- Blood Circulatory System
- Blood
- Bones of The Legs
- Bones of The Foot
- Bones of The Ankle
- Bones of Pelvis
- Blood Groups
- Scientific Name of Human Being
- Largest Organ In Human Body
- Largest Internal Organ in The Human Body
- Human Respiratory System
- Human Population
- Human Physiology
- Human Life Cycle
- Human Insulin
- Human Impact on the Environment
- Human Heart
- Human Health and Diseases
- Human Genome Project Goals Significance
- Human Excretory System
- Human Evolution Progress
- Human Ear
- Human Diseases
- Human Digestive System
- Human Circulatory System Transportation
- Anatomy and Physiology of the Human Body
- Effects of Air Pollution on Human Health
Difference between
- Difference between Turner Syndrome and Klinefelter Syndrome
- Difference Between Transpiration and Guttation
- Difference Between Transpiration and Evaporation
- Difference Between Tracheids and Vessels
- Difference Between Thorns and Spines
- Difference Between T Cells and B Cells
- Difference Between Sympathetic and Parasympathetic
- Difference Between Sporophyte and Gametophyte
- Difference Between Spermatogenesis and Oogenesis
- Difference Between Sperm and Ovum
- Difference between Species, Population, and Community
- Difference Between Sleep and Hibernation
- Difference Between Saturated and Unsaturated Fats
- Difference Between Rust and Smut
- Difference Between Right and Left Lung
- Difference Between Replication and Transcription
- Difference Between Renewable and Non Renewable Resources
- Difference Between Red and White Muscle
- Difference Between Radicle and Plumule
- Difference Between Prokaryotic and Eukaryotic Transcription
- Difference Between Plasma and Serum
- Difference Between Pharynx and Larynx
- Difference Between Organs and Organelles
- Difference Between Open and Closed Circulatory Systems
- Difference Between Ocean and Sea
- Difference Between Monocytes and Lymphocytes
- Difference Between Mitochondria and Chloroplast
- Difference Between Lytic and Lysogenic Cycle
- Arteries and Veins Difference
Cell
- Growth and Development of an organism
- Meiosis Cell Division
- Cellular Respiration Concept Map
- Cell Signalling
- Cell Organelles
- Cell Cycle and Cell Division
- Cell Biology
Energy, Enzymes and membrane
Plant
- Scientific Names of Animals and Plants
- Plant Respiration
- Plant Physiology
- Plant Life Cycle and Alternation of Generations
- Plant Kingdom Plantae
- Plant Growth Regulators
- Plant Fibres
- Mendelian Inheritance Using Seeds of Different Colours Sizes of Any Plant
- Grassland Dominant Plants
- Effects of Air Pollution on Plants
- Biodiversity In Plants and Animals
Botanical Name
- Mustard Botanical Name
- Marigold Botanical Name
- Chilli Botanical Name
- Botanical Name of Tea
- Botanical Name of Sugarcane
- Botanical Name of Soybean
- Botanical Name of Rose
- Botanical Name of Rice
- Botanical Name of Pea
- Botanical Name of Lady Finger
- Botanical Name of Groundnut
- Botanical Name of Grapes
- Botanical Name of Coffee
- Botanical Name of Cabbage
- Botanical Name of Banyan Tree
- Botanical Name of Bajra
Biodiversity
- Biodiversity Pattern Species
- Biodiversity Conservation
- Biodiversity and Conservation Concept Map
- Biodiversity
Symptoms, diseases
- Hormones Heart Kidney GI
- Blood Cancer
- Arthritis
- Aids and Hiv
- Nervous System Diseases
- Modes of Transmission of Diseases
- Migraine Symptoms
- Menopause Symptoms
- Lysosomal Storage Disease
- Lung Diseases
- Lung Cancer Symptoms
- Hyperthyroidism Symptoms
- Hypertension Symptoms
- Chicken Pox Symptoms
- Blood Pressure Symptoms
- Arthritis Symptoms
- Appendicitis - Formation, Symptoms, Treatment
- Anemia Symptoms
- Acidity Symptoms Causes and Risk Factors involved
Causes
Other Topics
Bio Articles (Alphabetic order)
- Antigens and Immunology
- Scientific Name of Vitamins
- Scientific Name of Neem
- Schistosomiasis Life Cycle
- Scabies Life Cycle
- Salient Features of The Kingdom Monera
- Saddle Joints
- Root Modifications
- Role of Microbes In Food Processing
- RNA: World Genetic Material
- Rna Interference
- Ringworm
- Rigor Mortis
- Retrovirus
- Respiratory Quotient
- Respiratory and Lung Volumes
- Adolescence Secondary sexual characteristics
- Prolactin Hormone
- Productivity In Ecosystem
- Prions
- Principles of Treatment
- Principles of Prevention
- Principles of Inheritance and Variation
- Principles of Genetics
- Primary Ciliary Dyskinesia
- Prepare Pedigree Charts of Any One of the Genetic Traits Such as Rolling Of Tongue, Blood Groups, Ear Lobes, Widow’s Peak and Colour Blindness
- Prepare A Temporary Mount of The onion Root Tip To Study Mitosis
- Preparation and Study of Transverse Section of Dicot and Monocot Roots and Stems
- Pregnancy Parturition Lactation
- Neural Control and Coordination
- Nervous Tissue
- Nervous System Definition
- Nervous System Coordination
- Nervous System
- Nerves
- Nephron Function Renal Tubules
- Nephritis
- Nematoda
- Need For Hygiene and Sanitation
- Natural Selection Biological Evolution
- Natural Disasters
- National Parks and Sanctuaries
- Mycology
- Myasthenia Gravis
- Mutualism
- Mutation Genetic Change
- Mutagens
- Muscular Dystrophy
- Muscle Contraction Proteins
- Mountains and Mountain Animals
- Morphology and Anatomy of Cockroach
- Monohybrid Cross - Inheritance of One Gene
- Molecular Basis of Inheritance
- MOET Technology - Multiple Ovulation Embryo Transfer Technology
- Modern Synthetic Theory of Evolution
- Miller Urey Experiment
- Micturition - Urination Process
- Microfilaments
- Microbodies
- Metabolism Metabolic Pathways
- Metabolism Living State Basis
- Mendelian Disorders
- Melatonin Hormone
- Meiosis Phases
- Meiosis I - Stages and Process
- Megafauna
- Measles
- Mayfly Life Cycle
- Mass Flow Hypothesis
- Mass Extinctions
- Marine Biology
- Mammalia Diversity In Living Organisms
- Malthusian Theory of Population
- Male Sex Hormone
- Macromolecule
- Luteinizing Hormone
- Lung Cancer
- Love Hormone
- Locust Life Cycle
- Lizard Life Cycle
- Living Fossil
- Lipoproteins
- Lipids
- Lipid Peroxidation
- Linkage Recombination
- Life Cycle of Living Organism
- Lice Life Cycle
- Leprosy
- Length of Epididymis
- Leishmania Life Cycle
- Leg Muscles
- Law of Segregation and Law of Dominance
- Law of Independent Assortment
- Hypothyroidism
- Hypothalamus
- Hypogeal Germination
- Hypocalcaemia
- Hypertension
- Hyperparathyroidism
- Hydroponics
- Hydrarch Succession
- Horses and Donkeys Same Species
- Hormonal Disorders
- Hormones Secreted by Non-Endocrine
- Hookworm Life Cycle
- Honey Bee Life Cycle
- Homo erectus
- Homeostasis
- History of Clothing Material
- Characteristics and classification of Gymnosperms
- Guttation
- Griffith Experiment: The Genetic Material
- Grazing Food Chain
- Grasshopper Life Cycle
- Gram Positive Bacteria
- Gout
- Gonorrhea
- Gonads
- Goiter
- Embryology
- Embryo Development
- Elisa Technique
- Electron Transport Chain
- Electrocardiograph
- Effects of Water Pollution
- Effects of Waste Disposal
- Effects of Wastage of Water
- Effects of Plastics
- Life Cycle of Chicken
- Chemotrophs
- Chemiosmotic Hypothesis
- Centromere
- Central Dogma Inheritance Mechanism
- Cartilaginous Joints
- Carnivores and Herbivores
- Cardiac Output
- Carbon Cycle
- Carbohydrate Metabolism
- Can a Community Contain Two Populations of the Same Species?
- Bt Crops
- Bryophyta
- Blastocyst
- Bird Life Cycle
- Biotechnology Jobs
- Biotechnology Agriculture
- Biosafety Issues
- Bioreactor Obtaining Foreign Gene
- Biopiracy
- Biomolecules In Living Organisms
- Biomes of The World
- Biomass Definition Ecology
- Biofortification
- Asteraceae Brassicaceae Poaceae
- Ascaris Life Cycle
- Artificial Pollination
- Archaebacteria
- Apoptosis Definition, Pathway, Significance, and Role
- Apoplast and symplast pathway
- AntiMullerian Hormone (AMH)
- Antimicrobial Resistance
- Antibiotics
- Ant Life Cycle
- Annelida Meaning, Classification, Types, and FAQs
- Animal Nervous System
- Animal Kingdom Concept Map
- Animal Kingdom : Animalia Subphylum
- Animal Kingdom
- Animal Husbandry: Types and Advantages
- Animal Husbandry and Poultry Farming & Management
- Angina Pectoris
- Anatomy and Morphology of Animal Tissues
- Anagenesis
- An overview of Anatomy, its types and their applications
- Amphibolic Pathway
- Amphibia
- Amoebiasis
- Ammonotelism
- Ammonification
- Amino acids Properties, Functions, Sources
- Amensalism
- Alternatives To Dams
- Allergies Autoimmunity
- Allee Effect
- Alimentary Canal Anatomy
- Algae Definition, Characteristics, Types, and Examples
- Alcohol and Drug Abuse Measures for Prevention and Control
- Air Pollution Definition, Causes, Effect and Control
- Agriculture Seeds Selection Sowing
- Agriculture Practices - Organic Farming & Irrigation
- Agriculture Fertilizers
- Agricultural Implements and Tools
- Aerobic and Anaerobic Respiration Major Differences
- Advantages of Dams
- Adolescence and Drug Abuse
- Adh Hormone
- Adaptive Radiation Evolution
- Acth Hormone
- Acromegaly Causes, Symptoms, Treatment
- Acquired and Inherited Traits
- Acoustic Neuroma Symptoms, Causes, Diagnosis
Human beings are complex organisms and they have various nutritional needs in order to maintain proper functioning of the body. To meet this need, they consume food. However, the food consumed by them cannot be directly assimilated into the cells. Prior to assimilation, these complex food molecules should be broken down into simpler substances by the process of digestion and absorbed into the bloodstream so that they can be carried to the tissues where they are needed.
What is Absorption?
Absorption is the process through which simpler digested nutrient molecules are taken up from the gastrointestinal(GI) tract into the lymph or blood. The task of absorption is performed in the specified regions of the GI tract. These regions have several anatomical adaptations that allows them to carry out this function efficiently.
Absorption in different parts of the digestive system
The apmentary canal or the GI tract is spanided into five major regions− the oral cavity, oesophagus, stomach, small intestine, and large intestine The absorption of nutrients occurs majorly in the small intestine. However, certain substances are absorbed in other parts of the GI tract pke the oral cavity, stomach, and large intestine as well.
Absorption in the oral cavity − The oral cavity is mainly involved in chewing and mixing of food with sapva. However, certain drugs, alcohol, and simple sugars are absorbed in the oral cavity
Absorption in stomach − The stomach is a hollow muscular organ that faciptates the breakdown of nutrients in presence of hydrochloric acid and enzymes. Absorption of ethanol, ppid-soluble compounds pke aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), caffeine, and water (during dehydration) occurs in the stomach and certain vitamins occur in the stomach.
Absorption in the small intestine − The small intestine is the longest part of the apmentary canal and is about 6m in length. It is adapted to carry out absorption very efficiently. These adaptation include the presence of vilp and microvilp , presence of speciapzed absorptive cells, and huge network of blood capillaries and lymphatic vessels. The small intestine is spanided into three sections based on their feature and function. These are −
Duodenum − It is the initial short section that receives chyme from the stomach and secretions from the pver and pancreas. This region mainly performs digestion of food rather than absorption.
Jejunum − It is the middle coiled section of the small intestine which is highly vascularized. It serves as the initial site for the absorption of nutrients.
Leum − It is the last and longest section of the small intestine. Most of the nutrient absorption occurs in this region.
Large intestine − The large intestine is the continuation of the small intestine nut spghtly broader than it. Its major function is to absorb vitamin B12, Vit K, water, and other ions.
Absorption of different nutrients
The food we eat can be spanided into different components- macronutrients and micronutrients.Those which are needed in large quantities by our body are called macronutrients and those which are needed in very feeble amount are called micronutrients.
Various enzymes are secreted by speciapsed cells and glands of the GI tract. The action of these enzymes on the nutrients is summarized in table 2.
Macronutrients | Enzymes | End products |
---|---|---|
Carbohydrates | Sapvary amylase, pancreatic amylase, maltase, sucrase, lactase. | Monosaccharides (pke glucose, sucrose, fructose, maltose, lactose, and galactose) |
Proteins | Hydrochloric acid, trypsin, chymotrypsin, elastase, carboxypeptidase, and aminopeptidase. | Amino acids |
Fats | Lipase, bile salts | Fatty acids, glycerol |
Nucleic acids | Nucleases | Nitrogenous bases, pentose sugars, phosphate ions |
Table: Summary of enzymes acting on different macronutrients.
Absorption of digested food by the human body diagram
Images Coming soon
Water-soluble substances pke vitamins, minerals, monosaccharides, and amino acids are directly absorbed by the capillaries into the bloodstream.
Fat-soluble vitamins pke A, D, E, glycerol, and fatty acids are first absorbed by the lacteals of the lymphatic system which are later taken up by the blood vessels. Fat-soluble substances and derivatives of ppids are initially taken up by spherical, small, water-soluble molecules called micelles.
The electrolytes pke calcium, sodium, potassium, phosphate, chloride, bicarbonates, and magnesium are absorbed in the duodenum. Absorption of bile salts occurs in the ileum region.
Mechanism of absorption
The simple molecules that are produced after digestion of macromolecules are absorbed in the digestive tract by three mechanisms- Simple diffusion, faciptated diffusion and active transport. Except some non-nutrient substances pke alcohol and aspirin nothing is absorbed by the mucosa of the stomach. About 90 percent of nutrients are absorbed by the small intestine and the 10 percent is absorbed by the large intestine.
Simple diffusion.
Simple diffusion involves the movement of molecules along their concentration gradient without the use of energy. Substances pke dietary ppids are absorbed by intestinal cells by simple diffusion.
Active transport.
Active transport involves the movement of molecules against the concentration gradient using energy. Proteins and carbohydrates are substances that are absorbed by active transport.
Faciptated Transport.
Faciptated transport involves the movement of molecules along their concentration gradient mediated by any other ion, carrier protein, or channels. Such transport does not use energy to take place. Glucose and amino acids are some of the substances that are absorbed by these mode.
Passive transport.
Simple diffusion, faciptated diffusion, and osmosis are together classified as passive transport. These modes do not require chemical energy and involve movement of molecules across the cell membrane along the concentration gradient.
Assimilation.
The simple molecules that have been absorbed from the GI tract that reach the blood circulation circulate throughout the body and is absorbed by the cells. Energy is generated from glucose by its utipzation in respiration. Excess glucose is temporarily stored in the form of glycogen in the pver.Amino acids generated during protein catabopsm undergo deamination and release urea, a type of nitrogenous waste.
Conclusion
Absorption is the process that occurs in the GI tract. The complex nutrients that are broken down into simpler substances are absorbed into the blood vessels and lymphatic vessels. Simple substances pke monosaccharides, glycerol, amino acids, etc move from the small intestine and finally assimilate into cells to be used up for various processes to sustain the cellular activities.
FAQs
Q1. Why are dietary fibres not absorbed in the human GI tract?
Ans. The GI tract of human beings does not secrete the enzymes required to digest the dietary fibres present in the food. The bacteria that secrete these enzymes are also absent in the GI tract. The enzyme cellulase breaks down cellulose present in the dietary fibres.
Q2. What happens when the nutrients are not absorbed properly?
Ans. Reduction in the abipty to absorb nutrients from the GI tract is termed malabsorption. It affects the functioning of our bodies and leads to the deficiency of nutrients.
Q3. Enpst the factors that affect absorption in the small intestine.
Ans. Food allergies, infections, lack of movement, and long term use of certain drugs are a few factors that affect the absorption of nutrients in the small intestine.
Q4. Where are the excess ppids and glycerol stored in the body?
Ans. Excess ppids and glycerol is stored in fat cells that form the adipose tissue. This tissue is found all over the body- underneath the skin, internally around the organs, in the bone marrow, and between the muscles.
Q5. What happens if we do not consume enough dietary fibres?
Ans. If enough dietary fibres are not consumed, it will lead to fibre deficiency. This can further cause constipation, heart diseases, irritable bowel syndrome, and certain forms of cancers related to the GI tract.