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Med Physiology Certificate > Gastro Physiology > Flashcards

Gastro Physiology Flashcards

1
Q

Define the direction of movement of materials in Secretion

A

mOVEMENT OF MATERIALS FROM THE Blood to the lumen of GI tract

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2
Q

Carbohydrates:
Proteins:
Fats:

A

Sugar
Amino acid
Lipid

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3
Q

Paracrine hormones are delivered through:

A

Simple diffusion, neighboring cells release hormones to local area

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4
Q

_________________ NS tends to inhibit Enteric
_________________ NS tends to promote Enteric

A

Sympathetic
Parasympathetic

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5
Q

The ____________ nerve is associated with enteric nervous system promotion

A

Vagus nerve and vasovagal reflexes

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6
Q

The _____________ is associated with parasympathetic promotion of the enteric nervous system

A

Sacral outflow

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7
Q

The ganglia of the sympathetic NS project from __________-___________

A

Thoracic lumbar region

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8
Q

The ganglia of the Parasympathetic NS project from the _________ _____________ ____________ of the ______________ in the medulla to the upper portion of the GI

A

dorsal motor nucleus
vagus

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9
Q

Parasympathetic control of the lower GI is directed by the _____________ nerves from the S2-S4.

A

Splanchnic

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10
Q

The pudendal nerve is a ____________ never that arises from the S2-S4 region and under control of the parasympathetic control. This directs the sensory and motor control of the ___________ __________ _________

A

Pudendal
external anal sphincter

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11
Q

T/F: The internal anal sphincters is under both control of the parasympathetic and sympathetic nervous system

A

True

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12
Q

The X cranial nerve is:

A

Vagus nerve

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13
Q

What is the layer surrounding the mucosa?

A

Muscularis Mucosae

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14
Q

Describe the layer of nerves and muscular layer that surrounds the muscularis mucosae that comprises the plexus

A

Innermost > Outermost
1.) Submucosal plexus
2.) Circular smooth muscle
3.) Myenteric plexus

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15
Q

What is the layer that surrounds the myenteric plexus?

A

Interstitial cells of Cajal

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16
Q

What are the two outermost layers of the gut

A

Innermost > outermost
Longitudinal muscle
Serosa

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17
Q

Where is the myenteric plexus located?

A

Between the longitudinal and circular smooth muscle layers

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18
Q

Where is the submucosal plexus?

A

Within the submucosal layer

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19
Q

The myenteric plexus is involved in:
1.) coordinating _______________ muscle activity
2.) Regulates _____________ & ____________________ smooth muscle electrical and contractile elements
Also runs:

A

Smooth
Circular & longitundinal
Throughout the enitre length of the GI tract

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20
Q

Describe the submucosal plexus:
1.) Control _________ & ____________ secretion and absorption
2.) Within the:
3.) Control local tissue blood flow
4.) Regulates ____________ ______________ properties

A

1.) Fluid and electrolyte secretion
2.) Small & large intestine
4.) Regulates luminal surface problems

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21
Q

Name the cells that allow for communication between ANS and Enteric nervous system

A

Interstitial cells of Cajal

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22
Q

How do electrical and motor events move as waves in the gut?

A

Smooth muscle cells have “gap junctions” between them for depolarization in one cell fiber

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23
Q

The Myenteric plexus controlls:

A

Circular and longitudinal smooth muscle which it is sandwiched in between

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24
Q

Name two inhibitory non adrenergic noncholinergic neurotransmitters
How do they work?

A

Vasoactive Intestine peptide (VIP)
Nitric oxide
Inhibit junction potentials that disallows depolarization

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25
Q

Name two excitatory neurotransmitters
How do they work?

A

Substance P
Acetylcholine (ACh)
Excite junction potential or enhance junction potential

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26
Q

What does BER stand for

A

Basal electrical rhythm

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27
Q

Where do BER come from?

A

Interstitial cells of Cajal

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28
Q

T/F: The BER slow waves will short circuit throughout the local smooth muscle of the gut. But they must stimulate the calcium cells in the smooth muscle by reaching the threshold

A

True

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29
Q

If the ______ waves reach the threshold for calcium ion channels in the smooth muscle, then the voltage will activate the calcium ion channels to trigger:
This will ultimately cause:

A

BER
Calcium voltage change for depolarization
Smooth muscle mechanical activity

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30
Q

The longer the BER stay at the threshold, the:

A

Greater the force and duration of muscle contraction and directly related to amplitu

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31
Q

What do the interstitial cells of Cajal have to do regarding mechanical events in the gut?

A

Stimulate voltage wave

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31
Q

First is: which is correlated to electrical slow waves
To result in:

A

Basal Electrical rhythm

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32
Q

Where are the calcium channels depolarized?

A

In the SMOOTH muscle! But they are stimulated from the interstitial cells of Cajal

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33
Q

T/F: Peristalsis is the longest form of gut muscle contraction

A

False, it stretches distance approx 2 cm long in the small intestine

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34
Q

How many long peristaltic events occur?

A

3
1.) Esophagus
2.) Colon
3.) Migrating motor complex

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35
Q

How many peristaltic events occur?

A

Total of 4

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36
Q

Define peristalsis:

A

ONE WAY MOVEMENT of sweeping coordination of circular and longitudinal smooth muscle of the gut

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37
Q

Peristalsis moves in what direction?

A

From proximal to distal, ALWAYS in ONE direction

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38
Q

Where do contraction and relaxation occur during peristalsis? Describe what happens psychically

A

Stimulation of the bolus touching the lumen of the gut To coordinate:
Upstream is contraction
Relaxation downstream
The absence of contact with the mucosal layer will result in inhibitory motor neurons

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39
Q

Segmentation contractions involve what type of smooth muscle?

A

Circular smooth muscle

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40
Q

In segmentation, what is happening to the bolus

A

It is being pushed/propelled to the center of the bolus itself

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41
Q

Segmentation is a ______________ contraction dominated by:

A

Stationary
Circular smooth muscle contraction

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42
Q

What is the function of segmentation

A

For mixing and allowing the bolus to be in contact with the mucosal layer

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43
Q

How is there net movement of the bolus down the GI if the peristalsis is largely small sweeping?

A

Differential rates of movement where rapid segmentation in the proximal gut, slow segmentation at the distal and peristalsis in between net to move bolus

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44
Q

When does the migrating motor complex occur?

A

Post prandial

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45
Q

What hormone initiates the migrating motor complex?

A

Motilin in the stomach antrum

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46
Q

____________ __________ _____________

A

A SINGLE continuous electrical wave that sweeps one way distally from stomach, and affects all smooth muscle of GI tract

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47
Q

Define: ileus

A

Arrest of movement of peristalsis and segmentation in the GI tract in the absence of food

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48
Q

When the electrical activity of the MMC will:

A

Initiate a single mechanical peristaltic sweep

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49
Q

About how often does the Migrating motor complex in the absence of food?

A

Approx every two hours

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50
Q

What is importance of the migrating motor complex?

A

Prevents from food and bacterial from moving retrograde back up the GI tract

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51
Q

What are the two regions of the esophagus?

A

Upper third: striated muscle
Distal two third: smooth muscle

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52
Q

When is the lower esophageal sphincter relaxed? When contracted?

A

Almost always contracted, only relaxed when swallowing, vomiting, or burping

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53
Q

What prevents acid from coming up from the stomach?

A

Lower esophageal sphinger

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54
Q

What is happening during GERD?

A

Acid, HCl is irritating the esophagus lining from reflux from the stomach

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55
Q

What is Achalasia? What is the physiologic dysfunction?

A

Cannot swallow
Idiopathic degeneration of ganglion cells of the myenteric plexus and/or dorsal motor nucleus or vagal fibers
Causes failure of the LOWER esophageal to relax

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56
Q

What is being lowered around the lower esophageal sphincter that allows acid to enter?

A

Decreased lower esophageal sphincter pressure

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57
Q

What physiologic change during pregnancy induces increased GERD?

A

Progesterone decreases pressure of the lower esophageal sphincter

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58
Q

Delayed gastric emptying and gastric distension from air intake can cause:

A

Decrease lower esophageal sphincter pressure that causes GERD

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59
Q

What is gastric accomodation?

A

Refers to the ability of the vagal nerve to maintain low pressure in the stomach despite increased volume, has high compliance

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60
Q

Define vago:
Define: vasal
of the Vasovagal reflex

A

Afferent from stomach to head via vagus
Efferent from head to stomach via Cranial X nerve, the vagal

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61
Q

Where is sympathetic innervation arising from when regarding the distal GI?

A

L 1 L2

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62
Q

Where is parasympathetic innervation arising from when regarding the distal GI?

A

S2-S4

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63
Q

The internal anal sphincter is what type of muscle?
What type of muscle is the external anal sphincter?

A

Smooth
Skeletal

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64
Q

The ____________ ____________ _________ and _________ ___________ receive both sympathetic and parasympathetic innervation.

A

internal anal sphincter
myenteric plexus

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65
Q

___________ ______________, ______________, & internal anal sphincter are innervated by the parasympathetic region originating from S2-S4.
The postganglionic neurons synapse directly on the myenteric plexus to:

A

Distal colon, rectum
Enhance smooth muscle activity via muscarinic acetylcholine type receptors

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66
Q

_________________ innervation arises from paravertebral and prevertebral ganglia of the abdominal and pelvic cavity through noradrenergic activity of submucosal plexus and myenteric plexus. This all results in:

A

Sympathetic
Vasoconstriction of mucosa, inhibit fluid secretion into lumen, inhibits colonic motor activity

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67
Q

In addition to sympathetic and parasympathetic activity of the GI tract there is:

A

Somatomotor component

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68
Q

What are the peudenal nerves and are they sympathetic or parasympathetic?

A

Come from S2-S4 with efferent pathway to contract external anal sphincter & afferent sensory pathway from the internal and external sphincters
Neither, they are somatomotor

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69
Q

Describe a difference between sympathetic and parasympathetic nerves and their traveling to the gut

A

The sympathetic nerves do not synapse until they reach the organ where it will synapse on α-Adrenergic receptors for inhibitory mechanisms

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70
Q

Compare ganglion b/t sympathetic and parasympathetic nerves

A

Parasympathetic have long pre-ganglion that then synapse on a ganglion and has post ganglion further from the organ they ultimately act ON

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71
Q

What stimulates the orthocholic reflex?

A

standing in upright position

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72
Q

What stimulates the gastroileal reflex?

A

Ingestion of food

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73
Q

What stimulates the gastrocholic reflex?

A

Ingestion of food

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74
Q

The gastroileal and gastrocholic reflexes do what?

A

Trigger peristaltic movement to push the bolus into the rectum via myenteric plexus stimulation

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75
Q

What organ and where does the gastroileal reflex stimulate?

A

Stomach and ileum of small intestine

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76
Q

What stimulates the gastroileal reflex? What efferent response occurs?

A

Food stimulates afferent vagus nerve to synapse in the medulla
Efferent outflow through the vagus nerve to stimulate the myenteric plexus of the ileum of the small intestine

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77
Q

The gastroileal reflex is considered a:

A

Vago-vasal reflex

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78
Q

What stimulates the gastrocholic reflex? What efferent response occurs?

A

Mediated by pelvic splanchnic nerves or intrinsic nerves
The afferent vagus nerve synapses in the brainstem, then a tract descends down the spinal cord with outflow via S2-X4 to the lower intestine

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79
Q

What are the three reflexes involved in the first part of defecation that move the bolus to the anus

A

gastrocholic reflex
gastroileal
orthocholic

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80
Q

The pelvic splanchnic nerve is:

A

Parasympathetic

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81
Q

The pudendal and levator ani nerves are:

A

Somatomotor nerves

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82
Q

The stretching of the rectum sends signals through afferent pathways and parasympathetic response through:
And somatomotor response through:
Originating at the:

A

Pelvic splanchnic nerves
Pudendal nerves
S2-S4

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83
Q

The external anal sphincter is under:
The internal anal sphincter is under:
What does this tell you about the type of muscle?

A

Voluntary, sympathetic control
Involuntary, parasympathetic control
External is striated muscle
Internal is smooth muscle

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84
Q

What contracts the internal anal sphincter?
What relaxes it?

A

Contracts: Sympathetic hypogastric nerve
Relaxed: Pelvic nerve efferent pathway will inhibit/override the sympathetic activity

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85
Q

T/F: The external anal sphincter plays a minor role in defection

A

True

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86
Q

What might you incur about the defection of a person with spinal transection before the sacral region?

A

There are only active local reflexes like through the pelvic splanchnic nerves and pudendal & levator ani nerves

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87
Q

T/F: First occurs is gastric emptying followed by colon filling

A

False they may overlap

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88
Q

Where is the emetic center?

A

Medulla

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89
Q

What might signals to the emetic center?

A

Vagal and parasympathetic afferents
Stretch receptors

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90
Q

Where do Afferent signals originate that stimulate the emetic center??

A

5HT3-3 Receptors
Serotonin receptors

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91
Q

What is 5 HT?

A

Serotonin

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92
Q

Where does 5 HT come from?

A

Enterochromaffin cells that release serotonin

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93
Q

What stimuli might stimulate the enterochromaffin cells? Describe the pathway following their stimulation

A

1.) Ex. staph enterotoxin Or syrup of Ipecac stimulates enterochromaffin cell
2.) Enterochromaffin cells secrete 5-HT aka serotonin
3.) 5-HT stimulates 5HT-R3 receptors which send afferent vagal signal to emetic brain center of medulla to initiate vomiting

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94
Q

Describe the Chemoreceptor trigger zone?

A

Area in the 4th ventricle that senses the composition of the blood brain barrier to detect poison, toxin, etc. to induce vomiting

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95
Q

Describe some mechanisms that induce vomiting once triggered by the medulla (4)

A

1.) Increasing abdominal pressure
2.) d/c respiration
3.) Relax lower esophageal sphincter
4.) Diaphragm and abdominal muscles contract to induce reverse peristalsis

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96
Q

What is IBS?

A

Visceral discomfort or pain assoc. with disturbed defecation

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97
Q

While IBS may be considered idiopathic, it is primarily due to:

A

Serotonin type 3 receptor (5HT3-R) increased sensitivity and gut sensitivity/motility

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98
Q

Celiac disease is a autoimmune disorder of the:
Intolerance to:
Untreated, this can cause:

A

Small intestine
Gluten
Flattening of the villi that interferes with nutrient absorption

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99
Q

Name the two major irritable bowel diseases:

A

1.) Ulcerative colitis
2.) Chron’s disease

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100
Q

What is the concern of UC?
What is one possible cause?

A

Inflammation of the mucosal lining of the colon, flares
Associated to colorectal carcinoma
Sometimes a response to bacterial overgrowth

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101
Q

Where does Chron’s disease occur normally?

A

In terminal ileum of small intestine, ileocecal valve of proximal colon

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102
Q

Which of the IBD disorders cause inflammation of ALL layers of the intestine?
What are the physiologic repercussions?

A

Chron’s disease
Stricture of the gut
Cancer of the distal small bowel including other colorectal cancers

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103
Q

T/F: Both IBS and IBD are autoimmune disorders

A

False, only Chron’s disease and celiac disease are autoimmune

104
Q

Taste or smell of food, tactile sensation of food in the mouth, or thoughts of food do what?

A

(SNS)Sends signals to the medulla oblongata which stimulates the vagus nerves to stimulate the stomach to release HCL & pepsin
(PNS) Gastrin is also release and travels through the blood to further stimulate HCL and pepsin release

105
Q

Describe the gastric secretion phase

A

Stomach distension stimulates the afferent vagus nerves to the medulla oblongata which signals the afferent vagus nerves to cont. secreting pepsin and HCL

106
Q

What stops gastric secretions?

A

When chyme reaches the duodenum
pH < 2 and lipids present
1.) Impulses to the medulla decreases PNS to inhibit gastric glands
2.) Local reflexes in the gut decrease gastric secretions
3.) Local hormones secretin, GIP (gastric inhibitory peptide) and cholecystokinin through the circulation to the gastric glands for inhibition

107
Q

What does GIP do? What does it stand for ?

A

GIP inhibits gastric secretions when the chyme reaches the duodenum
Gastric inhibitory peptide

108
Q

What is an acinus?

A

Cluster of salivary glands of the mouth

109
Q

Describe the structure of an acinus

A

A cluster, triad of cells
The stem is comprised of duct cells then each extension may be a different type of acinus salivary gland

110
Q

Name the 3 types of acinus salivary glands

A

1.) Mucus
2.) Mixed
3.) Serous

111
Q

What do mucus salivary glands do?

A

Produce glycoprotein mucins to lubricate food

112
Q

What do serous acinus glands do?

A

Produce watery saliva
α amylase
Lysozyme
Peroxidases
IgA

113
Q

Where are mucus acinar cells mostly located?

A

Sublingal gland

114
Q

Where are serous acinar cells mostly located?

A

Parotid gland

115
Q

What does the submandibular gland do? What type of salivary glands are here?

A

Secretes 70% of the total saliva
Comprised of Mixed acinus cells that secrete mixed types of saliva

116
Q

What is the most basic unit of the salivary gland?

A

Salivon

117
Q

T/F: There are receptors on the acinus of salivon
If they are present, what do they do?

A

True, there are α & β, muscarinic receptors and NK1
They control the release of enzymes, lysozymes and mucous secretions

118
Q

Describe the composition of a salivon

A

Distal end is the acinus a bulb like formation lined with acinar cells. Secrete saliva w/salts, mucins, and enzymes in to the inner space
Intermediate and proximal end is the duct and is modified by removal of Na+ and Cl- in exchange for K+ and HCO3-

119
Q

What is Sjogren’s disease?

A

Autoimmune disorder characterized by destruction of salivary glands
Inhibited salivons = dry mouth

120
Q

Is the control of saliva production determined by the PNS or SNS?

A

Both

121
Q

Where are the majority of receptors in the salivon?

A

Acinar cells

122
Q

________________ & ___________________ responses stimulate saliva production which originate in salivary nuclei of the brainstem by the _____________________________ Nervous system

A

Unconditioned
Conditioned
Parasympathetic

123
Q

The parasympathetic NS is involved with ____________________ receptors to increase salivary fluid secretion.

A

Muscarinic

124
Q

How do receptors of the parasympathetic NS stimulate saliva production?

A

Acetylcholine acts on M3 Receptors to increase inc saliva production by increasing blood flow through Nitric Oxide increase delivery

125
Q

How does the sympathetic NS stimulate salivary glands?

A

Catecholamines will stimulate acinar cells to produce Amylase through β adrenergic receptors

126
Q

Name 2 catecholamines

A

Epinephrine
Norepinephrine

127
Q

T/F: At high sympathetic activity salivation increases

A

False, at high sympathetic activity and inc. circulating catecholamines will vasoconstrict and decrease saliva production

128
Q

What are the two divisions of the pancreas?

A

Exocrine and endocrine

129
Q

What is the overarching goal of the exocrine pancreas?

A

Produce enzymes and bicarbonate ion

130
Q

What does the endocrine pancreas do?

A

Produces insulin

131
Q

Describe the structure of the pancreas

A

Similar to acinar cells
Long duct in the middle, acinar collection coming off with multiple acinar making up a lobule

132
Q

What does the common bile duct have to do with the main pancreatic duct?

A

They merge proximal to the small intestine duodenum

133
Q

Describe the pathway from the main pancreatic duct to the acinus

A

Largest to smallest
Main pancreatic duct > interlobar ducts > lobule > intercalated ducts > acinus

134
Q

What do pancreatic acinar cells produce?

A

Zymogen

135
Q

Overall the pancreas produces bicarbonate and zymogen. Where does each come from?

A

Bicarbonate comes from epithelial duct cells
Zymogen come from pancreatic acinar cells

136
Q

What afferent nerves stimulate the M3 muscarinic receptors of the pancreatic duct cells and pancreatic acinar cells?

A

Vagus nerves from the dorsal motor nucleus

137
Q

The gastric phase involves the release of gastrin through vagus stimulation. Describe it

A

The antrum (distal portion) of the stomach will stimulate the vagus nerves to act on G cells. These G cells produce gastrin

138
Q

What neurotransmitter stimulates G cells?
Where are G cells and what do they secrete?

A

GRP stimulates
G cells in the distal portion of stomach and secrete gastrin

139
Q

What does GRP stand for?

A

Gastrin releasing peptide

140
Q

The sight, smell, or taste of food will stimulate the vagus to release gastrin from the stomach. What else can elicit gastrin release?

A

The physical presence of food, more specifically peptides and AA, in the stomach can stimulate G cells for gastrin production

141
Q

What does gastrin do?

A

Stimulates acinar cells in the pancreas to produce enzymes and additional water

142
Q

What two channels are imperative to bicarbonate secretion from duct cells of the pancreas?

A

CFTR channel & HCO2/Cl exchanger

143
Q

What does the CFTR channel do?
What does it stand for?

A

Allows chloride to move into the duct cells
Cystic fibrosis transmembrane regulator

144
Q

What does the HCO3/Cl- channel do? Where is it located?

A

Exchanges luminal Cl- to secrete HCO3
In the pancreatic duct cells

145
Q

In the duodenum, the presence of stomach acid with H+:

A

Stimulates S cells of the duodenum
These cells secrete hormone Secretin

146
Q

What does Secretin do?

A

Acts on duct cells of the pancreas to simulate bicarbonate production via HCO3/Cl & CFTR exchange loop

147
Q

The presence of fats and proteins in the duodenum:

A

Produces a vagovagal reflex to target the acinar cells to make enzymes

148
Q

Different from the vagovagal reflex induced by presence of fats and proteins, describe how breakdown of fats and proteins controls CCK production

A

Breakdown of lipids and fats stimulates the I cells to release CCK

149
Q

What does CCK do?

A

Hormone that travels in the blood to activate pancreatic acinar cells to release enzymes

150
Q

What two ions are continually secreted from the pancreas? One is present in high levels, one in very low, which is which?

A

Na+ is always present in high concentration
K+ is present in present at a very low concentration
Their concentrations do not waiver

151
Q

Describe the difference in Cl- and HCO3 concentration compared to increased and decreased secretion rate

A

High secretion rate: Bicarb is higher concentration to buffer incoming H+ ion
Low/none secretion rate: Cl- is higher concentration

152
Q

At high secretion rate what ions have a larger concentration coming from the pancreas?
At high secretion rate what ions have a larger concentration coming from the pancreas?

A

High secretion: Na &HCO3

Low secretion: Na+/Cl-

153
Q

What activates the zymogens once they reach the duodenum?

A

Duodenal enterocyte cells of the duodenum release Enterokinase
Trypsinogen + Enterokinase = Trypsin

154
Q

What is significant about trypsin?

A

Trypsin can act on its own as an enzyme
But it also convers all the other zymogens that are secreted from the pancreas

155
Q

There are 4 regions of the stomach, name 3

A

Fundus: body
Antrum: distal portion
Pylorus: end

156
Q

Where are oxyntic glands?

A

AKA gastric glands that invaginate on the mucosa of the stomach

157
Q

Where are superficial epithelial cells located?
What do they do?

A

Around the outside of the oxyntic glands
Secrete mucous, bicarb. and Trefoil peptide

158
Q

Where are Mucous neck cells located?
What do they do?

A

Make mucous to protect

159
Q

What do trefoil cells do?

A

Involved a repair mechanism of the surface of the oxyntic glands

160
Q

What is the purpose of having mucous cells and superficial cells on the outer edges of the oxyntic cells?

A

They protect the glands from stomach acid and the Trefoil peptides provide repair mechanisms

161
Q

Where are Endocrine cells in the oxyntic cells?
What are the three most important kinds?

A

G cells
D cells
ECL cells
At the bottom of oxyntic glands

162
Q

What do G cells do?

A

Secrete gastrin

163
Q

What do D cells secrete?

A

Somatostatin

164
Q

What do Enterochromaffin cells secrete?Re

A

Histamine

165
Q

What is the overall purpose of having endocrine cells in the oxynthic glands of the stomach?

A

Regulate acid secretion

166
Q

What do Chief cells do in the oxyntic glands

A

Produce pepsinogen
Gastric lipase

167
Q

What does pepsinogen do?

A

Is a zymogen, in the acid it converts to pepsin

168
Q

What does gastric lipase?

A

Break down lipids

169
Q

What is the purpose of the chief cells?

A

They start the digestion of fats and lipids in the stomach

170
Q

List the 6 Types of cells comprising the oxyntic cells:

A

Superficial epithelial cell
Mucous neck cell
Stem cell
Parietal cell
Chief cell
Endocrine cell

171
Q

Both the endocrine cells and parietal cells are involved in acid of the stomach. Define how they are different

A

Endocrine is REGULATION
Parietal cells MAKE THE ACID

172
Q

What do parietal cells do?
Where are they located?

A

In the oxyntic gland of the stomach
Make H+ and intrinsic factor

173
Q

What is intrinsic factor (IF) ?

A

Involved in the absorption of the vitamin B12
IF binds with Vit B12 and moves into the small intestine. The IF protects Vit B12 from being broken down until it reaches the small intestine for absorption

174
Q

Why are parietal cells also called oxyntic cells?

A

They have a lot of mitochondria within thus they use a lot of Oxygen, oxy stands for O

175
Q

The submucosal plexus of the stomach receives vagal efferent signals to stimulate the chief cells which:

A

Production of pepsin

176
Q

The submucosal plexus of the stomach receives vagal efferent signals to stimulate the parietal cells which:

A

HCL and Intrinsic factor (IF)

177
Q

The submucosal plexus of the stomach receives vagal efferent signals to stimulate the ECL cells which:

A

Produce histamine

178
Q

The submucosal plexus of the stomach receives vagal efferent signals to stimulate the G cells via what neurotransmitter?
What do they produce

A

GRP
Produces gastrin

179
Q

Name the two products of the oxyntic glands that do not directly enter the lumen of the digestive tract

A

Histamine acts on the lamina propria
Gastrin, hormone, goes into the blood

180
Q

What does somatostatin do? Where does it come from? What triggers its release?

A

Inhibits stomach acid production
Comes from D cells within the oxyntic glands at the antrum of the stomach
Stomach acid stimulates its release

181
Q

What cells does somatostatin inhibit?

A

Inhibits G cells to stop acid production

182
Q

What is special about the parietal cell activation

A

They have three receptors, all of which must be activated to produce IF & HCL

183
Q

What binds to the parietal cells to activate them?

A

1.) Acetocholyine
2.) Histamine
3.) Gastrin

184
Q

Aside from directly acting on parietal cells to play part in HCl & IF release, how does gastrin indirectly stimulate Parietal cells

A

Gastrin stimulates the ECL cells to produce Histamin

185
Q

ECL cells produce histamine to act on parietal cells for Acid production, what simulates ECL cells??

A

Gastrin stimulates ECL cells as well as Acetylcholine so that the ECL cell can secrete histamine

186
Q

What is different about the histamine receptor of the parietal cell?

A

The receptor is an H2 receptor
The inflammatory response is by an H1 receptor

187
Q

When all three receptors of the parietal cell are activated what happens next?

A

1.) ATP converted to cAMP
2.) cAMP enhances proton

188
Q

Describe the mechanism through which HCl is made by the parietal cell

A

1.) There is an antiport at the basolateral membrane that moves HCO3 out and Cl- in
2.) The H+ proton is produced by CO2 + H20 conversion to H+ & HCO3 by carbonic anhydrase
The HCO3 is exchanged at the basolateral membrane for an Cl
The Cl is moved out of the cell into the lumen via exchange of K+
The H+ is moved into the lumen by H+/K+ transporter
So K+ moves out of the cell thanks to Cl- and gets recycled for use again thanks to H+

189
Q

What might blocking an H2 receptor do?

A

Would decrease acid production by the parietal cell

190
Q

What suffix medications block the H2 receptors?
What is the result of using an H2 antagonist?

A

“-dine”
H2 antagonist
They decrease acid production

191
Q

Describe how Prilosec and Nexium decrease acid production at the parietal cells?

A

They block the H+/K+ ATPase at the luminal side of the parietal cells so H+ cannot leave the cell and enter the lumen to form HCL
AKA PPI, proton pump inhibitor

192
Q

What are two sources of peptic ulcers?

A

H pylori
NSAID COX-1 inhibitors

193
Q

Why do H pylori create peptic ulcers?

A

The bacteria excrete an enzyme that breaks down the surface mucous. The stomach cells are no longer protected from proteases and acid in the stomach = Inflammation

194
Q

T/F: Prostaglandins are protective. What makes them

A

True
Made by cyclooxygenase enzymes (COX 1)

195
Q

NSAIDs inhibit COX-2 and COX-1 enzymes. What does this cause?

A

Inhibits mucosal defenses, makes the protective forces weaker

196
Q

Describe the ileal break mechanism

A

A cooperation for gastric emptying
When there are nutrients in the ileum, three peptide hormones are secreted to act on the stomach to delay gastric Emptying

197
Q

Gastric emptying is _________________ with isosmotic non caloric foods

A

Fastest

198
Q

Lower pH gastric content empties _____________ compared to higher pH liquids

A

Slower

199
Q

Particle size influences gastric emptying. Smaller particle size empties ____________________ compared to larger particle size. This concept is only applicable to the fed state, not the fasting. Why does this not apply in the fasting state?

A

Faster
Because of the migrating motor complex. This complex will push all contents at the same rate

200
Q

Describe “Dumping syndrome”

A

Uncontrolled gastric emptying due to lack of feedback inhibition by duodenum

201
Q

In dumping syndrome _______________ food can make it to the colon due to uncontrolled gastric emptying. What does this cause?

A

Undigested food
More stool production

202
Q

What is gastroparesis

A

Severely delayed or stopped gastric empyting

203
Q

What is pyloric stenosis?
What are the consequences of this disorder?

A

The pyloric region of the stomach (the most distal end) is unable to allow chyme into the duodenum
Irritation of stomach due to distention from contents, vomiting, reduced nutrient intake

204
Q

What two components drive gastric emptying into the duodenum?

A

Hormone and neuronal pathways

205
Q

What are the two enterogastrones that decrease gastric secretions and gastric emptying?

A

They are from the duodenum to inhibit
Secretin from the S cells to decrease gastric secretion
Presence of fats and hydrophobic AA will stimulate I cells to release CCK

206
Q

Where in the brain do the actions of Ghrelin and Leptin ultimately act?

A

Act in the hypothalamus

207
Q

The ______________ of the stomach, in the absence of food stimulates _____ cells to produce Ghrelin. Ghrelin then stimulates the vagus to stimulate the hypothalamus to activate feeding behavior and enhance feeling of appetite.

A

Fundus
P/D1

208
Q

_________________ tissue in the accumulation of lipids causes the release of Leptin. The leptin then stimulates the Vagus to act in the hypothalamus suppress appetite

A

Adipose tissue

209
Q

What inhibits D cells?

A

Acetylcholine

210
Q

Describe from largest to smallest the structural organization of the small intestine.

A

Lining > villi > villus > enterocyte (Smallest)

211
Q

The villi are covered by ____________. Each __________ are lined by a layer of epithelial cells. Each epithelial cell is known as: . Each of these cells has an apical membrane on the __________________ side that faces the lumen of the small intestine

A

Villus
Villus
Enterocyte
Apical

212
Q

On the enterocytes, the villus is the region of:
While the crypt region is where ______ occurs

A

Absorption
Secretion

213
Q

Aside from different action mechanisms, what is structurally different between the villus and crypt cells

A

Villus cells the capillaries are inside and surrounded by epithelial cells
Whereas the crypt cells, the capillaries are wrapped around the epithelial cells

214
Q

Where does the blood flow from the villus cells in the small intestine?

A

To the portal blood that go to the liver

215
Q

Where does the majority of nutrient absorption occur?

A

Upper Jejunum

216
Q

List the 3 regions of the small intestine from proximal to distal

A

Duodenum
Jejunum
Ileum

217
Q

When proteins reach the small intestine, they break down into 3 possible components. What are they?

A

1.) Free AA
2.) Peptide
3.) Dipeptide

218
Q

What is the ultimate product being delivered to the portal blood when referring to protein nutrient absorption in the jujenum

A

The villus enterocytes will secrete amino nitrogen (Free amino acids) from the basolateral side into the portal blood for delivery to the liver

219
Q

What do aminopeptidases do on the apical membrane of villus enterocytes of the jujenum

A

Free AA
Di & Tripeptides

220
Q

What is special about Di & tripeptide absorption in the jujenum?

A

They are absorbed whole into the cytoplasm and once inside the enterocyte they are wholly hydrolyzed by aminopeptidases to free Amino Acids

221
Q

Name the two ways free amino acids may be absorbed by the apical membrane of enterocytes

A

Sodium dependent or independent transporters

222
Q

While the enterocytes are secreting free amino acids into the portal blood, how are the cells themselves receiving nutrients? Or in during the fasting state?

A

They absorb nutrients from the portal blood

223
Q

What is the major energy source in enterocytes?

A

Glutamine

224
Q

What is the major source that contributes to amino nitrogen supply to the portal blood?

A

Di-peptide

225
Q

________________________ is a dipeptide of aspartic acid and phenylalanine and a carboxyterminal end

A

Aspartame

226
Q

What is special about the active transport mechanism of aspartame at the apical membrane of enterocytes? After transported into the cell, how is it broken down into free AA?

A

Uses a H+ transport pump
The aminopeptidase that reside in cytosol break down to Asp and Phe

227
Q

People with Phenylketonuria will have to be weary of:
Why?

A

Aspartame, as when it breaks down into Phe and Asp and is released into the portal blood
People with this condition must be weary of the amount of Phe circulating in the blood

228
Q

Starch is the storage of glucose in:
Glycogen is the storage of glucose in:

A

Plants
Animals

229
Q

Starch and glycogen are hydrolyzed:
By

A

Within the lumen of the small intestine
Pancreatic amylase

230
Q

When starch and glycogen are broken down in the lumen of the small intestine:

A

They are further broken down by the apical membrane proteins into free glucose to be absorbed by apical enterocytes once as a monosaccharide

231
Q

_________________ is hydrolyzed by lactase, an enzyme on the apical enterocyte membrane, into the subsequent components: Glucose & ____________

A

lactose
Galactose

232
Q

The disaccharide, sucrose (fructose and glucose), is hydrolyzed by _________________ and enzyme on the apical membrane of the enterocyte

A

Sucrase

233
Q

The only meaningful carbohydrate is:

A

In the monosaccharide forms

234
Q

Name the two two monosaccharide transporters on the apical enterocyte membrane

A

1.) SGLT 1
2.) GLUT 5

235
Q

The GLUT 5 is _______________ independent transport mechanism. It transports ______________ into the cytosol enterocyte

A

Sodium
Fructose

236
Q

SGLT 1 is a ____________________ dependent transport mechanism. It transports ______________ and some galactose into the enterocyte cytoplasm by secondary active transport

A

Sodium
Glucose

237
Q

What transporter on the basolateral side of enterocytes transports monosaccharides to the portal blood?

A

GLUT 2

238
Q

What is lactose non-persistence?

A

With maturation, the lactase loses its ability to hydrolyze lactose into its monosaccharide constituents which then creates a lactose surplus in the small intestine

239
Q

On a molecular level, what does a buildup of lactose do in the small intestine?

A

Will draw water from the portal blood to the lumen of the jejunum that increases the flow of luminal content into the colon

240
Q

When the luminal content is delivered to the colon due to lactose intolerance, what happens?

A

Bacteria here undergo anerobic metabolism (fermentation) to hydrolyze the lactose
This makes gas
Increases stool activity
Creates short chain fatty acids that irritate the colon lumen

241
Q

Describe osmotic diarrhea

A

Can be due to the ingestion of lactose in a lactose intolerance person. The presence of non hydrolyzed lactose will draw water from the blood into the lumen of the GI and increase the volume luminal content

242
Q

Describe the composition of lobule of the liver

A

Hepatocytes with Canaliculi between them. These canaliculi come together to form ducts which eventually form the bile duct

243
Q

Describe the duct flow from the L & R bile duct from the liver to the duodenum of the small intestine

A

L & R hepatic duct converge to the common hepatic duct.
The common hepatic duct splits
1.) Common bile duct to the sphincter of Oddi where it joins the pancreatic duct to join the duodenum
2.) Cystic duct to the gallbladder

244
Q

What is the difference between the Sphincter of Oddi and the Ampulla of Vater? How are they similar?

A

They are in the same region, between the duodenum, pancreas, common bile duct
Ampula of Vater is where the common bile duct reaches the duodenum
While the sphincter of Oddi is the sphincter that controls release of secretion from the pancreatic duct AND common bile duct

245
Q

Where is the initial formation of bile?

A

Bile salts are made in the hepatocytes and transported through a sodium transporter into the canaliculi space

246
Q

The result of bile salts being transported into the canaliculi causes:

A

H2O osmotically follows the bile movement into the Canaliculi space
Lipophilic waste compounds also flow into the canaliculi space

247
Q

Describe how the secretion modification similar to the pancreatic duct modification?

A

Cl- is reabsorbed and HCO3 is secreted into the lumen of the common bile duct
+ H20 to dilute the bile components

248
Q

What is the difference between bile acid and bile liquid?

A

Bile acid is a component of bile liquid
The bile liquid is also comprised of H2O, solutes, and lipophilic compounds

249
Q

Na+, K+, HCO3-, Ca+2, Mg+2 are electrolytes that are within bile liquid and are at high concentration in the _______________________ because this organ concentrates bile by removing water

A

Gallbladder

250
Q

What are the precursors to bile acids?

A

Cholesterol

251
Q

Bile acid + ______________ = bile salt

A

Na+

252
Q

___________________ Osmotically follows bile acids into canaliculi

A

Water

253
Q

What is the main purpose of bile?

A

Act as surfactant in the small intestine to break the surface tension between lipids and water

254
Q

_____________ is the major route to rid the body of excess cholesterol synthesized by the liver

A

Bile lipids

255
Q

What is the role of CCK in the when considering GALLBLADDER & LIVER

A

The hormone stimulates gallbladder contraction

256
Q

Name 4 actions of CCK

A

1.) Inhibit gastric emptying
2.) Contract gallbladder
3.) Stimulate pancreas to make and release lipases
4.) Relaxes the sphincter of Oddi

257
Q
A

Med Physiology Certificate (4 decks)

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