Download Human Digestion

Human Digestion
“Who has the Guts?”
Swallowing
Digestive Anatomy
Digestion
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There are 2 types of digestion:
Mechanical Digestion – breaks food
into smaller pieces to increase
surface area exposure to digestive
enzymes
Chemical Digestion – breaks organic
compounds into their building
blocks
Mechanical/ Chemical Digestion
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Chewing
Salivary glands release saliva which
moistens the chewed food, now called a
Bolus.
The tongue pushes the bolus to the back
of the throat, called the Pharynx.
A flap of skin called the Epiglottis flips
down and covers the entrance to the
Trachea during swallowing
Swallowing
Digestion Overview
Peristalsis/Alimentary Canal
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The bolus passes through the esophagus
by peristalsis
Peristalsis
Food continues to pass through the
Alimentary Canal (any part that food
passes through)
Mouth-Pharynx-Esophagus-StomachSmall Intestine-Large Intestine-Anus
Accessory organs play a role in digestion,
but food never enters them
Salivary glands-Pancreas-Gall BladderLiver
Anatomy of Digestion
Chemical Digestion
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Enzymes break down the organic
compounds (polymers) into their
building blocks (monomers) so they
can be absorbed into the blood
stream and transported to all cells
Carbohydrates – Simple sugars
Protein – Amino acids
Lipids – Glycerol and 3 Fatty acids
Nucleic acids - Nucleotides
Look in your textbook
Chapter 38-2
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Compare the digestion of
Carbohydrates and Protein.
Follow the digestion of Carbs from
the time they enter your mouth
until the end products are absorbed
into your blood.
Do the same for Protein.
Do you know your guts?
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Try the quiz.
Digestion of Carbohydrates
Mouth – Mechanical digestion breaks the
carbs into smaller pieces to increase the
surface area exposure to enzymes.
Saliva lubricates the bolus. It contains the
enzyme Amylase which begins the
Chemical digestion of Carbs.
Polysaccharides are broken into shorter
chains.
Swallowing pushes the bolus into the
esophagus
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Carbs in the Stomach
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Peristalsis moves the bolus to the
stomach.
Cardiac sphincter opens and bolus enters
the stomach
Bolus now mixes with the gastric juices of
the stomach.
This acidic mixture is now called Chyme
Mechanical digestion (churning) continues
No chemical digestion of Carbs here
because of the acidity of the chyme
Protein is digested here
Carbs in the Duodenum
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Pyloric sphincter opens and chyme
moves into the duodenum.
Pancreas secretes:
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Alkaline secretion that neutralizes the
acidic chyme
Pancreatic amylase and disaccharase
continue the breakdown of carbs into
simple sugars
Absorption of Simple Sugars
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Small intestine is about 6 meters
long!
The lumen of the small intestine is
lined with Villi.
Absorption of Carbs
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Each villi has microvilli on it’s surface
The infolds increase surface area contact
so the simple sugars can pass into the
blood by diffusion.
Small Intestine
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Absorption is complete here.
Peristalsis moves the digested food
mass to the Large Intestine (Colon)
Large Intestine
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Main function is to absorb water from the
unusable waste that remains.
Too much water absorption –
constipation!
Not enough water absorption – diarrhea!
Bacteria in colon produce Vitamin K
Feces passes from descending colon to
rectum and then is excreted through the
anus (anal sphincter)
Accessory organs and their Functions
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Salivary glands – Amylase
Pancreas – Amylase
- Disacharase
Liver – produces bile which is stored
in the Gall Bladder and secreted
into the duodenum through the
Common Bile Duct
- Bile emulsifies fats
Digestion
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Human Digestion
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Have another look
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Digestion Animation
Digestive Problems
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Heart burn – acidic gastric juice
enters the esophagus
Gastric ulcer – mucus lining of the
stomach deteriorates and the
gastric juice of the stomach begins
to digest the stomach wall
Pig Dissection