Unit 8 C: Explore the physiology of the digestive system and the use of corrective treatments for
dietary related diseases.
Organs and enzymes The role of organs/ enzymes within digestion.
secreted by certain organs.
Buccal cavity (mouth) Mechanical digestion occurs within the mouth. The food is
taken in and with the assistance of the teeth, is chewed into
smaller pieces to allow a larger surface area for chemical
digestion. In the saliva, the enzyme salivary amylase breaks
down the starch into maltose (sugar)
Pharynx The pharynx leads to the oesophagus, the food (bolus)
bounces off a cartilage called the epiglottis, diverting the food
from the trachea into the oesophagus.
Oesophagus The two sphincters at the top and bottom of the oesophagus
control the movement of the bolus into and out of the
oesophagus (made of 4 layers of thick, muscular walls). These
muscles contract and relax to push the food to the stomach
(peristalsis).
Stomach The stomach consists of thick muscle layers of longitudinal,
circular and oblique smooth muscle fibres, lined with epithelial
cells. The food remains in the stomach between two to six
hours where the muscular walls of the stomach generates
peristaltic movement to churn the food, mixing it with the gastric
juice (produced by the epithelial cells), which contains acid and
enzymes to form chyme.
Small intestine The small intestine acts as a digestive organ and an endocrine
- Duodenum gland, secreting the hormones secretin and cholecystokinin
- Jejunum (CCK) which stimulate the release of digestive fluids (e.g.
- Ileum pancreatic juice from the pancreas, bile from the gallbladder).
There are three structures within the small intestine, the
duodenum (around 1 foot long), the jejunum (3 to 6 feet long)
and the ileum (6 to 12 feet long). The duodenum consists of
smooth muscle cells lined with epithelium. The pyloric sphincter
controls the release of chyme into the duodenum where the
rate of flow is limited by the ability of the duodenum to
neutralise the strong acid. The processes of chemical digestion
occurs; carbohydrates, proteins and fats are broken down into
glucose (from the enzyme maltase), amino acids (with the help
of the enzyme peptidases) , fatty acids and glycerol (from the
enzyme lipase). The duodenum also receives pancreatic juice
and bile from the liver. The jejunum extends from the
duodenum to the ileum (with peristalsis moving the digested
chyme along the jejunum and ileum). In ileum the walls are
thinner and highly folded into finger like projections called villi.
The villi provides a large surface area to allow the
molecules/nutrients, that our bodies need, to be absorbed into
the blood. Any other indigestible matter is passed into the large
dietary related diseases.
Organs and enzymes The role of organs/ enzymes within digestion.
secreted by certain organs.
Buccal cavity (mouth) Mechanical digestion occurs within the mouth. The food is
taken in and with the assistance of the teeth, is chewed into
smaller pieces to allow a larger surface area for chemical
digestion. In the saliva, the enzyme salivary amylase breaks
down the starch into maltose (sugar)
Pharynx The pharynx leads to the oesophagus, the food (bolus)
bounces off a cartilage called the epiglottis, diverting the food
from the trachea into the oesophagus.
Oesophagus The two sphincters at the top and bottom of the oesophagus
control the movement of the bolus into and out of the
oesophagus (made of 4 layers of thick, muscular walls). These
muscles contract and relax to push the food to the stomach
(peristalsis).
Stomach The stomach consists of thick muscle layers of longitudinal,
circular and oblique smooth muscle fibres, lined with epithelial
cells. The food remains in the stomach between two to six
hours where the muscular walls of the stomach generates
peristaltic movement to churn the food, mixing it with the gastric
juice (produced by the epithelial cells), which contains acid and
enzymes to form chyme.
Small intestine The small intestine acts as a digestive organ and an endocrine
- Duodenum gland, secreting the hormones secretin and cholecystokinin
- Jejunum (CCK) which stimulate the release of digestive fluids (e.g.
- Ileum pancreatic juice from the pancreas, bile from the gallbladder).
There are three structures within the small intestine, the
duodenum (around 1 foot long), the jejunum (3 to 6 feet long)
and the ileum (6 to 12 feet long). The duodenum consists of
smooth muscle cells lined with epithelium. The pyloric sphincter
controls the release of chyme into the duodenum where the
rate of flow is limited by the ability of the duodenum to
neutralise the strong acid. The processes of chemical digestion
occurs; carbohydrates, proteins and fats are broken down into
glucose (from the enzyme maltase), amino acids (with the help
of the enzyme peptidases) , fatty acids and glycerol (from the
enzyme lipase). The duodenum also receives pancreatic juice
and bile from the liver. The jejunum extends from the
duodenum to the ileum (with peristalsis moving the digested
chyme along the jejunum and ileum). In ileum the walls are
thinner and highly folded into finger like projections called villi.
The villi provides a large surface area to allow the
molecules/nutrients, that our bodies need, to be absorbed into
the blood. Any other indigestible matter is passed into the large
