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Block 3 Week 1 Meg > Ward: Gastric physiology of digestion > Flashcards

Ward: Gastric physiology of digestion Flashcards

1
Q

Two primary types of secretion

A

Digestive enzymes

Mucus

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2
Q

Type of gland: located in the epithelium, found in most parts of the GI tract, respond to local stimulation of the epithelium by extruding their mucus onto the epithelial surface to act as a lubricant and to protect the epithelial surface

A

single cell mucous glands

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3
Q

In the small intestine, invaginations of the epithelium into the submucosa

A

Crypts of Leiberkuhn

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4
Q

Located in the stomach and upper duodenum, often secrete acid and pepsinogen.

A

Tubular glands

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5
Q

More complex glands with a primary function to provide secretions for digestion and emulsification of food

A

salivary glands, pancreas, and liver

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6
Q

Briefly discuss the mechanism of secretion by glandular cells.

A

Capillaries transport nutrients into the glandular cell
Secretory substances synthesized in ER/Gogli
Transported into Golgi where modification occurs
Discharged into cytoplasm as secretory vesicles which are stored in the apical ends of cells until the cell gets a signal to empty its contents

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7
Q

Briefly describe water and electrolyte secretion

A
  1. nerve stimulation moves Cl- ions into cell
  2. Na+ follows into cell
  3. Water follows and creates hydrostatic pressure
  4. Ruptures secretory border
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8
Q

Local stimulation can occur in two ways

A

Direct contact

Epithelial stimulation

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9
Q

How does the parasympathetic ANS stimulate secretion?

A

increases the rates of glandular secretions, especially the glands of the upper GI tract, also glands of the distal large intestine

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10
Q

How does the sympathetic ANS stimulate secretion?

A

If parasympathetic innervation is low, sympathetic stimulation will increase secretion. If parasympathetic stimulation is high, it will reduce secretion.

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11
Q

Hormones in the stomach and intestine are liberated from the mucosa in response to what?

A

the presence of food in the lumen

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12
Q

Constituents of saliva

A 
Serous secretion
Mucus secretion
Lactoferrin
Proteolytic enzymes
Thiocyanate ions
Binding glycoprotein for IgA
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13
Q

What is saliva composed of?

A

Electrolytes, glycoproteins, and water

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14
Q

Properties of mucus (ABDAS)

A 
Adherent so it tightly binds to particles
Barrier to mucosa
Decreases resistance
Amphoteric properties
Strongly resistant to digestion
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15
Q

Four types of salivary glands

A

Parotoid (1/4)
Sublingual
Submandibular (2/3)
Buccal

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16
Q

How are all the salivary glands drained?

A

By a single major excretory duct

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17
Q

Lie outside the wall of the GI tract and are connected via ducts that empty into the GI tract itself

A

Acinus glands

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18
Q

Involved with directing fluids into the oral cavity.

A

Ductal cells

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19
Q

Contractile cells involved in helping move serous and mucous secretions into ducts.

A

Myoepithelial cells

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20
Q

What happens to Na, Cl, and K+ levels in the saliva during maximal saliva secretion?

A

Concentrations of these ions begin to reach the level found in the plasma, because reabsorption cannot occur quick enough relative to the marked increase in saliva production. Na+ and Cl- increase, and K+ decreases

21
Q

Things that activate salivary nucleus of the medulla

A 
Reflexes
Smell
Taste
Pressure
Nausea
22
Q

Things that inhibit salivary nucleus of the medulla

A

Fatigue
Sleep
Fear
Dehydration

23
Q

Secretion is increased by contractions of these cells, which are innervated by the parasympathetic system

A

Myoepithelial cells

24
Q

What is released in response to parasympathetic stimulation? What does this produce? What does this result in?

A

Kallikrein
Bradykinin
Vasodilation and growth of salivary glands

25
Q

Pathophysiology: Associated with chronic ulcerations of the buccal mucosa and with dental caries.

A

Xerostomia (dry mouth)

26
Q

Pathophysiology: Absence of saliva

A

Congenital xerostomia

27
Q

Pathophysiology: Atrophy of the glands and decreased saliva production

A

Siogren’s syndrome

28
Q

Pathophysiology: Na+ concentrations increased

A

Addison’s disease

29
Q

Pathophysiology: Na+ concentrations decreased

A

Cushing’s syndrome

30
Q

Pathophysiology: Causes excessive salivation

A

Tumors

31
Q

Four constituents of gastric juice

A
  1. intrinsic factor
  2. H+ ions
  3. pepsin
  4. mucus
32
Q

secretes acid, pepsinogen, mucus and intrinsic factor and is located on the proximal 80% of the stomach.

A

Oxyntic gland area

33
Q

The distal 20% of the stomach, which synthesizes and secretes the hormone gastrin and mucus.

A

Pyloric gland area

34
Q

Gastric mucosa made up of two areas

A

Oxyntic gland area

Pyloric gland area

35
Q

Contain the acid-producing parietal cells and the peptic or chief cells, which secrete the enzyme precursor pepsinogen

A

Oxyntic glands

36
Q

What do parietal cells produce?

A

HCl

37
Q

What is the pH created by HCl secretion of parietal glands?

A

0.8-1

38
Q

Between meals the cytoplasm of the parietal cell is dominated by numerous (blank)

A

tubulovesicles

39
Q

The cell also possesses an intracellular (blank) that is continuous with the lumen of the oxyntic gland. During acid secretion the tubulovesicles become microvilli and project into the (blank). This increases the (blank) of the cell.

A

canaliculus; canaliculus; surface area

40
Q

The activities of what two enzymes increases during HCl secretion?

A

carbonic anhydrase

ATPase

41
Q

Summarize the mechanism of HCl secretion by parietal cells.
How does H+ get pumped out?
Where does the supply of H+ come from?

A

H+ pumped out of APICAL cell membrane by H+/K+ ATPase if adequate supply of K+ outside cell
(H+ comes from dissociation of H20
Carbonic acid is formed from Co2 and H20 in a rxn catalyzed by carbonic anhydrase)
BASOLATERAL membrane exchanges Cl- for bicarb

42
Q

What things occur when parasympathetic stimulation of salivary glands?

A

Vasodilation
Secretion
Myoepithelial cell contraction

43
Q

Sympathetic activation of salivary glands increases (blank), while parasympathetic stimulation increases (blank) and (blank)

A

cAMP; IP3; Ca+

44
Q

Component of gastric secretion; required for the absorption of vitamin B12 by the ileal mucosa (released from Parietal cells).

A

intrinsic factor

45
Q

Component of gastric secretion; necessary for the conversion of pepsinogen to pepsin; also kills bacteria

A

H+

46
Q

Component of gastric secretion; begins the breakdown of protein; released from chief cells

A

pepsin

47
Q

Component of gastric secretion; protects the mucosa lining of the stomach, lubricates and neutralizes a small amount of acid

A

mucus

48
Q

The gastric glands lie deep in the stomach wall and receive these two things.

A

rich blood supply

autonomic innervation

49
Q

Present where the glands open into the pits. These cells divide and the daughter cells migrate to the surface where they become mature mucous cells and down into the glands where they become parietal cells in the oxyntic gland area or G cells in the region of the pyloric gland mucosa

A

mucous neck cells

Block 3 Week 1 Meg (17 decks)

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