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SF3_3 (Kereen) > Littleton Part I > Flashcards

Littleton Part I Flashcards

1
Q

What are the constituent of saliva?

A

Mucins

Amylase (starch breakdown)

lipase

lysozyme

IgA

Nerve Growth factor

Epidermal Growth factor

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2
Q

What are the functions of saliva?

A

lubrication

digestion of starch

digestion of fat

antibacterial

immune protection

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3
Q

Saliva Secreation and Chewing have several functions, what are they?

A
  1. Disruption of food resulting in smaller particles
  2. Aid in the formation of a bolus for swallowing
  3. Initiation of starch and lipid digestion
  4. Facilitation of taste
  5. Clensing of mouth and selective antibacterial action
  6. Clearance and neutralization of refluxed gastric material in the esophagus
  7. Production of intraluminal gastric and duodenal stimuli
  8. Regulation of food intake and eating behavior
  9. Aids in speech
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4
Q

Is salivary secretion hypotonic, isotonic, or hypertonic?

A

It is a plasma-like isotonic when first secreted into the acinar cells and as it passes through the duct it becomes hypotonic. Therefor the saliva that is actually secreted is hypotonic

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5
Q

What is the direction of ions in the ductal cells?

A

Chloride and Sodium are heavily reabsorbed

Bicarbonate and potassium are secreted byt to a lesser extent

(Net loss in ions)

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6
Q

Stimulated salivary secretion is ___________ dependent and alkaline.

A

Flow

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7
Q

As flow rate increases what happens to the ions?

A

pH, sodium, and bicarb increase then plateau

chloride steadily increases

potassium decreases then plateau

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8
Q

What occurs with flow rate of saliva nad pH while sleeping?

A

Flow rate decreases

pH becomes more acidic

(this is why you wake up with a weird taste in your mouth)

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9
Q

What are the two spinchters in the esophagous?

A

Upper esophageal sphincter

Lower esophageal sphincter

They remain tonically contracted (myogenic tone)

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10
Q

Neurotransmitters mediate swallow-induced esophagel peristalsis and les relaxation. What are the names of the neurotransmitters involved?

A

Ach - stimulates contraction

NO/VIP - cause relaxation

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11
Q

What maintains salivary amylase activity in the stomach?

A

Buffers and substrate protection

(this allows it to be neutralize)

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12
Q

What occurs to the pH and concentration of salivary amylase as you go from the esophagous to the pylorus?

A

Esophagous

pH - 7-8

amylase - 100 units

body of stomach

pH 5-6

(buffers are then released)

duodenum

pH 6-7

salivary amylase 50 units

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13
Q

What are the layers of the digestive tract?

A

Serosa

Muscularis External

Submucosa

Mucosa

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14
Q

What is the name and function of the plexus located in the submucosa layer?

A

Submucosal plexus

“inner wall of circular muscle layer, nut in submucosa layer”

SENSORY FUNCTION

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15
Q

Motor function of the GI is controlled by?

A

Myenteric plexus

Located between the circular and longitudinal layers of the muscularis externa

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16
Q

Describe the serosa?

A

Connective tissue lining

If damaged, the peritoneum is exposed and this must be surgically repaired

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17
Q

Describe the Submucosa?

A

Contains vessels and nerves

If damaged occurs at this layer you develop a ulcer (damage extends through the muscularis mucosa)

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18
Q

What are the two layers of the muscularis externa?

A

Outer longitudinal muscle

Inner circular muscle

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19
Q

Name and Describe the layers of the mucosa

A

(from inner to outter)

Mucous Membrane

line villi, epithelial cells, sensory

Lamina Propria

connective tissue

Muscularis Mucosa (interna)

muscular, movement in villi upon contraction

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20
Q

Damage to the mucosa is known as?

A

Erosion

(superficial to the muscularis mucosa)

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21
Q

The stomach and the proximal duodenum are normally exposed to what?

A

HCL

Pepsin

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22
Q

The cells in the cardia are sensitive to what?

A

Change in the concentration of ions and motility

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23
Q

Duodenal ulcers are typically associated with which part of the duodenum?

A

Duodenal bulb

this is the first part after the plyoric spinchter

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24
Q

What is the difference betwen the Right and left colon function and slow wave propagation?

A

Right colon (ascending)

slow wave propagation is backward

Last stop for absorption of water and electrolytes

Left colon (descending)

slow wave propagation is forwards

Formation and storage of feces

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25
Q

What are the three mechanism of communication response in the GI tract?

A

Endocrine

sensor cell -> hormone released into circulation -> target cells

Neurocrine

sensory neuron -> interneuron -> secretomotor neuron -> Neurotransmiter realeased close to target cell

more rapid in eliciting a response

Paracrine

released into interstitium and the target cell is near by

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26
Q

What is the localizaiton and fuction of amylin?

A

Localization

Pancreatic Beta cells

Function

decrease insulin secretion

decrease gastric emptying

satiety factor

27
Q

What is the function and localization of Ghrelin?

A

Localization

CNS, Stomach, Intestine

Function

released by fasting

increease gastric activity

increase growth hormone release

28
Q

What is the localization and function of PP (pancreatic polypeptide)?

A

Localization

Pancreatic PP secreting cells (Islet of Langerhan)

Function

decrease post prandial exocrine pancreatic secretion via vagal-dependent pathway

Undigested fat -> PP stimulated -> slows down other pathways -> fat can be effectively broken down

Stimulus - Vagus

Physio funciton

+ small intestine absorption

  • pancreatic exocrine secretion
  • pancreatic endocrine secretion
29
Q

Gastrin (G)

A

Main Active Form - G17 and G34

Localization - antrial G cells

Function - regulation of gastic hydrogen ion concentration

Stimulus - distention of stomach (main), peptides and AA

Distribution - Antrum, duodenum, jejunum

Physio action

+gastric acid and peptide secretion

+growth fo stomach and intestine mucosa

+ gastric motility

+closure LES

30
Q

Cholecystokinin (CCK)

A

Main Active Form - CCK8, 33, 39, 58

Localization - Intestinal I cells

Function - regulation of pancreatic enzyme secretion

Stimulus - fat, peptides and AA

Distribution - Duodenum, jejunum, ileum

Physio Actions

+ gall bladder contraction

+ relaxation of sphinchter of oddi

+ pancreatic enzyme release

  • gastric emptying

+ pancreatic aqueous secretion

  • gastric acid and pepsin secretion
31
Q

Gastin releasing peptide (GRP)

A

Main Active Form - GRP

Localization - GI nerves

Function - gastrin release and acid secretion

32
Q

Somatostatin

A

Main Active Form - SS14, SS28

Localization - Gastric D cells

Function - Paracrine regulator of hydrogen ions and gastrin

Stimulus - ACid in lumen

Distribution - fundus, small intestine, colon

Physio action

  • gastrin, secretin, VIP, GIP, motilin
  • gastric acid secretion
  • pancreatic exocrine secretion
  • gastric motility
33
Q

Secretin

A

Main Active Form - Secretin 17

Localization - Intestinal S cells

Function - regulation of pancreatic bicarbonate

Stimulus - Acid

Distribution - duodenum, jejunum, and Ileum

Physio action

+ pancreatic aqueous secretion (bicarb and water)

+ pancreatic enzyme secretion

  • gastric acid and pepsin secretion
  • gastric emptying
34
Q

Gastrin inhibitory peptide (GIP)

A

Main Active Form - GIP 43

Localization - Intestinal K cells

Function - regulation of insulin release/inhibitor of hydrogen ions

Stimulus - fat, glucose (glucose dependent insulin otropic peptide)

Distribution - Duodenum, jejunum, Ileum

Physio Action

  • gastric acid and pepsin secretion
  • gastric emptying

+ insulin secretion

35
Q

Motilin

A

Main Active Form - Motilin 22

Localization - Intestinal M cells

Function - interdigestive intestinal motility

Stimulus - fasting

Distribution - duodenum, jejunum, ileum

physio action

+ contraction of intestinal smooth muscle, MMC

36
Q

Calcitonin gene-related peptide (CGRP)

A

Main Active Form

Localization - primary afferents and myenteric neurons

Function - neural mediator of primary afferents

physio action - circular musclular contraction

37
Q

Pancreatic polypeptide (PP) related

A

Main Active Form - PP - , neuropeptide Y, protein YY - 36

Localization - Enteropancreatic (PP-&L) endocrine cells, sympathetic neurons

Function - Neural modulation of sympathetic transmission, inhibiotr of pancreas

38
Q

Vasoactive Intestinal Polypeptide (VIP)

A

Main Active Form - VIP 28

Localization - Myenteric Inhibitory motoneurons/submucosal neurons

Function - neural inhibitor of motiolity/ stimulant of fluid secretion

Stimulus - distension

Distibution - Fundus, Antrum, small intestine, colon

Physio action

+ smooth muscle relaxation and sphincter relaxation

+ intestinal secretion of electrolytes and water

+ dilation of peripheral blood vessels

39
Q

Histamine

A

Main Active Form

Localization - ECL cells

Function - stimulus of gastric acid secretion

Stimulus - injury (vagus post ganglionic)

Distribution - mast cells (ECL)

Physio action

+ gastic secretionof HCL and pepsin

40
Q

Norepinephrine

A

Main Active Form

Localization - extrinsic digestive nerves

Function - vascular regulation

41
Q

Serotonin

A

Main Active Form

Localization - EC cell of digestive tract

Function - Stimulate peristalsis

42
Q

Substance P

A

Main Active Form

Localization - digestive nerves

Function - neurotransmitter

Stimulus - distention

Distrubtion - excitatory motor neurons

Physio actions

+ intestinal motility

43
Q

There are two forms of gastrin (large form in intestine and small one in the stomach), what is unique about gastrin?

A

On the carboxy end there are for AA that are essential. They are needed for minimal gastrin activity. It is found in the small (17) and large (34) form of gastrin. Also found in CCK but CCK has a couple more essential AA added that are essential.

44
Q

What is the Pentagastrin?

A

It is a combination of the 4 essential AA need for gastrin activity plus Beta-ALA.

It can be injected in a patient to generate gastrin activity.

45
Q

How does trypsin affect gastin?

A

Converts big gastrin to small gastin in the small intestine

46
Q

Parasympathetic innervation to the GI tract

A

Cranial

Vagus (75%, up to transverse colon)

Sacral

Pelvic n.

47
Q

Sympathetic innervation to the GI tract

A

Thoracolumbar

(intermediolateral cell column)

Splanchnic nerves (preganglionic)

Postganglionic

Celiac plexus

superior mesenteric plexus

inferior mesenteric plexus

48
Q

What are the three division of the ANS that innervate the gastointestinal tract?

A

Sympathetic division - Thoracolumbar

Enteric division - Plexuses Submucosal-Myenteric

Parasympathetic division - Cranionsacral

49
Q

Nitric oxide (NO)

A

Stimulus - distention

Distribution - inhibitory, motor neurons

Physio action

+ smooth muscle relaxation (nonadrenergic; noncholinergic mediator of smooth muscle relaxation)

+ release of VIP

50
Q

Acetylcholine (Ach)

A

Stimulus - action potential

Physio action - enhances all GI functions

51
Q

Describe Peristalsis and how the propulsive and recieving segment differ.

A

Propulsive Segment (wants to close up)

relaxation of longitudinal muscles (relaxation is passive)

contraction of circular muscles (Substance P, Acetycholine, CTRP)

Recieving segment (wants to open up)

contraction of longitudinal muscles (acetycholine)

relaxation of circular muscles (VIP and NO)

52
Q

The regulation of peristalsis requires?

A

It requires reflexes

distension -> sensory neurons -> cholinergic interneuron -> exitatory motor neuron -> SP/Ach -> circular muscle (contraction of propulsive segment)

distension -> sensory neurons -> chollinergic interneuron -> inhibitory motor neuron -> VIP/NO -> circular muscle ( relaxation in recieving segment)

53
Q

Persitalsis occurs in which part of the esophagus?

A

Bottom 2/3

54
Q

What is the difference between the proximal stomach, distal stomach, and pylorus?

A

Proximal stomach = storage

Distal stomach = preparatory chamber

Pyloric antrum sphincter and duodenum = emptying mechanism

55
Q

Antrial contraction forces contents into ______?

A

Corpus

56
Q

Terminal Antrial contraction does what?

A

closes pyloric canal and pylorus

57
Q

How does peristalsis affects the width of the stomach?

A

It provides a narrow orifice so that gastric content can be propelled forward and a portion of food is propelled backwards for further digestion

58
Q

Jet retropulsion does what?

A

Produces emulsification

59
Q

How is defecation initiated?

A

Ano-rectal distansion intiates a defecation response

60
Q

Involuntary Defecation Reflex

A

Propulsive motility of descending colon and rectum

61
Q

Voluntary Defection Reflex

A

closure of glottis

descent of diaphragm

contraction of abdominal wall muscles

(all of these cause a increase in intra-abdominal pressure

62
Q

Relaxation of internal anal sphincter and external anal sphincter is caused by what?

A

Distansion of rectum

(this leads to defecation)

63
Q

The colonic response to a meal is initiated by what?

A

By signals from the stomach and intestine

SF3_3 (Kereen) (14 decks)

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