Digestive system

Question 1

tunics

Answer 1

four layers of tissue that the alimentary tract from the esophagus to the anal canal has
- includes: mucosa, submucosa, muscularis and serosa

Question 2

Mucosa

Answer 2

• a tunic
• absorptive and secretory layer
• simple columnar epithelium
• supported by lamina propria
• has a muscularis mucosa
• has goblet cells

Question 3

lamina propria

Answer 3

thin layer of connective tissue in the mucosa that contain lymph nodes - important against disease

Question 4

muscularis mucosae

Answer 4

thin layer of smooth muscle responsible for folds at various parts of the alimentary tract that increase absorptive surface area

Question 5

goblet cells

Answer 5

secrete mucous
found in the mucosa throughout most of the alimentary tract

Question 6

submucosa

Answer 6

second tunic layer
- thick, highly vascular layer of connective tissue that serves mucosa
- absorbed molecules from mucosa enter into blood and lymph vessels of submucosa
- also has glands and nerve plexes
- has submucosal plexus

Question 7

submucosal plexus

Answer 7

provides nerve supply to muscularis mucosa

Question 8

Muscularis

Answer 8

third tunic layer
aka muscularis externa
responsible for segmental contractions and persitaltic movement
has inner circular and outer longitudinal layer
these contract
has myenteric plexus

Question 9

myenteric plexus

Answer 9

btw the two muscle layers of the muscularis
- provides nerve supply to entire alimentary tract (sympathetic and parasympathetic fibres)

Question 10

serosa

Answer 10

last tunic layer
areolar tissue covered with a layer of simple squamous epithelium

Question 11

vagus nerve

Answer 11

supplies parasympathetic activity to esophagus, stomach, small intestine, pancreas and gallbladder

Question 12

What supplies innervation for distal, large intestine?

Answer 12

sacral region

Question 13

what percent of vagus nerve fibres are afferent?

Answer 13

80%

Question 14

What are the sites where parasympathetic fibres synapse with post ganglionic fibres?

Answer 14

submucosal and myenteric plexus

Question 15

deglutition

Answer 15

swallowing - voluntary

Question 16

epiglottus

Answer 16

covers vocal chords which close off opening to larynx to prevent chocking

Question 17

What connects esophagus to stomach?

Answer 17

esophageal sphincter
not a real sphincter since it lets food other way when puking

Question 18

what is most distendible portion of GI tract?

Answer 18

stomach

Question 19

stomach functions

Answer 19

store food, initiate digestion of proteins, kill bacteria with acid and move food to small intestine

Question 20

regions of the stomach

Answer 20

cardia
fundus
body
pyloric antrum
pyloric sphincter

Question 21

rugae

Answer 21

long folds of the stomach
seen when empty

Question 22

gastric pits

Answer 22

openings of the rugae folds, contain/lined with gastric glands

Question 23

gastric glands (7)

Answer 23

• mucous neck cells
• parietal cells
• chief/zymogenic cells
• ECL (enterochromatin) cells
• G cells
• D cells
• P/D1 cells

Question 24

mucous neck cell

Answer 24

gastric gland
secrete mucous

Question 25

parietal cells

Answer 25

gastric gland
secrete HCl and intrinsic factor

Question 26

chief/zymogenic cells

Answer 26

gastric gland
secrete pepsinogen

Question 27

ECL

Answer 27

enterochromaffin cells
gastric gland
secrete histamine and serotonin

Question 28

G cells

Answer 28

gastric gland
secrete gastrin into blood

Question 29

D cells

Answer 29

gastric gland
somatostatin hormone into blood

Question 30

P/D1 cells

Answer 30

secrete ghrelin into blood
gastric gland

Question 31

intrinsic factor

Answer 31

only stomach function essential for life
needed for intestinal absorption of vit. B12 which is needed for the development of RBCs in bone marrow

Question 32

Function of the stomach’s high acidity/low pH

Answer 32

pH of gastric juice is 2
1) protein denaturation
2) weak pepsinogens digest eachother
3) pepsin is more active at a low pH (optimum 2)

Question 33

peptic ulcers

Answer 33

penetrations of mucosa of stomach or duodenum,
penetrate muscularis mucosa too
caused by H. pylori cause this
bacteria can survive highly acidic environment

Question 34

brunners glands

Answer 34

• in submucosa, unique to duodenum
• secrete bicarbonate to neutralize acid

Question 35

crypts of Lieburkuhn

Answer 35

intestinal crypts w paneth cells and stem cells

Question 36

Paneth cells

Answer 36

line the intestinal crypts / crypts of Lieburkuhn
- secrete lysozyme and derensis

Question 37

why are intestinal stem cells important in the crypts

Answer 37

divide by mitosis to replenish and produce specialized cells needed for cell replacement on the villi and repair of intestinal mucosa

Question 38

segmentation

Answer 38

major contractile activity from small intestine is actually not peristalsis - it’s SEGMENTATION!
muscular contraction of lumen that occur spontaneously at different segments
more frequently in proximal than distal end of small intestine
mix the chime
the motion of slow waves is initiated by depolarizations by intersitial cells of Cajal

Question 39

intersitial cells of Cajal

Answer 39

5% of cells in muscularis layer of small intestine
- conduct depolarizations that trigger contractions of smooth muscle cells by voltage gated Ca2+

Question 40

Large intestine anatomy order

Answer 40

ileocal valve–> cecum –> ascending colon –> transverse colon –> descending colon –> sigmoid colon –>rectum –> anus

Question 41

taenia coli

Answer 41

external layer of smooth muscle in colon
bunches to form pouches - haustra

Question 42

islets of Langerhon

Answer 42

cells of the pancreas that secrete insulin and glucagon

Question 43

gallstones

Answer 43

created when the liver releases saturated cholesterol solution in gallbladder