end organ damage

Causes of Cancer Substances that cause cancer are called carcinogens. Normal cells can be converted to cancer cells by treatment with a wide variety of chemicals, ionizing radiations and several DNA and RNA-containing viruses. Radiations (e.g., solar ultraviolet radiation, major cause of skin cancer) and many chemicals carci..

;The soil particles pass dirough the alimentary canal of the earthworm. They are broken into fine state. Such a soil comes to have higher water holding capacity. 4. Worm castings of the animal are rich in organic matter and several mineral salts like K + , Mg 2+ , P0 4 3 ", Ca 2+ , NO3- etc. 5. Like any other animal, earthworm adds nitro..

Entamoeba histolytica causes amoebic dysentery or amoebiasis and abscess formation in the liver, lungs and brain. 1. Amoebic Dysentery. The proteolytic enzyme secreted by the parasite damages the mucous membrane of the intestine. This may result in the formation of bleeding ulcers that cause dysentery. In dysenter..

. Mutations are inherited when their causative genes are copied during DNA replication and passed on to the cell's descendants. Mutation in a somatic (body) cell may cause changes in the hereditary characteristics of the cell, and may causc damage, including cancer, to the body parts formed of the decendants of that cell. Mutation in a g..

. 5. Response. The processed message may elicit a response in the form of a sensation like pain or an action like secretion by a gland or contraction by a muscle. 6. Origin. Nerve tissue is ectodermal in origin. 7. Extracellular Matrix. An extracellular matrix is absent. 8. Connective Tissue. A special connective tissue is associated with nerve ce..

The acoustico-lateralis system consists of (a) lateral line system having neuromasts, (6) pit organs, (c) ampullae of Lorenzini, and (d) the internal ear. These organs are in a common system because they are similar in development and struoture, with similar sensory cells, and they receive stimuli through a liquid me..

Q.16. Why is the atmosphere essential for life ? Ans. (i) Oxygen. Atmosphere contains oxygen which is essential for combustion and respiration of most organisms. (ii) Carbon Dioxide. Atmosphere provides carbon dioxide for photosynthesis of plants. (iii) Protection. Atmosphere filters out lethal cosmic ra..

. The waves of impulses pass along the nerve fibres. Transmission of nerve impulse The'receptor cells in the sense organs are sensitive to stimuli. Any perceptible change in the environment, external or internal is a stimulus. The dendrites which penetrate deep into the receptor cells receive the impulses or the neural message in the rec..

(a) Otolith Organ. It is the central sac of membraneous labyrinth which is suspended into the bony labyrinth by trabeculae of connective tissue. It has two chambers : (i) Upper larger utriculus (ii) Lower smaller sacculus. The two are connected through a narrow utriculosaccular duct. From the posterior end of sacc..

Sensory Organs or Receptor Organs The sense organs or the receptor organs of Hirudinaria are especially modified epidermal cells. There are four types of receptor organs: 1. Nerve endings : 2. Annular receptors .3. Segmental receptors and 4. Eyes. Nerve Endin..