What Is Nutrition?
Nutrition is the process of transfer of energy source from outside to the body of living organisms, providing energy necessary for performing basic life processes like nutrition, respiration, reproduction, etc. Energy is needed by all living organisms to perform life activities.
What are Nutrients?
- Nutrients are the energy providing substances which are consumed by living beings.
- All living organisms need nutrients to build up most of their own body molecules and to get energy for doing work.
Modes of Nutrition
Depending upon the modes of obtaining nutrients, the organisms are divided into
- Autotrophic nutrition
- Heterotrophic Nutrition
Autotrophic nutrition is the mode of nutrition performed by green plants; some bacteria etc., for manufacturing their own food from inorganic sources, i.e. CO₂ and water. These organisms are called autotrophs.
What is Photosynthesis ?
Photosynthesis is the process by which green plants synthesize organic food as carbohydrates in the presence of sunlight, chlorophyll, water, Carbon Dioxide , and some other raw materials.
- Chlorophyll is green coloured photosynthetic pigments.
- Photosynthesis occurs only in those cells which possess chlorophylls.
Chloroplasts are the site of photosynthesis, present in leaves of a plant. They contain a green coloured pigment, chlorophyll that traps solar energy from the Sun.
2 Steps Of Photosynthesis
Photosynthetic process occurs in two steps
- Light reaction
- Dark reaction
- Light reaction occurs in the grana thylakoids of chloroplasts and dark reaction occurs in the Stroma.
- In light reaction, the green pigments – chlorophylls absorb light, become excited, emit electrons which travel through electron transport chains and water is photo oxidized to evolve molecular 0₂.
- In a dark reaction, the carbon dioxide is reduced to carbohydrate by the Calvin-Benson cycle. ReadMore…
- The heterotrophs cannot synthesize their own food, but are dependent on the autotrophs for their nutrition.
- Nutrition in animals is heterotrophic that is mostly holozoic.
- The holozoic animals may be herbivorous, carnivorous or omnivorous. Human beings are omnivorous. Readmore..
3 Important types of Heterotrophic Nutrition
- Holozoic Nutrition (e.g. Amoeba, humans) Read More…
- Saprotrophic Nutrition (e.g. fungi)
- Parasitic Nutrition (e.g. ticks, lice, leech, etc.)
Nutrition in Amoeba
- Amoeba, which is a unicellular omnivore, gathers and ingests food with the help of pseudopodia.
- Amoeba engulfs food by the process of phagocytosis using pseudopodia.
- It lacks special organs for nutrition.
Nutrition In Human Beings
Nutrition in human beings involves the breakdown of complex substances ingested from outside in the body by different parts of the Alimentary Canal. Read More..
Human Digestive System
Human digestive system consists of the alimentary canal, i.e. a tube-like structure consisting of
- Buccal cavity
- Small intestine
- Large Intestine
- Digestive juices.
- Mouth is the first part of the digestive system which helps in the intake of food.
- Tongue is a muscular organ which bears taste buds. It also helps in mixing the chewed food with saliva.
- Teeth help in chewing food.
- Mouth opens into a buccal cavity that further opens into the pharynx.
- Buccal cavity contains teeth and tongue. It receives saliva from 3 pairs of salivary glands.
Esophagus or the food pipe helps in the transfer of food from mouth down to the stomach.
- Stomach is a J-shaped organ which stores and partially digest the food entering through the food pipe.
- Stomach receives gastric juice from numerous microscopic gastric glands.
- Intestine is the main organ of digestion and absorption.
- Small intestine is a long, greatly coiled tube.
- Small intestine is longer in length compared to the large intestine.
- Small intestine receives bile and pancreatic juice by bile-pancreatic duct.
- Larger part of the small intestine releases intestinal juice which completes the digestion of food.
- The digested food is absorbed in the small intestine and goes into the blood.
- The small intestine opens into the large intestine where water is absorbed from the digested food.
- Bloodstream carries digested food into the cells where it is utilized. The utilization of food is called assimilation.
- Anus is the end point of the alimentary canal from where the waste is removed out from the body.
5 Important Digestive Glands
- Salivary Glands
- Gastric Glands
- Intestinal glands
- Pancreas and
- Salivary glands (in mouth) secrete saliva containing salivary amylase which helps in the digestion of starch.
- Saliva also contains mucin and starch digesting enzyme ptyalin.
Gastric Glands present in the stomach secrete digestive juice
Gastric juice contains –
- HCl, which disinfects the food and activates protein degradation,
- Pepsin and rennin break proteins into proteoses and peptones
- Gastric lipase converts some fats into monoglycerides and fatty acids.
Intestinal Glands present in the walls of the Small Intestine secrete intestinal juice containing amylolytic, proteolytic and lipolytic enzymes.
- Liver is the largest gland of our body and it secretes bile juice for emulsification of fats.
- Bile contains bile salt and bile pigments. Bile salts emulsify fats to facilitate the action of lipase.
- Pancreas secretes pancreatic juice containing trypsin, amylase and lipase enzymes.
- Pancreatic juice has 3 inactive Proteases, Pancreatic amylase and Pancreatic Lipase.
Process Of Digestion
The process of digestion in all involves
- Ingestion- Intake of food by mouth
- Absorption -Passage of digested food from alimentary canal to blood,
- Assimilation- Distribution of digested food to cells of the body
- Egestion- The elimination of undigested food (waste) from the body.
What is Respiration ?
- Respiration can be defined as the biochemical process in which the food (respiratory substrate) is oxidized to release energy in the form of ATP.
- As a catabolic process, it causes biochemical oxidation of nutrients such as glucose.
- The first step in respiration is breathing, a kind of ventilation, which involves the intake of oxygen and release of carbon dioxide.
2 Types of Respiration
- Aerobic Respiration
- Anaerobic Respiration
- Aerobic respiration is the complete breakdown of food in the presence of oxygen.
- It releases large amount of energy in the form of ATP molecules.
- ATP (Adenosine Triphosphate) is the energy currency of every cell.Read more…
- Anaerobic Respiration is an incomplete breakdown occurring in the absence of oxygen, releasing a small amount of energy.
- It can be alcoholic fermentation, i.e. sugar breaks into ethanol and CO₂ or lactic acid fermentation, i.e. sugar breaks into lactic acid. Readmore…
Exchange of Gasses in Plants
- The energy produced in plants by Respiration is utilized in growth and life functions.
- In leaves, exchange of gasses occurs through diffusion of oxygen through stomata into the cells of the leaf.
- In roots, exchange of gasses occurs by diffusion from air present in soil particles to the roots.
- In stems, exchange of gasses occurs through small pores present in the stems called lenticels. Read More..
Exchange of Gasses in Animals
- Exchange of gasses in animals may occur through their skin or through specific respiratory organs.
- Animals have specific organs for gaseous exchange. These organs are skin, trachea, book lung, gills and lungs.
- These organs have structures that increase the surface area and are in contact with oxygen rich atmosphere.
- Earthworms use skin and frogs use both skin and lungs for gaseous exchange.
- Insects have an elaborate tracheal system for gaseous exchange.
Exchange of Gasses in Aquatic Organisms
- In Aquatic Organisms the rate of breathing is higher as compared to terrestrial organisms as these organisms utilize oxygen dissolved in water which is present in lesser amount compared to others.
- Respiration occurs through gills and body surfaces.
- Gaseous exchange in fishes takes place through gills.
Exchange of Gasses in Terrestrial Organisms
These organisms use atmospheric oxygen for Respiration.
Human Respiratory System
- Human respiratory system consists of two major components – Respiratory tract and Respiratory organs.
- The respiratory tract includes external nostrils, nasal cavities, pharynx and trachea.
- The respiratory organs are a pair of lungs. Lungs with Bronchi and Bronchioles and Alveoli.
- Nostrils and nasal passage initiate the process of respiration by breathing in the air.
- Air passing inward through the nasal chambers is warmed, moistened, disinfects and cleaned of dust particles to keep the lungs healthy.
- Larynx is located in the neck and helps in the sound production.
- Trachea, a non-collapsible air conducting tube, exhibits the presence of incomplete rings of cartilages; which also helps keep it open.
- Bronchi and bronchioles are the branches into which trachea further divides.
- Bronchioles are formed by repeated branching of bronchi.
- Alveoli are the functional units of the lungs. These provide surface area for gaseous exchange in humans.
- Lungs are the primary organs for respiration, present in the thoracic cavity.
- Each lung is enclosed in two membranes, the pleura.
- Ribs are 12 pairs of bones, helps in respiration by movement of intercostal muscles attached to them.
- Diaphragm is a muscular partition between thorax and abdomen. It forms the base of the chest cavity and helps in breathing.
Mechanism of Gaseous Exchange in Human Beings
- Gaseous Exchange in Humans Oxygen is absorbed via inhalation.
- Exchange of oxygen and carbon dioxide occurs between blood and alveoli.
- Carbon dioxide is exhaled through lungs, i.e. exhalation and oxygen is assimilated in the body.
- Hemoglobin is the pigment present in Red Blood Cells (RBCs) which takes up the oxygen from the air in lungs and carries it to the tissues ReadMore…
What is Transportation?
Transportation can be defined as the life process in which a substance (Made or absorbed) in one part of the body of an organism is carried to other parts of its body.
All the cells of body need oxygen, water, minerals and organic food for their survival and Maintenance.
Transportation in Plants
- Transportation mechanisms of plants are different from those of animals.
- The substances picked up from the atmosphere (such as water, minerals, oxygen, carbon dioxide, etc.) by some specific cells or synthesized in some particular cells (green cells synthesize sugars, cells of stem apex and root apex synthesize hormones), need to be transported to other parts of plants.
- Transportation in plants consists of two pathways using two different conducting tissues.
- Xylem transports water and minerals obtained from the soil.
- Phloem transports food prepared from the leaves to other parts of the plant, i.e translocation.
- The water is absorbed actively by water potential difference between soil solution and root hairs.
- Once inside the root hairs, water moves from epidermis to cortex, from cortex to endodermis and from endodermis to xylem vessels and tracheids.
- Water and minerals move upward through xylem tracheids and vessels. These cells are dead and thick-walled but possess pits for movement of water from cell to cell.
- Two theories explain the ascent of sap-root pressure theory and transpiration pull and cohesion-tension theory.
- Transport of water occurs due to transpiration pull and root pressure.
- The water column in the xylem tracheids and vessels moves upwards due to pull generated by transpiration.
- The pressure exerted by transpiration on the walls of xylem is called transpiration pull.
- Transpiration is the loss of water in the form of vapors from living tissues of aerial parts of plants.
- It causes upward movement of water and minerals.
- Transportation of organic solutes from leaves to other parts of plants is called translocation. It occurs through phloem.
- Transport of food The products of photosynthesis are transported from the leaves to other parts by using energy derived from ATP.
Transportation in Human Beings
In Human Beings, there are two types of circulatory systems:
- Blood Vascular system
- Lymphatic system
Human circulatory system consists of blood, the heart and a network of blood vessels.
Blood is a specialized connective tissue consisting of plasma and formed elements (i.e RBC, WBC and platelets).
Composition of Blood
Blood consists of
- Blood plasma (The Fluid Matrix)
- Blood corpuscles (Erythrocytes, Leukocytes and Platelets).
- Blood helps in the transport of nutrients, gasses, waste products, etc. It also regulates body temperature and pH.
- The blood corpuscles are made in bone marrow.
- Blood clotting is an important property of blood.
- Blood clotting occurs when a tissue is wounded or a blood vessel is ruptured.
- A blood clot plugs the injury and stops further flow of blood.
- Clotting of blood is a complex process. Read More ..
Location of Heart
Heart is present between the lungs in the thoracic cavity slightly tilted to the left.
Human heart is four-chambered consisting of two auricles and two ventricles each separated by septum
4 chambers of Human heart
- Left atrium (Auricle)
- Right atrium(Auricle)
- Left ventricle
- Right ventricle
- The cardiac cycle (heart beat) involves repeated rhythmic contraction and relaxation of heart muscles.
- Contraction is called systole and relaxation is called diastole.
- The blood circulation in the human heart is double circulation.
- Normality of heartbeat is detected by electrocardiography.
- Blood Pressure (BP) is the force exerted by blood on the walls of a blood vessel. It is measured by a sphygmomanometer. The normal range of BP in the human body is 120/80 mm Hg.
- An artificial pacemaker is a pulse generator which is inserted in the body to initiate heart beats. Readmore..
- Blood vessels associated with the circulatory system include arteries, veins and capillaries.
- Arteries take oxygenated blood from the heart to various body parts.
- Arteries are thick-walled and have no valves.
- Veins transport deoxygenated blood from body tissues to the heart.
- Veins are thin-walled with valves to prevent the backflow of blood.
- Capillaries are thin, narrow tubes which connect arteries to veins, allowing exchange of materials between blood and body cells. ReadMore..
- Lymphatic system is the second important circulatory system in human beings which transports lymph. Readmore..
- Lymph is similar to plasma with less proteins.
- Lymph carries digested and absorbed fat from intestine and drains back excess fluid to blood.
What is Excretion?
Excretion can be defined as a biological process by which an organism gets rid of excess or toxic waste products of metabolism.
- Waste products are nitrogenous materials (such as ammonia, urea and uric acid), carbon dioxide, pigments, inorganic salts, excess water, etc.
- In unicellular organisms, wastes are excreted via diffusion through the cell surface, while multicellular organisms have developed specialized organs for the function of excretion.
- Amoeba has contractile vacuole, which serves the function of excretion and osmoregulation.
- The excretory organs of earthworm are nephridia. Readmore….
Osmoregulation is a process that maintains the amount of water and proper ionic balance in the body.
Human Excretory System
Human excretory system includes
- A pair of Kidneys
- A Urinary bladder
- And A Urethra.
- Kidneys are primary organs of the excretory system.
- Kidneys are bean-shaped, located towards the back of the abdominal cavity.
- There are two kidneys in human beings.
- Each kidney contains about a million nephrons.
- A nephron is the structural and functional unit of excretion. ReadMore..
- The impure blood entering into the glomerulus is filtered out in the Bowman’s capsule.
- The glomerular filtrate passes through a long tube where reabsorption of useful materials takes place.
Ureters are paired, thin, muscular tubes coming from each kidney which carry urine to the urinary bladder.
Urinary bladder is a muscular, pear-shaped bag where urine is temporarily stored.
Urethra is a duct which transmits the urine stored in the bladder to the exterior of the body.
Formation Of Urine
Formation of urine occurs to filter out waste products from the blood.
3 Stages of Urine Formation
- Ultrafiltration in glomerulus
- Selective Reabsorption of useful substances like glucose, amino acids, etc., in tubular part and
- Tubular secretion, i.e. active secretion of ions, metabolites, etc, from blood into urine.
Urine is the end product of the filtration process containing urea, uric acid, ammonium salts and urochrome pigment (imparts yellow color to urine).
Removal of urine Urine remains stored in the bladder until the pressure expands too much and controls the urge to urinate.
Kidney disorders occur when one or both kidneys stop functioning or Malfunctions.
Haemodialysis (Artificial Kidney)
- The failure of both kidneys immediately need medical intervention. In case of kidney failure, a matching kidney from a healthy person may be transplanted.
- Haemodialysis is the process used in case of kidney failures. It acts as an artificial kidney and removes nitrogenous waste from the body.
- An artificial kidney machine may be employed in order to get rid of metabolic wastes from the blood.
- The artificial kidney functions on the same principle as the normal kidney and the procedure is called dialysis. Readmore….
Excretion In Plants
- Excretion in plants occurs to remove the wastes produced by them.
- The major excretory products of plants are excess of oxygen, carbon dioxide, water, excess of salts, latex, gums, resins, calcium oxalate and many other toxic substances.
- Gaseous waste products are carbon dioxide during respiration and oxygen during photosynthesis. These are excreted out through stomata and lenticels.
- Liquid waste products are excess water, gums, i.e. degradation products of internal tissues, resins, etc. These are excreted via or hydathodes (guttation).
- Solid waste products are stored waste substances in cell vacuoles and tissues with dead cells. Plants get rid of them by dropping their leaves.
- Some plant wastes are useful products for human beings, e.g. essential oils, gums (used to make adhesives), resins, natural rubber (tyre industry) and tannin (for leather treatment), etc. Readmore..