Organization of Body & Basic Tissues

ORGANIZATION OF HUMAN BODY

TISSUE

Collection of similar cells with similar function is known as tissue.The tissue is studied with the help of microscope (Histology)

Tissues are seen after staining and in laboratory routine stain is haemotoxylin and eosin ( H & E ). In this stain the cytoplasm is pink(acidophilic) and nucleus looks violet / blue (basophilic)

TYPES OF BASIC TISSUES OF THE BODY

1.Epithelial tissue

2.Connective tissue

3.Muscular tissue

4.Nervous tissue

1. EPITHELIAL TISSUE / EPITHELIUM 

Defination: It is one of the basic tissues of the human body which is composed of closely adherent / aggregated  cells with very little amount of extracellular / intercellular material. It is separated from other tissues by basal lamina

TYPES OF EPITHELIUM

A. MEMBRANOUS EPITHELIUM: It is generally known as surface epithelium. In this type the cells are arranged in such a way that they form a  membrane / sheet / layer, and covers the external surface of body or lines the internal surface of a viscus,  tube or cavity.( Epithelium, Endothelium & Mesothelium)

B. GLANDULAR EPITHELIUM / GLANDS: In this cells do not form a membrane / sheet but the cells are arranged into isolated groups with special function of secretion ( enzymes, hormones, lubricants etc). The functional / secretary part of the  tissue is called the parenchyma while the supporting part is called the stroma.

TYPES OF MEMBRANOUS EPITHELIUM

1. SIMPLE / UNILAYERED- i. Squamous ii. Cuboidal iii. Columnar
2.  STRATIFIED / MULTILAYERED- most abundant is Stratified 
3.  squamous cornified & noncornified Pseudostratified ciliated columar 
4. Transitional / Urothelium

1. Simple Epithelium

            

  2. Stratified Epithelium

Stratified squamous noncornified

Transitional

Stratified squamous cornified

Pseudostratified columnar

GLANDULAR EPITHELIUM / GLANDS

1.Exocrine Glands-

2. Endocrine Glands

Ecrine/Merocrine, Apocrine & Holocrine

FEATURES / CHARACTERISTICS OF EPITHELIA

1. Predominentally cellular with little intercellular material

2. Basal surface of epithelia lie over a basal lamina

3. Have ability of regeneration and repair

4. Are  avascular ( No direct blood supply)

5. Have nerve supply

6. Are derived from all the three embryonic germ layers

FUNCTIONS OF EPITHELIA

1. Protection

2. Selective barrier and Diffusion

3. Absorption

4. Secretion / Excretion

5. Sensory eg Olfacory and  Taste bud epithelia

APPLIED ASPECTS OF EPITHELIA:

Apoptosis & Necrosis

Metaplasia: change of one type of epithelium into another type

Tumour / Neoplasm / Cancer / Oncogenesis: Abnormal, uncontrolable and purposeless growth

Benign tumour: slow growth and remains localized

Malignant tumour: rapid growth and invades the surrounding tissue

Metastasis / Secondaries: When the tumour cells from primary site  spread to distant site / organ and start growing there.

Carcinoma: tumour of membranous epithelia

Adenoma: tumour of glands

APOPTOSIS (Programmed / Natural Cell Death).

CONNECTIVE TISSUE

Defination: It is one of the basic tissue which comprises of relatively few cells and abundant amount of intercellular / extracellular matrix. It connects and supports the other tissues of the body. It is reverse to epithelial tissue

Components:

A.CELLS

B.Extracellular / Intercellular matrix ( Fibres + Ground Substance).

OR

1.Cells

2.Fibres ( collagen, reticular & elastic)

3.Ground Substance

TYPES / Classification of C.T

1.Connective tisuue proper e.g fascia, tendon, ligaments; cellls- Fibrocytes

2.Adipose & Reticular tissue; cells-Adipocytes & Reticulocytes

3.Bone; cells-Osteocytes

4.Cartilage; cells-Chondrocytes

5.Blood; cells- Erythrocytes & Leukocytes

LOOSE CONNECTIVE TISSUE

MUSCULAR TISSUE

Definition: It is one of the basic tissues which consists of long cells known as muscle cells / muscle fibres. The cell cytoplasm contains contractile filaments (actin & myosine). The basic property of this tissue is that it shows contractility hence producing the movement.

NERVOUS TISSUE

Definition: It is one of the basic tissue which consists of nerve cells proper (neuron) and supporting cells (neuroglia).

The property of this tissue is to receive the stimuli (impulses), propagates them to the centre and produces the response of the stimuli. The neuron has a cell body (soma) and processes (neurites as axon & dendrites).