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U6 Physiology > Salivary/ Gastric Function > Flashcards

Salivary/ Gastric Function Flashcards

1
Q

Hormones are released from endocrine cells. Where do they go before they get to their target cells?

A

Release from endocrine cell, to portal circulation, through the liver, to the systemic circulation, to the target cell

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2
Q

What are neurocrines? What are some examples?

A

Molecules synthesized in neurons and released following an action potential. Includes ACh, VIP, NE, and substance P

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3
Q

What are paracrines?

A

Molecules released from endocrine cells of the GI tract that act on the same tissue that secretes them

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4
Q

What cells release gastrin? What is the function of gastrin?

A

Released by antral mucosal cells (G cells) in response to distension
Causes an increase in HCl secretion from the stomach

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5
Q

What part of the GI tract releases CCK? What is the function of CCK?

A

Intestinal cells release

Inhibits gastric emptying and increases the gallbladder contractions and increases pancreatic enzymes into the duodenum

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6
Q

What part of the GI tract secretes secretin? What is the function of secretin?

A

Intestines release
Increase of HCO3 release from pancreas
Decreases HCl secretion from the stomach

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7
Q

What part of the GI tract secretes motilin? What is the function?

A

Intestines release during fasting

Increases the contractions of the distal stomach to try and clear the contents (sweep)

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8
Q

What part of the GI tract secretes glucose-dependent insulinomic peptide (GIP)?

A

Intestines release in response to fat and carbs

Stimulates pancreas insulin secretion, inhibits HCl secretion from parietal cells

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9
Q

Where in the GI tract do carbohydrates get digested?

A

Mouth (amylase), small intestine (pancreatic enzymes), brush border (disaccharidoses)

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10
Q

Where in the GI tract are lipids digested?

A

Mouth (lingual lipase), stomach (gastric lipase), small intestine (pancreatic lipase)

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11
Q

Where in the GI tract are proteins digested?

A

Stomach (gastrin), small intestine (pancreatic chymotrypsin), brush border (dipeptidases)

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12
Q

What are the three functions of saliva?

A

Lubricate (moisten food/aid in swallowing), digest (amylase/lipase), protect (clear bacteria)

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13
Q

Of the three salivary glands, 2 produce mucus-like saliva and one produces watery saliva? What are these glands?

A

Mucus: sublingual and submandibular
Water: parotid

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14
Q

What is Sjogren syndrome?

A

Chronic and progressive autoimmune disease that destroys the salivary and lacrimal glands. Difficulty swallowing/speaking/dental cavities

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15
Q

What is xerostomia?

A

Dry mouth- from inadequate saliva production

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16
Q

At low rates of saliva secretion, how does the composition of saliva compare to plasma?

A

Saliva has more potassium and is more hypotonic

17
Q

At high rates of saliva secretion, what happens to the composition of the secretion?

A

Becomes more similar to plasma- have more sodium and less potassium (this is because the transporters can’t keep up)

18
Q

What are some factors that can cause an increase in salivation?

A
  1. ANS- PNS strongly stimulates the salivary glands, SNS causes a smaller stimulus for salivation
  2. Higher brain stimulation (CNS)- see/smell something and because PNS is close to the appetite centers in the brain get stimulation
  3. Reflexive- when eat something that irritates the stomach/intestine start to increase salivation to try and clear the irritant
19
Q

What are the two types of glands in the stomach? Where are they found? What are the main types of cells in these two glands?

A
  1. Oxyntic glands- proximal 80% of stomach- have peptic (chief cells) and parietal cells
  2. Pyloric glands- distal 20% of stomach- have mucus cells, G cells, and D cells
20
Q

What causes achlorydia? What are the symptoms?

A

Gastric enteritis causes achlorydia (lack of stomach secretion) destroying the parietal cells and can result in decreased HCl and pernicious anemia (because lose intrinsic factor and can’t absorb Vit B12)

21
Q

What cells secrete: pepsinogen, gastric lipase, HCl, intrinsic factor, gastrin, somatostatin?

A

Peptic cells (chief): pepsinogen/gastric lipase
Parietal cells: HCl and Intrinsic factor
G cells: Gastrin
D cells: somatostatin

22
Q

What stimulates pepsinogen release?

A

Vagus stimulates the initial pepsinogen to release going to the stomach where it gets cleaved into pepsin. Pepsin then can cleave other pepsinogens into pepsin

23
Q

How does the stomach mucosal cells prevent itself from the acidic environment?

A

Has a mucus layer that has HCO3

24
Q

How does chronic NSAID use lead to gastric enteritis?

A

NSAIDs inhibit prostaglandins and prostaglandins function to stimulate the secretion of mucus and HCO3

25
Q

Is the venous blood from the GI tract acidic or alkaline?

A

Alkaline - because the parietal cell exchanges Cl- for HCO3 at the basolateral surface

26
Q

What is the primary target for GERD/ gastric ulcer patients?

A

The H+/K+ ATPase- this pump leads to the release of H+ into the GI tract

27
Q

What factors can cause vomiting?

A

Head trauma (concussion), intestinal/stomach irritant, systemic irritant (sensed in the 4th ventricle of the brain), virus/bacterial

28
Q

What happens to the serum after prolonged vomiting?

A

Alkalosis, hypokalemia, dehydration

29
Q

How does the vagus nerve stimulate HCl secretion from parietal cells? Name both the direct and indirect pathways.

A

Direct: ACh is released, binds to the M3 receptor, get Gq pathway with an increase of Ca and increased activity of the H/K ATPase
Indirect: Vagus stimulates enterochromaffin-like cells (ECL) which causes histamine release which binds to H2 receptor, get Gs pathway, activation of cAMP, increased H/K ATPase. Vagus also causes release of gastrin releasing peptide which acts on G cells to release gastrin, which binds to CCKb receptors and activation of Gq pathway and increase Ca

30
Q

How does somatostatin inhibit HCl secretion?

A

D cells are stimulated with increased H+ which causes increased somatostatin release and activates the Gi pathway causing decreased cAMP and decreased H/K ATPase function

31
Q

What are the three phases of HCl secretion? What is the primary cause of secretion in each phase?

A
  1. Cephalic phase- smelling/tasting- from vagus
  2. Gastric phase-distention of stomach- from vagus and directly from the G cells in antrum
  3. Intestinal phase-sense protein products

U6 Physiology (13 decks)

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