ,joints; dermis of
skin
Fibrous
joint
capsule
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Nuclei of
fibroblasts
Collagen
fibers
Connective tissue proper: Areolar connective tissue
Description: Most widely
distributed variety of CT
•Soft, pliable, like cobwebs
Function: Wraps and cushions
organs
Location: Under epithelia of body,
universal packaging material
Epithelium
Lamina
propria
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Elastic
fibers
Collagen
fibers
Fibroblast
nuclei
Connective tissue proper: Adipose connective tissue
Description: Closely packed
adipocytes
Function: Reserve fuel
insulation; supports & protects
organs.
Nucleus of
fat cell
Location: Hypodermis; around
kidneys and eyeballs; in
abdomen; breasts.
Adipose
tissue
Mammary
glands
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Vacuole
containing
fat droplet
Connective tissue proper: Reticular connective tissue
Description: Network
of reticular fibers
Function: Fibers form a
soft internal skeleton that
supports other cells
Location: Lymphoid organs
(lymph nodes, bone marrow,
and spleen).
White blood
cell
(lymphocyte)
Reticular
fibers
Spleen
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Others: blood
Description: Red and white
blood cells in a fluid matrix
(plasma).
Plasma
Function: Transport of
respiratory gases, nutrients,
wastes, and other substances.
Location: Contained within
blood vessels.
Neutrophil
Red blood
cells
Lymphocyte
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MUSCLE TISSUE
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(a) Skeletal muscle
Description: Long, cylindrical,
multinucleate cells; obvious
striations.
Striations
Function: Voluntary
movement
Nuclei
Location: Skeletal muscles
attached to bones or
occasionally to skin.
Part of
muscle
fiber (cell)
Photomicrograph: (approx. 460x).
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(b) Cardiac muscle
Description: Branching,
striated, Have intercalated
discs.
Striations
Intercalated
discs
Function: Propel blood into
circulation; involuntary
control.
Location: Walls of the heart.
Nucleus
Photomicrograph: (500X);
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(c) Smooth muscle
Description: Spindle-shaped
Cells; no striations; cells form
sheets.
Function: Propels substances
or objects; involuntary control.
Smooth
muscle
cell
Location: Mostly in walls
of hollow organs.
Nuclei
Photomicrograph: Sheet of smooth muscle (200x).
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NERVOUS TISSUE
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Nervous tissue
Description: Neurons w/ cell
processes that extend from the
cell body; Contains supporting
cells
Nuclei of
supporting
cells
Neuron processes Cell body
Axon
Dendrites
Cell body
of a neuron
Function: Transmit electrical
signals from sensory receptors
to effectors.
Location: Brain, spinal
cord, and nerves.
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Neuron
processes
Steps in Wound Repair
• Inflammation
• Increased blood flow with healing components &
clotting factors to damaged area (redness, swelling,
pain, heat) due to the release of inflammatory
chemicals
• Clot forms and exposed portion forms scab
• Organization and restored blood supply
• Granulation tissue forms=new capillaries and
phagocytes and fibroblasts
• Regeneration and fibrosis
• Surface ET regenerates, scab detaches, underlying
scar tissue
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Scab
Epidermis
Blood clot in
incised wound
Inflammatory
chemicals
Migrating white
blood cell
Artery
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Regenerating
epithelium
Area of
granulation
tissue
ingrowth
Fibroblast
Macrophage
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Regenerated
epithelium
Fibrosed
area
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