Intro To gi

Question 1

What is absent in smooth muscles?

Answer 1

Troponin

Question 2

Characteristics of Smooth muscles?

Answer 2

No striations, no troponin, calcium binds to calmodulin

Question 3

Where is the source of calcium found in smooth muscles? And why?

Answer 3

In the ECF because SR is poorly developed

Question 4

Is smooth muscle autonomic or somatic?

Answer 4

Autonomic because of para and sympathetic

Question 5

Types of smooth muscle?

Answer 5

Single unit and multi unit

Question 6

Single unit characteristics:

Answer 6

1. Walls of hollow viscera
2. Contracts as a single unit because of gap junctions
3. Syncytial

Question 7

Describe smooth muscle contraction

Answer 7

1. Action potential
2. L type voltage gated calcium channels
3. Calcium comes into cell from ecf
4. Calcium binds to calmodulin and forms calcium calmodulin complex
5. Activates MLCK
6. Activates myosin ATPase

Question 8

Describe relaxation of smooth muscle:

Answer 8

In cytosol free Ca2+ decreases and causes calcium calmodulin to dissociate, MLCK gets dissociated

1. Nitric oxide stimulates cGMP
2. MLCP gets activated and removes phosphate group
3. Myosin actin dissociates from eachother

Question 9

Where is multi unit smooth muscles found?

Answer 9

In ciliary muscles

Question 10

How do multi units contract?

Answer 10

Independently as multiple units

Question 11

Which is syncytial and non syncytial?

Answer 11

Single units are syncytial and multi units are non syncytial

Question 12

What kind of enzymes do lysosomes contain?

Answer 12

It contains acidic enzymes called hydrolase

Question 13

What are the steps of smooth muscle AP?

Answer 13

Slow wave potential
Spikes
Depolarization
Hyperpolarization

Question 14

What are slow wave potentials?

Answer 14

Below threshold, move slowly, resting membrane potential
Generated by pacemaker which are interstitial cells of cajal… located in myentric plexus

Question 15

What are spikes of smooth muscle AP?

Answer 15

True action potential
Generated when RMP becomes more positive

Question 16

What activates spike and depolarization?

Answer 16

Parasympathetic

Question 17

What are the two types of enteric nervous system?

Answer 17

Myentric plexus and meissners plexus

Question 18

What are the location and function of myentric plexus?

Answer 18

Muscularis later and motility

Question 19

What is the location and function of meissners plexus?

Answer 19

Submucosa and secretion

Question 20

What muscles are found in the muscularis layer?

Answer 20

Circular (inside) and longitudinal (outside)

Question 21

What is secreted by the parietal cells?

Answer 21

HCL and IF which stimulate the absorption of B12

Question 22

What is secreted by the chief cells?

Answer 22

Pepsinogen

Question 23

What part of the stomach are parietal and chief cells found?

Answer 23

Body of stomach

Question 24

What is found in the antrum?

Answer 24

G cells, D cells and mucous cells

Question 25

What are found in the Antrum of the stomach?

Answer 25

G cells which secretes gastrin mucous cells secrete mucous for protection d cells secrete somatostatin

Question 26

What cells are found in the pylorus of stomach?

Answer 26

I cells secrete CCK S cells secrete secretin K cells GIP

Question 27

Function of parasympathetic system

Answer 27

Contraction stimulated by Ach, increase in motility, increase in secretion and gastrin, and decrease constriction of sphincters

Question 28

Function of sympathetic

Answer 28

Relaxation stimulated by no, vip, decrease in motility, decrease in secretion and gastrin, and increase constriction of sphincters

Question 29

What is the function of GIP?

Answer 29

Stimulates insulin release

Question 30

What is the functions of somatostatin and what cells are they released from?

Answer 30

D cells and they inhibit gastric acid secretions. There is a decrease in gastric acid, pancreatic secretion and gall bladder contraction

Question 31

What are the functions of secretin?

Answer 31

It stimulates bicarbonate secretion and inhibits gastric emptying

Question 32

What is released by fat cells of adipose tissue?

Answer 32

Leptin

Question 33

What is released from mucosal cells during fasting?

Answer 33

Ghrelin

Question 34

What stimulates anorexiagenic neurons and what does it do?

Answer 34

Leptin and decreases appetite

Question 35

What stimulates orexigenic neurons and what does it do?

Answer 35

Ghrelin and increased appetite

Question 36

Difference between incretins and and amylin?

Answer 36

Incretins secretes insulin from the pancreas and Amylin slows gastric emptying and lowers plasma glucose

Question 37

Where is vitamin B12 absorbed ?

Answer 37

Ileum

Question 38

A 35-year-old man with decreased gastrointestinal motility is shown to have no slow waves on electric potential and force transducer recordings from gastrointestinal muscles over a period of 60 seconds. Which of the following is the best description of slow waves in the gastrointestinal tract? A. Contraction of skeletal muscle B. Depolarization and repolarization of smooth muscles cells C. Hyperpolarization of smooth muscle cells D. Increase in secretions of smooth muscle cells E. Relaxation of smooth muscle cells

Answer 38

B

Question 39

A 10-year-old boy consumes a cheeseburger, fries, and chocolate shake. The meal stimulates the release of several gastrointestinal hormones. The presence of fat, carbohydrate, or protein in the duodenum stimulates the release of which. Hormone from the duodenal mucosa?