Digestive System

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Digestive System

• DP Biology -- Jan 2008

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Digestion

• Digestion is the breakdown of large food
• molecules into smaller pieces
• Proteins into _______
• Polysaccharides into _______
• Triglycerides into __________
• Nucleic acids into _________

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Digestion

• Digestion is the breakdown of large food
• molecules into smaller pieces
• Proteins into amino acids
• Polysaccharides into sugars
• Triglycerides into fatty acids glycerol
• Nucleic acids into nucleotides

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Digestion

• Why is digestion necessary?

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Digestion

• Why is digestion necessary?
• Only relatively small molecules can be absorbed
  into body cells
• The molecules found in food are not exactly the
  same as what is needed in our body they need to
  be rearranged

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Digestive Enzymes

• Digestion of food molecules is greatly sped up by
  the action of digestive enzymes
• Digestive enzymes are secreted into the
  alimentary canal -- the continuous, hollow tube
  that runs from your mouth to your anus -- by
  secretory glands.

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Digestive Enzymes
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Path of Food

• What is the path that food takes
• through the body?

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Path of Food

• What is the path that food takes
• through the body?
• mouth esophagus stomach
• small intestine large intestine
• anus

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Path of Food

• What is the path that food takes
• through the body?
• mouth esophagus stomach
• small intestine large intestine
• anus

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Functions of Digestive organs

• Mouth
• physical and chemical digestion
• pH 7
• amylase from salivary
• glands digests carbs

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Functions of Digestive organs

• Mouth
• physical and chemical digestion
• pH 7
• amylase from salivary
• glands digests carbs
• Esophagus
• carries food to stomach

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Functions

• Stomach
• Physical digestion of food
• Churning of muscular wall breaks down food

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Functions

• Stomach
• Physical digestion of food
• Churning of muscular wall breaks down food
• Chemical digestion of food
• Pepsin HCl digest proteins

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Functions

• Stomach
• Physical digestion of food
• Churning of muscular wall breaks down food
• Chemical digestion of food
• Pepsin HCl digest proteins
• Prevention of disease
• HCl kills bacteria that might cause food
  poisoning

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Functions

• Small intestine
• Chemical digestion of food
• protease, amylase, lipase secreted by
  pancreas

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Functions

• Small intestine
• Chemical digestion of food
• protease, amylase, lipase secreted by
  pancreas
• Absorption of food
• molecules pass through cell membrane of villi

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Functions

• Small intestine
• Chemical digestion of food
• protease, amylase, lipase secreted by
  pancreas
• Absorption of food
• molecules pass through cell membrane of villi
• Fighting disease
• Peyers patches detect
• pathogens and produce
• antibodies

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Functions

• Large intestine
• Absorption of water and minerals
• Formation / passage of feces

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Absorption

• Process of taking molecules into the cells of
  
• alimentary canal
• Mostly
• occurs
• in villi of
• small
• intestine

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Villi structure function

• Villi microvilli increase surface area for
  absorption

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Villi structure function

• Villi microvilli increase surface area for
  absorption
• Single
• layer of
• epithelial
• cells for
• easy
• absorption

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Villi structure function

• Blood vessels close to epithelial cells for
  transport of food molecules into blood

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Villi structure function

• Blood vessels close to epithelial cells for
  transport of food molecules into blood
• Lacteal
• branch of
• lymphatic
• system
• carries
• away
• lipoproteins

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Assimilation

• After food molecules are absorbed by the
  digestive system, they are transported by blood
  vessels and lymph to cells of the body for
  assimilation
• Assimilation is the process of building the
  digested food molecules into the tissues of the
  body