1. KILIMANJARO CHRISTIAN MMEDICAL UNIVERSITY
COLLEGE
Faculty of Nursing and Rehabilitation Medicine
Department of Anatomy and Neuroscience
Anatomy Lecture for BSc.Nursing and BSc.Physiotherapy
LECTURE 6
TOPIC: CONNECTIVE TISSUES
Date: Nov. 7th 2022, from 10:30 am -12:30pm, GYM – Physiotherapy School
Lecturer: J. S. Kauki, BSc, MSc, on PhD, Email: jskauki@gmail.com.
Office ext. 70 Block C, 3RD Floor, Anatomy dept.
2. Outline
Objectives
Introduction, definition and general features of connective
tissues
Connective tissue cells
Connective tissue matrix fibers
Connective tissue Ground substances
Classification and description of different types of connective
tissues
Summary
3. CONNECTIVE TISSUES
Objectives:
Describe the general features of connective tissue.
Describe the structure, location, and function of the
various types of connective tissue.
4. Connective tissue - Introduction
Connective tissue is among the most abundant and widely
distributed tissues in the body.
Being in many forms, connective tissue has a variety of functions:
It binds together, supports, and strengthens other body tissues.
It protects and insulates internal organs.
It compartmentalizes structures such as skeletal muscles.
Blood, which is a fluid connective tissue, serves as the major
transport system within the body.
5. General Features of Connective Tissue
Connective tissue consists of two basic elements:
Extracellular matrix and Cells.
Extracellular matrix
Is the material located between its widely spaced cells.
Consists of protein fibers (extracellular fibers) and ground substance
(extracellular matrix).
Extracellular fibers
Are secreted by the connective tissue cells
Determine the many functional properties of the tissue
Also controls the surrounding watery environment via specific proteoglycan
molecules
Ground substance / Extracellular matrix is the material between the cells
and the fibers, and determines much of the tissue’s qualities. Eg. Cartilage is firm
but pliable while the bone is hard and inflexible.
Connective tissues usually are highly vascular, except cartilage which is
avascular and tendons which has scanty blood supply.
Except for cartilage, connective tissues are supplied with nerves.
6. Connective Tissue Cells
Embryonic mesenchymal cells give rise to the cells of connective tissues.
The immature connective tissue cells (~blast) are
Fibroblasts in loose and dense connective tissue,
Chondroblasts in cartilage, and
Osteoblasts in bone.
Blast cells retain the capacity for cell division and secrete the extracellular
matrix which determines the characteristic of the tissue.
In cartilage and bone, once the extracellular matrix is produced, the
immature cells differentiate into mature cells with names ending in -cyte,
namely chondrocytes and osteocytes.
Mature cells (~cyte) have reduced capacities for cell division and secretion
of extracellular matrix and are mostly involved in monitoring and
maintaining the extracellular matrix.
8. 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.
Wandering macrophages have the ability to move throughout the tissue
and gather at sites of infection or inflammation to carry out phagocytosis.
Fibroblasts:
Are large, flat cells with branching processes.
Are present in all the general connective
tissues, and usually are the most numerous.
Fibroblasts migrate through the connective
tissue, secreting the fibers and certain
components of the ground substance of the
extracellular matrix.
9. Plasma cells
Are small cells that develop from B lymphocyte.
Plasma cells secrete antibodies, proteins that attack or neutralize foreign
substances in the body.
Thus, plasma cells are an important part of the body’s immune response.
Most plasma cells reside in connective tissues, especially in the
gastrointestinal and respiratory tracts although they are found in many
places in the body .
They are also abundant in the salivary glands, lymph nodes, spleen, and
red bone marrow.
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 body’s reaction to injury or
infection. In addition, researchers have recently discovered that mast
cells can bind to, ingest, and kill bacteria.
10. Adipocytes / Fat 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 cells:
Are not found in significant numbers
in normal connective tissue. However,
in response to certain conditions they
migrate from blood into connective
tissues. For example, neutrophils
gather at sites of infection, and
eosinophils migrate to sites of parasitic
invasions and allergic responses.
11. Collagen Fibers:
• Large fibers made of the protein collagen
and are typically the most abundant
fibers.
• Promote tissue flexibility.
Elastic Fibers:
• Intermediate fibers made of the protein
elastin.
• Branching fibers that allow for stretch
and recoil
Reticular Fibers:
• Small delicate, branched fibers that have
same chemical composition as collagen.
• Forms structural framework for organs
such as spleen and
lymph nodes.
12. Clinical correlation
Marfan syndrome
Is an inherited disorder caused by a defective fibrillin gene.
The result is abnormal development of elastic fibers.
Tissues rich in elastic fibers are malformed or weakened.
Structures affected most seriously are the covering layer of bones
(periosteum), the ligament that suspends the lens of the eye, and the walls
of the large arteries.
People with Marfan syndrome tend to be tall and have disproportionately
long arms, legs, fingers, and toes.
A common symptom is blurred vision caused by displacement of the lens
of the eye.
The most life-threatening complication of Marfan syndrome is weakening
of the aorta (the main artery that emerges from the heart), which can burst
suddenly.
13. Ground Substance
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.
Contains water and an assortment of large organic molecules, many of which
are complex combinations of polysaccharides and proteins.
The polysaccharides include hyaluronic acid, chondroitin sulfate, dermatan
sulfate, and keratan sulfate. Collectively, they are referred to as
glycosaminoglycans (GAGs).
Except for hyaluronic acid, the GAGs are associated with proteins called
proteoglycans
The proteoglycans form a core protein and the GAGs project from the protein
like the bristles of a brush.
One of the most important properties of GAGs is that they trap water,
making the ground substance more jellylike.
14. Hyaluronic Acid:
Complex combination of
polysaccharides and proteins
found in “true” or proper
connective tissue.
Chondroitin sulfate:
Jellylike ground substance of
cartilage, bone, skin and blood
vessels.
Other ground Substances:
Dermatin sulfate, keratin sulfate,
and adhesion proteins
15. Hyaluronic acid
Is a viscous, slippery substance that binds cells together, lubricates joints, and
helps maintain the shape of the eyeballs.
White blood cells, sperm cells, and some bacteria produce hyaluronidase, an
enzyme that breaks apart hyaluronic acid, thus causing the ground substance of
connective tissue to become more liquid.
The ability to produce hyaluronidase helps white blood cells move more easily
through connective tissues to reach sites of infection and aids penetration of an
oocyte by a sperm cell during fertilization.
It also accounts for the rapid spread of bacteria through connective tissues.
Chondroitin sulfate provides support and adhesiveness in cartilage, bone, skin, and
blood vessels.
The skin, tendons, blood vessels, and heart valves contain dermatan sulfate.
Bone, cartilage, and the cornea of the eye contain keratan sulfate.
Adhesion proteins are responsible for linking components of the ground substance
to one another and to the surfaces of cells.
The main adhesion protein of connective tissue is fibronectin, which binds to
both collagen fibers and ground substance, linking them together.
Fibronectin also attaches cells to the ground substance.
16. Clinical correlation
In recent years, chondroitin sulfate and glucosamine (a proteoglycan) have
been used as nutritional supplements either alone or in combination to promote
and maintain the structure and function of joint cartilage, to provide pain relief
from osteoarthritis, and to reduce joint inflammation.
Although these supplements have benefited some individuals with moderate to
severe osteoarthritis, the benefit is minimal in lesser cases. More research is
needed to determine how they act and why they help some people and not
others.
17. I. Embryonic connective tissue
A. Mesenchyme
B. Mucous connective tissue
II. Mature connective tissue
A. Loose connective tissue
1. Areolar connective tissue
2. Adipose tissue
3. Reticular connective tissue
B. Dense connective tissue
1. Dense regular connective tissue
2. Dense irregular connective tissue
3. Elastic connective tissue
C. Cartilage
1. Hyaline cartilage
2. Fibrocartilage
3. Elastic cartilage
D. Bone tissue
1. Compact bone
2. Cancellous (Spongy)
bone
E. Liquid connective tissue
1. Blood tissue
2. Lymph
Classification of Connective Tissues
18. Embryonic Connective Tissue
MESENCHYME
Consists of irregularly shaped
mesenchymal cells embedded in a
semifluid ground substance that
contains delicate reticular fibers.
Location: Found almost exclusively in
the embryo, under skin and along
developing bones of embryo; some
mesenchymal cells are found in adult
connective tissue, especially along
blood vessels.
Function: Forms almost all other types
of connective tissue
19. Connective Tissue cont…
Embryonic Connective Tissue
A. mesenchyme
B. mucous
20. Embryonic connective tissue
MUCOUS CONNECTIVE TISSUE
Description: Consists of widely
scattered fibroblasts embedded in a
viscous, jellylike ground substance
that contains fine collagen fibers.
Location: Umbilical cord of fetus.
Function: Support.
21. 1. Loose Connective Tissue:
A) Areolar tissue
Widely distributed
under epithelia
B) Adipose tissue
Hypodermis, within
abdomen, breasts
C) Reticular connective
tissue
Lymphoid organs such
as lymph nodes
1. Areolar CT
• Content: Consists of all 3 types of fibers
(Collagen, Elastic and Reticular),
several types of cells, and semi-fluid
ground substance
• Distribution: Found in subcutaneous
layer and mucous membranes, and
around blood vessels, nerves and
organs.
• Function: Strength, support and
elasticity
22. Loose Connective Tissue cont…….
2. Adipose tissue / Fat tissue
Content: Consists of
adipocytes; "signet ring"
appearing fat cells that store
energy in the form of
triglycerides (lipids).
Distribution: Found in
subcutaneous layer, around
organs and in the yellow
marrow of long bones
Function: Supports, Protects,
Insulates, and serves as an
energy reserve.
23. Loose Connective Tissue cont…:
3. Reticular CT
Content: Consists of fine
interlacing reticular fibers
and reticular cells
Distribution: Found in
liver, spleen and lymph
nodes
Function: Forms the
framework (stroma) of
organs and binds together
smooth muscle tissue
cells
24. 2. Dense Connective Tissue:
• Dense connective tissue contains
more numerous and thicker fibers
and far fewer cells than loose CT
A. Dense regular connective tissue
• Consists of bundles of collagen fibers
and fibroblasts
• Forms tendons, ligaments and
aponeuroses
• Function: Provide strong
attachment between various
structures
25. :
B. Dense irregular connective
tissue
Consists of randomly-arranged
collagen fibers and a few
fibroblasts
Found in fasciae, dermis of skin,
joint capsules, and heart valves
submucosa of digestive tract
Function: Provide strength
26. ELASTIC CONNECTIVE TISSUE
Consists predominantly of elastic fibers with
fibroblasts in spaces between the fibers.
Location: Lung tissue, walls of elastic
arteries, trachea, bronchial tubes, true vocal
cords, suspensory ligaments of penis, and
some ligaments between vertebrae.
Function: Allows stretching of various
organs. Elastic connective tissue is quite
strong and can recoil to its original shape
after being stretched.
Elasticity is important to the normal
functioning of lung tissue, which recoils as
you exhale, and elastic arteries, which recoil
between heartbeats to help maintain blood
flow.
27. Supportive Connective Tissue:
CARTILAGE:
Jelly-like matrix (chondroitin
sulfate) containing collagen and
elastic fibers and chondrocytes
surrounded by a membrane called
the perichondrium.
Unlike other CT, cartilage has NO
blood vessels or nerves except in
the perichondrium.
The strength of cartilage is due to
collagen fibers and the resilience is
due to the presence of chondroitin
sulfate.
Chondrocytes occur within spaces in
the matrix called lacunae.
29. Supportive Connective Tissue cont….
1. Hyaline Cartilage
Is the most abundant type
Contain fine collagen
fibers embedded in a gel-
type matrix. Occasional
chondrocytes inside
lacunae.
Found in embryonic
skeleton, at the ends of
long bones, in the nose and
in respiratory structures.
Function: Provides support
and allows movement at
joints
30. Supportive connective tissue cont…
2. Fibrocartilage
Contains bundles of collagen
in the matrix that are usually
more visible under
microscopy.
Found in the pubic symphysis,
intervertebral discs, and
menisci of the knee.
Function: support and fusion,
and absorbs shocks.
31. 3. Elastic Cartilage
Threadlike network of elastic
fibers within the matrix.
Found in external ear, auditory
tubes, epiglottis.
Function: Gives support,
maintains shape, allows
flexibility
Supportive connective tissue cont…
32. Application: Tissue Engineering Technology
The technology of tissue engineering, which combines synthetic material
with cells, has allowed scientists to grow new tissues in the laboratory to
replace damaged tissues in the body.
Tissue engineers have already developed laboratory-grown versions of skin
and cartilage using scaffolding beds of biodegradable synthetic materials or
collagen as substrates that permit body cells to be cultured.
As the cells divide and assemble, the scaffolding degrades and the new,
permanent tissue is then implanted in the patient.
Other structures currently under development include bones, tendons, heart
valves, bone marrow, and intestines.
Work is also under way to develop insulin-producing cells for diabetics,
dopamine-producing cells for Parkinson disease patients, and even entire
livers and kidneys.
33. BONE TISSUE
Bones are organs composed of several different
connective tissues, including bone or osseous
tissue, the periosteum, red and yellow bone
marrow, and the endosteum (a membrane that
lines a space within bone that stores yellow bone
marrow).
Bone tissue is either compact or spongy,
depending on how its extracellular matrix and
cells are organized.
The basic unit of compact bone is an OSTEON
or haversian system. Each osteon has four parts:
1. The lamellae (singular is lamella) are
concentric rings of extracellular matrix that
consist of mineral salts (mostly calcium and
phosphates), which give bone its hardness and
compressive strength, and collagen fibers, which
give bone its tensile strength. The lamellae are
responsible for the compact nature of this
type of bone tissue.
34. 2. Lacunae (singular is lacuna) are small spaces
between lamellae that contain mature bone cells
called osteocytes.
3. Canaliculi :Projecting from the lacunae (little
canals), networks of minute canals containing the
processes of osteocytes. Canaliculi provide routes
for nutrients to reach osteocytes and for wastes to
leave them.
4. A central (haversian) canal which contains
blood vessels and nerves.
Spongy bone lacks osteons. Rather, it consists of
slender columns of bone called trabeculae),
which contain lamellae, osteocytes, lacunae, and
canaliculi.
Spaces between trabeculae are filled with red bone
marrow.
Bone function: Support, protection, storage; houses blood-
forming tissue; serves as levers that act with muscle tissue to
enable movement.
35. Liquid Connective Tissue
Blood tissue (or simply blood) is a connective tissue
with a liquid extracellular matrix and formed
elements.
The extracellular matrix is called blood plasma.
The blood plasma is a pale yellow fluid that
consists mostly of water with a wide variety of
dissolved substances; nutrients, wastes, enzymes,
plasma proteins, hormones, respiratory gases, and
ions.
Suspended in the blood plasma are formed
elements; red blood cells (erythrocytes), white blood
cells (leukocytes), and platelets (thrombocytes).
Red blood cells transport oxygen to body cells and
remove some carbon dioxide from them.
White blood cells are involved in phagocytosis,
immunity, and allergic reactions.
Platelets participate in blood clotting.
36. Liquid Connective Tissue cont……
LYMPH
Lymph is the extracellular fluid that flows in lymphatic vessels.
This connective tissue consists of several types of cells in a clear
liquid extracellular matrix that is similar to blood plasma but with
much less protein.
The composition of lymph varies from one part of the body to
another. For example, lymph leaving lymph nodes includes many
lymphocytes, a type of white blood cell, in contrast to lymph from
the small intestine, which has a high content of newly absorbed
dietary lipids.
37. In Summary
We have;
Described the general features of connective tissues.
Described Connective tissue cells
Described connective tissue matrix fibers
Described Connective tissue Ground substances
Classified and described different types of connective
tissues
