Anas Zoology

  Eukaryotic Cell Eukaryotic Cell The cells which contain true nuclei are called eukaryotic cells. Eukaryotic cells are found in animals, plants, algae and fungi. They are larger in size as compared to prokaryotic cells. The cells may vary in shape, size and physiology but they all have a typical structure with little variations in number and location of cellular organelles. The eukaryotic cell have a outer covering membrane called plasma membrane / cell membrane. Inside the cell a membrane-bound nucleus is present. Between the nucleus and plasma membrane, cytoplasm is present in which various cellular organelles like mitochondria, golgi complex, centrioles etc can be seen. ✱ Shape: Eukaryotic cells exhibit diversity. They can be spherical, triangular, tubular, cuboidal, polygonal, cylindrical, oval, rounded or elongated. Shape of cells may vary from organ to organ. A single organ may show variations in shape of cell. ✱ Size: Eukaryotic cells are microscopic. They are larger in size

The stratified epithelium tissue consist of two or more layers of cells.  An epithelium tissue consist of cells that form membranes, which cover and line the body surfaces and glands.  The stratified epithelium tissue can be further classified in 4 types: Stratified Squamous Epithelium Stratified Cuboidal Epithelium Stratified Columnar Epithelium Transitional Epithelium 1) Stratified Squamous Epithelium: Description: There are several layers of cells which are cuboidal to columnar in shape. The apical cells are squamous and basal cells are cuboidal or columnar. Location: Forms superficial layer of skin (Keratinized form), lining of mouth, oesophagus, part of epiglottis and also covers the tongue. Function: Protection (against microorganisms and water loss) 2) Stratified Cuboidal Epithelium: Description: Several layer of cells in which the cells are cube shaped in both the apical surface and basal surface. Location: Pancreatic duct, Sweat glands. Function: Protection, absorption and sec

The simple epithelium tissue consist of a single layer of cells. An epithelium tissue consist of cells that form membranes, which cover and line the body surfaces and glands. The simple epithelium tissue can be further classified into 4 types: Simple Squamous Epithelium Simple Cuboidal Epithelium Simple Columnar Epithelium Pseudostratified Columnar Epithelium Simple Squamous Epithelium: Description: Single layer of cells with a centrally located nucleus. The cells are flat. Location: Lines the heart, blood vessels, bowman's capsule, air sacs of lungs and inner surface of the eardrum (tympanic membrane). Function: Filtration, diffusion and osmosis. Simple Squamous Epithelium Simple Cuboidal Epithelium: Description: Single layer of cells with a centrally located nucleus. The cells are cube shaped. Location: Surface of ovary, anterior surface of eye lens, lines the kidney tubules, found in the ducts of pancreas. Function: Secretion and absorption. Simple Cuboidal Epithelium Simple Col

 The skin and their associated structure make up the integumentary system. Skin protects terrestrial organisms from desiccation and from heat loss. The largest organ of mammal is skin. It protects the body against physical,chemical, and biological attacks, it helps to regulate body temperature, it is used to communicate to other individuals, and a skin derivative provides nourishment for the young. Mammal skin is composed of two layers, the dermis and the epidermis. Below the dermis there is a layer known as hypodermis, some may consider this as the third layer of skin. HISTOLOGY OF SKIN : Skin has four layers of cells is referred to as thin skin. From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum and stratum corneum. Most part of the skin can be classified as thin skin. Thick skin is found only on the palms of the hands and the soles of the feet. It has a fifth layer, called the stratum lucidum, which is located between the stratum corn

 1) SQUAMOUS EPITHELIUM: It is a type of simple epithelial tissue. It forms the lining of the oral cavity, oesophagus, alveoli of lungs, blood vessels, kidney tubules etc. The cells are polygonal, flattened and resting over a basement membrane. They look like the tiles of a floor, hence are also called as pavement epithelium. Each cells shows a clear cytoplasm with the nucleus in the centre. The cells are closely packed with very little intercellular substance called matrix. They form a thin sheet and provide protection to the underlying tissue. 2) MUSCLE FIBRE: A) Smooth/Unstriated Muscle Fibre: It is a type of muscular tissue in the visceral organ. It occurs in the forms of layers or bundles in the wall of the hollow organs like the alimentary canal, blood vessels, trachea, urinary bladder. The muscle cells(fibres) are spindle shaped, tapering at both the ends and broad in the centre. Each cells shows a central nucleus surrounded by cytoplasm called sarcoplasm. There are myofibrils i