digestive system

Question 1

what makes up the alimentary system?

Answer 1

GI tract
mouth
pharynx
esophagus
stomach
small intestine (duodenum, jejunum, ileum)
large intestine

Question 2

list the accessory glands

Answer 2

teeth, tongue, salivary glands, gallbladder, liver, pancreas

Question 3

list the 6 essential digestive activities

Answer 3

ingestion, propulsion, mechanical digestion, chemical digestion, absorption, defecation

Question 4

what are the four major tissue layers of the digestive tract?

Answer 4

mucosa
submucosa
muscularis externa
serosa

Question 5

what are the mechanoreceptors found in the GI tract?

Answer 5

mechanoreceptors
chemoreceptors

Question 6

what do mechanoreceptors respond to?

Answer 6

stretch as food moves through by sending messages

Question 7

what do chemoreceptors respond to?

Answer 7

osmolarity, pH changes, digestive substrates and end products

Question 8

what reflexes do mechano and chemoreceptors initiate?

Answer 8

• activate or inhibit digestive glands
• stimulate smooth muscle to mix and move lumen contents

Question 9

what are the regulatory mechanisms of the GI tract?

Answer 9

intrinsic and extrinsic controls including:
- short reflexes
- hormones
- long reflexes

Question 10

list the four digestive processes

Answer 10

motility, secretion, absorption, digestion

Question 11

what is motility?

Answer 11

muscular contractions, mix and move forward

Question 12

what are the two types of motility?

Answer 12

peristalsis and segmentation

Question 13

what is the mucosa layer’s function?

Answer 13

secretions, absorption, digestive enzymes

Question 14

what is the submucosa responsible for?

Answer 14

blood and nerve supply

Question 15

what is the muscularis externa responsible for?

Answer 15

motility
- outer longitudinal muscle
- inner circular muscle

Question 16

what is the serosa responsible for?

Answer 16

connective tissue layer

Question 17

what are the components of a long reflex?

Answer 17

external stimuli –> CNS –> efferent impulses –> local nerve plexus –> effectors (smooth muscle/glands) –> response (change in contractile/sensory activity)

Question 18

where is segmentation seen the most?

Answer 18

in the small intestine, primarily for chemical digestion

Question 19

what are some of the hormones secreted?

Answer 19

CCK, gastrin, secretin

Question 20

where are digestive enzymes secreted?

Answer 20

mouth, stomach, small intestine

Question 21

where is mucous secreted from?

Answer 21

mouth, stomach, small intestine

Question 22

what structures aid in absorption?

Answer 22

villi and microvilli

Question 23

what’s the fxn of villi and microvilli?

Answer 23

increase surface area for absorption

Question 24

what are the two components of digestion?

Answer 24

mechanical digestion (chewing) and chemical digestion (enzyme break-down)

Question 25

what enzymes digest carbs?

Answer 25

amylase, lactase and maltase

Question 26

where is amylase secreted from?

Answer 26

salivary glands (acts in mouth) and pancreas (acts in SI)

Question 27

where are lactase and maltase secreted from?

Answer 27

SI wall, act in SI

Question 28

what are some examples of carbs?

Answer 28

starch, disaccharides, monosaccharides, complex carbs

Question 29

what happens with complex carbs?

Answer 29

gas formation, incomplete digestion

Question 30

what enzymes digest proteins?

Answer 30

pepsin, trypsin, chymotrypsin, carboxypeptidase, aminopeptidase, dipeptidases

Question 31

where is pepsin secreted?

Answer 31

in the stomach (acidic environment)

Question 32

where are trypsin/chymotrypsin, carboxypeptidase and aminopeptidase secreted?

Answer 32

in the pancreas (acting in the SI)

Question 33

where are dipeptidases secreted?

Answer 33

in the SI

Question 34

protein digestion outline

Answer 34

protein -> polypeptides -> dipeptides -> amino acids -> blood absorption

Question 35

what is needed for fat digestion?

Answer 35

an emulsifier to increase surface area (no chemical change)

Question 36

what's the emulsifier used to digest fat?

Answer 36

bile

Question 37

where is bile made?

Answer 37

in the liver

Question 38

where is bile stored?

Answer 38

in the gallbladder

Question 39

is bile an enzyme?

Answer 39

no, it's an emulsifier

Question 40

what enzyme digests fat?

Answer 40

lipase

Question 41

where is lipase secreted?

Answer 41

in the pancreas (acts in the SI)

Question 42

what's the general overview of fat digestion?

Answer 42

fat -> bile -> smaller fat globules -> lipase -> glycerol + fatty acids

Question 43

what is secreted in the mouth?

Answer 43

mucous for lubrication, salivary amylase for starch digestion

Question 44

what are the functions of chewing?

Answer 44

increase surface area and decrease choking

Question 45

what coordinates the contractions from the swallowing reflex?

Answer 45

the medulla

Question 46

what does the medulla close to prevent food from going into trachea?

Answer 46

epiglottis

Question 47

what separates the esophagus from the stomach?

Answer 47

the gastroesophageal sphincter

Question 48

what is heartburn?

Answer 48

acid reflux -> a faulty valve

Question 49

what's hiatal hernia?

Answer 49

when a part of the stomach moves into the chest

Question 50

what are the sections of the stomach?

Answer 50

fundus, body and antrum

Question 51

what are the two sphincters of the stomach?

Answer 51

gastroesophageal and pyloric

Question 52

what's the function of rugae?

Answer 52

deep folds that allow for expansion

Question 53

what are the 4 functions of the stomach?

Answer 53

storage, mixing, secretion and absorption

Question 54

what is secreted from the stomach?

Answer 54

acid, pepsin, mucous and intrinsic factor

Question 55

what's the function of acid in stomach?

Answer 55

it activates pepsin

Question 56

what's the fxn of pepsin

Answer 56

protein digestion

Question 57

what cells secrete acid?

Answer 57

parietal cells

Question 58

what cells secrete pepsin?

Answer 58

chief cells

Question 59

in what form is pepsin secreted?

Answer 59

in an inactive form

Question 60

what helps in absorption of B12?

Answer 60

intrinsic factor

Question 61

what's the inactive form of pepsin?

Answer 61

pepsinogen

Question 62

what is absorbed by the stomach?

Answer 62

aspirin and alcohol

Question 63

what enzyme digests nucleic acids?

Answer 63

nucleases

Question 64

what organ secretes nucleases?

Answer 64

the pancreas, acting in the SI

Question 65

how are vitamins dealt with?

Answer 65

they are absorbed

Question 66

what triggers the swallowing reflex?

Answer 66

food in pharynx

Question 67

what do chief cells secrete?

Answer 67

pepsinogen

Question 68

what converts pepsinogen into pepsin?

Answer 68

HCl

Question 69

what pH level can the stomach drop to?

Answer 69

2-3

Question 70

how is acid formed?

Answer 70

HCl produced by parietal cells

Question 71

how does the stomach protect itself from the acid?

Answer 71

with mucous and tight junctions + high cell replacement

Question 72

what is formed by the mixing of the stomach?

Answer 72

chyme