Gi Phys, Gi Hormones

Front 1

What is chyme?

Back 1

Mixture of food particles, enzymes, and gut secretions produced in stomach.

Front 2

Three divisions of large intestine

Back 2

Cecum, Colon, Rectum

Front 3

Three divisions of small intestine

Back 3

Duodenum, Jejunum, Ileum

Front 4

What are the 5 sphincters in GI tract?

Back 4

1) Upper and lower esophageal
2) Pyloric
3) Oddi
4) Ileo-cecal
5) Anal (internal and external)

Front 5

What is the Enteric Nervous System (ENS)?

Back 5

Cell bodies within wall of gut. 10^8. "Little brain."

Front 6

What is largest endocrine organ of body?

Back 6

gut

Front 7

What is the Extrinsic Nervous System?

Back 7

Part of the ANS

Front 8

Where do preganglionic parasympathetic fibers to the gut arise?

Back 8

1) Esophagus - Transverse colon: Dorsal motor nucleus of vagus nerve (DMV)

2) Remainder of colon, rectum, anus: Sacral division of spinal cord (S2-4)

Front 9

Where do preganglionic fibers to the gut travel?

Back 9

1)1) Esophagus - Transverse colon: Vagus

2) Remainder of colon, rectum, anus: Pelvic nerve

Front 10

What is the preganglionic neurotransmitter?

Back 10

ACh

Front 11

What is the postganglionic neurotransmitter?

Back 11

ACh or one of the neurotransmitters released by neurons of enteric NS

Front 12

Is Vagus primarily afferent or efferent?

Back 12

90% afferent

Front 13

Where do preganglionic sympathetic fibers to the gut arise?

Back 13

Thoracic and lumber spinal cord and pass thru sympathetic chain ganglia.

Front 14

What are the prevertebral ganglia? What's their significance?

Back 14

Celiac ganglia, superior and inferior mesenteric ganglia. It's where the preganglionic sympathetics synapse.

Front 15

Where do most postganglionic sympathetic fibers terminate?

Back 15

On other neurons in the enteric ns. Stimulation of these usually results in general inhibition of gut fxn due to presynaptic inhibition.

Front 16

What layers is the myenteric plexus between?

Back 16

Longitudinal (outer) and circular (inner) muscle layer

Front 17

What layers is the submucousal plexus between?

Back 17

circular (inner) muscle layer and muscularis mucosae.

Front 18

What are the Three types of afferent nerves that detect sensory info from various layers of gut?

Back 18

1) Vagal afferent fibers: Connect to nucleus of solitary tract (NST) and dorsal motor nucleus (DMN)

2) Extrinsic primary afferet neurons: from Dorsal root ganglion

3) Intrinsic primary afferent neurons (IPANS): from myenteric and submucosal neural plexuses of ENS.

Front 19

What are reflex arcs that coordinate activity over long distances and between different regions in gut?

Back 19

Long Arc reflexes: Efferent and Afferent limbs are part of EXTRINSIC N.S.

Front 20

Are long arc reflexes more involves with para or sympathetic ns?

Back 20

BOTH

Front 21

long arc reflexes with parasympathetic ns are usually (excitatory, inhibitory)?

Back 21

Excitatory

Front 22

What is the vagovagal reflex?

Back 22

afferent and efferent fibers of the vagus nerve[1] coordinate responses to gut stimuli via the dorsal vagal complex in the brain. The vagovagal reflex controls contraction of the gastrointestinal muscle layers in response to distension of the tract by food. This reflex also allows for the accommodation of large amounts of food in the gastrointestinal tracts.

Front 23

long arc reflexes with sympathetic ns are usually (excitatory, inhibitory)?

Back 23

inhibitory

Front 24

What is the intestino-intestinal reflex?

Back 24

Mediates inhibition between regions of the intestine. Afferent component=extrinsic primary afferent neurons. Efferent=sympathetic neuron.

Front 25

What are short arc reflexes?

Back 25

How the ENS controls local fxn independent of CNS input. Only extend at most a few cm from stimulus. Peristaltic reflex is an example.

Front 26

What are intestinofugal or viscerofugal neurons?

Back 26

Enteric neurons that project axons to prevertebral ganglia. Involved in long arc reflexes and in regulating sympathetic input to enteric neurons.

Front 27

What is the main transmitter of enteric ns?

Back 27

ACh

Front 28

What are the actions of Enkephalins (opioid peptides?)

Back 28

Generally inhibitory; restrain ACh release from enteric neurons.

Front 29

What are the actions of Tachykinins (substance P and neurokinin A)?

Back 29

Major contractile neurotransmitter mediating non-cholinergic responses. found in excitatory motor neurons and interneurons.

Front 30

What are the actions of Vasoactive intestinal peptide (VIP?)

Back 30

Major relaxant for smooth muscle and excitatory for secretory cells. Found in inhibitory motor neurons and excitatory secretomotor neurons.

Front 31

What are the actions of Gastrin releasing peptide ? (GRP)

Back 31

Found in long interneurons of intestine and gastric enteric neurons that stimulate Acid secretion and gastrin section

Front 32

What are the actions of somatostatin?

Back 32

Major inhibitory transmitter of gut.

Front 33

What are the actions of nitric oxide?

Back 33

Relaxant

Front 34

What type of hormones are gut hormones?

Back 34

Polypeptides. Amidated on C-end.

Front 35

What activates gastrin?

Back 35

Gastrin is for H+ secretion. Secretion turned on by food, inhibited by H+ (enough H+ present, don't need more gastrin). Actions are H+ secretion and growth of gastric mucosa.

Front 36

What activates CCK? What is it for?

Back 36

CCK is for fat. Secretion turned on by food, esp fat digestion products. Actions = secretion of pancreatic enzymes (fat digestion), gall bladder contraction (bile for fat digestion/absorption), inhibits gastric emptying (slows delivery of chyme to intestine b/c fat digestion/absorption takes lots of time.

Front 37

What activates secretin? What's it for?

Back 37

Secretin is for neutralization of H+. Secretion turned on by H+. Actions = secretion of HCO3 by pancreas and intestine, growth of pancreas (neutralizes H+), inhibition of gastric H+ secretion

Front 38

What activates Glucose-dept Insulinotrophic peptide (GIP)?

Back 38

GIP is for insulin. Secretion turned on by food. Actions are "I’s" = "I"nsulin secretion and "I"nhibition of gastric H+ secretion

Front 39

Where is gastrin found?

Back 39

G cells in gastric antrum

Front 40

Where is CCK, Secretin, and GIP located?

Back 40

Small intestine

Front 41

Gastrin and _____ are in the same family.

Back 41

CCK

Front 42

At high doses of gastrin, what actions might we expect?

Back 42

Because in same family as CCK, you might expect it would mimic CCK in huge (pharmacologic) concentrations.

Front 43

Secretin and _____ are in same family.

Back 43

GIP

Front 44

What cells release somatostatin?

Back 44

Antral D cells

Front 45

What does somatostatin do?

Back 45

It's released from intestinal cells in response to meal and acid as well as neural and hormonal factors. <b>Inhibits secretion, motility and hormone release throughout gut.</b>