GI 2

Question 1

What is digestion?

a)the absorbtion of water and various other substances into the body
b)the mechanical and chemical breakdown of food
c) the movement of food through the digestuve system
d) all of the above

Answer 1

the mechanical and chemical breakdown of food

Question 2

what are the 4 functions/processes of the digestive system

Answer 2

digestion
secretion
absorbtion
motility

Question 3

what are some challenges of the digestive system

Answer 3

Avoiding Autodigestion: not damaging our own cells

Mass Balance: we secrete a lot more than we ingest

Defense: absorbing stuff without bacteria and viruses (lyphocytes protect us)(80% in small intestine)

Question 4

name 3 fluid secretions

Answer 4

water
digestive enzymes
mucus (goblet cells in intestine)

Question 5

motility

Answer 5

refers to the movement of material through the GI tract as a result of muscle contraction

Question 6

two purposes of motility

Answer 6

1. moves food from mouth to aus
2. mechanically mixing food breaks it into uniformly small particles

Question 7

where do you see tonic contrations

Answer 7

sphicters

Question 8

where are you most likey to see phasic contractions?

Answer 8

esophagus, posterior region of stomach, small & large intestines

Question 9

slow waves

Answer 9

slow waves are modified by chemical input from nerons, hormones, paracrine signals. THER ARE CONTINUIOUS

Question 10

which layer of the GI tract contains the portion of the ENS that interacts with epithelial cells lining the lumen?

mucosa
sub,ucosa
muscularis extarna
serosa

Answer 10

submucosa -

there are 2 nerve networks that make the the ENTERIC NERVOUS SYTEM (ENS)

Question 11

intersitial cells of Cajal (ICC)

Answer 11

they found pacemaker cells in the GI tract

they called it Interstitial cells of CAJAL

they serve to slow wave activity and will spontaneuosly depolarize

Question 12

3 main patterns of motility

Answer 12

1) MIGRATING MOTOR COMPLEX (motilin)
2) PERISTALTIC CONTRACTIONS
3) SEGMENTAL CONTRACTIONS

Question 13

1) MIGRATING MOTOR COMPLEX (motilin)

Answer 13

cycles/contrations that empty the GI tract between meals. begins at stomach and ends at ileum

-2hours after eating (first quiescent 45-60mins)
-20-30min period of infrequent peristalitic contactions (procced in a forward diretion)
-5-15min cycle rapid forceful contractions

Question 14

2) PERISTALTIC CONTRACTIONS

Answer 14

wave pushing everything forward.

Question 15

3) SEGMENTAL CONTRACTIONS

Answer 15

small segments alternatively contact and relax circular and longitudinals (churns and mixes stuff)

Question 16

Which can GI REGULATE??

motility
absorbtion
secretion
digestion
motility and digestion
secretion and motility

Answer 16

secretion and motility - regulated by NEURAL & GI PEPTIDES

Question 17

Enteric Nervous system

Answer 17

made of 1. submucosal and 2. myenteri plexus form the ENS

500 mill nerons (HUGE) largest part of peripheral ervous system that controls GI tract

is a part of the peripherical NS but acts more like the Central NS

Question 18

short reflexes

Answer 18

short relfexes integtrate into the ENS

this is why people call it its own nervous system - cuz it dont need a brain (autonomous)

there are also long relexes

Question 19

GI PEPTIDES

Answer 19

alter motility and secretion (inhibit and excite)

inculdes
-hormones (some can act as paracrine signals)
-neuropeptides
-cytokines

Question 20

commonalities with ENS and CNS

Answer 20

intrinsic neruons: entirly within the GI tract - smililar to the interneurons in the Central NS

neurotransmitters and neuromodulators - many identical to CNS

glial support cells - similar to astrocytes

diffusion barrier - like blood gut barrier

*intergrating center - can function autonomously

Question 21

myenteric plexus

Answer 21

motility part of the ENS

Question 22

submucosal plexus

Answer 22

secretion from GI secretory cells part of the ENS

Question 23

cephailc reflex

Answer 23

a long relfex the begins in the brain - can happens from smelling food, seeing food, thinking about food.

this stimulus can effect motility in the GI tract

Question 24

_____ nervous system enhances GI functioning

Answer 24

parasymathetic NS

Question 25

_____ nervous system inhibits GI functioning

Answer 25

sympathetic NS

Question 26

Which region of the GI tract contains a very large amount of bacteria?

esophagus
stomach
small intestine
large intestine

Answer 26

large intestine! - cuz it is less leaky and HUGE