TISSUES Tissue is group of cells working together for a
specific function Types of tissue : 1. Epithelial Tissue 2.
Connective Tissue 3. Muscle Tissue 4. Nervous Tissue
Slide 3
Objectives Describe the general features of connective tissues.
Describe the structure, location, and function of the various types
of connective tissues.
Slide 4
Connective tissues are one of the most abundant and widely
distributed tissues in the body. Function: 1. They bind together 2.
Support 3. strengthen other body tissues 4. protect and insulate
internal organs 5. compartmentalize structures such as skeletal
muscles 6. serve as the major transport system within the body
(blood) 7. stored energy, reserves (adipose, or fat, tissue) 8. and
are the main source of immune responses.
Slide 5
General Features of Connective Tissues Connective tissues
consist of two basic elements: 1. extracellular matrix 2. Cellular
elements
Slide 6
Extracellular matrix is the material located between its widely
spaced cells. The extracellular matrix consists of protein fibers
and ground substance the material between the cells and the fibers.
The extracellular fibers are secreted by the connective tissue
cells and account for many of the functional properties of the
tissue in addition to controlling the surrounding watery
environment via specific proteoglycan molecule
Slide 7
Connective Tissue Cells Fibroblasts : are large, flat cells
with branching processes. They are present in all the general
connective tissues, and usually are the most numerous. Fibroblasts
migrate through the connective tissues, secreting the fibers and
certain components of the ground substance of the extracellular
matrix
Slide 8
Slide 9
Macrophages Develop from monocytes, a type of white blood cell.
Macrophages have an irregular shape with short branching
projections and are capable of engulfing bacteria and cellular
debris by phagocytosis. Fixed macrophages reside in a particular
tissue; examples include alveolar macrophages in the lungs or
splenic macrophages in the spleen.
Slide 10
Plasma cells : are small cells that develop from a type of
white blood cell called a B lymphocyte. Plasma cells secrete
antibodies, proteins that attack or neutralize foreign substances
in the body. Mast cells: are abundant alongside the blood vessels
that supply connective tissue. They produce histamine, a chemical
that dilates small blood vessels as part of the inflammatory
response, the bodys reaction to injury or infection. In addition,
researchers have recently discovered that mast cells can bind to,
ingest, and kill bacteria.
Slide 11
Adipocytes also called fat cells or adipose cells, are
connective tissue cells that store triglycerides (fats). They are
found deep to the skin and around organs such as the heart and
kidneys. White blood cell
Slide 12
Slide 13
Connective Tissue Extracellular Matrix Each type of connective
tissue has unique properties, based on the specific extracellular
materials between the cells. The extracellular matrix consists of
two major components: (1) the ground substance and (2) the
fibers.
Slide 14
Ground substances: is the component of a connective tissue
between the cells and fibers. The ground substance may be fluid,
semifluid, gelatinous, or calcified. It supports cells, binds them
together, stores water, and provides a medium for exchange of
substances between the blood and cells. It plays an active role in
how tissues develop, migrate, proliferate, and change shape, and in
how they carry out their metabolic functions. Assignment component
of the ground substances??
Slide 15
Fibers Three types of fibers are embedded in the extracellular
matrix between the cells: collagen fibers, elastic fibers, and
reticular fibers. They function to strengthen and support
connective. 1. Collagen fiber. 2. Reticular fiber. 3. Elastic
fiber.
Slide 16
- Collagen fiber: are very strong and resist pulling forces
(tension), allows tissue flexibility. The properties of different
types of collagen fibers vary from tissue to tissue. Collagen
fibers often occur in parallel bundles. The bundle arrangement adds
great tensile strength to the tissue. Chemically: collagen fibers
consist of the protein collagen, which is the most abundant protein
in your body, representing about 25% of the total. Collagen fibers
are found in most types of connective tissues, especially bone,
cartilage, tendons (which attach muscle to bone), and ligaments
(which attach bone to bone).
Slide 17
Collagen types Collagen type I - 90% of all collagen. Forms
bone, tendons, skin. Made by fibroblasts, osteoblasts,
odontoblasts. Collagen type II found in cartilage. Made by
chondroblasts. Forms fibrils, not fibers. Collagen type III
component of reticular fibers in lymphoid organs. Collagen type IV
made by endothelial and epithelial cells
Slide 18
Slide 19
Slide 20
Elastic fibers which are smaller in diameter than collagen
fibers, branch and join together to form a fibrous network within a
connective tissue. An elastic fiber consists of molecules of the
protein elastin surrounded by a glycoprotein named fibrillin, which
adds strength and stability. Because of their unique molecular
structure, elastic fibers are strong but can be stretched up to
150% of their relaxed length without breaking. Equally important,
elastic fibers have the ability to return to their original shape
after being stretched, a property called elasticity. Elastic fibers
are plentiful in skin, blood vessel walls, and lung tissue.
Slide 21
Slide 22
Reticular fibers consisting of collagen arranged in fine
bundles with a coating of glycoprotein, provide support in the
walls of blood vessels and form a network around the cells in some
tissues, such as areolar connective tissue, adipose tissue, nerve
fibers, and smooth muscle tissue. Produced by fibroblasts,
reticular fibers are much thinner than collagen fibers and form
branching networks. Like collagen fibers, reticular fibers provide
support and strength.
Slide 23
Slide 24
Classification of Connective Tissues I. Embryonic connective
tissues A. Mesenchyme B. Mucous connective tissue II. Mature
connective tissues A. Loose connective tissues 1. Areolar
connective tissue 2. Adipose tissue 3. Reticular connective tissue
B. Dense connective tissues 1. Dense regular connective tissue 2.
Dense irregular connective tissue 3. Elastic connective tissue
Slide 25
C. Cartilage 1. Hyaline cartilage 2. Fibrocartilage 3. Elastic
cartilage D. Bone tissue E. Liquid connective tissue 1. Blood
tissue 2. Lymph
Slide 26
Embryonic Connective Tissues A. MESENCHYME Description
Irregularly shaped mesenchymal cells embedded in semifluid ground
substance that contains delicate reticular fibers. Location Almost
exclusively under skin and along developing bones of embryo; some
in adult connective tissue, especially along blood vessels.
Function Forms almost all other types of connective tissue.
Slide 27
Slide 28
B. MUCOUS CONNECTIVE TISSUE Description: Widely scattered
fibroblasts embedded in viscous, jellylike ground substance that
contains fine collagen fibers. Location: Umbilical cord of fetus.
Function: Support.
Slide 29
Slide 30
Mature Connective Tissues: Loose Connective Tissues A. AREOLAR
CONNECTIVE TISSUE Description: One of the most widely distributed
connective tissues; consists of fibers (collagen, elastic,
reticular) arranged randomly and several kinds of cells
(fibroblasts, macrophages, plasma cells, adipocytes, mast cells,
and a few white blood cells) embedded in semifluid ground substance
Location: In and around nearly every body structure (thus, called
packing material of the body): in subcutaneous layer deep to skin,
nerves, and body organs. Function: Strength, elasticity,
support.
Slide 31
Slide 32
B. ADIPOSE TISSUE Location: Wherever areolar connective tissue
is located: subcutaneous layer deep to skin, around heart and
kidneys, yellow bone marrow, padding around joints and behind
eyeball in eye socket. Function Reduces heat loss through skin;
serves as an energy reserve; supports and protects organs. In
newborns, BAT generates heat to maintain proper body
temperature.
Slide 33
Slide 34
C. RETICULAR CONNECTIVE TISSUE Description Fine interlacing
network of reticular fibers (thin form of collagen fiber) and
reticular cells. Location Stroma (supporting framework) of liver,
spleen, lymph nodes; red bone marrow; reticular lamina of basement
membrane; around blood vessels and muscles. Function Forms stroma
of organs; binds smooth muscle tissue cells; filters and removes
worn-out blood cells in spleen and microbes in lymph nodes.
Slide 35
Slide 36
D. DENSE REGULAR CONNECTIVE TISSUE Description Shiny white
extracellular matrix; mainly collagen fibers regularly arranged in
bundles with fibroblasts in rows between bundles. Location Forms
tendons (attach muscle to bone), most ligaments (attach bone to
bone or muscle to bone). Function Provides strong attachment
between various structures. Tissue structure withstands pulling
(tension) along long axis of fibers.
Slide 37
Slide 38
E. DENSE IRREGULAR CONNECTIVE TISSUE Description Collagen
fibers; usually irregularly arranged with a few fibroblasts.
Location Often occurs in sheets, such as fasciae (tissue beneath
skin and around muscles and other organs), reticular (deeper)
region of dermis of skin, kidneys, liver, testes, lymph nodes; also
in heart valves. Function Provides tensile (pulling) strength in
many directions.
Slide 39
Slide 40
F. ELASTIC CONNECTIVE TISSUE Description Predominantly elastic
fibers with fibroblasts between fibers; unstained tissue is
yellowish. Location Lung tissue, walls of elastic arteries,
trachea, bronchial tubes, true vocal cords, suspensory ligaments of
penis, some ligaments between vertebrae. Function Allows stretching
of various organs; is strong and can recoil to original shape after
being stretched.
Slide 41
Slide 42
Cartilage A. HYALINE CARTILAGE Description Hyaline cartilage
contains a resilient gel as ground substance and appears in the
body as a bluish- white, shiny substance prominent chondrocytes are
found in lacunae surrounded by perichondrium (exceptions: articular
cartilage in joints and cartilage of epiphyseal plates, where bones
lengthen during growth). Location Most abundant cartilage in body;
at ends of long bones, anterior ends of ribs, nose, parts of
larynx, trachea, bronchi, bronchial tubes, embryonic and fetal
skeleton. Function Provides smooth surfaces for movement at joints,
flexibility, and support; weakest type of cartilage.
Slide 43
Slide 44
B. FIBROCARTILAGE Description Chondrocytes scattered among
clearly visible thick bundles of collagen fibers within
extracellular matrix; lacks perichondrium. Location Pubic symphysis
(where hip bones join anteriorly), intervertebral discs. Function
Support and joining structures together. Strength and rigidity make
it the strongest type of cartilage.
Slide 45
Slide 46
C. ELASTIC CARTILAGE Description Chondrocytes in threadlike
network of elastic fibers within extracellular matrix;
perichondrium present. Location Lid on top of larynx (epiglottis),
part of external ear (auricle). Function Provides strength and
elasticity; maintains shape of certain structures.
Slide 47
Slide 48
Test Your Self
Slide 49
Slide 50
Slide 51
Slide 52
Slide 53
Slide 54
References: Books - Wheathers Functional histology Fifth
edition. - DiFiore's Atlas of Histology with Functional
Correlations Online links: - Pathpedia.com