Zoology lecture notes and study materials

Epithelial Tissue: (Types, Structure, Functions & Examples)


classification of epithelial cells

Classification of Epithelial Tissue in Animals

Epithelial Tissue: (Structure, Classification and Functions)
(Structure Classification and Functions of Simple and Compound Epithelium)

What is Epithelium?

Ø  Epithelium is a tissue system in animals.

Ø  Epithelium constitutes the outer layer of body surfaces, linings of the alimentary canal and the walls of hollow structures.

Ø  It covers the internal or external surfaces of the body.

Ø  Epithelial cells are held together by carbohydrate based cementing materials.

Ø  They also possess special junctions between the cells.

Ø  The bottom layer of epithelium is rest on the basement membrane.

Ø  The basement membrane composed of a network of fibrous proteins particularly rich in collagens.

Ø  Epithelial layers are NOT provided with any blood vessels.

Ø  The cells of the epithelium obtain nutrients and oxygen by diffusion from the lymphatic vessels.

Ø  Nerve endings occur in the epithelial tissues for receiving stimuli.

What are the Functions of Epithelial Tissue?

Ø  Epithelium provides protection to the underlying structures.

Ø  Protect organs from injuries by external agencies or pressure.

Ø  Prevent infection by microorganisms.

Continue reading

Zoology lecture notes and study materials

Classification of Arthropoda with Identification Characters for Each Sub-Phylum and Class


How Arthropods further classified

.

Arthropods are classified into five sub-phylum and each then subdivide into classes (a total of 16 classes according to recent classification of animal taxa).

Phylum Arthropoda:

I.   Sub-phylum: Trilobitomorpha (extinct arthropods)

Class 1: Trilobita

II.   Sub-phylum: Chelicerata (spiders, horseshoe crabs)

Class 1: Arachnida
Class 2: Merostomata
Class 3: Pycnogonida

III.  Sub-phylum: Myriapoda (centipedes, millipedes)

Class 1: Chilopoda
Class 2: Diplopoda
Class 3: Pauropoda
Class 4: Symphyla

IV.  Sub-phylum: Crustaceae (crabs, prawns, shrimps)

Class 1: Branchiopoda
Class 2: Remipedia
Class 3: Cephalocarida
Class 4: Maxillopoda
Class 5: Ostracoda
Class 6: Malacostraca

V.   Sub-phylum: Hexapoda (insects)

Class 1: Insecta
Class 2: Entognatha

Continue reading

Zoology lecture notes and study materials

Phylum Arthropoda : General Characters


what are the general characters of phylum arthropoda

Arthropoda is a largest Phylum of Kingdom Animalia, includes about 80% of all known animal species in the biosphere including terrestrial and aquatic biomes. The phylum includes insects, crustaceous, centipedes, millipedes, spiders etc. The word Arthropoda is derived from two Greek words, ‘arthro’ = joint and ‘podo’ = foot. Phylum Arthropoda is characterized by:

@. Segmented body plan

@. Paired jointed appendages

@. Chitinaceous exoskeleton

.

General characters of Phylum Arthropoda:

@. Cosmopolitan distribution

@. Presence of exoskeleton, made of chitin

@. Chitin= a structural homo-polysaccharide of N-acetylglucosamine linked by β-1, 4 glycosidic bond

@. Segmented appearance of body

Continue reading