HISTOLOGY

حيوان Zoology 106عملي

Biological tissue is a group of cells that perform a similar function.

Cells-->tissues-->organ-->system-->individual

The study of tissues is known as histology,

Orin connection with disease ,histopathology

What are Tissues?

The word tissue is derived from a Latin word meaning to "weave." Cells that make up tissues are sometimes "woven" together with extracellular fibers. Or part of an organism consisting of an aggregate of

cells having a similar structure and function .

Likewise, a tissue can sometimes be held together by a sticky substance that coats its cells.The fundamental types of tissues in animals are epithelial, nerve, connective, muscle, and vascular

tissues.

1 .Epithelial TissueThe covering of internal and external surfaces of the body, including the lining of vessels and other small cavities. It consists of cells joined by small amounts of

cementing substances .

Function:-helps to protect organisms from microorganisms ,

-injury, and fluid loss.- Lining of mouth and nose, internal surface of GIT ,

-respiratory system, genitalia and urinary system.

-

-characterized by bonding of each cells together- -has thin layer that supports cells called basement membrane (on

which epithelium can grow and regenerate after injuries).-name is derived from the number of cells and shape of cells

Epithelium is classified according to number of cells:1.Simple- composed of single layer of cell (found where

absorption and filtration occur) .2 .Stratified- composed of two or more layers of cells

3 .Pseudostratified

Epithelium is classified according to shape of cells 1 .Columnar

2 .Cuboidal3 .Squamous

Simple Columnar Epithelium

Stratified squamous epithelium

Stratified columnar epithelium

2 .CONNECTIVE TISSUES-to support, anchor and connect various parts of the

body

Connective tissue proper1.Adipose - adipocytes that store fat (little matrix) –

around eyes and kidneys

2 .Areolar (loose) – fibroblasts and a matrix of tissue fluid, collagen, and elastin fibers –

The fibres of areolar connective tissue are arranged in no particular pattern but run in all directions and form a

loose network in the intercellular material  .

Collagen (collagenous) fibres are predominant. They usually appear as broad pink bands  .

Some elastic fibres, which appear as thin, dark fibres are also present .

Microscopic view of areolar connective tissue.

Loose or areolar connective tissueName the

arrows

Schematic representation of the adipose connective tissue.

Quiz Draw the ACT

Enlarged microscopic view of adipose connective tissue.

microscopic image adipose tissue

3 .Muscle TissueFunction: Specialized for contraction

Specific terms for muscle tissue:

.1 muscle cells – fibres.2 cytoplasm - sarcoplasm;

3 .cell membrane- sarcolemma.

Three types of muscle tissue according to its structure, function and location :

a. Skeletal or striated b. Smooth

c. Cardiac

SSC

a. SKELETAL (STRIATED) MUSCLE CELLS

Characteritics of skeletal muscle cell1 .Highly modified

2 .Giant3 .Have lots of cells (fiber)

4 .Each fiber is cylindrical in shape5 .Nucleus is located at the edge of the cell inside the

sarcolemma.6 .Cross- striped (or striated) appearance of light and dark

banding7 .Voluntary (contraction under conscious nervous control)

                      

  

Schematic Representation of Skeletal Muscle Tissue

Microscopic view of skeletal muscle tissue (tongue)

Label the skeletal muscle fiber (section of a tongue)

Microscopic view of skeletal muscle tissue

3 .CARDIAC MUSCLE TISSUE -Cardiac muscle is a highly specialized tissue restricted

to the wall of the heart  .

-It is also an involuntary type of muscle, as its contraction is not consciously controlled.

-Intercalated discs- junction of one cell with one another

Schematic representation of cardiac muscle tissue

Heart muscle showing branching fibers