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Introduction to the Digestive System
The digestive system is essentially a long tube which is about
six meters long and it runs all the way from the mouth right
down to the anus
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You 've got mechanical and chemical
digestion
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after food has entered the mouth it passes into the pharynx,
so the funks is this sort of muscular tube which joins onto
the nasal cavity in the the mouth and it connects them to
the esophagus and the larynx
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behind you 've got this tube which runs down at
the stomach and this is the esphagus so i 've
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Mouth
Food begins its journey through the digestive system in the mouth, also known as the oral cavity
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Teeth chop food into small pieces, which are moistened by saliva before the
tongue and other muscles push the food into the pharynx
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The teeth are 32 small, hard organs found along the anterior and lateral edges of

the mouth
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Teeth are living organs and contain blood
vessels and nerves under the dentin in a soft region known as the pulp
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Tongue
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It is a small organ made up of several pairs of muscles covered in a thin,
bumpy, skin-like layer
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The taste buds on the surface of the tongue
detect taste molecules in food and connect to nerves in the tongue to send taste

information to the brain
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Salivary Glands
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The salivary glands

are accessory organs that produce a watery secretion known as saliva
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The body also uses saliva to
lubricate food as it passes through the mouth, pharynx, and esophagus
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It carries swallowed masses of chewed food along its length
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The function of this sphincter is to close of the end of the esophagus and trap food in the stomach
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the small intestine is highly
convoluted
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So this really really serves to increase the surface area, so it helps
by having a larger surface area
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the small intestine starts at the pylorus of the
stomach, and it ends up there cecum
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So you can see it sort of
relation to the skin
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the function of the large intestine is to
absorb water
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You 've
got the ascending colon, which is this first part on the right which
ascends and then the transverse colon, which descends down into the last part
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the liver receives nutrient rich blood from the gut via a vein called
the portal vein
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it processes the products of digestion and also

produces bile
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Peritoneal Cavity
The peritoneum is a thin serous membrane which lines the abdominal cavity and a lot
of the viscera within it
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So a service membrane is one which produces sarris fluid
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This is what confused me when I was learning about it so I 'm going to draw a
diagram and will talk about the peritoneal cavity
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these organs are
not actually there 's no organ which is actually inside the peritoneal cavity, but some
of these organs are suspended by that mason trees or by the doubling up of the
visceral peritoneum so that they are inside
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the diphragm and extends all the
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So that 's the
greatest sac so that's the great sac so next
what we 'll do is we
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peritone
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we 'll trace their path
through the
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cavity
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Ligaments of the Liver
The liver has various ligaments which attach from its surface to the diaphragm and
also to the anterior abdominal wall
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if we rotate the liver round, we 're going to take a look at the
superior surface of the liver so imagine looking at this view so we're look ing at the
same view I just showed you in the 3d model
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the lesser omentum connects the the liver to the lesser
curve of the stomach and to the first part
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the porta
hepatis connects the porta
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lesser curvature of the
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It is about 6 inches long and
shaped like short, lumpy snake with its “head” connected
to the duodenum and its “tail” pointing to the left wall of
the abdominal cavity
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Large intestine
The large intestine is a long, thick tube about 2
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It is
located just inferior to the stomach and wraps around the superior and lateral border of the small
intestine
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Feces in the large intestine
exit the body through the anal canal
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The six primary processes of the
digestive system include:
1
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Secretion of fluids and digestive enzymes

3
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Digestion of food into smaller pieces

5
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Excretion of wastes

Ingestion
The first function of the digestive system is ingestion, or the intake of food
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The mouth and stomach
are also responsible for the storage of food as it is waiting to be digested
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Secretion
In the course of a day, the digestive system secretes around 7 liters of fluids
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Saliva moistens dry food and contains salivary
amylase, a digestive enzyme that begins the digestion of carbohydrates
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Hydrochloric acid helps to digest food
chemically and protects the body by killing bacteria present in our food
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Finally, bile is used to emulsify large masses of lipids into tiny
globules for easy digestion
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Swallowing is the process of using smooth and skeletal muscles in the

mouth, tongue, and pharynx to push food out of the mouth, through the pharynx, and into
the esophagus
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Peristalsis is a muscular wave that travels the length of the GI tract, moving

partially digested food a short distance down the tract
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Segmentation
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Segmentation helps to increase

the absorption of nutrients by mixing food and increasing its contact with the walls of the
intestine
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Mechanical
digestion is the physical breakdown of large pieces of food into smaller pieces
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Bile produced by the liver is also used to mechanically
break fats into smaller globules
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Chemical digestion begins in the mouth with salivary amylase in saliva splitting
complex carbohydrates into simple carbohydrates
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The pancreas secretes an incredibly strong digestive cocktail known as
pancreatic juice, which is capable of digesting lipids, carbohydrates, proteins and nucleic acids
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Absorption
Once food has been reduced to its building blocks, it is ready for the body to absorb
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Most absorption takes place in the walls of the small intestine, which are densely
folded to maximize the surface area in contact with digested food
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The large
intestine is also involved in the absorption of water and vitamins B and K before feces leave the
body
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Defecation removes indigestible substances from the body so that they do not accumulate inside
the gut
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Digestive Disorders
Common digestive disorders include gastroesophageal reflux disease, cancer, irritable bowel
syndrome, lactose intolerance and hiatal hernia
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