Chapter 21, 22 digestion and Metabolism Flashcards
What are the two categories of the organs in the digestive system. What is the funtion of each?
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Digestive organs
- makes a continuous tube from where food enters the mouth until it leaves as waste through anus -
Accessory 0rgans
- not part of the tract/tube but assists with digestion
How long is the distance from the mouth to anus? What are the organs digestion? And accessory?
- gastrointestinal tract is 30ft long
- Organs of digestion: mouth - pharynx - esophagus - stomach - small intestine - large intestine - anus
- Acessory organs: teeth, tongue salivary glands, liver, gallbladder, pancreas
What is the function of mouth and pharynx and salivary glands? What are the exocrine secretions?
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Functions:
a. Mouth and pharynx: chewing begins and intitiation of swallowing
b. Salivary glands: moisten food, lubrication, polysacharide-digesting enzyme -
Secretions:
- Salivary glands: salt water, mucus, amylase
What is the function and secretion of the esophagus?
- Function: move food to stomach by peristatic waves, lubrication
- Secretion: mucus
What are the functions and secretions of the stomach?
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Function:
a. store, mix, dissolve and continue *digestion of food *
b. regulate emptying dissolved food into small intestine
c. solubilization of food particles
d. kill microbes and activate pepsinogen to pepsins
e. protein digesting enzymes
f. lubricate and protect epithelial surface - Secretion: HCI, pepsins, mucus
What is the function and secretion of the pancreas?
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Function:
a. secretion of enzymes and bicarbonate
b. digest carbohydrates, fats, proteins, and nucleic acids
c. neutralize HCI entering small intestine from stomach - Secretion: enzymes and bicarbonate
What is the function and secretion of the liver?
- Function:
a. secretion of bile
b. solubilize water-insoluble fats
c. neutralize HCI entering small intestine from stomach
elimination in feces - Secretion: bile salts, bicarbonate, organic waste products and trace metals
What is the function of the gallbladder?
Function: store and concentrate bile between meals
What are the functions and secretions of the small intestine?
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Function:
a. digestion and reabsorption of most substances
b. mixing and propulsion of contents
c. food digestion
d. maintain fluidity of luminal contents
e. lubrication - Secretion: Enzymes, salt and water, mucus
What is the function and secretion of the large intestine
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Function:
a. storage and concentration of undigested matter
b. absorption of salt and water
c. mixing and propulsion of contents
d. defacation - Secretion: mucus
Where does digestion take place? And absorption? What about secretion and motility?
- Digestion: takes place in the digestive tube which is outside of the body and open at both ends
- Absorption: occurs along the tube
- Secretion and motility: take place as food travels through tube
What are the 4 processes of the digestive system?
Food enters the lumen of the digestive tract
- Digestion occurs in the lumen
- Motility occurs and keeps food traveling through digestive tract
- Absorption occurs which takes substances through lumen, pass the wall, and through interstitial fluid to the blood
- Secretion occurs from the cell wall into the lumen of the tract, neighboring cells or the blood.
What happens to food during digestion? What are the two types of digestion? How are they different?
- Food is broken down into simple organic molecules to make ATP, build tissues, and enzymes
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Mechanical
- physically breaks down nutrients into smaller pieces -
Chemical
- chemical breakdown of nutrient polymers into smaller building blocsk using digestive enzymes
What happens to polymers during digestion?
Polymers are broken down into simple monomers through hydrolysis which are simple building blocks that can be absorbed by the blood stream
Memorize how these polymers are broken down!
What is Motility? What are the methods?
- Movement through the GI tract as muscles push digesting material along
- a. mastication
b. deglutination
c. peristalsis
d. segmentation
What is secreted via endocrine and exocrine? WHat do secretions regulate?
- Exocrine digestive enzymes, acids, and mucus are secreted
- Endocrine hormones to regulate digestion are secreted
- Daily mass fluid balance is the digestive system is regulated
How are the input and output of fluid balanced?
- *Input**:
- 2.0L food and drink
- 1.5L saliva
- 0.5L bile
- 2.0L gastric secretions
- 1.5L pancreatic secretions
- 1.5L intestinal secretions
- *Total = 9.0L in lumen**
Output
-7.5L absorbed by small intestine
-1.4L absorbed by large intestine
-0.1L excreted in feces
Total = 9.0L removed from lumen
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What occurs in the oral cavity? What are the functions in the oral cavity?
- Ingestion of food occurs
- Functions:
a. Mastication breaks apart and mixes food with saliva
b. Saliva coats and lubricates food to aid swallowing
c. Salivary amylase begins digestion of carbohydrates
How long is the esophagus? How many muscles are needed for deglutition? What action forces the bolus to travel to the stomach?
- *Hungs Voice* “Six inches.hehehehe..”
- 10 inches long after the transiition from skeletal muscle at the top to the smooth muscle at the bottom - 25 muscles are needed to coordinate swallowing
- Peristalsis moves a bolus down to the stomach
How long is food usually stored in the stomach? What happens in the stomach?
- 2-4 hours
- a. HCI acid and enzymes are secreted
b. protein digestion begins