Phys 1

Question 1

7 functions of the GI tract

Answer 1

1. Ingestion
2. Propulsion
3. Mechanical digestion
4. Chemical digestion
5. Hormone secretion
6. Absorption
7. Elimination

Question 2

Layers of teh GI tract

Answer 2

1. mucosa (interior along lumen)
2. submucosa
3. muscularis
4. serosa (exterior)

Question 3

Two muscularis layers

Answer 3

• longitudinal muscle
• circular muscle
• allow for lots of “squishing” along alimentary canal

Question 4

Three major oral cavity salivary glands

Answer 4

1. parotid
2. submandibular
3. sublingual
   - also have buccal glands distributed through cheek
   - all produce saliva

Question 5

Saliva

• fn
• enzyme

Answer 5

• clean and moisten oral cavity
• moisten food for compaction into bolus
• allow for taste
• amylase

Question 6

salivary amylase

Answer 6

carbohydrate breakdown

Question 7

Salivary gland cells (2)

Answer 7

1. serous cells: watery secretions with ions and enzymes

2. mucous cells: secretion of mucin

Question 8

Mucin def

Answer 8

glycoprotein that bind water, creating mucus

Question 9

Two triggers for salivation

Answer 9

1. chemoreceptors

2. pressure receptors

Question 10

Salivation neural activity

Answer 10

• impulse to salivary nucleus of medulla

- Motor impulse to tongue and salivary gland via facial nerve and glossopharyngeal nerve

Question 11

Esophagus

- describe

Answer 11

• muscular tube
• collapsed
• pierces diaphragm
• joins stomach via the gastroesophageal sphincter

Question 12

Mucosa

• cell type
• glands
• other features

Answer 12

• stratified squamous
• esophageal glands - release mucus
• rugae - allow for expansion when swallow bolus

Question 13

Muscularis composition

Answer 13

• proximal 1/3 skeletal (intentional control)
• middle 1/3 mixed skeletal and smooth
• distal 1/3 smooth (autonomic control)

Question 14

Regions of the stomach

Answer 14

• cardia
• fundus
• body
• pylorus (antrum)
• pyloric sphincter

Question 15

Muscular layers of stomach

Answer 15

• circular
• longitudinal
• oblique (not seen in other areas of GI tract)

Question 16

Stomach mucosa

Answer 16

• simple columnar epithelium
• surface mucous cells
• gastric pits (lead to glands)
• gastric glands

Question 17

Stomach gastric glands (5)

Answer 17

• Mucous neck cells
• Parietal cells
• Chief cells
• Enteroendocrine cells
• ECL cells

Question 18

Mucous neck cells

Answer 18

• stomach gastric gland
• stem cell population
• in epithelium
• form the neck of the pit

Question 19

Parietal cells

Answer 19

• stomach gastric gland
• enhanced production by histamine and gastrin
• produce HCl (aka gastric acid)
• Intrinsic factor production (B12 absorption requirement)

Question 20

Chief cells

Answer 20

• stomach gastric gland

- produce pepsinogen and gastric lipase

Question 21

Pepsinogen

Answer 21

• produced by chief cells
• converted to pepsin in low pH
• proteinase

Question 22

Gastric lipase

Answer 22

• produced by chief cell

- lipolysis

Question 23

Enteroendocrine cells

Answer 23

• stomach gastric gland
• release hormones
• hormone released is specific to cell type and location

Question 24

Stomach specific enteroendocrine cell

Answer 24

G cells

Question 25

G cells

Answer 25

- stomach enteroendocrine cell | - produce gastrin

Question 26

Gastrin

Answer 26

- produced by G cells in stomach - released stimulated by peptides and aa in stomach - Increases gastric acid (HCl) production by parietal cells - stimulates contractions in the intestine (move out what is there, prepare for new food)

Question 27

ECL cells

Answer 27

- stomach gastric gland - enterochromaffin-like cell - stimulated by gastrin - release histamine - Stimulate HCl secretion via parietal cell

Question 28

Histamine - what cell does it affect in GI tract - how

Answer 28

- parietal cells: release HCl | - H2 receptor on parietal cell

Question 29

Three phases of gastric regulation

Answer 29

1. Cephalic 2. Gastric 3. Intestinal

Question 30

Cephalic phase of gastric regulation

Answer 30

- sight, smell, thought - receptor activity goes to hypothalmus - output from medulla vagal nuclei (vagus nerve) - stimulates gastric gland secretions (mucus, HCl, enzymes, gastrin, histamine)

Question 31

Gastric phase of gastric regulation

Answer 31

- food enters stomach - distention causes secretory activity (myenteric and vagal reflex) - gastrin and histamine increase HCl

Question 32

Intestinal phase of gastric regulation

Answer 32

- begins when stomach drips chyme into duodenum - intestinal secretions begin - gastric activity is inhibited (vagal feedback and hormones)

Question 33

What hormones are secreted during the intestinal phase of gastric regulation that inhibit gastric activity?

Answer 33

- secretin | - GIP

Question 34

Small intestine - what major part of digestion occurs here - two physical characteristics

Answer 34

- majority of absorption - plicae circulares - villi

Question 35

Plicae circulares in small intestine

Answer 35

- circular folds of mucosa and submucosa - slow propulsion and increase mixing - increase SA for greater absorption

Question 36

Villi in small intestine

Answer 36

- fingerlike mucosal projections, project off plicae circulares - columnar epithelium - contain lacteal and capillary network - increase SA

Question 37

What anatomical feature is between the villi?

Answer 37

Intestinal crypts - contain intestinal glands - contain stem cells

Question 38

Duodenal glands fn

Answer 38

- type of mucus gland in duodenum - secrete bicarb rich mucus into intestinal glands to neutralize acidic chyme - get duodenal ulcers if dysfunctional (HCl erodes tissue)

Question 39

Microvilli

Answer 39

- plasma membrane projections from ea intestinal columnar cell - aka brush border

Question 40

Three things that increase SA in intestine

Answer 40

- Plicae (line intestine) - villi (alone the plicae) - brush border (on each cell)

Question 41

Cell types of small intestine (5)

Answer 41

1. Enterocytes 2. Goblet cells (mucous cells) 3. Paneth Cells 4. M Cells 5. Enteroendocrine cells

Question 42

Enterocytes

Answer 42

- absorptive columnar cells - contain brush border (microvilli) - enzymes at brush border

Question 43

Paneth cells

Answer 43

- located in crypts | - produce non specific defensive secretions/antimicrobials (defensins, lysozyme, phosopholipase)

Question 44

M cells

Answer 44

- overlie lymphoid tissue (Peyer's patches) in ileum | - endocytose antigens for transport to lymphoid cells

Question 45

Peyer's patches

Answer 45

- lymph tissue in the intestine | - part of MALT (mucosa associated lymphoid tissue) which is found in GI, respiratory, and GU tracts

Question 46

Stomach enteroendocrine cells

Answer 46

- microvilli have nutrient receptors and signal transduction systems - activation stimulates hormone release basally (CCK, GIP, Secretin)

Question 47

What are the 3 enteroendocrine cells in the small intestine

Answer 47

- I cells (CCK) - K cells (GIP) - S cells (Secretin)

Question 48

CCK

Answer 48

- From I Cells in intestine - release stimulated by aa and FA in small intestine - inhibits gastric secretions - stimulates pancreas to release digestive enzymes, stimulates gallbladder contraction

Question 49

GIP

Answer 49

- From K cells in intestine | - gastric inhibitory peptide

Question 50

Secretin

Answer 50

- from S cells in intestine - release stimulated by acidic pH in small intestine - stimulate pancreatic juice and bile production