CONNECTIVE TISSUE AND MUSCLES

Dr. Lubna Nazli

OBJECTIVES

• Definition & features of connective tissue.• Classification.• Adipose tissue.• Cartilage: its features.• Types of cartilage.• Features of bone• Cells of bone• Muscle• Types of muscles.

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Features of connective tissue

• Connective tissue consists of dispersed cells with no intercellular contact and extracellular material called matrix.

• The matrix consists of protein fibers and ground substance .

• Connective tissues have their own blood supply (except cartilage).

• It is the most abundant tissue.

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Classification of connective tissue

Fluid Con. Tissues1. Blood 2. Lymph

Con. Tissue Proper

1.Loose

2.Dense

Supportive Con. Tissues 1.Cartilage

2.Bone

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Connective tissue proper - composed of two types depending on proportion of cells, fibers & ground substance.

• loose connective tissue • dense connective tissue

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Loose Connective Tissue (areolar tissue):

• Loose connective tissue has loose , irregular arrangement of connective tissue fibers & abundant ground substance. There are plenty of cells found in matrix.

• Eg: areolar, adipose & myxomatous

Dense connective tissue:

• It has thicker and densely packed collagen fibers, has few cells and less ground substance.

Eg: tendons & ligaments. Bone & cartilage

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Adipose tissue

• It is a specialized connective tissue. • Its cells are closely packed and it has little matrix. • The adipose cells store lipid in a large vacuole which

fills each cell.• Adipose is important for shock absorption and

insulation.• It is found around many organs such as the heart,

eyes, kidneys, spleen & under the skin.

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• most of the volume of the cell is occupied by a large lipid droplet. The cytoplasm appears as a thin layer enveloping the lipid and the peripheral nucleus is crescent shaped.

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Alcohol used during this tissue preparation dissolves the lipids from the cells and they appear as circular, empty cells.

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CARTILAGE

• It is a specialized connective tissue.• Cells in cartilage are found within spaces

called lacunae. • The lacuna allows the cell to be bathed in fluid

from which it receives nutrients and gets rid of wastes by diffusion.

• Cartilage is avascular.

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Features of Cartilage

• It has the basic structure of connective tissue (Cells & Matrix)

• Stiff matrix to resist compression• Avascular• Matrix is mostly water

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Types of Cartilage

3 types1. HYALINE Eg: Nose, trachea, costal cartilages, ends of long bones

2. ELASTIC Eg: External ear, epiglottis

3. FIBROCARTILAGE Eg: Intervertebral discs, pubic symphysis, knee joint

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Hyaline Cartilage

In hyaline cartilage fibers are large and mainly collagen.

The optical density of these fibers is the same as the ground substance surrounding them and as so they are not visible within the extracellular matrix.

Hyaline cartilage appears as a very uniform, glossy type tissue with evenly dispersed chondrocytes in lacunae.

Perichondrium is found around hyaline cartilage.

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Elastic cartilage

• It has dense bundles of elastic fibers.• Perichondrium is also found around elastic cartilage • Found only in the epiglottis and ear.

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Fibrocartilage

It has dense bundles of collagen fibers.No perichondrium.Eg: intervertebral discs and the symphysis pubis.

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Features of bone

• Widely separated cells surrounded by large amounts of matrix containing collagen fibers and mineral salts (mainly calcium and phosphorus).

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Bone cells

• Osteoblasts - bone forming cells - produce matrix

• Osteocytes - mature bone cells• Osteoclasts – phagocytic cells.

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Osteons or Haversian system

• Osteons, or Haversian systems, are the units of structure in mature bone.

• They are tightly arranged running generally parallel to the long axis of the bone.

• At the center of each is an Haversian canal which carries blood vessels and nerves.

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• Canaliculi (small canals) connect the Haversian canals with lacunae containing the osteocytes.

• Osteocytes extend processes into the canaliculi and receive nutrients and get rid of wastes through the canaliculi.

• The lacunae and canaliculi form lamellae or layers of two types: concentric lamellae form circular rings around each Haversian canal, and interstitial lamellae, fill in the spaces between existing osteons.

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• Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal

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Bone or osseous tissue is found in two different forms:

• compact bone • cancellous or spongy bone

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Compact Bone

• Compact bone is a very dense tissue forming the outer layer of all bones and the thickened shafts or diaphyses of long bones.

• In a microscopic view, compact bone always contains numerous osteons or Haversian Systems. Each consists of a central canal through which blood vessels and nerves pass. Surrounding this canal are multiple concentric lamellae or layers of bone.

• Haversian systems are only found in compact bone.

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Cancellous (Spongy) Bone

• One of the most obvious features of cancellous or spongy bone is the absence of Haversian Systems or Osteons.

• During bone formation, the first bone to form is always cancellous. Where compact bone is needed, cancellous bone forms first and later is remodeled into the denser, compact type.

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• Bones of the skeleton contain a combination of both types of bone tissue organization.

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MUSCLE TISSUE

• Made of elongated cells• Found in muscles, heart and glands that

contract• Functions to produce movement.

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• There are three structurally and functionally distinct types of muscles.

• smooth muscle (involuntary, unstriated)• skeletal muscle (voluntary, striated)• cardiac muscle. (involuntary, striated)

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Smooth Muscle

• Smooth muscle consists of spindle shaped cells of variable size.

• Smooth muscle cells contain one centrally placed nucleus.The innervation of smooth muscle is provided by the autonomic nervous system.

• Smooth muscle makes up the visceral or involuntary muscle.

• Eg: walls of hollow organs.

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Skeletal Muscle

• Skeletal muscle consists of very long tubular cells (also called muscle fibres).

• Skeletal muscle fibres contain many peripherally placed nuclei.

• Skeletal muscle fibres show cross-striations. It is therefore also called striated muscle.

• Skeletal muscle is innervated by the somatic nervous system.

• Skeletal muscle makes up the voluntary muscle. • Eg: muscles that move the skeleton

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Cardiac Muscle

• Cardiac muscle consists of muscle cells with one centrally placed nucleus.

• Cardiac muscle is innervated by the autonomic nervous system.

• Cardiac muscle exhibits cross-striations. • Cells branch & joined by intercalated discs.• Cardiac muscle is for these reasons also called

involuntary striated muscle. • Eg: walls of the heart

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