Phys 63-64: GI Principles and Propulsion

Question 1

GI Wall muscle layers (out to in)

Answer 1

1) Serosa
2) Longitudnal
3) Circular
4) Submucosa
5) Mucosa

Question 2

What happens in a muscle that functions as syncytium

Answer 2

Action potential in one area travels in all directions of muscle

Question 3

Two types of electrical waves in GI muscle

Answer 3

Slow wave

Spike

Question 4

Slow waves are caused by _____

Answer 4

Undulating changes in resting membrane potential

Question 5

Electrical pacemakers of smooth muscle cells aka

Answer 5

Interstitial cells of cajal

Question 6

Ion channels in nerve fibers (which ions?) (in GI*)

Answer 6

Calcium-sodium channels

Lots of calcium and sodium

Question 7

Factors that depolarize GI smooth muscle membrane

Answer 7

1) Stretching of muscle
2) Stimulation by acetylcholine
3) Simulation by specific GI hormones

Question 8

Factors that make GI smooth muscle membrane less excitable

Answer 8

1) Norepi/Epi
2) Sympathetic

Question 9

Calcium ion influx into smooth muscle causes

Answer 9

Contraction.

Question 10

Tonic contraction characteristics

Answer 10

Non-rhythmic. Continous and last several minutes-hours

Question 11

Myenteric vs submucosal plexus

Answer 11

Myenteric: GI movement
Submucosal: Secretion

Question 12

Enterogastric reflexes

Answer 12

Intestine tells stomach to chill

Question 13

Gastrocolic reflex

Answer 13

Stomach tells colon to move

(la de hoy empuja la de ayer)

Question 14

Gastrin secretion site

Answer 14

G Cells of antrum

Question 15

Gastrin action

Answer 15

stimulates gastric acid secretion and mucosal growth

Question 16

Secretin site of secretion

Answer 16

S cells

Question 17

Secretin function

Answer 17

Stimulates pepsin secretion, pancreas and gall bladder

Inhibits gastrin

Question 18

Glucose-dependent insulinotropic peptide site of secretion

Answer 18

K cells (duodenum and jejunum)

Question 19

Glucose-dependent insulinotropic peptide action

Answer 19

Stimulates insulin release

Inhibits acid secretion

Question 20

Motilin site of secretion

Answer 20

M cells (duodenum and jejunum)

Question 21

Substance secreted due to vagal stimulation of gastric mucosa

Answer 21

Gastrin-releasing peptide

Question 22

Cholecystokinin actions

Answer 22

Contracts gallbladder, slows gastric emptying. Inhibits apetite

Question 23

Stimulus for peristalsis

Answer 23

Gut distention

Question 24

liver sinusoids lined by ______. Function?

Answer 24

Reticuloendothelial cells

Funcion is to remove bacteria from portal circulation

Question 25

mechanics of the pharyngeal stage of swallowing:

Answer 25

The trachea is closed, the esophagus is opened, and a fast peristaltic wave initiated by the nervous system of the pharynx forces the bolus of food into the upper esophagus

Question 26

Sensory impulses in mouth go to

Answer 26

Tractus solitarious

Question 27

Areas in medulla/pons controlling swalloing

Answer 27

Deglutition Swallowing center

Question 28

Primary vs secondary esophagus peristalsis

Answer 28

Primary: Follows first wave of food down Secondary: remaiing food distends esophagus and initiates second wave

Question 29

Waves that mix food in stomach

Answer 29

Constrictor waves/ mixing waves

Question 30

Maximum segmental contraction frequency determined by

Answer 30

Frequency of slow waves in intestinal wall

Question 31

gastroileal reflex

Answer 31

intensifies peristalsis in the ileum and forces the remaining chyme through to large intestine.

Question 32

Longitudnal strips of muscle in colon AKA

Answer 32

Teniae coli

Question 33

External anal sphincter controlled by

Answer 33

Pudendal nerve

Question 34

Parasympatheic defecation reflex

Answer 34

Chyme in rectum stimulates nerves that synapse at spine and then return via pelvic nerves to cause peristalsis

Question 35

Peristalsis during peritonitis

Answer 35

Inhibited