Exam 3

Question 1

primary digestive organs

Answer 1

mouth/oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus

Question 2

accessory digestive organs

Answer 2

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

Question 3

accessory organs defn

Answer 3

help with digestion but are not part of the alimentary canal

Question 4

region-specific motilities function

Answer 4

region-dependent duration of ingested food for digestion and further exchange between the canal and wall of the GI tract

Question 5

esophagus motility time

Answer 5

rapid pass

Question 6

stomach motility time for 50% emptying

Answer 6

2.5 to 3 hours

Question 7

small intestine motility time for 50% emptying

Answer 7

3 to 4 hours

Question 8

colon motility time

Answer 8

30 to 40 hours

Question 9

skeletal muscles in GI tract

Answer 9

chewing or masticatory muscles, tongue, upper esophageal sphincter, upper esophagus, external anal sphincter

Question 10

what causes visceral smooth muscle contraction?

Answer 10

phosphorylation of myosin

Question 11

steps of smooth muscle contraction

Answer 11

activator signal (e.g. ACh) -> action potential induced membrane depolarization -> voltage-gated Ca++ channels open -> Ca++ influx -> activation of myosin light chain kinase (MLCK) -> phosphorylation of myosin -> contraction

Question 12

steps of smooth muscle relaxation

Answer 12

inhibitor signal (e.g. NO) -> increase in cGMP -> activation of myosin light chain phosphatase (MLCP) -> dephosphorylation of myosin -> relaxation

Question 13

functions of GI tract

Answer 13

secretion, digestion, absorption, motility

Question 14

alimentary canal wall layers (outside -> in)

Answer 14

serosa - muscularis externa - submucosa - mucosa

Question 15

nerve endings in submucosa

Answer 15

Meissner’s plexus

Question 16

nerve endings in muscularis externa

Answer 16

Auerbach’s plexus

Question 17

third branch of ANS

Answer 17

enteric nervous system

Question 18

most variable layer of alimentary canal in structure and function

Answer 18

mucosa

Question 19

components of mucosa layer

Answer 19

epithelial cells, lamina propria, muscularis mucosae

Question 20

types of epithelial cells

Answer 20

protective, secretory, absorptive

Question 21

where is protective epithelia most abundant

Answer 21

esophagus

Question 22

what are the types of secretory epithelia

Answer 22

mucus secreting cells, enteroendocrine cells, enterochromaffin-like cells

Question 23

enterochromaffin-like cells

Answer 23

secrete neurotransmitters

Question 24

enterocytes

Answer 24

absorptive; most abundant in the small intestine but the large intestine contains some too

Question 25

lamina propria

Answer 25

a connective tissue: immune cells, lacteal, and capillaries

Question 26

muscularis mucosae

Answer 26

a smooth muscle layer responsible for the folds and villi which increase surface area

Question 27

submucosa

Answer 27

a connective tissue layer with arteries, veins, and lymph vessels

Question 28

submucosal plexus

Answer 28

Meissner’s plexus; senses the environment within the lumen, and regulates the blood flow, epithelial cell function, and secretion from exocrine glands

Question 29

muscularis externa consists of

Answer 29

circular and longitudinal muscle in a perpendicular orientation

Question 30

myenteric plexus

Answer 30

Auerbach’s plexus; controls motility of the digestive tract by controlling contraction and relaxation of circular and longitudinal muscles independently

Question 31

stomach myenteric plexus

Answer 31

contains a third layer of muscle: oblique

Question 32

enteric nervous system

Answer 32

brain of the gut; local nervous system controlling local GI activities

Question 33

ENS sensory neurons

Answer 33

receive information from sensory receptors in the mucosa and muscle and relay the information to the interneurons

Question 34

ENS interneurons

Answer 34

function as the integrating center that connects sensory neurons and enteric motor neurons

Question 35

ENS motor neurons

Answer 35

act directly on effector cells of smooth muscle, secretory cells, and epithelial cells

Question 36

how is ENS modulated

Answer 36

the innervation and activity of the ANS

Question 37

how many neurons in gut

Answer 37

500 million

Question 38

tonic contraction

Answer 38

sustained contraction; no movement of food

Question 39

peristalsis

Answer 39

adjacent segments of the GI canal alternately contract and relax for unidirectional movement of food

Question 40

segmentation

Answer 40

non-adjacent segments of the GI canal contract and relax for bidirectional movement of food

Question 41

where does tonic contraction occur and why

Answer 41

sphincters, no movement of food content until controlled relaxation by ANS occurs