Digestive System The digestive system is complete with a mouth and an anus. The alimentary canal present in the body cavity is divided into three regions: foregut, midgut and hindgut. Foregut– Pharynx, Oesophagus, Crop and Gizzard The mouth opens into a short tubular pharynx, leading to a narrow tubular passage called oesophagus. This in turn … Read more
Morphology Cockroaches are household pests. They are usually black or brown bodied. They are also the vectors of several diseases. Habitat Cockroaches are nocturnal omnivores. They are found in wet and damp places. External appearance Cockroaches are triploblastic and bilaterally symmetrical organisms. They have a dorsoventrally compressed body. The size can range from 1 to 3 inches. The … Read more
Earthworms are hermaphrodites. Testis and ovary are present in the same individual. Male reproductive organ Two pairs of testis are present in the 10th and 11th segments. The vas defferentia from the testis joins the prostatic duct in the 18th segment. Paired Accessory glands at present in the 17th and 19th segments. The prostate gland and the spermatic … Read more
Body wall The body wall of earthworm has an external covering of a thin, flexible cuticle. The cuticle has many perforations, though which epidermal glands release their secretions. The epidermis consists of Columnar cells (supporting cells) Glandular cells (which secrete mucus) Sensory or receptacle cells (receives various types of stimuli) Basal cells (present between columnar … Read more
Earthworm is a reddish brown terrestrial invertebrate. They are commonly known as ‘Friends of Farmers’ since they increases the fertility of soil. The most common Indian earthworms are Lampito mauritii (Syn. Megascolex mauritii), Perioynx excavatus and Metaphire posthuma (Syn. Pheretima posthuma). Habitat It usually occupies the upper moist layers of soil which is rich in decaying organic matter. … Read more
The nervous tissue is composed of densely packed nerve cells commonly known as neurons. The neurons are capable of conducting nerve impulses. The nervous tissue arises from ectoderm of a growing embryo. Neurons There are more than 100 billion neurons in a nervous system. They vary in shape and size. All neurons have 3 main … Read more
The muscle cells are also known as muscle fibres because they are thin, long and cylindrical. They are arranged parallel to each other. The muscle fibres are composed of numerous fine fibrils called myofibrils. The muscular tissue is responsible for locomotion and various types of movements in the body organs. The contraction and relaxation of … Read more
Connective tissue is the most abundant tissue found in an animal body. They have large amount of extracellular materials called the matrix. The cells are widely separated. They are termed connective tissue because their main function is to link and support all other tissues in the body. Connective tissue includes cartilage, bones, adipose tissue, blood … Read more
Glandular Epithelium Glands are secretory structures formed by secretory epithelium. Some columnar or cuboidal epithelium gets specialized for secretion and is called glandular cells. They are of 2 types. Unicellular Glands: It consists of small isolated patches of secretory epithelium scattered in the inner lining. (E.g. Goblet cells in the intestinal mucosa.) Muticellular glands: It … Read more
All complex animals consist of only four types of cells. These cell types vary in structure according to their function. The basic classification of animal tissues is as follows: EPITHELIAL TISSUE Cells of epithelial tissue form a layer on free surfaces which either faces a body fluid or faces the external environment. Hence, it either … Read more