Thasnim Rashid
unit 8.
Learning aim C:
Digestive system
Mouth:
In the mouth, indigestion, mechanical digestion and chemical digestion also occur. The mouth is the
beginning of the digestive tract. The mechanical digestion that occurs in the mouth is due to the chewing
in the mouth - otherwise known as mastication. The purpose of this process is for chemical digestion to
work quicker; all the enzymes and food particles have a larger surface area to volume ratio. Moving onto
the chemical digestion, it occurs due to the salivary glands, saliva contains key enzymes like amylase and
lingual lipase that break down starch. The mouth is a hollow inside the body that is oval in shape. Eating
and speaking are the mouth's two primary functions. Lips, vestibule, mouth cavity, gums, teeth, hard and
soft palate, tongue, and salivary glands are all parts of the mouth (Dworken, 2018). The oral cavity, or
buccal cavity, is another name for the mouth. When we taste food, our salivary glands secrete saliva into
our mouth. Mastication breaks down food into smaller particles that are more easily destroyed by salivary
enzymes once it reaches the mouth. To complete this duty, our teeth can execute a cutting function. The
tongue, followed by the roof of the mouth and the soft palate, contributes in mixing the food with the
saliva. (The Editors of Encyclopedia Britannica, 2014)
Pharynx:
The pharynx, often known as the throat, is a part of both the respiratory and digestive systems. It
transports air, food, and liquids from the nose and mouth to the stomach. The pharynx is a muscle lined
cavity, food is forced into the pharynx by the tongue. There are sensory receptors that are present in the
pharynx, these sensory receptors are there to respond and to start up the swallowing reflex. (Britannica,
2017)
Oesophagus:
The oesophagus is a muscular tube that connects the pharynx with the stomach, the oesophagus is
approximately 25cm long. The oesophagus is lined by tissue called the mucosa; this tissue is present to
secrete mucus, which’ll keep the lining of the oesophagus moist and lubricated- this is important because
it’ll allow food to pass through more smoothly. In the oesophagus, food turns into bolus, it then moves
down the oesophagus by the usage of peristalsis. (Hoffman, 2009)
Stomach:
The stomach is a muscular organ that receives food from the oesophagus, parietal cells in the stomach
secrete acid, therefore making the stomach an acidic place. When food enters the stomach, the food is
mixed with the gastric juices which then form chyme, pepsin and gastric lipase. The stomach's sole
function is to store food and release it at a rate that allows the intestines to process it. In preparation for
digestion, the stomach mixes and grinds the meal into a thinly split chyme that increases the surface area
of the food. (Hoffman, 2009b)
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Small intestine:
The duodenum, jejunum, and ileum are the three sections of the small intestine. It aids in the digestion of
meals from the stomach. It absorbs nutrients (vitamins, minerals, carbs, fats, proteins), as well as water,
from meals so that the body may use them. The digestive system includes the small intestine.
Food/chyme in the small intestine is mixed with enzymes that come from the pancreas, this form of
pancreatic lipase, pancreatic amylase and proteases are formed due to the enzymes. The emulsification
of lipids occurs in the small intestine, enzymes released from the gallbladder helps emulsify the lipids.
(Cleveland Clinic, 2021)
Large intestine:
Absorbing water and electrolytes, generating and absorbing vitamins, and creating and driving faeces
toward the rectum for disposal are all important tasks of the large intestine. In the large intestine,
caecum receives food from the small intestine. Furthermore, chyme that is mixed with bacteria that end
digestion is present in the large intestine, after this occurs, chyme turns into faeces and the undigested
fibres then pass onto the rectum.The large intestine has the anus, colon and rectum. These all play a key
role in digestion and the digestive system. The main function of the large intestine is to absorb water and
any leftover electrolytes. The digestion that occurs in the large intestine is called chemical digestion, once
again, the synthesis of faeces also occurs in the large intestine. The large intestine allows smooth
digestion to occur in our digestive system and without our large intestine, complications would arise. The
water that is absorbed in the large intestine tends to be water from cellulose, this is an example of a
liquid that is absorbed by the large intestine. (Children's Hospital of Pittsburgh, 2019)
Rectum:
The rectum, which is at the bottom of your large intestine, holds stool until it releases it out of your anus
during a stool movement. The rectum receives stool material from the descending colon, which is
transferred through peristalsis, or regular muscular contractions. (Millar, 2022) The rectum is seen as a
temporary storage area for food that has not been digested, meaning it is an extremely important part of
the digestive system.It has voluntary smooth muscles and uses the anus to remove faeces from the body.
Additionally, it is the point at which we pass stool out of the body. The digestive system includes the
bowel colon, rectum, and anus. Food flows down the food pipe, which is the oesophagus, to the stomach
when you swallow it. In our bodies, digestion begins here. (RUIZ.ATENODORO, 2019)
Anus:
The last section of the digestive tract is the anus. It's a 2-inch tube composed of the pelvic muscles and
the internal and external anal sphincters. The upper anus lining has the potential to perceive rectal
materials. It indicates whether the contents are liquid, gaseous, or solid. The anus is the last section of the
digestive tract. It's canal that is roughly around 2 inches, it is also a canal that is made up of the pelvic
floor muscles and the internal and external anal sphincters. The upper anus lining has the ability to detect
rectal contents. It will tell you if the contents are liquid, gas, or solid. (RUIZ.ATENODORO, 2019)
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The anus is the point at which the gastrointestinal tract leaves the body and exits. The anus begins at the
bottom of the rectum, which is the last section of the large intestine of the colon. The anorectal line is the
line that divides the anus from the rectum. The anus is surrounded by tough tissue called fascia, which
connects it to neighbouring tissues. (RUIZ.ATENODORO, 2019)
The external sphincter ani is a group of circular muscles that form the wall of the anus and keep it closed.
To keep the anus's surface moist, glands secrete fluid. Furthermore, the anus begins at the bottom of the
rectum, which is the last section of the large intestine of the colon. The anorectal line is the line that
divides the anus from the rectum. The anus is surrounded by tough tissue called fascia, which connects it
to neighbouring tissues that are around the anus. (RUIZ.ATENODORO, 2019)
Liver:
The liver is in charge of making bile, the bile that is made in the liver emulsifies lipids and fats in the body.
The liver is also a storage area for many of the key important substances. The function of the liver is to
filter the blood that arrives from the digestive tract before allowing it to pass through the rest of the
body. Another function of the liver is to detoxify chemical substances that are in the liver, the chemicals
that are present in the liver help with metabolism. (bitesize, 2023a)
Gallbladder:
The gallbladder is a component of the digestive system. Its fundamental purpose is to store bile. Bile is a
substance that aids in the digestion of lipids. Bile is a combination of mostly cholesterol that concentrates
bile and removes bile into the small intestine lumen when induced to contract. (bitesize, 2023a)
Pancreas:
Moving onto the pancreas. During digestion, your pancreas produces enzymes, which are pancreatic
fluids. Sugars, lipids, and carbohydrates are broken down by these enzymes. Your pancreas also produces
hormones, which aid digestion. Chemical messengers flow through your bloodstream. There are two key
functions of the pancreas, these include the following: exocrine function, the exocrine function is to
produce enzymes that help quicken the rate of digestion and the endocrine system, the endocrine system
is responsible for sending signals and hormones to control and maintain the sugar levels in our
bloodstreams. (bitesize, 2023a)
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