Physio - GI motility (edited)

Question 0

How are smooth muscle cells in GI tract functionally coupled?

Answer 0

• are connected by nexus that allow fast communiction bw cells and enables them to contract together

Question 1

2 different types of contraction of GI tract

Answer 1

1. Phasic– Short contraction (peristalsis) 2. Tonic– Can last for hours until inhibited (sphincters)

Question 2

T/F. Chewing is both voluntary & reflexive.

Answer 2

TRUE (stretch reflex) *we dont have to continuously think about chewing when eating

Question 3

3 Functions of chewing

Answer 3

1. Break down food 2. Lubricate with saliva 3. Increase surface area for chemical digestion

Question 4

When bolus contacts the back of the pharynx, ________ contract.

Answer 4

Superior constrictor muscles -> afferent innervation sends signal to swallowing center in medulla -> sends efferent signals via nonvagal nuclei to contract muscles of pharynx & esophagus

Question 5

As food moves through pharynx, ____ is closed off by epiglottis & bolus enters the _____.

Answer 5

Trachea; esophagus *Peristaltic movement is initiated in esophagus

Question 6

The esophagus closes once bolus has passed through to prevent _____.

Answer 6

Reflux of material back into esophagus *Inferior constrictor muscles

Question 7

Upper esophageal sphincter pressure is greater/less than atmospheric pressure.

Answer 7

Greater.

Question 8

Below UES through diaphragm, the pressure is greater/less than atmospheric pressure.

Answer 8

Less. *thorax has negative pressure

Question 9

Below diaphragm, the pressure is greater/less than the atmospheric pressure.

Answer 9

Greater.

Question 10

Primary peristalsis

Answer 10

Initiated by a swallow

Question 11

Secondary peristalsis

Answer 11

Not initiated by a swallow e.g. to clear any residual obstructions not cleared by the primary peristaltic wave

Question 12

Gastric Esophageal Reflux Disease (GERD)

Answer 12

Acid reflux from stomach into esophagus - mucosa of stomach is unaffected by acid but the esophagus is susceptible to acid damage. *heart burn

Question 13

Some causes of GERD

Answer 13

Hiatal hernia Pregnancy Failure of secondary peristalsis

Question 14

Orad area of the stomach

Answer 14

Few & weak contractions Primary function is storage Contains oxyntic glands

Question 15

Pyloric gland area of the stomach

Answer 15

Very strong muscular contractions

Question 16

Achalasia

Answer 16

Due to absence of ganglion in esophagus that contains VIP. Becomes contracted and material doesn’t move through it. Also possible in colon.

Question 17

Functional areas of the stomach

Answer 17

Orad (oxyntic gland) and Antrum.

Question 18

Where in the stomach has NO contractions?

Answer 18

Fundus

Question 19

Reflexive relaxation

Answer 19

Drop in fundus pressure allows the stomach to receive food Vago-vagal reflex -> VIP release causes NO release -> relaxation of the stomach

Question 20

Gastric motility contraction increases/decreases in strength and rate as it goes distally

Answer 20

Increases

Question 21

Gastric slow wave

Answer 21

Sets the maximum rate of contraction rate of the stomach 3-5 contractions/min **cannot be changed

Question 22

What creates the slow wave potentials in the stomach?

Answer 22

Interstitial cells of cajal.

Question 23

Amplitude of the wave is regulated how?

Answer 23

neural & hormonal activity *determines the strength of the contraction

Question 24

Which empties faster from stomach? Liquid or solid?

Answer 24

Liquid. DUH!!! Also greater the volume, the more rapid the rate of emptying.

Question 25

What empties fastest? Hypotonic, isotonic, or hypertonic?

Answer 25

ISOTONIC Saline Hypo-hypertonic inhibit emptying

Question 26

Acid stimulates/inhibits emptying.

Answer 26

inhibits \*needs time to neutralize before entering the gut

Question 27

Why does fat take longer to empty from stomach?

Answer 27

Not water soluble -\> longer to digest Triggers CCK release -\> slows down gastric emptying

Question 28

Failure to empty in stomach can be caused by...

Answer 28

Vagotomy (no vago-vagal reflex to cause peristalsis) Obstruction (ulcer or cancer)

Question 29

Symptoms of failure to empty

Answer 29

Fullness, loss of appetite, and nausea

Question 30

Increased emptying can be caused by...

Answer 30

Inadequate regulation

Question 31

Symptoms of increased emptying

Answer 31

diarrhea duodenal ulcer

Question 32

Almost all significant absorption occurs where?

Answer 32

Small intestine -\> very slow progression through small intestine

Question 33

Motor patterns of small intestine

Answer 33

Segmentation Peristalsis

Question 34

Motilin release is stopped when?

Answer 34

Once feeding begins -\> causes migratory motor complex to halt

Question 35

Intestinal contraction requires ___ on slow waves.

Answer 35

Spikes!!! \*no contraction without spike Like the stomach, the frequency of slow waves do not change, but the frequency of the spiking can change!

Question 36

There is no change in amplitude of the contractions in small intestine/stomach.

Answer 36

Small intestine!!! Only the frequency of spiking changes

Question 37

Max frequency of contraction in S.I. is greater proximally/distally.

Answer 37

Proximally \*decreases distally

Question 38

Function of the colon

Answer 38

Fluid & electrolyte absorption

Question 39

Colon is innervated by...

Answer 39

Vagus n. til 2/3 transverse colon The rest is innervated by pelvic n.

Question 40

Ileocecal sphincter is the junction btw

Answer 40

Ileum & Cecum

Question 41

If ileum is distended, what happens to the ileocecal sphincter?

Answer 41

Relaxes and allows material into colon from ileum

Question 42

What happens to the ileocecal sphincter if colon is distended?

Answer 42

Ileocecal valve contracts and prevents reflux of material from colon into small intestine.

Question 43

Ileocecal sphincter normally has what type of contraction? Tonic or phasic?

Answer 43

Tonic! Not vagal.

Question 44

What is the cause of the urge to poop?

Answer 44

2-3 times a day, haustrations in portions of colon disappear and cause peristalsis Also Rectum contracts and internal rectosphincter relaxes

Question 45

What type of movement does the colon have?

Answer 45

MASS MOVEMENT

Question 46

If conditions are not right for defecation, what happens?

Answer 46

External sphincter contracts and prevents defecation. Innervation via dorsal segments (pudendal n.)