• Human anatomy,  Zoology

    NERVOUS SYSTEM

    Nervous system is the most complex system in human. Its uniqueness is due to the vast complexity of thought process and control action it can perform. It co-ordinates physiological functions in human. Nervous tissue originates from ectoderm and is specialized for receiving stimuli and transmitted message. The nervous tissue consists of highly specialized cells called the neurons. Thus neurons are functional unit of nervous system. The detailed structure of a neuron is shown in Figure. A neuron is mainly divided into two parts: 1) Cell body or cyton and 2) Cell process. Cyton It is broader part of neuron which contains uninucleated cytoplasm. Except for centriole, all type of cell organelles…

  • Biology,  Human anatomy

    HUMAN DIGESTIVE SYSTEM

    Digestion involves the breaking of complex organic food molecules into simpler one by hydrolysis. Carbohydrates, proteins, fats and nucleic acids are large complex organic food molecules. They are insoluble and polymeric in nature. During digestion different enzymes helps in the breakdown of these complex polymers into soluble monomers which are required for energy generation. The different steps of digestion involve: Movement of food through the alimentary tract Secretion of digestive juices and digestion of food Absorption of water, various electrolytes, vitamins and digestive end products. Human digestive system mainly consists of two parts: 1) Alimentary tract and 2) secretory glands Alimentary tract: It provides continuous supply of nutrients, vitamins, electrolytes…

  • Biochemistry

    DIGESTIVE SYSTEM

    DIFFERENT MODE OF DIGESTION IN ORGANISMS The collective processes by which a living organism takes food which are necessary for their growth, maintenance and energy needs is called nutrition. The chemical substances present in the food are called nutrients. It is important to know the different modes of nutrition in all living organisms in order to understand energy flow within the ecosystem. Plant produces high energy organic food from inorganic raw materials. They are called autotroph and the mode of nutrition is known as autotrophic nutrition. Animals feed on those high energy organic food, are called as heterotrophs and their mode of nutrition is known as heterotrophic nutrition. Heterotrophic nutrition…

  • Biochemistry

    BIOTECHNOLOGY

    The word biotechnology has come from two words, bios (meaning biology) and technology (meaning technological application). Thus biotechnology is defined as the industrial application of living organisms and their biological processes such as biochemistry, microbiology, and genetic engineering, in order to make best use of the microorganisms for the benefit of mankind. Biotechnology is applied in many areas to produce foods and medicines, in the development of new diagnostic tools, gene therapy, and DNA finger-printing for forensic purposes. Applications of Biotechnology 1. Health and medicine Fighting infectious diseases: Biotechnology is used extensively in the study of infectious diseases such as SARS (Severe Acute Respiratory Syndrome), and influenza. As a result, more…

  • Biochemistry

    ORIGIN OF LIFE

    The earth was formed about five billion years ago. At that time it was extremely hot. The existence of life in any form at that high temperature was not possible. As such, two questions arise pertaining to life: 1. How did life originate on earth? 2. How did primitive organisms evolve into new forms resulting in the evolution of a variety of organisms on earth? Origin of life means the appearance of simplest primordial life from nonliving matter. Evolution of life means the gradual formation of complex organisms from simpler ones. Chemosynthetic Theory of Origin of Life Several theories have been put forth to explain the origin of life. The…

  • Biochemistry

    Krebs (Citric Acid) Cycle

    It is also known as TriCarboxylic Acid (TCA) cycle.  In prokaryotic cells, the citric acid cycle occurs in the cytoplasm; in eukaryotic cells, the citric acid cycle takes place in the matrix of the mitochondria. The cycle was first elucidated by scientist “Sir Hans Adolf Krebs” (1900 to 1981). He shared the Nobel Prize for physiology and Medicine in 1953 with Fritz Albert Lipmann, the father of ATP cycle. The process oxidises glucose derivatives, fatty acids and amino acids to carbon dioxide (CO2) through a series of enzyme controlled steps. The purpose of the Krebs Cycle is to collect (eight) high-energy electrons from these fuels by oxidising them, which are transported…

  • Biology,  Zoology

    Phylum Cnidaria/Coelenterata

    Kingdom: Animalia Habitat: aquatic, mostly marine. Habit: solitary or colonial. Each individual is known as zooid. Symmetry: radially symmetrical Grade of organization: tissue grade of organization. Germ layer: diploblastic, outer ectoderm and inner endoderm. Mesogloea separates these two layers. The body has a single opening called hypostome surrounded by sensory tentacles. Coelom: gastrovascular cavity or coelenteron. Nematocyst: organ for capturing and paralyzing pray, present in tentacles Nutrition: holozoic Digestion is both intracellular and extracellular. Respiration and excretion are accomplished by simple diffusion. Circulatory system: absent Nervous system: poorly develop, Many forms exhibit polymorphism ie. Polyp and medusa. Polyps are sessile, asexual stage. Medusa are free swimming, sexual stage Metagenesis: asexual…

  • Biochemistry

    Phylum Porifera

    Kingdom: Animalia Habitat: Aquatic, mostly marine, few are terrestrial Habit: They are solitary or colonial. Grade of organization: cellular grade of body Shape: Body shape is variable, mostly cylinder shaped Symmetry: Asymmetrical or radially symmetrical. Germ layer: Diploblastic animals. The adult body wall contains two layers, outer dermal layer and inner gastral layer. In between these two layers, there is a gelatinous and non-cellular mesoglea containing numerous free amoeboid cells. Coelom: Absent; acoelomate but spongocoel is present Surface of the body has numerous perforation called ostia (for the entry of water) and a large pore at the apex called osculum (for the exit of water). Water canal system present Endoskeleton:…

  • Biochemistry

    Glycolysis

    Carbohydrates are the first cellular constituents formed by photosynthetic organisms and result from the fixation of CO2 on the absorption of light. The carbohydrates are metabolized to yield a vast array of other organic compounds, many of which are subsequently utilized as dietary constituents by animals.The animals ingest great quantities of carbohydrates that can be either stored, or oxidized to obtain energy as ATP, or converted to lipids for more efficient energy storage or used for the synthesis of many cellular constituents. The major function of carbohydrates in metabolism is as a fuel to be oxidized and provide energy for other metabolic processes. The carbohydrate is utilized by cells mainly…

  • Human anatomy

    Human Eye: Anatomy, parts and structure

    The eye is the photo-receptor organ. Size and shape: Human eye is spherical about 2.5 cm in diameter. Location: it is situated on an orbit of skull and is supplied by optic nerve. There are 6 sets of muscles attached to outer surface of eyeball which helps to rotate it in different direction. Four sets of these muscles are straight muscles; superior, inferior, medial and lateral rectal muscle and two sets are oblique muscles; superior and inferior oblique muscles. Structurally two eyes are separated but some of their activities are coordinated so that they function as a pair. Anatomical structure of Eye Eye ball consists of three layers Outer fibrous…