Gastrointestinal Physiology: Secretion Flashcards

1
Q

What do the salivary glands secrete? What is the composition of its secretions? (3)

A

Mucus, dilute solution of NaHCO3 and NaCl, digestive enzymes (salivary amylase and lingual lipase)

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2
Q

What regulates the secretion of the salivary glands?

A

Nervous stimuli, autonomic nervous system

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3
Q

This stimulates the secretion of copious amounts of fluid in the salivary glands.

A

Parasympathetic nervous system

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4
Q

This stimulates the secretion of small volumes of viscous fluid in the salivary glands.

A

Sympathetic nervous system

  • this augments the parasympathetic response
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5
Q

What is the composition of gastric secretions? (4)

A

Mucus, intrinsic factor, digestive enzymes and acid + bicarbonate

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6
Q

What secretes mucus and bicarbonate in the stomach?

A

Epithelial cells

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7
Q

What secretes intrinsic factor in the stomach?

A

Parietal cells

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8
Q

What secretes digestive enzymes like pepsinogen in the stomach?

A

Chief cells

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9
Q

This contains bicarbonate which buffers acid at the epithelial surface. It also protects from abrasion at the stomach.

A

Mucus

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10
Q

This stabilises vitamin B12 and facilitates its absorption in the small intestine. It is secreted by the stomach.

A

Intrinsic factor/acid

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11
Q

This is an inactive for of pepsin, and is responsible for the digestion of proteins in the stomach.

Additional question:
What activates this protein in the stomach?

A

Pepsinogen

Pepsinogen activated by acid

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12
Q

This creates the optimum pH for pepsin action, dilutes food and denatures protein in the stomach.

A

Gastric acid

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13
Q

What are the 3 phases of gastric secretion? What stimulates each of the secretions?

A

The different regions of the body control secretion.

Cephalic phase (head) - CNS and ENS (local reflex and then the long reflex) - extrinsic
Gastric phase (stomach) - nervous (parasympathetic nervous system) and hormones
Intestinal phase (intestine) - nervous (enterogastric reflex) and hormonal (CCK and secretin)

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14
Q

What stimulates the cephalic phase? (2)

A

CNS and extrinsic parasympathetic nervous response via ENS

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15
Q

This is responsible for stimulating the secretion of parietal cells, chief cells and goblet cells during the cephalic phase. It also stimulates the secretion of the hormone gastrin.

A

Extrinsic parasympathetic response.

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16
Q

What stimulates the gastric phase? (3)

A

Stimuli in stomach, nervous and hormonal regulation

17
Q

This is responsible for stimulating the secretion from gastric glands, motility and gastrin secretion during the gastric phase. (2)

A

Local nervous reflex (ENS) and external (long) nervous reflex (CNS)

Remember ENS: local nervous system (short range)
CNS: long reflexes (far range)

18
Q

What stimulates the intestinal phase? (2)

A

Hormones and nerves

19
Q

This describes the long reflex from duodenum to brain to stomach as a part of what stimulates secretion in the intestinal phase.

A

Enterogastric reflex

20
Q

True or false. Both hormones and nerves inhibit secretion and motility in the intestinal phase.

A

True

21
Q

What is the composition of pancreatic secretion? (2) What cells secrete them?

A

Enzymes (acinar cells) and alkaline fluid (duct cells)

22
Q

True or false. Pancreas is the most important source of enzymes.

A

True

23
Q

What stimulates the pancreatic secretion of enzymes?

A

Hormone - CCK

24
Q

What stimulates arrival of CCK?

A

Arrival of lipids and carbohydrates in duodenum

25
Q

This is the proteolytic enzyme that converts trypsinogen to trypsin. Trypsin then converts other enzymes to their active form.

A

Enterokinase

26
Q

What stimulates the pancreatic secretion of HCO3/alkaline fluid?

A

Hormone - secretin

27
Q

What stimulates arrival of secretin?

A

Secretion of acidic chyme in duodenum

28
Q

This neutralises the avid chyme delivered from the stomach and creates optimum pH for pancreatic and intestinal digestive enzyme.

A

Alkaline fluid (HCO3)

29
Q

What is the composition of billiary secretions?

A

Bile salts, HCO3- rich fluid, bile pigments (excretory wastes)

30
Q

True or false. Cholesterol is an excretory product secreted by the pancreas.

A

False.

Cholesterol is an excretory product secreted by the liver.

31
Q

What stimulates initial delivery of billiary secretions?

A

Hormonal control - CCK and secretin

32
Q

What stimulates the secretion of bile from the liver?

A

Bile via enterohepatic circulation

33
Q

This is metabolically expensive to produce, and is reabsorbed and secreted which is what stimulates its reproduction.

A

Bile

34
Q

What is the composition of intestinal secretion? (3)

A

Mucus, isosmotic fluid (mixture of NaCl and NaHCO3), digestive enzymes (brush border enzymes)