Mohammed Salam Unit 8 LA C
Introduction:
Digestive system are composed with organs that have the ability to break down food into
smaller molecules. Which are then absorbed by the bloodstream, an enzyme is involved
with digestion process as it aids to break down by catalysing the substrate, and enzymes are
biological catalysts. Throughout this report, this topic will be based about nutrition and
health, I will talk about the digestive system roles, the deficiency of vitamins and coeliac
disease.
Digestive System:
Mouth
Pharynx
Oesophagus
Stomach
Small intestine
Duodenum
Jejunum
Ileum
Large Intestine
Rectum
Anus
Pancreas
Liver
Gall bladder
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,Mohammed Salam Unit 8 LA C
Mouth:
The mouth has other components such as teeth, tongue, salivary glands these parts of the
mouth cooperate as they help in the digestion process. Like for example, teeth are used for
chewing the food as they help to break down the food. The digestion process initially starts
from the mouth it has salivary glands where it secretes saliva. Saliva has many roles like for
example; saliva is in a liquid form when are secreted from the saliva gland this form allows
to protect the teeth from decaying by washing the small parts of the food which are stuck in
between the teeth. Saliva can moisten the food so that it can be easier to chew the food.
Saliva contains an enzyme called amylase which breaks down starch into maltose.
Pharynx:
The pharynx, generally known as the throat, is a muscular pipe passageway inside the body.
The larynx is linked to the oesophagus (where it leads to the stomach) and the trachea
(leading to the lungs). The pharynx is located in the centre of the neck. It initially comes
from at the bottom of the skull and is measured approximately 4.5 inches long. The pharynx
has many important roles such as:
Transports food and liquid to the digestive system
Pushes the food and liquid into the oesophagus so that it can prevent blockage of
the airways of the respiratory system.
makes an adequate pressure level in the ears and extracts fluid from the ears.
The pharynx has three parts, these includes:
Nasopharynx – upper part of the throat that connects the nasal cavities (nose) and
allows the air to pass through.
Oropharynx – is the middle section of the throat that connects to the mouth. Allows
movement of air, fluid, and food.
Laryngopharynx – it is located the bottom section of the throat and it is close to the
larynx or known as voice box. It maintains the passage of air to the lungs. It has other
roles which are similar as oropharynx as it allows food and fluid, and it goes down to
the oesophagus.
Here is a diagram of the parts of the pharynx which may contribute ideas of
examples how it would look like:
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,Mohammed Salam Unit 8 LA C
Oesophagus:
The oesophagus is part of the digestive system, the oesophagus is a muscular tube that
connects in between from the mouth and to the stomach. When food has been swallowed
the walls of the oesophagus contract together. This allows the food to move down from the
oesophagus to the stomach.
Above the oesophagus, there is a part of the oesophagus which is behind the windpipe or
often preferred to be called trachea. Trachea is a tubular passageway that connects from
the mouth and nose to the lungs, this passageway allows air to move in the lungs so that
you can breathe. Under the lungs, a layer of muscle called diaphragm it aids the lungs so
that you can breathe. Most part of the oesophagus sits above the diaphragm in the chest.
There are four layers of oesophagus which are:
Mucosa – it is the interior layer and helps to moist the food so that the food can pass
easily into the stomach.
Submucosa – it features glands that secretes mucus and maintains the oesophagus
to be moist.
Muscularis – It pushes food down into the stomach.
Adventitia – the exterior layer of the oesophagus and attaches any close parts of the
body.
Stomach:
“The stomach is a J-shaped organ that digests food. It produces enzymes (substances that
create chemical reactions) and acids (digestive juices). This mix of enzymes and digestive
juices breaks down food so it can pass to your small intestine”. (Cleveland Clinic, 2021) a
The stomach has important roles that allows to digest food and transport it to the small
intestine, here are the three functions that takes place before it is transported to the small
intestine:
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,Mohammed Salam Unit 8 LA C
Temporarily stores food in the stomach
Contracts and relaxes to mix the food and breaks down the food.
Stomach contains enzymes and these are produced to digest the food.
“Your stomach sits in your upper abdomen on the left side of your body. The top of your
stomach connects to a valve called the oesophageal sphincter (a muscle at the end of your
oesophagus). The bottom of your stomach connects to your small intestine”. (Cleveland
clinic, 2021) b
The stomach has five parts:
Cardia – upper part of the stomach, it contains cardiac sphincter this abstains the
food from travelling back up to the oesophagus.
Fundus – rounded part, it is next to the cardia.
Corpus (body) – largest part of the stomach. In the corpus, the stomach squeezes
and commence to mix the food.
Antrum – it holds food until the stomach is ready to send it to the small intestine.
Pylorus – lower section of the stomach. It features pyloric sphincters which is a ring
of tissue that regulates the content of the stomach and allows it to transport it to the
small intestine.
Small intestine:
After the stomach it is the small intestine, and it plays an important role in the digestive
system. When the food exits from the stomach it enters the small intestine. The intestines
can break down the food even further as it absorbs the nutrients of the food and turns the
waste into solid state. A large portion of digestion takes place in the small intestine, which is
the longest part of the digestive tract.
Small intestine is not a simple structure, it has three parts that make up the small intestines
these three sections are:
Duodenum –the initial part of the small intestine from which the stomach learns to
feed; it is a short, descending vessel approximately 10 inches long. The partially
digested food which came from the stomach will be mixed with bile from the liver
and pancreatic juice from the pancreas. Foods that are high in fat and protein are
more difficult for the body to digest than carbohydrate-rich foods. Chemical changes
in chyme, which passes through the pyloric sphincter into the duodenum, are
regulated by sensory receptors in the wall of the duodenum.
Jejunum – chyme enters jejunum from the duodenum, the walls of jejunum are
folded multiple times so that it has more surface area so that they can absorb more
nutrients. Jejunum’s surface consists of epithelial cells these type of cells have
microvilli. Microvilli creates tiny pores and increase the contact of cells in between
chyme. The whole wall of jejunum is folded into microscopic villi and forms large
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, Mohammed Salam Unit 8 LA C
pockets to enhance the surface area of jejunum the structure of jejunum allows to
absorb most of the nutrients and minerals.
Ileum - The walls become thin and narrow, and blood flow is reduced as it comes
from the jejunum. Food spends the most amount of time in the ileum, where the
most water and nutrients are absorbed. It is the last and longest section of the small
intestine.
Chyme – a partial liquid, that has been formed during digestion.
Large intestine:
The large intestine absorbs water and vitamins while the digested food is forming into
faeces. It is much shorter than small intestine in length wise, but the large intestine has
larger diameter than small intestine, so this is the reason why it got its name. the large
intestine is approximately 1.5 metres in length and 2.5 inches in diameter. The large
intestine and the small intestine are connected by the ileocecal sphincter, which is located
on the left side of the abdomen. Large intestine forms a sideways connection to the
ileocecal sphincter.
The large intestine consists of four tissue layers such as:
It is composed primarily of columnar epithelial tissue, known as the mucosa. The
mucosa in the large intestine lacks villi. However, it contains numerous mucous
glands which produce mucus to prevent rough food particles from damaging it.
Mucosa is enclosed by the submucosa by having layers of blood vessels and nerves.
The submucosa supports other layers that are found in the large intestine.
The muscularis is a layer that encloses the submucosa and contains many muscle
cells that enables to contract and move the large intestine.
Serosa is a thin layer, consisting of squamous epithelial tissue and it produces watery
fluid to apply lubrication on the surface of the large intestine. It protects the large
intestine by reducing friction from between the abdominal region, muscles, and
bones of the lower parts of the torso.
Food is converted into faeces in the large intestine, and essential vitamins are absorbed
from faeces through gut bacteria and reclaimed from faeces through water absorption. A
partial liquid of digested food is known as chyme it exits from the small intestine and enters
the large intestine by travelling through ileocecal sphincter. Chyme is mixed with good
bacteria that have already populated in the large intestine during the person’s lifetime as it
travels through the cecum. While the chyme moves through the large intestine the bacteria
digests substance in the chyme that cannot be digested by humans. Chyme is converted into
faeces in process of bacterial fermentation these bacteria that are found in the gut releases
vitamins such as vitamin K, B1, B2, B6, B7 and B12. Vitamin K is mostly produced in the gut,
and it is beneficial due to be known to clot up blood. The waste products from the gut
bacteria are carbon dioxide and methane these are released as gas when they exit from the
anus.
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