Unit 8 : physiology of human body systems
C:explore the physiology of the digestive system and the se of corrective treatments for
dietary related diseases
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The mouth:
Although food enters through the mouth, our digestive system prepares prior to food
entering our mouth. This is because when we smell food, our salivary glands release saliva
,into our oral cavity. When we place food in our mouths, we begin chewing in order to break
it down into smaller particles that our saliva's enzymes can easily target. Our teeth grind and
cut the food into smaller pieces, our tongue assists in mixing the food and saliva, and our
tongue and roof of mouth aid in the passage of food down our pharynx and oesophagus.
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The pharynx and oesophagus :
The pharynx connects our mouths to the oesophagus. From our pharynx, the food bolus can
take one of two paths: the incorrect path, which leads down the windpipe and into our
lungs, or the correct path, which leads to the oesophagus and then to our stomach.
Swallowing closes the windpipe to protect the lungs and forces food into the oesophagus.
Although the process is automatic, you have some direct control over it.
When foods enter our oesophagus, they pass down into our stomach. Our oesophagus is a
muscular tube that contracts in unison to transport food to our stomach. When the muscles
behind our food product contract, the muscles in front of the food relax, propelling our food
forward. When food reaches our stomach, a muscular valve relaxes, allowing food to pass
through. Our sphincter works by closing the stomach, preventing food or stomach acid from
refluxing into the oesophagus.
The stomach and small intestine:
When this process is complete, the glands that line our stomach secrete acid and enzymes
that aid in further breaking down the food, and our stomach mixes it more thoroughly.
When this process is complete, the food is transformed into a thick creamy fluid called
chyme. This thick fluid then travels down into the duodenum, the first section of our small
intestine, where the food is further broken down by pancreatic enzymes and liver bile.
The small intestine is divided into three segments: the duodenum, which aids in the
breakdown of food, and the jejunum and ileum, which function by absorbing nutrients from
processed foods into the blood stream via the intestine's walls. The remainder of the waste
accumulates in the upper gastrointestinal tract, which encompasses everything above the
large intestine and empties into the large intestine or colon.
The colon, rectum, and anus:
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The lower gastrointestinal tract's function is to solidify waste products or absorbed water
and to store waste products such as faeces and urine until they can be evacuated by going
to the bathroom. These organs also aid in the process of evacuating waste products from
our bodies.
The large intestine is divided into four sections: the ascending colon, the transverse colon,
the descending colon, and the sigmoid colon. Together, these sections measure
approximately 7 feet in length and are attached to the rectum. Waste products are also
moved along by peristalsis; they pass into our colon where they are absorbed and stool is
, formed. Our colonic stool is stored in our rectum, and our anal sphincter has the ability to
release or retain stool. When stool reaches the rectum, a signal is sent to the brain alerting
us to the need for bowel movement; you can then control the anal sphincter until you reach
the toilet.
Mechanical and chemical absorption
We break down larger pieces of food into smaller particles when we chew. This is referred
to as mechanical digestion. Mechanical digestion also includes the stomach's churning
action, as our stomach is warm, allowing fats to melt.
Our saliva, gastric juice, enteric juice, and pancreatic juice all contain enzymes that
hydrolyse macromolecules. Additionally, chemical digestion entails the hydrolysis of P5
macromolecules into smaller molecules.
Hydrolysis:
Hydrolysis is a natural method of decomposition that requires the introduction of acid to
break bonds. Hydrolysis reactions, in which water is used to split polymers into monomers,
are the inverse of dehydration synthesis, in which water is shaped while polymers are
synthesised from monomers. Hydrolysis reactions dissociate molecules and liberate energy.
In the digestive tract, biological macromolecules are consumed and hydrolysed to create
smaller molecules that can be consumed by cells and eventually broken down further to
produce energy.
Associated accessory organs are the Pancreas, liver and gallbladder:
Pancreas:
The pancreas regulates blood sugar by producing insulin and its also a main producer of
digestive enzymes that is part of the exocrine system. These enzymes are given out into our
duodenum and help with the digestion of the fats, proteins and carbohydrates.
Liver
The liver makes bile for fat digestion and elimination, nutrients are also stocked up in the
live and toxins
and chemicals are filtered by our liver.
Gallbladder;
Bile is stocked and released from the gallbladder, our gallbladder contracts and releases bile
when fatty foods are positioned in the duodenum.