Digestive System Anatomy and Function

Question 1

What are the 3 stages of swallowing?

Answer 1

1. Voluntary stage
2. Pharyngeal stage
3. Esophageal

Question 2

What is mastication?

Answer 2

Chewing-mechanical manipulation of food

-turns it into a bolus

Question 3

What secretions are there in the mouth?

Answer 3

1. Salivary amylase

2. Lingual lipase

Question 4

What is peristalsis?

Answer 4

Movement of bolus down the esophagus achieved through coordinated contractions and relaxations of both the circular and longitudinal muscles

Question 5

What controls peristalsis?

Answer 5

Medulla oblongata

-involuntary

Question 6

How is peristalsis initiated?

Answer 6

If food is still loved in the esophagus

Question 7

What happens to bolus in the stomach?

Answer 7

Liquifired to enhance enzymatic digestion, then mixed thoroughly via muscle contractions

Question 8

How much gastric juice is secreted into the stomach per day?

Answer 8

2-3L

Question 9

What is the purpose of the stomach?

Answer 9

Reservoir for food before entering into the SI

-holds food for the right amount of time

Question 10

What are the 2 sphincters present in the stomach?

Answer 10

1. Lower esophageal sphincter: lets food in and prevents it from coming back up
2. Pyloric sphincter: allows little bits of chyme into SI

Question 11

What are the 3 divisions of the stomach?

Answer 11

1. Fundus: receives food when it enters
2. Body: Where secretions are coming from
3. Antrum: Secretes hormones

Question 12

What are the 4 types of stomach layers?

Answer 12

1. Mucosa: Endo or exocrine cells, contains pits, has blood vessels, capillaries and collagen
2. Submucosa: Neural network, connects mucosa to smooth muscle, blood and lymph vessels
3. Smooth Muscle (Muscularis Externa): Muscle, neural network
4. Serosa: External layer of dense connective tissue, protects outside off stomach

Question 13

What are the 3 kind of exocrine cells?

Answer 13

1. Mucus neck cells: Mucus and bicarbonate. Keeps neutral layer to protect the stomach acid from itself
2. Chief cells: Pepsinogen and gastric lipase
3. Parietal cells: Intrinsic factor, H+, Cl- (combine to make HCl)

Question 14

What is the only endocrine cell?

Answer 14

G cells: Hormone gastrin

Question 15

How does the stomach reduce the bolus to chyme?

Answer 15

Gentle mixing waves sent every 15-25 seconds to mix contents with secretions. Moree vigorous mixing occurs as digestion proceeds beginning at the body and intensifying towards antrum.

Question 16

What is gastric emptying?

Answer 16

Pyloric sphincter is slightly open to allow small amounts of chyme into the SI

Question 17

What is chyme?

Answer 17

Liquified food that goes from the stomach into the SI

Question 18

How long does it take to breakdown the food once it enters in your stomach?

Answer 18

Depends on what content of the food was

Question 19

What are the 3 processes that occur until all contents of the stomach are gone?

Answer 19

1. Propulsion: gentle mixing waves
2. Grinding: vigorous mixing from body to pyloric
3. Retropulsion: Slight opening at pyloric sphincter where small amounts of chyme enter the duodenum

Question 20

What happens to salivary amylase in the stomach?

Answer 20

Gastric juices inactivate salivary amylase

Question 21

What happens to lingual lipase in the stomach?

Answer 21

Lingual Lipase is activated in the gastric juices

Question 22

What is pepsinogen and what is its role?

Answer 22

Pepsinogen is a protein that must encounter acid to produce the active enzyme called pepsin

Question 23

What is pepsin and what is its role?

Answer 23

Pepsin is responsible for beginning portent digestion in the stomach

Question 24

What are the 7 different functions of stomach acid?

Answer 24

1. Activates lingual lipase
2. Activates pepsin
3. Inactivates salivary amylase
4. Kills micorbes
5. Denatures proteins
6. Stimulates secretion or hormones
7. Gastric lipase

Question 25

In which part of the digestive tract does the most digestion occur?

Answer 25

Small intestine | -specifically the duodenum

Question 26

Where do the liver and pancreases solutions first interact with the chyme?

Answer 26

In the duodenum

Question 27

What are the 3 regions of the small intestine?

Answer 27

1. Duodenum 2. Jejunum 3. Ileum

Question 28

What are properties of the duodenum ?

Answer 28

- Location of enzymes mixing the chyme - Most digestion occurs here - Increase or decrease motility to optimize chemical digestion - smallest part

Question 29

What are properties of the jejunum?

Answer 29

- Villi to increase surface area for optimal absorption - Most absorption occurs here - Medium in size

Question 30

What are properties of the ileum?

Answer 30

- Less villi but can still absorb nutrients if necessary | - Largest part

Question 31

What are the 4 layers of the small intestine?

Answer 31

1. Mucosa: mixed epithelial cells, exo and endocrine, small blood and lymph vessels, crypts (invaginations), villi 2. Submucosa: Neural network, get info from mucosa to let train know contents and how much 3. Muscularis: Layers of smooth muscle (circular and longitudinal). neural network 4. Serosa: thin layer of connective tissue

Question 32

What is segmentation?

Answer 32

specialized mixing contractions in the small intestine to mix chyme with digestive juices that are secreted

Question 33

What kind of contractions is segmentation?

Answer 33

Localized mixing contractions that also function to increase the interactions of the food particles in the chyme with the absorptive cells in the intestinal mucosa

Question 34

What are the 7 cell types in the intestinal wall?

Answer 34

1. Absorptive cells-epithelial cells with microvilli 2. Goblet cells- secret mucus 3. Intestinal gland cells- secretes intestinal juice (watery mucus, slightly alkaline) 4. Paneth cells- secrete lysozyme 5. S cells- secretes secretin 6. CCK cells- secretes cholecystokinin 7. K cells- secretes glucose dependent insulinotrophic peptide (GIP)

Question 35

What are microvilli?

Answer 35

Also known as the brush border, increase the surface area of plasma membranes fo more nutrients can be absorbed

Question 36

What do microvilli contain?

Answer 36

Brush border enzymes to help in digesting some macromolecules

Question 37

What are the 6 brush border enzymes and what do the digest?

Answer 37

1. Lactase- glucose+galactose 2. Sucrase- glucose+fructose 3. Maltase- glucose+glucose 4. Aminopeptidase- removes AA side of a protein 5. Dipeptidase-cuts dipeptide into 2 single AA 6. Enteropeptidase-cuts trypsinogen into trypsin

Question 38

What is the main function of the large intestine?

Answer 38

1. To finish process of absorption - nutrients absorbed here are generally not those that were absorbed in the small intestine 2. Production of certain vitamins 3. Formation of feces

Question 39

What are the 3 sections of the large intestine?

Answer 39

1. Ascending colon 2. Transverse colon 3. Descending colon

Question 40

What is the appendix?

Answer 40

Little area attached to the start of the large intestine that contains the good bacteria

Question 41

What is a haustra?

Answer 41

Intestine bubbles/sections. When chyme passes from bubble to bubble it flips/turns in each section. this helps to get nutrient and water out that is still in there. Flips through every bubble

Question 42

What is the gastroileal reflex?

Answer 42

Presence of food stimulates the opening of the ileocecal valve

Question 43

What is the haustral churning?

Answer 43

Mixing of large intestine contents from one haustra to the next

Question 44

What is peristalsis and mass peristalsis of the large intestine?

Answer 44

Unidireftional movement of the lumen contents out of the large intestine -Mass: allows for a more forceful contraction to signal you have to go to the bathroom