Transcript oesophagus and stomach - Curriculum for Excellence Science

The Oesophagus
How does food get to the stomach?
The Oesophagus
How does food travel along the oesophagus?
The Epiglottis
Mouth
Direction
of food
Muscles behind
food contract
Food
Muscles in front
of food relax
Stomach
The oesophagus
Food is transported from the mouth to the
stomach through the oesophagus.
Food is pushed along the digestive tract by
muscles; this process is known as peristalsis.
The Stomach
The Stomach Video
http://www.ltscotland.org.uk/glowscience/hum
an_body/digestion/film_185/index.html
The Stomach
What are conditions like inside the stomach?
Since the stomach is acidic which enzyme work wells?
The Stomach
In what two ways does the stomach help to
digest food?
The Stomach
• The stomach is a muscular bag which contracts to help
mix the food with digestive juices.
• Pepsin is produced by the stomach. It breaks down
protein into amino acids.
• The stomach is acidic to provide the optimum pH for
pepsin activity.
The Stomach
There is a ring of muscle found at
the opening and exit of the
stomach.
The ring of muscles at the
entrance stops stomach acid getting
into the oesophagus.
What happens if stomach acid
does get into the oesophagus?
Heartburn
The Small Intestine
The start of the small intestine
2
Liver
3
Gall bladder
Stomach
1
4
Pancreas
Small intestine
5
The Liver and the Gall Bladder
• The liver produces bile
• The gall bladder stores bile
• Bile splits big blobs of fat into smaller blobs which
are easier for enzymes to digest
The Pancreas
• The pancreas produces and releases the
enzyme lipase
• Lipase breaks down fats into fatty acids and
glycerol
Now large insoluble food molecules have been broken down
into small soluble molecules
Carbohydrate
Protein
Fat
e.g. starch
Amylase
Lipase
Pepsin
The Small Intestine
• All the nutrients from digestion are absorbed by the
small intestine
• The surface of the small intestine is covered in villi
The Villi
• Villi increase the surface area of the small intestine.
This means that more nutrients can be absorbed and
faster.
Features of the villi
Thin epithelium
The skin of each villus is
only one cell thick, this
allows absorption to
happen very fast.
Lacteal
The lacteal absorbs
fatty acids and glycerol
Good Blood Supply
The blood capillaries
absorb simple sugars
and amino acids
The Large Intestine
Large Intestine
Large intestine
Appendix
Appendix
Rectum
Rectum
All that enters the large intestine is waste material and water.
The Large Intestine
• The large intestine absorbs excess water from
the waste material
The Rectum
• The rectum stores faeces until it is convenient to
expel it