4.1 Digestive System Part 1

Question 1

4 tissue layers of digestive tract

Answer 1

Mucosa
Submucosa
Muscularis
Serosa
Myenteric plexus

Question 2

Mucosa Function

Answer 2

Absorption and secretion

Question 3

Submucosa function

Answer 3

Secretion

Question 4

Muscularis function

Answer 4

Motility

Question 5

Myenteric plexus function

Answer 5

Innervation
-Motility
-Stretch detection
“Gut brain”

Question 6

What does the myenteric plexus regulate?

Answer 6

Muscularis motility and secretions

Question 7

How much CNS input does the myenteric plexus operate under?

Answer 7

Minimal due to pacemaker capacity

Question 8

Enteric Nervous System (ENS)

Answer 8

Myenteric plexus and submucosal plexus

Question 9

Is the myenteric plexus responsive to the sympathetic or parasympathetic branch?

Answer 9

BOTH

Question 10

What is the submucosal plexus?

Answer 10

“Middle man,” regulates secretions by exocrine glands within submucosal layers

Question 11

Is the submucosal plexus responsive to the sympathetic or parasympathetic branch?

Answer 11

Parasympathetic ONLY

Question 12

Plexus

Answer 12

Bunch of neurons working together

Question 13

Basal Electrical Rhythm (BER)

Answer 13

Some GI neurons have a pacemaker rhythm ~3-12 depolarizations / minute

Question 14

How is BER spread?

Answer 14

Spread throughout the longitudinal smooth muscles in muscularis (via gap junctions)

Question 15

BER stimulates motility in muscularis for…

Answer 15

Peristalsis and mixing

Question 16

Peristalsis

Answer 16

Propulsive, unidirectional movement

Question 17

Mixing

Answer 17

Back and forth

Question 18

What is the BER pacemaker similar to?

Answer 18

SA node in heart

Question 19

How does the BER pacemaker work?

Answer 19

Na+ leakage leads to firing of action potential.. Ca influx and muscle contraction

Question 20

What in the BER determines the number of action potentials and then the force of contractions?

Answer 20

Resting membrane potential (hyper polarized -> fewer action potentials, etc)

Question 21

What in the BER determines the number of action potentials and then the force of contractions?

Answer 21

Resting membrane potential (hyper polarized -> fewer action potentials, etc)

Question 22

What does the parasympathetic division do to the RMP in BER pacemaker cells?

Answer 22

Depolarizes it

Question 23

Easier activation of BER pacemaker cells leads to…

Answer 23

• Increased glandular secretions

- Increased peristaltic contraction

Question 24

What does the sympathetic division do to the RMP in BER pacemaker cells?

Answer 24

Hyper polarizes it

Question 25

Slow contractions in GI motility leads to this phenomenon…

Answer 25

“Butterflies”

Question 26

How does the myenteric plexus modify motility locally?

Answer 26

Via vasoactive intestinal peptide

Question 27

Vasoactive intestinal peptide (VIP)

Answer 27

Neurotransmitter that relaxes regions out in front of a bolus material

Question 28

What does VIP respond to?

Answer 28

Physical stretching by foodstuff

Question 29

Chemo and mechanoreceptors send afferent signals back to the CNS via the….

Answer 29

Vagus nerve

Question 30

Mechanoreceptors: Highly fibrous, bulky foodstuff would lead to…

Answer 30

Stretch receptor activation and a feeling of satiety