Physiology Assignment: Human Digestive System Structure and Function

This report provides a comprehensive overview of the human digestive system, detailing its structure and the physiological processes involved in digestion. The report begins with an introduction to physiology and its relevance to the human body, emphasizing the importance of the digestive system for nutrient absorption and overall health. It then delves into the structure and function of each organ within the digestive system, from the mouth and esophagus to the stomach, small intestine, liver, gallbladder, pancreas, and large intestine. The report meticulously describes the processes of food ingestion, secretion of digestive fluids, mixing and movement of food through peristalsis and segmentation, digestion of food into smaller molecules, absorption of nutrients, assimilation of absorbed food by the body, and egestion of waste. It references key scientific literature to support its findings and provides an illustration of the digestive system. The report highlights the critical role of each organ in the digestive process and emphasizes the importance of a properly functioning digestive system for maintaining health.

Physiology and Digestive
Processes

Table of Contents
INTRODUCTION...........................................................................................................................2
Task 1...............................................................................................................................................2
CONCLUSION................................................................................................................................6
REFERENCES................................................................................................................................7

INTRODUCTION
Human body is made up of various organs and cells and physiology is concerned with the
study of functioning of these organs. It deals with the mechanical, physical and biochemical
functions which help to determine the health of an individual. As we all know that health is
wealth and hence, in this assignment the structure and functioning of digestive system is
described which is one of the important organ of the human body.
Task 1
Digestive system helps in food digestion which is important for every human being to
stay healthy. This is because of the reason that body needs nutrients (proteins, fats,
carbohydrates, vitamins, minerals and water) and energy which comes out when digestive
system converts the food into the same (Sherwood, 2015). This system breaks the nutrients into
parts which are small enough to be absorbed by the body and used for energy and growth. For
example, proteins breaks into amino acids, fats breaks into fatty acid and glycerols,
carbohydrates breaks into simple sugar etc.
To have a proper functioning of digestive system, it is important to understand its
structure which is shown as follows.

Illustration 1: Digestive system of human body
Sources: Science exhibition booklet, 2018

Food that is taken by the individuals passes though all these organs to have final
digestion. It moves through gastrointestinal tract by a process called as peristalsis. The hollow
organs inside it consist of a layer of muscles that helps in wall movement. This pushes food and
liquid and assists in mixing (Widmaier and et.al., 2014). The muscles behind the food contract
and squeeze it forward while the muscles in front of it help it to move forward.
Functioning of various organs:
 Mouth: Once the food is swallowed, the tongue pushes the food into the throat.
Epiglottis, which folds over the windpipe, consists of small flap of tissue to
prevent any chocking of food. After passing through salivary glands, it enters into
esophagus.
 Esophagus: It consists of a muscular tube which pushes the food in the throat to
the stomach as it is interconnected to both of them. At its inferior end, cardiac
sphincter is present which close one end of the esophagus to trap the food in the
stomach.
 Stomach: On the left side of abdominal cavity, the stomach is located. This acts as
a storage tank for the food. This helps in the digestion of large meals properly
since the body get time. It contains hydrochloric acid and digestive enzymes to
assists in the food digestion.
 Small intestine: It is a long tube of about 10 feet with a diameter of 1 inch located
just inferior to the stomach. It has a coiled structure with many folds to maximize
the food digestion and the nutrients absorption. Approximately, 90% of the
nutrients have been extracted from the food by it before it leaves small intestine.
 Liver and Gallbladder: Liver is located in the right of the stomach. It is the second
largest organ of the body. It assists in digestion by producing bile and secretes the
same into small intestine. Gallbladder is located just posterior to the lever (Hall,
2015). It helps to store and recycle excess bile from the small intestine. This can
be reused for the digestion of subsequent meals.
 Pancreas: It is a large gland located in the proximity of the stomach. Its length is
about 6 inches. It helps in the complete chemical digestion of the food by
secreting digestive enzymes into the small intestine.

 Large intestine: It is long tube of about 5 feet with a diameter of 2.5 inches. It
wraps itself around the borders of small intestine. It helps in water absorption. It
aids in breaking down the waste to extract small amount of nutrients with the help
of symbiotic bacteria.
 Finally, through anal canal, feces exit the body.
The primary processes of digestive system include:
1.) Food ingestion: Its first function is intake of food. Mouth is the organ responsible for it
which acts as an orifice through which the food enters the body. It is also responsible for
food storage (Geissler and et.al., 2017). This helps a body to eat in instalments each day
and to ingest more food at one time than it can process.
2.) Secretion: The digestive system secretes around 7 litres of fluids every day. This
includes saliva, mucus, enzymes, bile, hydrochloric acid etc. Saliva adds moisture to the
dry food and assists in carbohydrates digestion with the help of a digestive enzyme,
salivary amylase. Mucus serves as a lubricant inside gastrointestinal tract. The
hydrochloric acid helps to digest the food chemically. Enzymes help to convert large
molecules into small parts to ease the process of digestion. Similarly, bile is used to
emulsify large mass of lipids into tiny particles.
3.) Mixing and movement: For this, three processes are used by this system. They are as
follows:
 Swallowing: In this process, with the help of muscles in mouth, tongue and the throat the
food is pushes into the esophagus.
 Peristalsis: It is a muscular wave which travels throughout the length of gastrointestinal
tract to move the partially digested food to the stomach and the intestine.
 Segmentation: It occurs in small intestine to extract the nutrients out of the food by
mixing the food and increasing its contact with the walls of the intestine.
4.) Digestion: It is the process to chemically convert large particles into smaller one. Food
chewing with the help of teeth and the muscular mixing of food in stomach and intestine
assists in mechanical digestion of food. Bile also helps to convert fats into small
molecules mechanically (Feher, 2017). With the help of salivary amylase in the mouth,
the chemical digestion of food begins which breaks complex carbohydrates into their

simple form. Enzymes in stomach also help in this but the major portion of it is done in
small intestine with the help of pancreas (Bellmann and et.al., 2016).
5.) Absorption: After the breaking of food into smaller particles, absorption is done. It begins
in stomach where water and alcohol are directly absorbed into the bloodstream. Small
blood and lymphatic vessels in the small intestine picks up the small nutrients and carry
them to the rest of the body. The large intestine also assists in absorption of water,
vitamins B and K before the feces exit through the body.
6.) Assimilation: The transportation of absorbed food is carried out with the help of blood
and lymph (Jasnos and et.al., 2014). They transport the absorbed food to the different
body cells which helps in their growth and repair and also provides energy. Amino acids
are used for growth and repair. Excess of it is converted into the fat and is stored in the
body. Liver helps in deamination, by which amino group is removed from the amino acid
to form ammonia. This is converted into urea which is filtered from the blood in kidney.
Glucose is utilised to produce energy for various body activities. Stored fat is used as a
source of energy for the cells.
7.) Egestion: The process of elimination of the waste through anal canal is called as egestion.
For this, the peristalsis pushes the indigestible matter of small intestine to the large
intestine (Feher, 2017). Around 1500 ml of chyme passes into large intestine every day.
This is the complete functioning of digestive system of human body.
CONCLUSION
To conclude, we can say that the digestive system is a significant organ of human body.
This is important to have a proper functioning of it to maintain health of an individual. For this it
is beneficial to have proper food intake. To assist in the same, food intake should be in
instalment.

REFERENCES
Sherwood, L., 2015. Human physiology: from cells to systems. Cengage learning.
Widmaier, E.P. and et.al., 2014. Vander's human physiology. McGraw-Hill,.
Hall, J.E., 2015. Guyton and Hall textbook of medical physiology e-Book. Elsevier Health
Sciences.
Geissler, C. and et.al., 2017. Human nutrition. Oxford University Press.
Feher, J.J., 2017. Quantitative human physiology: an introduction. Academic press.
Jasnos, K. and et.al., 2014. Carbon monoxide in human physiology--its role in the
gastrointestinal tract. Postepy higieny i medycyny doswiadczalnej (Online). 68. pp.101-
109.
Bellmann, S. and et.al., 2016. Development of an advanced in vitro model of the stomach and its
evaluation versus human gastric physiology. Food Research International. 88.pp.191-
198.
Online:
Digestive system of human, 2018. [online] Available through<
bodyhttps://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-
how-it-works>