Connective Tissues

CONNECTIVE TISSUES

Connective tissue is the medium which surrounds and supports the other tissues of the body.

Composed predominantly of intercellular material (extracellular matrix) which is secreted mainly by the connective tissue cells, cells and fibres There are two types of cells;

• 1.Resident cells (fixed cells)

2.Wondering cells

Resident Cells

• Resident cells are cells that originates within the connective tissue,these include:
• Fibroblasts:
• Macrophages (histiocytes)
• Mast cells
• Adipocytes
• Pigment cells (melanocytes)

Undifferentiated mesenchymal cells

Wondering cells

These are the cells which are temporarily found within the connective tissues depending on the needs of the body, example during infection. They include monocytes, lymphocytes and granulocyte

Types of fibre found in Connective tissues

• There three types of fibres found in connective tissue:

1.Collagen fibres💯(produce collagen protein) Most abundant fibres formed by the union of many collagen fibrils that are made up of collagen proteins.

• 2.Elastic fibres(made up of elastin protein)
• These are fine fibres made up of elastin protein (tropoelastin)
• They allow some degree of distention and stretching.

3.Reticular fibres,

Smaller fibres that branch and anastomose to form a netlike supporting framework known as reticulum.

Collagen Fibres

Most abundant fibres formed by the union of many collagen fibrils that are made up of collagen proteins.

They are tough, inextensible and possess a high tensile strength and therefore stretching is restricted and they appear white in fresh sections Form major part of tendons, ligaments, cartilage, teeth (Dentin and cementum) and bones.💯 There are many types of collagen fibres but the most important are type I, II, III, and IV.

Elastic Fibres

These are fine fibres made up of elastin protein (tropoelastin) whereas allowing some degree of distention and stretching When stretched they usually recover the original form and dimension when the force is eliminated and the elastic limit is not exceeded.

Elastic fibres changes as the age advances where it loses its resilience and they appear yellow in fresh sections.

Elastic fibres exist as accompanying structure of collagen fibres in the capsule of many organs, vascular walls and the elastic cartilage.

Also in ligamentum nuchae and ligamentum flava of the spinal cord.

Reticular Fibres

Smaller fibres that branch and anastomose to form a netlike supporting framework known as reticulum.

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.

Reticular fibres form the supporting framework in the hemopoietic (Bone marrow) and lymphoid organs such as the thymus, lymph node, spleen.In these organs the reticular fibres are produced by reticular cells.

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Connective Tissues

Also found in endocrine glands, small blood vessels, veins, muscle cells, fat tissue, and in spaces between the epithelium with connective tissue.

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.

In wound healing the reticular fibres are the first to be formed and as the wound improves they gradually change to become collagenous.

sevency 👀

Adipose Tissue

Formed by aggregation of fat cells (adipocytes) with few other cells such as macrophages,fibroblasts, and leukocytes.

Basically it is a storage tissue that stores nutritive material in the form of natural fat that can be used to produce energy when the need arises.

• Other functions includes; protection and insulation

There are two types which include white adipose tissue and brown adipose tissue.

Cartilage

It is a tough specialized connective tissue made up of cells, fibres and ground substances.It is avascular and consists of cells called Chondroblasts and Chondrocytes Ground substance (matrix) is homogenous and surrounds the lacunae in which the cartilage cells lie.Fibres present are either collagen or elastic fibres Perichondrium is a specialized membrane that covers the cartilage,It is made up of dense regular connective tissue with many blood vessels and nerve fibres There are three types of cartilage based on the types of fibres it contains and the composition of the ground substance,which are;

• Hyaline cartilage
• Elastic cartilage

Fibro cartilage

CONNECTIVE TISSUE

Connective tissue is the medium which surrounds and supports the other tissues of the body.

Composed predominantly of intercellular material (extracellular matrix) which is secreted mainly by the connective tissue cells, cells and fibres There are two types of cells;

• 1.Resident cells (fixed cells)

2.Wondering cells

Types of fibre found in Connective tissues

• There three types of fibres found in connective tissue:

1.Collagen fibres

Most abundant fibres formed by the union of many collagen fibrils that are made up of collagen proteins.

• 2.Elastic fibres
• These are fine fibres made up of elastin protein (tropoelastin)
• They allow some degree of distention and stretching.

3.Reticular fibres

Smaller fibres that branch and anastomose to form a netlike supporting framework known as reticulum.

Connective Tissues

Also found in endocrine glands, small blood vessels, veins, muscle cells, fat tissue, and in spaces between the epithelium with connective tissue.

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.

In wound healing the reticular fibres are the first to be formed and as the wound improves they gradually change to become collagenous.

Cartilage

It is a tough specialized connective tissue made up of cells, fibres and ground substances.It is avascular and consists of cells called Chondroblasts and Chondrocytes Ground substance (matrix) is homogenous and surrounds the lacunae in which the cartilage cells lie.Fibres present are either collagen or elastic fibres Perichondrium is a specialized membrane that covers the cartilage,It is made up of dense regular connective tissue with many blood vessels and nerve fibres There are three types of cartilage based on the types of fibres it contains and the composition of the ground substance,which are;

• 1.Hyaline cartilage
• 2.Elastic cartilage

3.Fibro cartilage

Common types of connective tissue diseases

A connective tissue diseases are diseases that affect the joints (parts of the body that connect the structures of the body together).It is presented by the inflammation of the joints (arthritis).It may be infective or non-infective.

In most cases, all signs of inflammation are present (swollen joints, hot, tender and red) and there is limitation of movements.These includes;

• 1.Acute pyrogenic arthritis
• 2.Gout
• 3.Chronic joint disease
• 4.Osteoarthritis
• 5.Generalized bone disease
• 6.Osteomalacia

7.Osteoporosis

Acute pyrogenic arthritis

• This is the infection of the joints by pus-producing bacteria

It is caused by any pyrogenic bacteria like staphylococci.

The infection may start suddenly without any obvious cause or may occur from other septic focus nearby like osteomyelitis The patients complain of pain, swelling and reduced movement of the joint Gout

This is arthritis due to congenital abnormality of uric acid metabolism, leading to abnormal high uric acid in the blood.Uric acid is deposited in joints and also around the joints and in the ear cartilages.

The kidney may be damaged and kidney stones may form in them.The disease is commonest in men over 40 years.The acute episodes may be precipitated by alcohol excess, surgery, infections or treatment with thiazide diuretics which raise serum uric acid even in normal people.

Patients experience irritability and malaise a day or two before acute attack of gout and sudden severe pain starts in one joint especially that of big toe.

Chronic joint disease

• Rheumatoid arthritis

The cause is thought to be abnormal immunological reactions.

Women are affected then men at the age between 20 – 40 years and psychological factors are often involved.

The patient notices pain and stiffness of a joint, then swollen joints and finally radiate to the wrist, knee and hips.

• Osteoarthritis
• This is due to a degeneration of the articular cartilage of joints.

It is common to older people.

The exact cause is not certain but it comes with age particularly in people who have done heavy work.

It also occurs after injuries that have involved a joint or bone.

The only symptom is aching pain in the joints, worse at the end of the day and relieved by rest.

Generalized bone disease

• Osteoporosis

It is a condition in which the bones are thinned though their composition is normal.

It can be caused by immobilization; when a limb is put in plaster or stay in bed for a long time, menopause in women, old age, Cushing’s syndrome and steroid treatment.

• The pain occurs only when there is bone fracture.
• Osteomalacia
• This is a different form of weakening of bones due to vitamin D deficiency.
• It is common in adults. muscular weakness and may be tetany.
• The weakened bones may collapse and deform.

There are bone pains, often