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What are the layers of the GI tract?
- -Mucosa(innermost layer)
- -Submucosa
- -Muscularis
- -Serosa
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What is the function of the Mucosa layer in the GI tract?
Its the innermost layer, nutrients pass through.
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What is the function of the Submucosa layer in the GI tract?
Connctive tissue, lymph and blood vessels, nerves.
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What is the function of the Muscularis layer in the GI tract?
Two or three layers of smooth muscle, responsible for motility in GI tract.
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What is the function of the Serosa layer in the GI tract?
Outermost layer, connective tissue sheath.
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What are the 5 digestive system processes?
- -Mechanical processing and movement
- -Secretion
- -Digestion
- -Absorption
- -Elimination
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What happens in mechanical processing and movement?
Chewing and mixing.
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What happens during secretion?
Fluid, digestive enzymes and hormones, bile, acid, alkali, mucus.
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What happens during digestion?
Breaking down food to smallest absorbable units.
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What happens during absorption?
Through mucosa, into blood or lymph vessels.
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What happens during elimination?
Undigestied material eliminated.
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What are the 3 feeding types?
- -Herbivores: Eat plant material
- -Carnivores: Eat other animals
- -Omnivores: Eat both plant and animal materials
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Why do skull and tooth patterns vary?
According to feeding types.
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Where does digestion begin?
Mouth
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What type of teeth are there?
- -Incisors
- -Canines
- -Premolars
- -Molars
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What is the function of the tongue?
Made of skeletal muscle, moves food in mouth and taste.
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What is the function of swallowing?
Delivers food to stomach.
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What is the voluntary phase of swallowing?
The tongue pushes bolus of food into pharynx.
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What is the involuntary phase/swallowing reflex of swallowing?
- Receptors in pharynx stimulated by presence of food:
- -Soft palae rises
- -Larynx rises slightly
- -Epiglottis closes opening to trachea
- -Tongue pushes food further
- -Food enters esphagus
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What is the function of the pharynx?
- -Common passageway for air and food
- -Participates in swallowing
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What is the function of Esophagus?
Connects pharynx to stomach, assists passage of food.
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What is the function of the stomach?
Food storage, digestion, regulation of delivery.
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What is the pH inside the stomach?
2(acidic)
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What does stomach contraction do?
Blend food and propel forward.
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What is the function of the small intestine?
- -Digestion
- -Absorption: 95% of food absorbed
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What are the accessory organs of the digestive system?
Pancreas, Liver and Gallbladder
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What is the function of the pancreas?
- Exocrine function:
- -Secretes digestive enzymes and sodium bicarbonate
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What is the function of the Liver?
- -Produce bile
- -Hepatic portal systems: Drains blood from digestive tract
- -Metabolic functions: Storage, synthesis, and chemical processing
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What is the function of the Gallbladder?
Stores bile
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What is the function of the Large Intestine?
Absorbs nutrients and water and eliminates waste.
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How are proteins and carbohydrates absorbed?
Through active transport
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How are lipids absorbed?
They are broken down and reassembled.
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How is water absorbed?
Through osmosis.
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How is digestion regulated?
Through the endocrine and nervous systems. Regulation dependent on volume and content of food.
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What is the required dietary allowances?
- -Protein: 50 grams
- -Carbohydrates: 300 grams
- -Lipids: 40 grams
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What is the function of fiber in our diet?
Helps things move quickly through digestive tract.
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What is our major energy source?
Comes from simple or complex carbohydrates.
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