LEC 17: GI tract motility Flashcards Preview

Anatomy > LEC 17: GI tract motility > Flashcards

Flashcards in LEC 17: GI tract motility Deck (75):
1

How do horses carry out food prehension?

Rip w/ teeth
-- and--
Manipulate with lips

2

How do cattle carry out food prehension?

Rip w/ hard palate and lower teeth
-- and --
Manipulate w/ tongue

3

How do carnivores carry out food prehension?

Cut w/ incisors
--- and --
Rip w/ canines

4

What are the three stages of swallowing?

Voluntary - Pharyngeal - Esophageal

5

What happens in the voluntary phase of swallowing?

Bolus to back of oral cavity

6

What happens in the pharyngeal phase of swallowing?

Oral cavity to esophagus

7

What happens in the Esophageal phase of swallowing?

Food to stomach

8

What are the three types of motility?

Propulsive - Retentive - Mixing

9

How does propulsion increasing affect transit time?

Decreases

10

What is the stimulus for peristalsis?

Distension

11

What is happening behind the bolus of food?

Longitudinal muscles - relax
Circular muscles - contract

12

What is happening around the bolus of food?

Longitudinal muscles - contract
Circular muscles - relax

13

Where does the sensory from the GI tract transmit to?

Dorsal vagal complex

14

What does the dorsal vagal complex activate?

Somatic
-- and --
Vagal

15

What do the cranial and caudal sphincters do?

Prevent food and air to enter the esophagus

16

What causes orad contraction?

ACh

17

What causes caudad distension?

NO

18

What do the vagal efferents act on?

Myenteric nerves

19

What does myastenia gravis cause?

Ab's block/alter/destroy Ach receptors

20

What is the major characteristic of the LES?

Myogenic, tonic contraction -- independent of neural input increases if stretched

21

What can increase LES contraction?

ACh - Gastrin - NOR

22

What can decrease LES contraction?

NO

23

What are the origin of electrical activity in the GI tract?

ICC

24

What do the gap junction btwn the SM and ICC allow for?

Contractions can occur together

25

What does the basal electric rhythm of ICC allow for?

Nothing; not strong enough to start AP; only set timing

26

What direction do ICC waves move in?

Aboral direction

27

What is the rate of an ICC wave in the SI of a dog?

~20/min

28

What induces the PM depolarization in ICC?

Cytosolic Ca2+ oscillators

29

What is the GI motility modulated by?

ANS

30

What is the direct effect of ENS on the ICC?

Contration --> via voltage change through gap junction

31

How do ICC waves become contractions?

Factors that cause depolarization or hyperpolarization

32

What are depolarizing factors of the ICC?

Stretching -- ACh/Substance P -- PNS - GI hormones

33

How is Gi contraction supressed?

SNS (via NOR)
-- and--
VIP/NO

34

What is the frequency of the slow waves in the stomach?

3-5m

35

What is the frequency of the slow waves in the SI?

10-20m

36

What is the frequency of the slow waves in the colon?

6-8m

37

What is the function of the fundus?

Storage

38

What is the function of the antrum?

Grinding
-- and --
Sieving

39

What is the adaptive reflex?

Reflexive response of proximal region to food entering stomach

40

What does vagal stimulation cause in the stomach?

Proximal region: Suppresses contraction
Distal region: Stimulates peristalsis

41

What is the motility like in the antrum?

Intense slow wave activty and contraction

42

What is the motility like in the body?

Strong waves of peristalsis from body to pylorus

43

What does gastrin do?

Stimulate motility
-- and --
Gastric acid secretion

44

What is the limiting factor of motility in the stomach?

Digestion and absorption in the SI

45

What slows emptying in the stomach?

Low pH in duodenum
-- and --
High fat in stomach

46

What is secreted in response to fat and low pH?

CCK
-- and --
Secretin

47

What does CCK do?

Inhibits antrum motility

48

What stimulates CCK secretion?

Fat

49

What does Secretin do?

Inhibits antrum motility

50

What stimulates secretin secretion?

low pH

51

What does duodenal distension cause?

Inhibition of stomach motility

52

What is the interdigestive motility complex?

Relaxtion of pylorus w/ strong waves of peristalsis through stomach

53

What is the point of the interdigestive motility complex?

Force out anything in stomach

54

When do interdigestive motility complexes occur?

once an hour

55

What two major things are involved in vomiting?

Motility of the GI tract
-- and --
Pressure regulation in abdomen and thorax

56

Where is the vomiting center?

Reticular formation in the medulla

57

What are the four things that input into the vomiting center?

Higher center - Vestibular app. - Vagal afferent - CRTZ

58

What does the high center sense?

Trauma - Intracranial pressure

59

What does the vestibular apparatus sense?

Motion sickness

60

What does the vagal afferent fibers sense?

Peritoneum - Bile ducts - Heart

61

What does the CRTZ sense?

blood borne - Drugs - Toxins

62

What are the two phases of the digestive period?

Nonpropulsive
-- and --
Propulsive

63

What is the MMC?

Migrating motility complex

64

What doe the MMC do?

Strong contractions, entire SI
Forceful emptying of SI

65

What are the motility patterns of the large intestines?

Segmentation -- Retropulsion -- Propulsion

66

What does the colonic pacemaker do?

Antiperistaltic motility -- shift site of pacemaker

67

What is the rectospincteric reflex?

Feces enters rectum - Internal sphincter relaxes - Rectal walls contraction

68

What voluntary structure can stop the rectosphincteric reflex?

External anal sphichter

69

Where does the PNS control of the sphincter originate?

Sacral spinal cord

70

What is the stimulus/response of the orthocolic reflec?

Stimulus: Standing up
Response: Increased colonic motility/mass movemetn

71

What occurs with the fear-stress induced defecation?

Fear - CRH - Activates PNS - Enhance colonic motility

72

What is the stimulus/response to the gastrocolic reflex?

Stimulus: Full stomach
Response: Increase colonic motility --> fills rectum

73

What is the stimulus/response enterogastric reflex?

Stimulus: Digesta in the duodenum
Response: inhibition of gastric emptying

74

What is the stimulus/response of the coloileal reflex?

Stimulus: Full colon
Response: Inhibition of ileum emptying

75

What is the stimulus/response of the ileogastric reflex?

Stimulus: Full ileum
Response: Inhibition of gastric emptying