Review the structure and function of the GI tract - Answers
GI tract organs - Answers mouth
pharynx
esophagus
stomach
small intestine
large intestine
accessory organs - Answers teeth
tongue
gallbladder
salivary glands
liver
pancreas
organs used for mechanical processing of food - Answers oral cavity
teeth
tongue
salivary glands - Answers -contain amylase enzyme to break down carbs
-bolus formation
pharynx - Answers muscular propulsion of food into esophagus
esophagus - Answers passageway that uses peristalsis to move food toward the stomach
stomach - Answers -chemical digestion via acid and pepsin (digest proteins into amino acids)
-mechanical digestion via muscular contractions
-3 layers of smooth muscle
What role(s) does the liver serve? - Answers estimated to have over 200 functions
,-produces bile
-stores vitamins and minerals and converts them to be useable by the body
-metabolizes hormones and drugs
-synthesizes proteins, glucose, and clotting factors
-changes ammonia to urea
-converts fatty acids to ketones
-can store large amounts of glucose as glycogen
-can synthesize glucose from amino acids, glycerol, and lactic acid during times of fasting or increased
demand
-can convert excess carbohydrates to triglycerides for storage in adipose tissue
-is a major site for protein synthesis and degradation.
liver - Answers -bile synthesis
-store and release nutrients (glycogen and lipids)
-maintains concentrations of glucose, amino acids, and fatty acids in blood
-cholesterol synthesis
-inter-conversion of nutrient types when needed
gallbladder - Answers -stores bile
-when a fatty meal is consumed, the gallbladder is signaled via hormones to contract
-when it contracts it empties bile into small intestine to aid in fat digestion
pancreas - Answers exocrine functions:
-produces pancreatic juice with enzymes and alkaline buffer (neutralizes stomach acid to not harm small
intestine) to aid in digestion in small intestine (protease to break down proteins, lipase for fats, amylase
for starch)
endocrine functions:
-secretes hormones (insulin and glucagon) to regulate blood glucose levels
-insulin drops blood glucose
, -glucagon raises blood glucose during fasting
small intestine - Answers -chemical digestion into macronutrients
-absorption of nutrients, vitamins, water, ions
-needs large surface area to absorb all nutrients
large intestine - Answers -mainly absorption of water
-microbiome helps produce some vitamins to be absorbed (vitamin K)
-elimination of indigestible food
-feces is eliminated via peristalsis
4 layers of the GI wall - Answers mucosal layer
submucosal layer
muscularis externa
serosal layer
mucosal layer - Answers -1 of 4 layers of the GI wall
-Produces mucus that lubricates and protects the inner surface of the alimentary canal
-Secretes digestive enzymes and substances that break down food
-Absorbs the breakdown products of digestion
-Maintains a barrier to prevent the entry of noxious substances and pathogenic organisms
submucosal layer - Answers -1 of 4 layers of the GI wall
-blood vessels, nerves, and structures to secrete digestive enzymes
muscularis externa - Answers -1 of 4 layers of the GI wall
-inner layer of circularly arranged smooth muscle cells and an outer layer of longitudinally arranged
smooth muscle layers
-These layers help move the contents through the GI tract
serosal layer - Answers -1 of 4 layers of the GI wall
-serous membrane
-outermost layer of organs, called the visceral peritoneum