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Flashcards in Physiology Deck (66):
1

Enteric nervous system comprises what

Myenteric and submucosal plexuses

2

Vagal-Vagal reflex: afferents go where

Nodose ganglion

3

Vagal vagal reflex: Efferents come from where?

NTS: Nucleus Tractus Solitarius

4

Gastrin: Source?

Stimuli of secretion

-G cells of stomach

-small peptides and aa
-Distention
-vagal stimulation (via GRP)

5

CCK: source?

Stimuli of secretion?

I cell of duodenum and jejunum

-Small peptides and a.a.
-Fatty acids

6

Secretin: source?

Stimuli of secretion?

S cell of the duodenum

-H+ in duodenum
-Fatty acids in duodenum

7

GIP: source?

stimuli of secretion?

What does it do?

Duodenum and jejunum

-Glucose

-stimulates insulin

8

What does the NT VIP do?

-relaxation of smooth muscle
-increase intestinal and pancreatic secretion

9

what does the NT GRP do?

-increases Gastrin secretion

10

What 2 NTs are used for food intake regulation

-Neuropeptide Y
-Substance P

11

What is it called when the GI smooth muscle, even subthreshold depolarizes and can produce weak contraction

Basal Contractions

12

Sub thrshold depolarization and repolarization of the GI membrane potential

slow waves

13

What 3 things stimulate depolarization of the slow waves?

what stimulates hyper polarization?

-stretch
-ACh
-Parasympathetics

-Norepinephrine
-Sympathetics

14

pacemaker for GI smooth muscle

Interstitial cells of Cajal (ICC)

15

slow waves occur spontaneously in the ICC and spread how

gap junctions

16

Smooth muscle cells response to slow wave depolarization with increased what?

Ca2+ channel open probability

17

3 phases of swallowing

-Oral phase
-pharyngeal phase
-Esophageal phase

18

involuntary swallowing reflex is controlled by what?

the medulla

19

What nerve sends afferent sensory input due to food in the pharynx to the swallowing center in the medulla?

Glossopharyngeal N.

20

Esophageal phase of swallowing contains what 2 types of peristaltic waves?

primary and secondary

21

Which wave of the esophageal phases can still occur after a vagotomy

secondary

22

Receptive relaxation occurs in what region of the stomach

orad

23

What does CCK do to the contractions and distensibility of orad region upon reception of food

-decreases contractions
-increases distensibility

24

how long does gastric emptying take

3 hours

25

What secretion from the duodenum inhibits gastric emptying

CCK

26

Large particles of undigested residue remaining in the stomach are emptied by what

Migrating myoelectric complexes (MMC)

27

-intervals for MMCs
-when do they occur?
-what mediateds them?
-when are they inhibited?

-90 min
-during fasting
-Motilin-mediated
-inhibited by feeding

28

What type of contractions:
-back and forth movements
-No forward propulsive movement

segmentation

29

What type of contrations:
-Circular and longitudinal muscles work in opposition and are reciprocally innervated

peristaltic

30

what does the myenteric plexus do?

regulates relaxation/contraction of intestinal wall

31

What does submucosal plexus (Meissner) plexus do?

sense the lumen environment

32

what inhibits contraction in small intestine via and interneuron and causes relaxation DISTAL (caudad) to the signal of distention

VIP and NO

33

what excites and stimulates contraction in the small intestine via and interneuron and causes relaxation PROXIMAL (Orad) to the signal of distention

ACh and substance P

34

What is released by ECCs and binds to receptors in IPANs, initiating peristaltic reflex

serotonin

35

Colon Absorbs what?

water and vitamins

36

What 2 things can cause achalasia

-Lack of VIP
-enteric system has been knocked out

37

LES stays closed during swallowing and elevation of LES resting pressure

Achalasia

38

-slow emptying of stomach/paralysis of stomach
-20% of type 1diabetics have this

gastroparesis

39

Causes of Gastroparesis

Damage to vagus nerve from:
-idiopathic
-high blood glucose (diabetic gastroparesis)

40

Ganglion cells absent from segment of colon

Hirschsprung disease

41

Failure to pass meconium

Hirschprung

42

what levels are low in Hirschsprung

VIP

43

What is saliva composed of

-H2O
-electrolytes
-a amylase
-lingual lipase
-Kallikrein
-mucus

44

Tonicity of saliva

HYPOtonic compared to plasma

45

-K+ and HCO3 in saliva
-Na and Cl?

-increased
-decreased

46

What cells form isotonic plasma like solution in the first step of salivary secretion

Acinar cells

47

What cells modify the isotonic solution that was created by Acinar cells to make it hypotonic

Ductas cells

48

How do vasopressin and aldosterone modify the composition of saliva

-decreases its Na
-increases its K

49

Parasympathetics to acinar and ductal cells for salivary secretions

-Vagus and Glossopharyngeal
-IP3 and Ca

50

Sympathetic to Acinar and ductal cells for salivary secretions

-T1-T3
-cAMP

51

What are the 2 unusual features in the regulation of salivary secretion

-EXCLUSIVELY under control of ANS
-increase by BOTH parasympathetics and sympathetics

52

What is required for absorption of vitamin B12 in the ileum

intrinsic factor

53

What kind of gland is in the proximal 80% (body and fundus) of the stomach and secretes acid

Oxyntic gland

54

What kind of gland has chief cells?
These secrete what?

Oxyntic
pepsinogen

55

What kind of gland is in the distal 20% (antrum) and synthesizes and releases gastrin

pyloric gland

56

What kind of gland has D cells?
These secrete what?

pyloric gland
somatostatin

57

What are the 2 Gq pathways leading to increase in IP3/Ca2 and H+ secretion in gastric parietal cells

-G cells -->Gastrin --> CCKB receptor
-Vagus -->Ach -->M3 receptor

58

What is the Gs pathway leading to increased cAMP and H+ secretion in gastric parietal cells

-ECL cells--> Histamine --> H2 receptor

59

What are the 2 Gi inhibitory pathways that decrease cAMP and inhibit secretion of H+ in gastric parietal cells

-D cells --> somatostatin
-Prostaglandins

60

Falling pH inhibits what?

gastrin release so decreases HCl secretion

61

what are the 2 pathways that the vagus nerve uses to stimulate HCl secretion from parietal cells

-Directly on parietal cells
-indirectly through GRP and G cells --> gastrin --> to parietal cells (atropine doesn't block this pathway)

62

What is in the protective layer of the mucosa to protect stomach from H+ and pepsin?
What secretes each?

mucus .. . mucous neck cells
HCO3- . . . Gastric epithelial cells

63

Unconjugated Jaundice diseases

-Gilbert's
-Crigler-Najjar syndrome

64

Conjugated Jaundice diseases

-Dubin-Johnson
-Rotor syndrome

65

transporter for fructose from lumen to cell?

cell to blood?

GLUT5

GLUT2

66

transporter for Glucose and Galactose from lumen to cell?

-cell to blood?

-SGLT 1

-GLUT2