Nutrition and Digestion: Structure, Function, and Enzymatic Hydrolysis

This report discusses the structure and function of the alimentary canal, principles of ingestion, digestion, absorption, assimilation, and egestion, and enzymatic hydrolysis of food molecules in the digestive system. It covers the role of each organ in the digestive process and how food molecules are broken down by specific enzymes. Course code and college/university not mentioned.

Nutrition and Digestion

Table of Content.
INTRODUCTION...........................................................................................................................1
MAIN BODY...................................................................................................................................1
Structure of alimentary canal and explain how elements of its structure can link to its function.
......................................................................................................................................................1
Illustrate the principles of ingestion, digestion, absorption, assimilation and egestion and
discuss how each of the processes can contribute to an efficient system....................................1
Explain how the food molecules are hydrolysed by enzymes and where in the digestive system
these reactions can take place......................................................................................................1
CONCLUSION................................................................................................................................1
REFERENCES................................................................................................................................2

INTRODUCTION
The term nutrition is generally a physiological as well as the biochemical procedure by
which an organism can use the food to support their life. In this, most of the parts of food can
consists of various complex organic molecules like carbohydrate, fats and proteins that have to
be broken down into a simpler forms before they can be effectively absorbed within the human
body. Such breaking down of the food as well as a subsequent absorption of the food
constituents can effectively occurs inside the alimentary canal (digestive tract). And, the
digestive tract combined with the other linked gland can constitute the digestive system. In this
project, it will cover the structure and functions of alimentary canal as well as the elements of its
structure which can effectively link to its functions. There is a discussion about the principles of
ingestion, digestion, absorption, assimilation as well as egestion which are involved in digestion
process and also the contribution of each processes to an efficient system. Along with this, there
is also a discussion about food molecules which are effectively hydrolysed by the specific
enzymes and its reactions that are take place in digestive system (Liu et. al., 2019).
MAIN BODY
Structure of alimentary canal and explain how elements of its structure can link to its function.
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The alimentary canal is generally refers to as the path by which the food elements can
enters inside the body as well as can moves out through the anus after digestion. The alimentary
canal is generally a tube like structure that can starts from the mouth and can end in the anus.
The alimentary canal can play an essential role within the human digestion and is also known as
the digestive tract. In alimentary canal, digestion is generally the process of breaking down of the
large food particles into a smaller ones as well as the water soluble particles, that can be easily
engrossed by the blood stream. In this, all the body parts are actively involved in the uptake as
well as digestion of the food component along with the egestion of an undigested material as
well. The organs which are involved in the alimentary canal is the oral and mouth cavity,
oesophagus, stomach, small intestine, the large intestine (Introduction to the Digestive System,
2021).
Oral and mouth cavity: It is generally the first part of the alimentary canal as the food is
ingested via the mouth. In this, the oral cavity can include the palate, tongue and teeth. Mouth is
mainly the first portion of the alimentary canal as it can receive the food and then moistens the
food with saliva, while the food is mechanically masticated by the teeth.
Palate: It is generally the roof of the oral cavity.
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Illustration 1: Buccal cavity

Tongue: It is a glandular and a muscular structure generally connected to the base of the oral
cavity. In this, its upper surface can involve small projections called as lingual papillae. These
are mainly of three types such as circumvallate, fungiform and a filiform.
Teeth: Teeth are essential for mechanical digestion of food. The teeth of human are diphyodont,
that is they generally involve the two sets of teeth-milk or the permanent teeth. In this, the
different types of teeth perform different role. such as incisors are chisel shaped and can help to
cutting of food, canines are pointed in many and can help to tearing the food, premolars are
uneven cups and are specifically used for chopping of the food and last the molars are used for
chewing and grinding of the food.
A tooth is made up of three parts root, neck and crown. Root is embedded in jaw, crown
is the visible part of tooth which is covered by a hard outer layer of enamel. Enamel covers the
layer of dentine that surrounds the pulp cavity. Inside the pulp cavity there are nerves and blood
vessels. Food in mouth is first chewed up by teeth to break it into small pieces and mixed with
saliva. Saliva is secreted by three pairs of salivary glands and contains dissolved substances such
as salivary amylase to hydrolyse starch into maltose, mineral salts to maintain mouth pH and
activation of salivary amylase, and mucin to bind food particles together.
Pharynx: It is generally the most common passage for both food and air and Epiglottis
can effectively help to prevent the entry of food into the windpipe.
Oesophagus: Oesophagus is a muscular tube via which the food components can pass
into the stomach. In this, the gastrointestinal sphincter can effectively control the motion of food
component into the stomach.
Stomach: It is more like a muscular bag which is placed at the upper left region of
abdominal cavity. It can generally involve four basic parts such as cardiac, fundus, body and a
pyloric portion. The cardiac part is generally present close to the cardiac system and opening of
stomach is also regulated by the sphincter known as gastro-intestinal sphincter. In this, the
fundus is generally a dome shaped and is particularly filled with air. The body is the actual part
of stomach. And rest the pyloric part can opens in the very first part of small intestine, duodenum
and its opening is actively regulated by the pyloric sphincter. In addition to this, it can hold the
food as it can serve as mixer and grinder of the food. It can generally secrete the acid as well as
the powerful enzymes which can help in breaking of the food down as well as altering it to a
consistency of liquid and paste. And from there, the food can move to the small intestine as well.
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Gastric juice secreted by gastric pits in mucosa of stomach linings are responsible for the
digestion of food. Gastric juice is a solution containing dissolved substances such as:
Hydrochloric acid: secreted by oxyntic cells is responsible for acidic pH of stomach, kills the
bacteria in food, activates stomach enzymes and inactivates salivary amylase enzyme.
Pepsin: secreted in inactivated form by zymogen cells and become activated by stomach acid. It
hydrolyses the polypeptides by breaking the peptide bonds.
Rennin: secreted by zymogen cells in inactivated form and become activated by stomach acid.
Mucus: secreted by goblet cells and are important for protecting the stomach wall from
hydrochloric acid and digestive actions of pepsin.
Small intestine: It is usually the longest part of the alimentary canal and it sub divided
into three parts such as duodenum, jejunum and Ileum. In this region, the bile, pancreatic as well
as the hepatic secretions are added to the food by the hepato-pancreatic duct as well.
Large intestine: The small intestine can open up in the large intestine and involve the
three main parts such as Caecum, colon and rectum. Appendix is a vestigial organ, the colon and
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Illustration 2: Internal and External structures of Stomach

rectum ends at anus. Every organ or part of the alimentary canal has its own role within the
digestive process. In this, Caecum can involve the symbiotic micro-organisms.
Illustrate the principles of Ingestion, Digestion, Absorption, Assimilation and Egestion and
discuss how each of the processes can contribute to an efficient system.
The food which a person can engulf generally involve a highly complex nutrients such as
carbohydrate, proteins and fats as well. As these such substances cannot be utilized as such by
the body of a person. Such that these have to be broken down into the simpler as well as a
smaller molecules before they can enter into the cells. The proteins should be broken down into
the amino acids, the carbohydrates into glucose, fats into the fatty acids and glycerol. It is known
that the glucose, amino acids, fatty acids as well as glycerol are generally the simpler substances
and it can be directly utilized by the human body (Dalile et. al., 2019). Such breaking down of
the complex food constituents as well as their linked absorptions is mainly accomplished by the
digestive system. The whole process can involved in the nutrition are as mentioned below:
Ingestion: It can involve taking in the food, chewing or sucking it as well as swallowing.
Digestion: It can help to convert the complex food by mechanical and chemical
breakdown into the simpler absorbable form.
Absorption: The process can involve the absorbing the digested food components from
the gut to reach the whole body tissues.
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Assimilation: The process can involve utilisation of the digested food nutrients by the
body tissues. The process can take place in small and large intestine.
Egestion: The process contains removal of undigested as well as unabsorbed food
component from the body. After the food component can pass through the small intestine, the
undigested food component can enters the colon, where the most of the water is reabsorbed. In
addition to this, the semi solid food components can be oose out via the colon by the peristaltic
movements of the muscles as well as is stored within the rectum as well. In this, as the rectum
expands in response to storage of the faecal matter, it can triggers the neural signalling which
needs to set up the urge to eliminate the undigested food components (Safari and Gérard, 2019).
Explain how the food molecules are hydrolysed by enzymes and where in the digestive system
these reactions can take place.
With help of chemical digestion, via a process known as hydrolysis, it can consume water
and digestive enzymes to effectively break down the complex molecules into simpler ones. In the
process of hydrolysis, the digestive enzymes can effectively speed up the hydrolysis process, that
is otherwise quite slow. In this, the digestion of carbohydrate, lipids, proteins are occur in
different ways such as:
Digestion of carbohydrate: It mainly begin within the mouth, where the salivary alpha-amylase
enzyme can attacks the alpha-glycosidic linkages in the starch. In this, a cleavage of the
glycosidic linkages can produce a mixture of maltose, dextrin and glucose as well. The primary
site of digestion of carbohydrate is in the small intestine.
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Digestion of lipids: Its digestion cab begin within the upper portion of the small intestine. And a
hormone that is secreted in the area can effectively stimulate the gall bladder to efficiently
discharge the bile into duodenum (Chen et. al., 2019).
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Digestion of proteins: The digestion can begin within the stomach where the actions of the
gastric juice can effectively hydrolysed about 10% of the peptide bonds. In this, the gastric juice
is generally a mixture of water which is more than 99%, an inorganic ions, HCl as well as
multiple enzymes and the other proteins.
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Illustration 3: Activation of some pancreatic enzymes in small intestine

CONCLUSION
From the above report, the findings of the study generally showed about the alimentary
canal which can involve multiple organs that alone play their key role in ingesting, digesting,
assimilating the food component. In the above report, it is concluded that how the food
components can be effectively hydrolysed with help of specific enzymes such as trypsin,
peptidase and many other enzymes as well.
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REFERENCES
Books and Journals:
Aguilar-Toalá, J.E., Hernández-Mendoza, A., González-Córdova, A.F., Vallejo-Cordoba, B. and
Liceaga, A.M., 2019. Potential role of natural bioactive peptides for development of
cosmeceutical skin products. Peptides, 122, p.170170.
Chen, H., Cheng, S., Fan, F., Tu, M., Xu, Z. and Du, M., 2019. Identification and molecular
mechanism of antithrombotic peptides from oyster proteins released in simulated
gastro-intestinal digestion. Food & function, 10(9), pp.5426-5435.
Chen, S., Han, Y., Huang, J., Dai, L., Du, J., McClements, D.J., Mao, L., Liu, J. and Gao, Y.,
2019. Fabrication and characterization of layer-by-layer composite nanoparticles based
on zein and hyaluronic acid for codelivery of curcumin and quercetagetin. ACS applied
materials & interfaces, 11(18), pp.16922-16933.
Dalile, B., Van Oudenhove, L., Vervliet, B. and Verbeke, K., 2019. The role of short-chain fatty
acids in microbiota–gut–brain communication. Nature reviews Gastroenterology &
hepatology, 16(8), pp.461-478.
Liu, W., Ye, A., Han, F. and Han, J., 2019. Advances and challenges in liposome digestion:
Surface interaction, biological fate, and GIT modeling. Advances in Colloid and
Interface Science, 263, pp.52-67.
Montesano, D., Gallo, M., Blasi, F. and Cossignani, L., 2020. Biopeptides from vegetable
proteins: New scientific evidences. Current Opinion in Food Science, 31, pp.31-37.
Pimentel, F.B., Alves, R.C., Harnedy, P.A., FitzGerald, R.J. and Oliveira, M.B.P., 2019.
Macroalgal-derived protein hydrolysates and bioactive peptides: Enzymatic release and
potential health enhancing properties. Trends in Food Science & Technology, 93,
pp.106-124.
Safari, Z. and Gérard, P., 2019. The links between the gut microbiome and non-alcoholic fatty
liver disease (NAFLD). Cellular and Molecular Life Sciences, 76(8), pp.1541-1558.
Tsiaoussis, J., Antoniou, M.N., Koliarakis, I., Mesnage, R., Vardavas, C.I., Izotov, B.N.,
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Online:
Introduction to the Digestive System, 2021 [Online] Available through:
<https://training.seer.cancer.gov/anatomy/digestive/>
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