Structure and Functions of Connective Tissues
Session 5: Structure and Functions of Connective Tissues
Total Session Time: 120 minutes
Prerequisites
Learning Tasks
By the end of this session students are expected to be able to:
Resources Needed:
SESSION OVERVIEW
|Step |Time |Activity/ |Content |
| | |Method | |
|1 |05 |Presentation |Introduction, Learning Tasks |
| |minutes | | |
|2 |05 |Presentation, |Definition of Connective Tissue |
| |minutes |Buzzing | |
|3 |10 |Presentation, |Type of cells found in connective|
| |minutes |Brainstorming |tissues |
|4 |30 |Presentation |Type of fibres found in |
| |minutes | |connective tissue |
|5 |30 |Presentation |Classification and Functions of |
| |minutes | |Connective |
| | | |Tissues |
|6 |30minutes|Presentation/Brainsto|Specialised connective tissue |
| | |rming | |
|7 |05 |Presentation |Key Points |
| |minutes | | |
|8 |05 |Presentation |Evaluation |
| |minutes | | |
SESSION CONTENTS
STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)
READ or ASK students to read the learning tasks and clarify
ASK students if they have any questions before continuing
STEP 2: Definition of Connective Tissue (5 minutes)
|Activity: buzzing (5 minutes) |
| |
|Ask students to buzz on the following question: |
| |
|What is the connective tissue? |
| |
|ALLOW few students to respond |
| |
|WRITE their responses on the flip chart/ board |
| |
|CLARIFY and SUMMARISE by using the content below |
tissues of the body.
o Composed predominantly of intercellular material (extracellular matrix)
which is secreted mainly by the connective tissue cells, cells and
fibres
STEP 3: Types of Cells Found in Connective Tissue (10 minutes)
|Activity: Brainstorming (5 minutes) |
| |
|Ask students to brainstorm on the following question: |
| |
|Which types of cells are found in the connective tissues?’ |
| |
|ALLOW few students to respond |
| |
|WRITE their responses on the flip chart/ board |
| |
|CLARIFY and SUMMARISE by using the content below |
There are two types of cells:
Resident Cells
These include:
o Fibroblasts:
o Macrophages (histiocytes)
o Mast cells
o Adipocytes
o Pigment cells (melanocytes)
o Undifferentiated mesenchymal cells
Fibroblasts
o Are flat, spindle shaped cells with branching of cytoplasmic processes
with elliptical and have elongated nucleus
o The shape differs depending on activity
o Fibroblasts are found in nearly all types of tissues
o Active fibroblasts have abundant cytoplasm
o Inactive fibroblasts (fibrocytes) are smaller and have diminished
cytoplasm
Functions of fibroblasts
o Synthesis
o Secretes connective tissue fibres, these include collagen, elastic and
reticular fibres.
o They also secrete substances such as glycosaminoglycans and glycoproteins
found in the extracellular matrix (ground substance).
o Differentiation into other cells: Fibroblasts are capable of changing
into a variety of cell types depending on the body need.
o Fibroblasts secrete connective tissue elements which help in remodelling
the extracellular matrix, which is important in wound healing and tissue
repair.
Histiocytes (Tissue Macrophages)
o They are polymorphic cells and can be ovoid or irregular with short and
blunt processes.
o They are derived from blood monocytes, which migrate into the tissues and
transform become histiocytes.
o Main role in tissue is phagocytosis and antigen presentation.
Mast cells
o Are large cells, round or oval in shape
o Play an important role in allergic reactions
o Mast cells are filled with secretory granules that are filled with
substances of inflammation such as histamine and heparin
o Heparin, is an anticoagulant and histamine, is released by the cells
under allergic conditions give rise to oedema, bronchospasm and other
forms of allergic reactions to the surrounding tissues
Wondering cells
tissues depending on the needs of the body, example during infection.
They include monocytes, lymphocytes and granulocyte
STEP 4: Types of Fibre Found in Connective Tissue (25 minutes)
There three types of fibres found in connective tissue:
collagen fibrils that are made up of collagen proteins
(tropoelastin)
netlike supporting framework known as reticulum
Collagen Fibres
o Most abundant fibres formed by the union of many collagen fibrils that
are made up of collagen proteins
o They are tough, inextensible and possess a high tensile strength and
therefore stretching is restricted
o They appear white in fresh sections
o Form major part of tendons, ligaments, cartilage, teeth (Dentin and
cementum) and bones
o There are many types of collagen fibres but the most important are type
I, II, III, and IV
Elastic Fibres
o These are fine fibres made up of elastin protein (tropoelastin)
o They allow some degree of distention and stretching
o When stretched they usually recover the original form and dimension when
the force is eliminated and the elastic limit is not exceeded
o Elastic fibres changes as the age advances where it loses its resilience
o Appear yellow in fresh sections
o Elastic fibres exist as accompanying structure of collagen fibres in the
capsule of many organs, vascular walls and the elastic cartilage
o Also in ligamentum nuchae and ligamentum flava of the spinal cord
Reticular Fibres
o Smaller fibres that branch and anastomose to form a netlike supporting
framework known as reticulum
o They are closely related to the collagen fibres because they contain
collagen fibrils and they show cross-banding pattern, and are
sometimes continuous with collagen fibres
o Reticular fibres form the supporting framework in the hemopoietic (Bone
marrow) and lymphoid organs such as the thymus, lymph node, spleen
o In these organs the reticular fibres are produced by reticular cells
o Also found in endocrine glands, small blood vessels, veins, muscle cells,
fat tissue, and in spaces between the epithelium with connective
tissue
o In these locations the reticular fibres are produced by fibroblasts,
smooth muscle cells, and the Schwann cells produce reticular fibres
that surround the nerve fibres
the wound improves they gradually change to become collagenous
STEP 5: Classification and Function of Connective Tissue (25 minutes)
Classification of Connective Tissues
o Loose connective tissue
o Dense connective tissue
o Adipose tissue
o Blood tissue
o Cartilage
o Bone tissue
o Lymphoid tissue
o Loose Connective Tissue (Areolar Tissue)
delicate, sparse and loosely arranged
intestine and in fascial spaces
exchange between tissues and blood, and also maintains osmotic
pressure
o Contains more fibres than the cellular component
o Fibres are densely packed with little space for ground substance
o Based on the fiber arrangement and direction dense Connective tissue is
divided into:
o Fibres are irregularly arranged
o Fibres are mainly collagen but in some made up of elastic fibres e.g.
walls of elastic arteries, and elastic ligaments e.g.
ligamentum flavum and ligamentum nuchae
o It forms the dermis of the skin, superficial fascia, fibrous capsule of
organs, tunica
o Predominant fibres are the collagen fibres
o The fibres are densely packed and regularly arranged parallel to each
other
o Its arrangement gives rise to a strong structure that withstands tension
exerted in one direction
o Comprises tendons, ligaments and aponeuroses
STEP 6: Specialized Connective Tissues (30 minutes)
Adipose Tissue
as macrophages, fibroblasts, and leukocytes
form of natural fat that can be used to produce energy when the need
arises
tissue
White Adipose Tissue
lipid vacuole, which fills the entire cells
Brown Adipose Tissue
numerous vacuoles (fat droplets)
colour when viewed in fresh conditions
replaced by white adipose tissue
Cartilage
ground substances
Chondrocytes
which the cartilage cells lie
and nerve fibres
contains and the composition of the ground substance
o Hyaline cartilage
o Elastic cartilage
o Fibro cartilage
Hyaline Cartilage
o Most abundant type of cartilage in human body
o It is solid but flexible and can be cut with a knife
and bronchi
long bones develop
Functions of Hyaline Cartilage
the synovial joints, making them to be smooth.
hence it assists in keeping the tubes patent.
replaced by bone tissue except at the distal ends of long bones where
they form the epiphyseal cartilage.
Elastic Cartilage
fibres.
(external ear), and theconiculate, cuneiform and arytenoids cartilages of
the larynx.
maintain the shape and flexibility of the organs.
Fibro Cartilage
perichondrium.
the intervertebral discs, pubic symphysis, articular discs in joints,
the cartilaginous lining of bony grooves in which tendons are lodged and
rims of certain articular cartilages.
|Activity: Brainstorming (10 minutes) |
| |
|[pic]REFER students to Worksheet (5.1): Different Types of Connective |
|Tissue. |
| |
|PROVIDE each student one worksheet 5.1. |
| |
|ASK students to look at the diagrams on the worksheet and fill in what |
|types of connective tissue they see and give the examples on where they|
|can be found in the body. |
| |
|GIVE the worksheet answers after completing or review their answers |
|using answer guideline of the worksheet. |
STEP 7: Key Points (5 minutes)
tissues of the body.
wondering cells
STEP 8: Evaluation (5 minutes)
References
Students,
United Kingdom: Churchill Livingstone Elservier.
ed.).Lippincott:
Williams & Wilkins.
Seeley, R. R., Stephens, T. D., & Tate, P. (2003). Anatomy and Physiology.
New York:
McGraw-Hill.
Shier, A., Butler, J., & Lewis, R. (2004). Hole’s Human Anatomy &
Physiology. New
York: McGraw-Hill.
Standring, S. (2008). Grays’s Anatomy The anatomical basis of clinical
practice. United
Kingdom: Churchill Livingstone Elservier.
Thibodeau, G. A.,& Patton, K. T. (1999). Anatomy & Physiology. Saint Louis:
Mosby,
Von Hoffman Press, Inc
Waugh, A., & Grant. A. (2006). Ross and Willson Anatomy and physiology in
Health and
illness. United Kingdom: Churchill Livingstone Elservier.
Worksheet 5.1: Different Types of Connective Tissue
Name the following types of connective tissue
1. This is ———————————————-
Answer: Dense regular connective tissue in a tendon
[pic]
Source: Standring, S., 2008.
2. This is ———————————————-
Answer: Elastic fibres
[pic]
Source: Standring, S., 2008.
3. This is ———————————————-
Answer: loose connective tissue
[pic]
Source: Standring, S., 2008.
4. This is ———————————————-
Answer: Adipose tissue
[pic]
Source: Standring, S., 2008.
5. This is ———————————————-
Answer: Fibrous connective tissue
[pic]
Source: Standring, S., 2008.
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