Descriptive Essay on the Digestive System in Mammals

The digestive system in Mammals

1. Introduction

The digestive system of Mammals is a system concerned with breaking down large food molecules into smaller food molecules by the help of digestive enzymes. This process is carried out by the help of enzymes so that can be absorbed in the bloodstream. A mammal is a group that belongs to class vertebrae in the kingdom Animalia. The mammalian digestive system has unique characteristics than other digestive systems. This digestive system is composed of the oral cavity that forms start point in the digestive pathway, tongue, mouth, esophagus, stomach, small intestine and large intestine till the anus(Bellmann et al., 2015). Salivary amylase, pepsin, trypsin, intestinal pancreatic lipase and nucleases are all involved in the digestion process in Mammals(Powell, Faria, Thomas-McKay & Pele, 2021).

2. Basics & Background

2.1 Mammals:

Mammalia is a class that is found all over the world. Mammals, it has been claimed, has a broader distribution and are more adaptable than any other single class of animals. Mammals are any member of the vertebrate group in which the young are fed milk from the mother's special mammary glands. Mammals have several unique characteristics(Wilson et al.,2021).

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2.2 Digestion:

Digestion is the mechanical and enzymatic breakdown of food into substances that can be absorbed into the bloodstream. Fats, carbohydrates, and proteins are the three macronutrients that must be digested before they can be absorbed. Mechanical digestion entails physically breaking down food substances into smaller particles so that chemical digestion can take place more effectively. are decomposed into molecules that can pass through the intestinal epithelium and enter the bloodstream to be used in the body during the digestion process. Chemical digestion is responsible for further degrading the molecular structure of ingested compounds by digestive enzymes into a suitable form so that can be absorbed into the bloodstream. Each of these processes is required for effective digestion, and deficiencies in either mechanical or chemical digestion can result in nutritional deficiencies and gastrointestinal pathologies. Nutritional substances, minerals, vitamins, and fluids enter the body via the gastrointestinal system. Lipids, proteins, and complex carbohydrates are digested (broken down into small, absorbable units), primarily in the small intestine. Digestive products such as vitamins, minerals, and water that cross the mucosa and enter the lymph or blood(Patricia & Dhamoon, 2020).

2.3 Structure :

The mammalian digestive system is much more different than the digestive system of those have a stomach andor caecum and colon to process plant cell walls by fermentation). The mammalian digestive tract begins from the mouth to the anus, with a length of about 5 m in average in humans. The macroscopic part are the buccal cavity, esophagus, stomach, small intestine, and large intestine (Bellmann et al., 2015). The mouth is the first part of the digestive tract and its floor is the tongue. Intrinsic and extrinsic muscle movements move food in the mouth and, in collaboration with the lips and gums, hold the food in place during mastication. The tongue then maneuvers food for chewing, shapes it into a rounded mass known as a bolus, and transfers it to the stomach. The bolus is placed in the back of the mouth for swallowing(elebi & Yrkan, 1999). The continuous multilayer stratified squamous epithelium in contact with the buccal cavity and esophagus lumen is designed to handle the high volume of rapidly passing food (Helander & Fändriks, 2014). The bolus will enter the stomach after passing through the esophagus and will be mechanically and chemically digested. Carbohydrate digestion does not occur in the stomach. Most chemical digestion occurs in the small intestine. The product of digestion in the stomach that is defined as chyme moves through the pylorus and into the duodenum. Chyme will be mixed with pancreatic and duodenum secretions. Mechanical digestion will continue to take place to a lesser extent. Many digestive enzymes are produced by the pancreas, including pancreatic amylase, pancreatic lipase, trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase. Many digestive enzymes are produced by the pancreas, including pancreatic amylase, pancreatic lipase, trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase. These enzymes are isolated from the acidic environment of the stomach and perform best in the more basic environment of the small intestine, in which the pH ranges from 6 to 7 due to pancreatic bicarbonate secretion. Pancreatic amylase, like salivary amylase, is responsible for the breakdown of starch into maltose and maltotriose(Pandiri ., 2014).

2.4 Role of enzymes :

The digestion of the major food macronutrients is a systematic process that involves the action of a large number of digestive enzymes. Carbohydrates and fats are digested by enzymes from the salivary and lingual glands, proteins are digested by enzymes from the stomach, and carbohydrates, proteins, lipids, RNA, and DNA are digested by enzymes from the pancreas' exocrine glands. Other enzymes that aid digestion can be found in the luminal membranes and cytoplasm of the cells that line the small intestine. The action of the enzymes is aided by hydrochloric acid (HCl) secreted by the stomach and bile produced by the liver. Endogenous enzymes such as buccal amylase, gastric pepsin, and intestinal pancreatic lipase and nucleases can affect the integrity of certain types of ingested particles. Although mammalian enzymes can degrade surface-adsorbed biochemicals from stable particles, readsorption of novel entities occurs(Powell, Faria, Thomas-McKay & Pele, 2021). Enzymes don't affect inorganic compounds and they affect mainly organic compounds such as lipids, carbohydrates and proteins (Jannin et al., 2014).

3. Discussion:

Mammal, (class Mammalia), any member of the vertebrate animal group whose young are fed milk from the mother's special mammary glands. In addition to these distinctive milk glands, mammals are distinguished by a number of other distinguishing characteristics digestion is the mechanical and enzymatic breakdown of food into substances that can be absorbed into the bloodstream. Fats, carbohydrates, and proteins are the three macronutrients that must be digested before they can be absorbed.Mechanical digestion entails physically breaking down food substances into smaller particles so that chemical digestion can take place more effectively. are decomposed into molecules that can pass through the intestinal epithelium and enter the bloodstream to be used in the body during the digestion process.Chemical digestion is responsible for further degrading the molecular structure of ingested compounds by digestive enzymes into a suitable form so that can be absorbed into the bloodstream.Each of these processes are required for effective digestion, and deficiencies in either mechanical or chemical digestion can result in nutritional deficiencies and gastrointestinal pathologies.Nutritional substances, minerals, vitamins, and fluids enter the body via the gastrointestinal system. Lipids, proteins, and complex carbohydrates are digested which means that broken down into small,and absorbable units, primarily in the small intestine. Digestive products such as vitamins, minerals, and water that cross the mucosa and enter the lymph or blood.In mammals, the digestive system consists of glandular organs with classes of cells that secrete enzymes for the extracellular digestion of food particles such as exocrine cells of the salivary gland, pancreas and also other organs with absorptive function like the small intestine. A huge number of other cell types, such as smooth muscle cells, neurons and entered.Gastrointestinal tracts vary considerably from those adapted for processing animal matter primarily in the small intestine, with small stomachs and large intestines, to those dominated by the stomach andor caecum and colon for the fermentation of plant cell walls.The oral cavity, also known as the mouth, is the first part of the digestive tract.The tongue is a muscular organ that represents and structures the oral cavity's floor.Intrinsic and extrinsic muscle movements move food in the mouth and, in collaboration with the lips and gums, hold the food in place during mastication. The saliva that is secreted in the mouth plays important role in digestion since it facilities the process of swallowing and chewing of food.Saliva is made up of fluids secreted by the major and minor salivary glands. Human saliva secretion volume is 1-1.5 liters per day. Salivary flow is diurnal and lowest during sleep, with a relatively constant basal level during waking hours and exacerbations of stimulated flow. Adults' basal rates range between 0.3 and 0.5 mlmin.Saliva is composed of 99.5 percent water and 0.5 percent solutes (electrolyte components, enzymes and other salivary proteins). The secretions of various glands differ significantly. The parotid glands secrete watery serous saliva rich in amylase, the sublingual gland viscous saliva, and the submandibular gland mucinous saliva.Salts such as chlorides, bicarbonates, sodium, potassium, and calcium phosphates are among the solutes found in saliva. Normal saliva constituents include dissolved gases and organic substances such as urea, uric acid, serum albumin, globulin, mucin, the bacteriolytic enzyme lysozyme, and digestive enzymes such as salivary amylase. Blood group antigen and lactoperoxidase are also in saliva. Saliva also supplies the tissues of the oral cavity with moisture and lubrication. The movement of saliva aids in the removal of pathogenic bacteria, food particles, and cells from the oral tissues.The tongue then maneuvers food for chewing, shapes it into a rounded mass known as a bolus, and transfers it to the stomach.The bolus is placed in the back of the mouth for swallowing.Swallowing is a well-ordered series of events that transport food and saliva from the mouth to the stomach.Swallowing or deglutition is defined as a complex reflex response that is triggered by afferent impulses in the trigeminal, glossopharyngeal, and vagus nerves.These impulses are incorporated in the nucleus of the tractus solitaries and the nucleus ambiguous. The trigeminal, facial, and hypoglossal nerves carry efferent fibers to the pharyngeal musculature and the tongue.Swallowing begins with the voluntary action of gathering oral contents on the tongue and propelling them back into the pharynx. The following stages of swallowing are involuntary.The bolus will enter the stomach after passing through the esophagus and will be mechanically and chemically digested.Carbohydrate digestion does not occur in the stomach. Most chemical digestion occurs in the small intestine. The product of digestion in the stomach that is defined as chyme moves through the pylorus and into the duodenum. Chyme will be mixed with pancreatic and duodenum secretions continuous multilayer stratified squamous epithelium in contact with the buccal cavity and esophagus lumen is designed to handle the high volume of rapidly passing food.The surface area of the stomach is almost small and the gastric epithelium allows the movement of macromolecules but a small passage of NPs is allowed.Before the particles can come into contact with the epithelial cells, they must first cross the mucosal barrier. The mucus is composed of mucin glycoproteins, which form a viscoelastic gel, which forms an adherent, undisturbed layer on the GI wall. In the stomach and large intestine, the mucus layer is strongly combined. Viscous materials are captured, but non-sticky materials can diffuse through the layer. In the small intestine, the mucus layer is thinner and there is less interaction between the lamellar threads, which makes it easier for the lumen content to enter the epithelium this allows for the absorption of nutrients while capturing, fixing, and removing potentially dangerous larger particles.The small intestine is made up of three consecutive parts: the duodenum, jejunum, and ileum. It is the longest section of the gastrointestinal tract. The outermost microscopic layer is composed of villi and microvilli, which extend into the cavity to form a very high surface area. The digestion of the major food macronutrients is a systematic process that involves the action of a large number of digestive enzymes.Carbohydrates and fats are digested by enzymes from the salivary and lingual glands, proteins are digested by enzymes from the stomach, and carbohydrates, proteins, lipids, RNA, and DNA are digested by enzymes from the pancreas' exocrine glands.Other enzymes that aid digestion can be found in the luminal membranes and cytoplasm of the cells that line the small intestine. The action of the enzymes is aided by hydrochloric acid (HCl) secreted by the stomach and bile produced by the liver.Endogenous enzymes such as buccal amylase, gastric pepsin, and intestinal pancreatic lipase and nucleases can affect the integrity of certain types of ingested particles. Although mammalian enzymes can degrade surface-adsorbed biochemicals from stable particles, readsorption of novel entities occurs.Enzymes don't affect inorganic compounds and they affect mainly organic compounds such as lipids, carbohydrates, and protein. Many digestive enzymes are produced by the pancreas, including pancreatic amylase, pancreatic lipase, trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase.These enzymes are isolated from the acidic environment of the stomach and perform best in the more basic environment of the small intestine, in which the pH ranges from 6 to 7 due to pancreatic bicarbonate secretion.Pancreatic amylase, like salivary amylase, is responsible for the breakdown of starch into maltose and maltotriose. Pancreatic lipase, which is secreted by the pancreas along with an important coenzyme called colipase, hydrolyzes the ester bonds in triglycerides to form diacylglycerols and monoacylglycerols.Trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase will be exposed to active peptidases.The pancreas does not secrete the active form of the peptidases; or else, autodigestion, as seen in pancreatitis, could occur.Trypsin, chymotrypsinogen, procarboxypeptidase, and proelastase, on the other hand, convert to trypsin, chymotrypsin, carboxypeptidase, and elastase.Trypsinogen is converted to trypsin by enterokinase, a duodenal enzyme.Chymotrypsinogen, procarboxypeptidase, and proelastase could be converted to their active form by the action of trypsin.Endopeptidases are those enzymes that hydrolyze the internal peptide bonds of protein and those enzymes are such as trypsin, chymotrypsin, and elastase. The enzymes that hydrolyze terminal peptide bonds on proteins are called carboxypeptidases.The common bile duct carries bile produced by the liver and stored in the gallbladder. Bile contains a mixture of bile salts, cholesterol, fatty acids, bilirubin, and electrolytes, which help emulsify hydrophobic lipids in the small intestine, which are necessary for hydrophilic pancreatic lipase to enter and function.Once in the duodenum, there will be a series of activations. Enterokinase produced in the duodenum activates trypsinogen as trypsin. Trypsin activates another trypsin.Then, the duodenum contributes a variety of digestive enzymes, including disaccharidases and dipeptidase. Maltase, lactase, and sucrase are examples of disaccharidases.Maltase breaks the glycosidic bond in maltose, yielding two glucose monomers; lactase breaks the glycosidic bond in lactose, yielding glucose and galactose; and sucrase breaks the glycosidic bond in sucrose, yielding glucose and fructose.Dipeptidase is an enzyme that cleaves the peptide bond in dipeptides. At this point, the mouth, stomach, and small intestine have converted triglycerides to fatty acids and monoacylglycerol, starch and disaccharides to monosaccharides, and large proteins to amino acids and oligopeptides.As a result, the digestive process has transformed macronutrients into forms that can be absorbed into the bloodstream and used by the body.

4. Conclusions & Recommendations:

Mammals are a group of vertebrates and belong to the kingdom Animalia. They have a unique digestive system that begins with the oral cavity and tongue and continues with the esophagus, stomach, small intestine and large intestine. Digestion is a process in which large food molecules are broken down to form smaller particles with help of mammalian digestive enzymes. The digestive system of Mammals has unique characteristics. These enzymes are like buccal amylase, gastric pepsin, and intestinal pancreatic lipase and nucleases. These enzymes affect mainly organic compounds such as lipids, carbohydrates, and proteins and don't affect inorganic compounds.

5. References:

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2. Celebi C.R., Yrkan S. (1999) Physiology of the Oral Cavity. In: Lotti T.M., Parish L.C., Rogers R.S. (eds)Oral Diseases. Springer, Berlin, Heidelberg. HTTPS:doi.org10.1007978-3-642-59821-0_2
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8. Patricia, J. J., & Dhamoon, A. S. (2020). Physiology, Digestion. In StatPearls. StatPearls Publishing.
9. Powell, J., Faria, N., Thomas-McKay, E., & Pele, L. (2010). Origin and fate of dietary nanoparticles and microparticles in the gastrointestinal tract. Journal Of Autoimmunity, 34(3), J226-J233. doi: 10.1016j.jaut.2009.11.006
10. Wilson, D. E. , Jones, . J. Knox and Armstrong, . David M. (2021, February 12).Mammal.Encyclopedia Britannica. https:www.britannica.comanimalmammal