Bioniac

            In the previous posts, we have discussed the anatomy of digestive system and the process of digestion. In this post we are going to discuss the process of absorption of digested food and diseases related to digestion. For the previous post (Part-1) click  here  and for the next post (Part-2) click  here . Absorption   of   Digested   Food •Absorption is the process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph.  •It is carried out by passive, active or facilitated transport mechanisms.  •Small amounts of monosaccharides like glucose, amino acids and some electrolytes like chloride ions are generally absorbed by simple diffusion. •The passage of these substances into the blood depends upon the concentration gradients. •However, some substances like glucose and amino acids are absorbed with the help of carrier proteins.  •This mechanism is called the f...

           In the previous post, we have discussed the anatomy of digestive system in brief. In this post we are going to discuss the process of digestion. For the previous post click  here . Process of Digestion : •It is completed in mechanical and chemical method.  •The buccal cavity performs two major functions, mastication of food and facilitation of swallowing.  •The teeth and the tongue with the help of saliva masticate and mix up the food thoroughly. •Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus. •The bolus is then conveyed into the pharynx and then into the oesophagus by swallowing or deglutition.  •The bolus further passes down through the oesophagus by successive waves of muscular contractions called peristalsis .  •The gastro-oesophageal sphincter controls the passage of food into the stomach. •The saliva secreted into the oral cavity contains electrolytes such as Sodiam ...

         In this post, we are going to discuss the anatomy of Digestive systems on brief accounts.           Food is one of the basic requirements of all living organisms which provides us with energy and organic materials in order to survive. The major components of our food are carbohydrates, proteins and fats. Vitamins and minerals are also required in small quantities. The water we take in, plays an important role in metabolic processes and also prevents dehydration of the body. Biomacromolecules in food cannot be utilised by our body in their original form. They have to be broken down and converted into simple substances in the digestive system. This process of conversion of complex food substances to simple absorbable forms is called digestion and is carried out by our digestive system by mechanical and biochemical methods. Components of Digestive system :           Our digestive system is consists o...

Phylum – Arthropoda • This is the largest phylum of Animalia which includes insects .  • Over two-thirds of all named species on earth are arthropods  •They have organ-system level of organisation. •They are bilaterally symmetrical , triploblastic , segmented and coelomate animals.  • The body of arthropods is covered by chitinous exoskeleton .  • The body consists of head, thorax and abdomen .  •They have jointed appendages ( arthros-joint , poda-appendages ). • Respiratory organs are gills , book gills , book lungs or tracheal system . • Circulatory system is of open type. • Sensory organs like antennae , eyes ( compound and simple ), statocysts or balancing organs are present. • Excretion takes place through malpighian tubules . • They are mostly dioecious .  • Fertilisation is usually internal . • They are mostly oviparous . • Development may be direct or indirect . Examples:  • Economically important insects – Apis (Honey bee), Bomby...

Phylum – Annelida • Latin , annulus : little ring • May be aquatic ( marine and fresh water ) or terrestrial ; free-living , and sometimes parasitic . •They exhibit organ-system level of body organisation and bilateral symmetry .  • T riploblastic , metamerically segmented   • coelomate . • Their body surface is distinctly marked out into segments or metameres  , which is why the phylum name is  Annelida   •They possess longitudinal and circular muscles which help in locomotion.  • Aquatic annelids like  Nereis possess lateral appendages ,  parapodia , which help in swimming.  • Circulatory system Closed .  • Nephridia (sing. nephridium ) help in osmoregulation and excretion. • Neural system consists of paired ganglia (sing. ganglion ) connected by lateral nerves to a double ventral nerve cord . • Nereis , an aquatic form, is dioecious , but earthworms and leeches are monoecious . • Sexual   Reproduction. Example: • Ne...

Phylum – Aschelminthes • Body is Circular   in cross-section. • Also called ROUNDWORM . • Free-living , aqatic , terrestrial , parasitic . •  Organ   level   of   body   organisation   is seen • Bilaterally   Symmetrical , Triploblastic , Pseudocoelomate . • Alimentary canal complete   with well developed Muscular   Pharynx . • Body waste is removed by an Excretory   Tube   through an Excretory   Pore . • DIOECIOUS   (Sex is seperate) • Oftern seen that Female are longer   than male • Internal   Fertilization • Development Direct / Indirect . Exmple: •   Ascaris (Roundworm) • Wuchereria   (Filaria worm) • Ancylostoma (Hookworm) Example of Aschelminthes: Ascaris

Phylum – Platyhelminthes • Dorso - ventrally   flattened   body structure(thats why it is called Flatworms ) • Mostly Endoparasitic • Bilaterally   symmetrical , Triploblastic , Acoelomate • Flatworms show Body - Level   of   Organisation . • In Parasitic form, Hooks   and Suckers   are present • Flame   Cells   help in Osmoregulation   and Excretion . • Hermaphrodite • Flatworm named Planeria   show high regenaration capacity. • Internal   fertilization. • Development through many larval stages. Example: •  Taenia (Tapeworm) •  Fasciola (Liver fluke)