Transcript 1 Lec 4 Tissues V9

CHAPTER
4
Tissue: The
Living Fabric:
© Annie Leibovitz/Contact Press Images
© 2013 Pearson Education, Inc.
Types of Primary Tissues
• Epithelial tissue
– Covers
• Connective tissue
– Supports
• Muscle tissue
– Produces movement
• Nerve tissue
– Controls
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Figure 4.1 Overview of four basic tissue types: epithelial, connective, muscle, and nervous tissues.
Nervous tissue: Internal communication
• Brain
• Spinal cord
• Nerves
Muscle tissue: Contracts to cause movement
• Muscles attached to bones (skeletal)
• Muscles of heart (cardiac)
• Muscles of walls of hollow organs (smooth)
Epithelial tissue: Forms boundaries between different
environments, protects, secretes, absorbs, filters
• Lining of digestive tract organs and other hollow
organs
• Skin surface (epidermis)
Connective tissue: Supports, protects, binds
other tissues together
• Bones
• Tendons
• Fat and other soft padding tissue
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Epithelial Tissue (Epithelium)
• Form boundaries
• Two main types (by location)
– Covering and lining epithelia
• On external and internal surfaces
– Glandular epithelia
• Secretory tissue in glands
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Characteristics of Epithelial Tissue
1. Cells have polarity—apical (upper, free)
and basal (lower, attached) surfaces
2. Are composed of closely packed cells
3. Supported by a connective tissue
reticular lamina (under the basal lamina)
4. Avascular but innervated
5. High rate of regeneration
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Classification of Epithelia
•
Ask two questions:
1. How many layers?
1 = simple epithelium
>1 = stratified epithelium
2. What is the shape of the cell
• Squamous
• Cuboidal
• Columnar
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Figure 4.2a Classification of epithelia.
Apical surface
Basal surface
Simple
Apical surface
Basal surface
Stratified
Classification based on number of cell layers.
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Cells of Epithelial Tissues
• Squamous cells
• Cuboidal cells
• Columnar cells
(If stratified, name according to apical layer of
cells)
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Figure 4.2b Classification of epithelia.
Squamous
Cuboidal
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Columnar
Classification based
on cell shape.
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Overview of Epithelial Tissues
• For each of the following types of epithelia,
note:
– Description
– Function
– Location
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Figure 4.3a Epithelial tissues.
Simple squamous epithelium
Description: Single layer of
flattened cells with disc-shaped
central nuclei and sparse
cytoplasm; the simplest of the
epithelia.
Air sacs
of lung
tissue
Nuclei of
squamous
epithelial
cells
Function: Allows materials to pass
by diffusion and filtration in sites
where protection is not important;
secretes lubricating substances in
serosae.
Location: Kidney glomeruli; air
sacs of lungs; lining of heart, blood
vessels, and lymphatic vessels;
lining of ventral body cavity
(serosae).
Photomicrograph: Simple squamous
epithelium forming part of the alveolar
(air sac) walls (140x).
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Simple Squamous Epithelium
• Two other locations
– Endothelium
• The lining of lymphatic vessels, blood vessels, and
heart
– Mesothelium
• The epithelium of serous membranes in the ventral
body cavity
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Figure 4.3c Epithelial tissues.
Simple columnar epithelium
Description: Single layer of tall
cells with round to oval nuclei;
some cells bear cilia; layer may
contain mucus-secreting
unicellular glands (goblet cells).
Microvilli
Simple
columnar
epithelial
cell
Function: Absorption; secretion
of mucus, enzymes, and other
substances; ciliated type propels
mucus (or reproductive cells) by
ciliary action.
Location: Nonciliated type lines
most of the digestive tract
(stomach to rectum), gallbladder,
and excretory ducts of some
glands; ciliated variety lines small
bronchi, uterine tubes, and some
regions of the uterus.
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Mucus of
goblet cell
Basement
membrane
Photomicrograph: Simple columnar
epithelium of the small intestine mucosa (660x).
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Figure 4.3d Epithelial tissues.
Pseudostratified columnar epithelium
Description: Single layer of cells
of differing heights, some not
reaching the free surface; nuclei
seen at different levels; may
contain mucus-secreting cells
and bear cilia.
Cilia
Pseudostratified
epithelial
layer
Function: Secrete substances,
particularly mucus; propulsion of
mucus by ciliary action.
Location: Nonciliated type in
male’s sperm-carrying ducts and
ducts of large glands; ciliated
variety lines the trachea, most of
the upper respiratory tract.
Trachea
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Photomicrograph: Pseudostratified
ciliated columnar epithelium lining the
human trachea (800x).
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Basement
membrane
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Figure 4.3e Epithelial tissues.
Stratified squamous epithelium
Description: Thick membrane
composed of several cell layers;
basal cells are cuboidal or
columnar and metabolically active;
surface cells are flattened
(squamous); in the keratinized
type, the surface cells are full of
keratin and dead; basal cells are
active in mitosis and produce the
cells of the more superficial layers.
Stratified
squamous
epithelium
Function: Protects underlying
tissues in areas subjected to
abrasion.
Location: Nonkeratinized type
forms the moist linings of the
esophagus, mouth, and vagina;
keratinized variety forms the
epidermis of the skin, a dry
membrane.
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Nuclei
Basement
membrane
Connective
tissue
Photomicrograph: Stratified squamous
epithelium lining the esophagus (285x).
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Connective Tissue
• Most abundant and widely distributed of
primary tissues
• Four main classes
– Connective tissue proper
– Cartilage
– Bone
– Blood
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Table 4.1 Comparison of Classes of Connective Tissues (1 of 2)
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Table 4.1 Comparison of Classes of Connective Tissues (2 of 2)
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Major Functions of Connective Tissue
•
•
•
•
•
Binding and support
Protecting
Insulating
Storing reserve fuel
Transporting substances (blood)
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Characteristics of Connective Tissue
• Three characteristics make connective
tissues different from other primary tissues
– Have mesenchyme (an embryonic tissue) as
their common tissue of origin
– Have varying degrees of vascularity (blood
vessels)
– Have extracellular matrix
• Connective tissue not composed mainly of cells
• Largely nonliving extracellular matrix separates
cells
– So can bear weight, withstand tension, endure abuse
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Connective Tissue Fibers
• Three types of fibers provide support
– Collagen
– Elastic fibers
– Reticular
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Cells
• "Blasts" cells
– Immature forum; mitotically active; secrete ground
substance and fibers
– Fibroblasts in connective tissue proper
– Chondroblasts in cartilage
– Osteoblasts in bone
– Hematopoietic stem cells in bone marrow
• "Cyte" cells
– Mature form; maintain matrix
– Chondrocytes in cartilage
– Osteocytes in bone
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Other Cell Types in Connective Tissues
• Fat cells
– Store nutrients
• White blood cells
– Neutrophils, eosinophils, lymphocytes
– Tissue response to injury
• Mast cells
– Initiate local inflammatory response against foreign
microorganisms they detect
• Macrophages
– Phagocytic cells that "eat" dead cells,
microorganisms; function in immune system
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Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue.
Cell types
Macrophage
Extracellular
matrix
Ground substance
Fibers
• Collagen fiber
• Elastic fiber
• Reticular fiber
Fibroblast
Lymphocyte
Fat cell
Mast cell
Neutrophil
Capillary
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Figure 4.8b Connective tissues.
Connective tissue proper: loose connective tissue, adipose
Description: Matrix as in areolar,
but very sparse; closely packed
adipocytes, or fat cells, have
nucleus pushed to the side by
large fat droplet.
Function: Provides reserve food
fuel; insulates against heat loss;
supports and protects organs.
Nucleus of
adipose
(fat) cell
Location: Under skin in
subcutaneous tissue; around
kidneys and eyeballs; within
abdomen; in breasts.
Adipose
tissue
Fat droplet
Photomicrograph: Adipose tissue from
the subcutaneous layer under the skin (350x).
Mammary
glands
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Figure 4.8g Connective tissues.
Cartilage: hyaline
Description: Amorphous but firm
matrix; collagen fibers form an
imperceptible network;
chondroblasts produce the matrix
and when mature (chondrocytes)
lie in lacunae.
Function: Supports and reinforces;
serves as resilient cushion; resists
compressive stress.
Chondrocyte
in lacuna
Location: Forms most of the
embryonic skeleton; covers the
ends of long bones in joint cavities;
forms costal cartilages of the ribs;
cartilages of the nose, trachea, and
larynx.
Costal
cartilages
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Matrix
Photomicrograph: Hyaline cartilage from
a costal cartilage of a rib (470x).
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Figure 4.8h Connective tissues.
Cartilage: elastic
Description: Similar to hyaline
cartilage, but more elastic fibers
in matrix.
Function: Maintains the shape of
a structure while allowing great
flexibility.
Chondrocyte
in lacuna
Matrix
Location: Supports the external
ear (pinna); epiglottis.
Photomicrograph: Elastic cartilage from
the human ear pinna; forms the flexible
skeleton of the ear (800x).
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Figure 4.8i Connective tissues.
Cartilage: fibrocartilage
Description: Matrix similar to but
less firm than that in hyaline
cartilage; thick collagen fibers
predominate.
Function: Tensile strength allows
it to absorb compressive shock.
Location: Intervertebral discs;
pubic symphysis; discs of knee
joint.
Chondrocytes
in lacunae
Intervertebral
discs
Collagen
fiber
Photomicrograph: Fibrocartilage of an
intervertebral disc (125x). Special staining
produced the blue color seen.
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Figure 4.8j Connective tissues.
Others: bone (osseous tissue)
Description: Hard, calcified
matrix containing many collagen
fibers; osteocytes lie in lacunae.
Very well vascularized.
Function: Supports and protects
(by enclosing); provides levers for
the muscles to act on; stores
calcium and other minerals and
fat; marrow inside bones is the
site for blood cell formation
(hematopoiesis).
Central
canal
Lacunae
Lamella
Location: Bones
Photomicrograph: Cross-sectional view
of bone (125x).
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Figure 4.8k Connective tissues.
Connective tissue: blood
Description: Red and white blood
cells in a fluid matrix (plasma).
Red blood
cells
(erythrocytes)
Function: Transport respiratory
gases, nutrients, wastes, and other
substances.
White blood
cells:
• Lymphocyte
• Neutrophil
Location: Contained within blood
vessels.
Plasma
Photomicrograph: Smear of human blood
(1670x); shows two white blood cells
surrounded by red blood cells.
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Figure 4.9a Muscle tissues.
Skeletal muscle
Description: Long, cylindrical,
multinucleate cells; obvious
striations.
Part of
muscle
fiber (cell)
Function: Voluntary movement;
locomotion; manipulation of the
environment; facial expression;
voluntary control.
Nuclei
Location: In skeletal muscles
attached to bones or occasionally
to skin.
Striations
Photomicrograph: Skeletal muscle
(approx. 440x). Notice the obvious banding
pattern and the fact that these large cells are
multinucleate.
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Figure 4.9b Muscle tissues.
Cardiac muscle
Description: Branching, striated,
generally uninucleate cells that
interdigitate at specialized
junctions (intercalated discs).
Intercalated
discs
Function: As it contracts, it
propels blood into the circulation;
involuntary control.
Striations
Location: The walls of the heart.
Nucleus
Photomicrograph: Cardiac muscle (900x);
notice the striations, branching of cells, and
the intercalated discs.
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Figure 4.9c Muscle tissues.
Smooth muscle
Description: Spindle-shaped
cells with central nuclei; no
striations; cells arranged closely
to form sheets.
Function: Propels substances or
objects (foodstuffs, urine, a baby)
along internal passageways;
involuntary control.
Nuclei
Location: Mostly in the walls of
hollow organs.
Smooth
muscle
cell
Photomicrograph: Sheet of smooth
muscle (720x).
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Nervous Tissue
• Main component of nervous system
– Brain, spinal cord, nerves
– Regulates and controls body functions
• Neurons
– Specialized nerve cells that generate and conduct
nerve impulses
• Neuroglia
– Supporting cells that support, insulate, and protect
neurons
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Figure 4.10 Nervous tissues.
Nervous tissue
Description: Neurons are
branching cells; cell processes
that may be quite long extend from
the nucleus-containing cell body;
also contributing to nervous tissue
are nonexcitable supporting cells.
Nuclei of
supporting
cells
Neuron processes Cell body
Axon Dendrites
Cell body
of a neuron
Function: Neurons transmit
electrical signals from sensory
receptors and to effectors (muscles
and glands) which control their
activity; supporting cells support
and protect neurons.
Neuron
processes
Location: Brain, spinal
cord, and nerves.
Photomicrograph: Neurons (350x).
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