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Physiology MRCEM part 1 > GI > Flashcards

GI Flashcards

1
Q

Layers of the GI tract (innermost to outermost)

A

Innermost mucosa
Submucosa
Muscularis externa
Outermost serosa

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2
Q

Innermost mucosa 3 layers

A
  1. Epithelial
  2. Lamina propia
  3. Muscularis mucosa
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3
Q

Submucosa contains?

A

Connective tissue, larger blood vessels and lymphatic vessels and the submucosal plexus

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4
Q

Muscularis externa composed of 3 layers

A

Inner circular muscle layer

Myenteric plexus between the two layers of muscle

Outer longitudinal muscle later
Myenteric plexus between the two layers of muscle

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5
Q

Main function of the submucosal plexus?

A

Parasympathetic input, secretomotor innervation

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6
Q

Myenteric plexus provides what innervation?

A

Motor innervation to the smooth muscle layers via sympathetic and parasympathetic input

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7
Q

3 glands that produce saliva?

A

Parotid
Submandibular
Sublingual

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8
Q

Sympathetic control of salivary production is via?

A

Cervical ganglionW

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9
Q

What does sympathetic innervation cause in terms of saliva?

A

Increase protein secretion resulting in increased production of thick mucoid saliva.

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10
Q

Parasympathetic control of saliva production controlled by?

A

Outflow coordinated by the medulla

-> innervation via facial and glossopharyngeal nerves

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11
Q

Voluntary phase of swallowing

A

Buccal

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12
Q

Two involuntary phases of swallowing

A

Pharyngeal and oesophageal

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13
Q

Which nerves transmit impulses from the pharynx mechanoreceptors to the swallow centre?

A

Glossopharyngeal and vagus

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14
Q

What does the stomach make food into to be released into the small intestine?

A

Chyme

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15
Q

Parietal cells produce?

A

HCL and intrinsic factor

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16
Q

Chief cells produce?

A

Pepsinogen

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17
Q

G cells produce?

A

Gastrin

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18
Q

Enterochromaffin like cells produce?

A

Histamine

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19
Q

Surface mucous cells produce?

A

Mucus

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20
Q

3 phases of gastric secretion

A

Cephalic, Gastric and intestinal

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21
Q

Myenteric plexus role?

A

Major nerve supply to the gastrointestinal tract and controls GI tract motility.

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22
Q

What triggers the cephalic phase ?

A

Sight, smell and taste of food, mediated by the action of the vagus nerve

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23
Q

What triggers gastric phase?

A

Distension of the stomach and chemical composition of food

24
Q

Two pathways at work during the gastric phase to stimulate stomach secretory activity?

A

Stomach mechanoreceptors stretched
-> vagovagal -> medulla -> vagus nerve
AND -> local reflexes

Food chemicals and rising pH -> G cells secrete gastrin into the blood

25
Q

Pathway in the intestinal stage stimulating stomach secretory activity

A

Presence of low pH and partially digested food in the duodenum -> intestinal gastrin released

26
Q

Two pathways in the intestinal stage inhibiting stomach secretory activity

A
  1. Distension of duodenum / presence of fatty acids / chyme

-> local reflexes
-> pyloric sphincter
-> vagal nuclei in the medulla

All stimulate the enterogastric reflex

  1. Distension of duodenum / presence of fatty acids / chyme

-> release of intestinal hormones

27
Q

What is added to duodenal chyme to allow it to be broken down further?

A

Water, bicarb and bile

28
Q

What creates the osmotic gradient in the small intestine?

A

sodium pump

29
Q

What happens to carbohydrate polysaccharides at the intestinal brush border to allow them to be absorbed?

A

Broken down by enzymes

Maltase / isomaltase / sucrase / lactase

30
Q

Which transporter moves monosaccharides across the apical membrane in the GI tract?

A

SGLT1 inhibitors

31
Q

How do monosaccharides across the basal membrane in the GI tract

A

Facilitated diffusion (GLUT2) OR simple

32
Q

How are lipids packaged by bile acids to allow them to enter the aqueous layers surrounding the microvilli ?

A

Emulsified and then form micelles (hydrophobic lipid molecules in the centre, surrounded by bile acids)

33
Q

Main mechanisms of calcium extrusion from the GI tract?

A

The plasma membrane Ca2+ ATPase (PMCA) and the plasma membrane Na+/Ca2+ exchanger (NCX) are the two mechanisms responsible for Ca2+ extrusion.

34
Q

What facilitates the uptake of non-haem ferrous iron (Fe2+) from the intestinal lumen?

A

he transporter protein Divalent Metal Transporter 1 (DMT1), located on the apical surface of enterocytes

35
Q

Where are most pancreatic enzymes activated?

A

duodenum

36
Q

Secretion stimulates what in the pancreas?

A

Secretion of the alkaline-richh fluid from the ductal cells

37
Q

Cholecystokinin stimulates what in the pancreas?

A

Secretion of the enzyme rich fluid from the ductal calls

38
Q

Somatostatin inhibits what in the pancreas?

A

Secretion from both acinar and ductal cells

39
Q

Gastrin stimulates what in the pancreAs?

A

Acinar cells to secrete pancreatic enzymes

40
Q

What is CCK stimulated by?

A

The presence of fatty acids/monoglycerides and small peptides/amino acids in the duodenum

41
Q

CCK action

A

Increase production of bile

stimulate release of stored bile

increase pancreatic bicarbonate secretion

stimulate pancreatic enzyme secretion

inhibit gastric emptying, inhibit gastric acid production

stimulate pepsinogen secretion

42
Q

Which types of cells release CCK?

A

I cells in the duodenum and jejunum

43
Q

Which types of cells release secretin?

A

S cells in the duodenum

44
Q

What stimulates secretin release?

A

A low pH and the presence of fatty acids in the duodenum

45
Q

Secretin actions

A

inhibit gastric acid secretion

inhibit gastric emptying

stimulate pepsinogen secretion

stimulate pancreatic bicarbonate secretion

increase pancreatic enzyme secretion

increase bile production

46
Q

What is the portal triad composed of?

A

Portal arteriole
Portal vein
Bile duct

(also contains lymphatic vessels and vagal parasympathetic fibres)

47
Q

The liver receives dual blood supply from?

A

Hepatic artery and portal vein

48
Q

Two main groups of bile constituents

A

Bile acid dependent and independent components

49
Q

The bile acid-dependent component is produced by…

& what are they

A

Hepatocytes

Bile acids, bile pigments and cholesterol

50
Q

The bile acid-independent component is made by the…

A

Ductal cells that line the bile ducts

51
Q

Enterohepatic circulation role?

A

The bile acid-independent component is made by the

52
Q

Bands of muscles in the large intestine wall called?

A

Taenia coli

53
Q

What innervates and caecum, ascending and transverse colon

A

Parasympa branches of the vagus nerve

54
Q

Role of intestinal bacterial flora (5)

A

Keep pathogenic bacteria at bay

Convert conjugated bilirubin to unconjugated

Synthesis of K, B12, thiamine and riboflavin

Breakdown primary bile acids to secondary

Break down cholestrol, some food additives and drugs

55
Q

Which monosaccharide isn’t absorbed by Na+ transport in the intestine?

A

Fructose

56
Q
A

Physiology MRCEM part 1 (7 decks)

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