Digestive System. Organs of Digestion Four components of digestion: ComponentRole IngestionThe...
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Transcript of Digestive System. Organs of Digestion Four components of digestion: ComponentRole IngestionThe...
Organs of Digestion
Four components of digestion:
Component RoleIngestion The taking in of nutrientsDigestion Break down of molecules into
complexesAbsorption Transport complexes to body tissuesEgestion Removal of indigestible materials
Two types of digestion
Physical Digestion: Breaking up food using forceeg. Teeth chewing, Stomach churning
Chemical Digestion: Breakdown of food using chemical reactions.eg. Stomach acid,
Beginning of Digestion
Chewing: Physical digestion that mixes food with saliva produced by the salivary glands. The chewing and mixing with saliva creates a food bolus
Function of saliva: 1) Activate taste buds 2) Lubricate food so it slides easily down the esophagus. 3) Contains the digestive enzyme amylase4) Dissolves food particles which can activate the taste
buds
Teeth and Their StructureComparing Different types of teeth for different
animals.
Understanding Human TeethCarnivores: All teeth are wedge shaped (no flat
molars) Teeth come together in a scissors like motion for tearing meat off the bone and breaking bones. Large canines for holding onto prey
Teeth and Their StructureOmnivores (Bear, Pig): Multipurpose teeth. - carnivore-like: Sharp incisors, Wedge like premolars, large
canines- Herbivore-like: Slightly flattened grinding molars in the very
back
Teeth and Their StructureHumans: Mainly herbivorous teeth. Some minor modifications- Omnivore-like: Sharp incisors, - Herbivore-like: Flat grinding molars in the back. Reduced
canines
Teeth and Their StructureHumans: Mainly herbivorous teeth. Some minor modifications- Omnivore-like: Sharp incisors, - Herbivore-like: Flat grinding molars in the back. Reduced
canines
Oral Cavity to Stomach
After food is chewed and mixed with saliva:
Esophagus: A muscular tube that runs from the mouth to the stomach
Peristalsis: The muscular contractions that occur in the esophagus pushing food towards the stomach.
Stomach
Stomach: A acid filled, muscular, mucus lined sack
Function:1) Storage of food (1.5 L)2) Initial digestion of
proteins
StomachSphincter: A circular muscle that
controls the passage of materials
Cardiac Sphincter: Controls the amount of food that enters the stomach. Prevents stomach acid from leaking into the esophagus.
Heartburn: cardac sphincter allows some stomach acid to leak into esophagus and break down the esophagus wall
Stomach
Sphincter: A circular muscle that controls the passage of materials
Cardiac Sphincter: Controls the amount of food that enters the stomach. Prevents stomach acid from leaking into the esophagus.
Heartburn: cardac sphincter allows some stomach acid to leak into esophagus and break down the esophagus wall
Stomach
Pyloric Sphincter: Regulates the amount of food entering the small intestine from the stomach.
Cells in the Stomach Wall
Cell FunctionMucous Cell
Secrete a protective mucous lining
Parietal Cell
Secrete Hydrochloric acid
Peptic Cell
Secretes a protein digesting enzyme, Pepsinogen.
Pepsin
Pepsinogen (inactive form): gets converted to pepsin (active form) once it reaches the acid.
Pepsin (active): breaks Protein chains into smaller chains called Peptones
Rennin
Rennin: Slows the passage of milk through the digestive tract. This increases the time allowed for it to breakdown (more nutrients can be extracted)
Adults: Cannot function in the acid stomach of an adult.
Baby: Allows the milk to curdle (forms solid clumps) Solids move through the digestive tract at a slower pace.