1-GI tract

Question 1

what are the 4 major functions of the GI system?

Answer 1

digstion
absorption
excretion
host defense

Question 2

how is blood supplied to the system? what is unusual about the blood circulatory pathway?

Answer 2

portal circulation, all the blood from the digestive tract empties directly into the liver

Question 3

what is the role of the autonomic system in regulation of GI physiology?

Answer 3

not 100% necessary

motility and secretion (sight/smell/emotions)

Question 4

what is enteric nervous system

Answer 4

intrinsic regulation

contained completely within the walls of the GIT

Question 5

what is intrinsic innervation

Answer 5

enteric regulation

contained completely within the walls of the GIT

Question 6

what is extrinsic innervation

Answer 6

autonomic nervous system
not 100% necessary
influences motility and secretion of gut (sight/smell/emotions)

Question 7

what is the role of hormones in regulation of the GI processes

Answer 7

they participate in a feedback control system that regulate some aspect of the GI system

Question 8

what is neurocrine

what do you call the substance

Answer 8

chemical messenger released from nerve travels across synapse and acts upon a post-synaptic synapse
neurotransmitter!!!!!

Question 9

what is endocrine

what do you call the substance

Answer 9

chemical messenger from cell released to blood into (distant) target
hormone!!!!!!!!!

Question 10

what is paracrine

Answer 10

chemical messenger diffuses through intestinal fluid to nearby cells

Question 11

what is autocrine

Answer 11

chemical messenger acts on the same cell that produced it

Question 12

what kinds of muscle activity occur in the GI tract

Answer 12

peristalsis and segmentation

Question 13

what is basic electrical rhythm

Answer 13

pacemaker cells that undergo spontaneous depolarization/repolarization

Question 14

what does the serosa do and what is it made of

Answer 14

connective tissue

encases intestine, forms connection point to abdominal wall

Question 15

what does the myenteric plexus do

Answer 15

influences smooth muscle (inbetween the circular and longitudinal muscle)

Question 16

submucosal plexus what do

Answer 16

influences secretion (between muscle, lymph and blood)

Question 17

what is peristalsis/ which muscle contracts and relaxes

Answer 17

circular contracts & longitudinal relax on oral side

longitudinal contracts & circular relax on anal side

Question 18

how does segmentation work

Answer 18

contraction and relaxation of intestinal sements with little net movement of contents towards large intestine

Question 19

where is most segmentation occuring

Answer 19

small intestine

Question 20

where are slow waves propagated

Answer 20

circular and longitudinal muscle

Question 21

how are slow waves depolarized more significantly

Answer 21

neural or hormonal input to bring it closer to threshold

Question 22

what kind of cells release gastrin

Answer 22

g cells

Question 23

where are g cells

Answer 23

stomach antrum

Question 24

what do g cells release

Answer 24

gastrin

Question 25

what stimulates gastrin release

Answer 25

peptides in stomach, parasym. nerves

Question 26

what does gastrin cause

Answer 26

more HCl and motility

Question 27

what cells secrete secretin

Answer 27

s cells

Question 28

what do s cells secrete

Answer 28

secretin

Question 29

what causes secretin release

Answer 29

acid in small intestine

Question 30

what does secretin release cause

Answer 30

less HCl, less motility | increased HCO3- and H2O from pancreas abd bile

Question 31

what cells release GIP

Answer 31

k cells

Question 32

where are k cells

Answer 32

small intestine

Question 33

where are s cells

Answer 33

small intestint

Question 34

what causes GIP release

Answer 34

glucose or fat in small intestine

Question 35

what does GIP release cause

Answer 35

raise insulin

Question 36

what cells release CCK

Answer 36

I cells

Question 37

where are I cells

Answer 37

small intestine

Question 38

what causes CCK release

Answer 38

digested fat/ protein in small intestine

Question 39

what happens when CCK is relased

Answer 39

lower HCl and motility | more pancreatic enzymes and bile released

Question 40

what are long reflexes

Answer 40

come from brain, go to gut

Question 41

what are short reflexes

Answer 41

receptors through nerve plexus to effector cells within the GI tract

Question 42

what is exocrine

Answer 42

chemical messenger secreted into ducts then onto epithelial surface ( no blood )

Question 43

does the enteric system depend on the CNS

Answer 43

no, independent of CNS

Question 44

what is in the enteric system

Answer 44

myenteric plexus & submucosal plexus

Question 45

does the intrinsic system depend on the CNS

Answer 45

no, independent of CNS

Question 46

what is in the intrinsic system

Answer 46

myenteric plexus & submucosal plexus