Post on 27-Dec-2015
Digestion
The process of breakdown of complex food molecules into simple molecules.
Process involves Ingestion (Intake of Food) Digestion( breakdown of food) Absorption ( Movement of digested food into
the blood stream) Assimilation (The process by which cell use
the food for cellular build up and processes) Egestion ( removal of waste as solid form)
Classification of organisms on the basis of nutrition
Nutrition: The process of intake of food and its conversion into living protoplasm in cells.
Autotrophs- Organisms which can prepare their food
Heterotrophs- Organism which cannot prepare their own food due to lack of chlorophyll.
Holophytic Nutrition: the mode of nutrition in which living organisms use inorganic material to prepare their own food
Holozoic Nutrition: The mode of nutrition in which living organisms ingest food from outside and digest it in their body to obtain energy.
Classification of Heterotrophs
Herbivores Carnivores Omnivores Parasites Scavengers Saprophytes Sanguivores.
Nutrition in Plants
Plants are autotrophs and therefore prepare their own food by the process of photosynthesis.
Photosynthesis: The process by which green plants prepare their own food in the presence of sunlight utilizing chlorophyll, CO2, water and minerals.
Structure of Leaf-
1. Cuticle2. Upper epidermis3. Pallisade parenchyma4. Bundle sheath5. Xylem6. Phloem7. Lower epidermis9. Spongy parenchyma10. Guard cells11. Intercellular spaceThe cells between the upper andlower epidermis are calledmesophyll cells.
Process of Photosynthesis
Photosynthesis is a two phase process:Light Reaction -Light dependent reaction takes
place in the thylakoids in grana.During this phase-a) Light is absorbed by photosensitive pigment
chlorophyll present in the thylakoids.b) Photolysis of water takes place. This forms
H+ ions. c) The energy currencies ATPs are generated.d) Reducing agent NADPH are formed.
Dark Reaction -Light independent reaction takes place in the stroma or the matrix of the chloroplast.
During this reaction –
a) CO2 is reduced into carbohydrates
Nutrition in Amoeba
In amoeba, The food is engulfed by the process of phagocytosis, and then digested intracellularly by enzymes.
Waste is expelled out by the Contractile Vacuole
Structure of the alimentary canal
Mouth- Oral cavity or Buccal cavity. Lined by squamous epithelial tissue. Contains tongue, teeth, salivary glands. Tongue – muscular organ used for taste, mixing food
and cleaning the oral cavity. Teeth- set of teeth is called Dentition. Human dentition is Heterodont (4 kinds of teeth),
Thecodont (Tooth in sockets in gums), Diphydont (Formed twice)
Teeth help in mastication of food.
Structure of the alimentary canal
Oesophagus Muscular tube connecting oral cavity to the
stomach Conveys masticated food (bolus) by waves of
relaxation and contraction – This is called Peristalsis.
Structure of the alimentary canal
Stomach Main organ of digestion Highly muscular Food is further churned and broken into simpler
molecules by the action of enzymes. Inner lining of stomach is called Mucosa. Stomach contains gastric cells that secrete HCL and
gastric juice. Entry of food guarded by Cardiac Sphincter and Exit
of food regulated by Pyloric sphincter.
Structure of the alimentary canal
Small Intestine Divided into three parts : Duodenum, Jejunum
and ileum Longest part of the alimentary canal. Site for digestion and absorption of digested
food (maximum) Inner lining folded into finger like projections
called villi. Receives digestive juices from liver, gall
bladder and pancreas.
Structure of the alimentary canal
Large intestine Divided into : Caecum, colon rectum and
anus. Most of the water is absorbed from the waste. Stores solid waste (faeces) in the rectum
temporarily. Exhibit muscular contractions and relaxation
called bowel movements – helping in defecation.
The exit is guarded by the anal sphincter
Structure of Associated Glands
Salivary glands- present in the oral cavity. Three pairs called parotid, sub maxillary and
sub-lingual Secretes saliva containing enzyme – salivary
amylase and a bactericidal enzyme called lysozyme.
Structure of Associated Glands
Liver The largest gland of the body Exocrine in nature Synthesizes and Secreted Bile. Regulates blood sugar by storing excess glucose as
glycogen Stores iron Converts excess amino acids into urea Manufactures fibrinogen and heparin( natural anti-
coagulant) Detoxifies body metabolites. Stores Vitamin a and D
Structure of Associated Glands
Pancreas Lobed mixed gland Secretes pancreatic juice Also secretes hormones Drains its secretions through the common bile
duct.
Process of digestion of food
Region of Alimentary Canal
Digestive glands
Digestive Juice
Enzyme in the juice
Class of food acted upon
Substance produced
Notes
Mouth Salivary Glands
Saliva Salivary amylase
Starch Maltose Slightly acidic or neutral; Mucus help form bolus
Stomach Gastric glands Gastric juice Pepsin Proteins Peptides and peptones
0.5% Hcl provides acidic medium for pepsin
Rennin Milk protein Clots milk
Duodenum Pancreas Pancreatic Juice
Trypsin Peptides and peptones
Amino acids Bile emulsifies fats and aids in their absorption into lacteals; Doudenum contents are slightly acidic.
Amylase Starch Maltose
Lipase Fats Fatty Acids and Glycerol
Process of digestion of food
Region of Alimentary Canal
Digestive glands
Digestive Juice
Enzyme in the juice
Class of food acted upon
Substance produced
Notes
Liver Bile No enzymes but has sodium salts and bile pigments
Fats Emulsified fats Sodium salts provide alkaline medium
Ileum Lining of the ileum
Succus Entericus
Erepsin Peptides Amino Acids Most absorption occurs in the ileum
Lipase Fats Fatty acids and Glycerol
Maltase Maltose Glucose
Sucrase Sucrose Glucose and Fructose
Lactase Lactose Glucose and Galactose