Upper GI Flashcards

1
Q

Digestion def

A

The process of breaking down macromolecules to allow absorption

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2
Q

Absorption def

A

The process of moving nutrients & water across a membrane

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3
Q

Give the 4 layers of the gut wall and what they’re made of

A

Mucosa:
-Epithelium
-Lamina propria
-Muscularis mucosae

Submucosa:
-Connective tissue

Muscularis:
-Smooth muscle(With nerve plexus)

Serosa/Adventitia:
-Connective tissue+/-epithelium

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4
Q

How many teeth are there in total and how many of each type?

A

32 total
8 incisors
4 canines
8 premolars
12 molars

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5
Q

What layer of gut wall are the longitudinal muscles in?

A

Muscularis

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6
Q

What layer of gut wall are the circular muscles in?

A

Muscularis

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7
Q

What layer of gut wall is the colonic epithelium?

A

Mucosa

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8
Q

What layer of gut wall are the submucosal glands in?

A

Submucosa

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9
Q

What layer of gut wall are the ganglion nerves and cells in?

A

Submucosa + Muscularis

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10
Q

What layer of gut wall is the stomach epithelium in?

A

Mucosa

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11
Q

What layer of gut wall is the small intestine epithelium in?

A

Mucosa

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12
Q

What is the major muscle involved in biting force?

A

Masseter
-Several other muscles control jaw position

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13
Q

What are the salivary glands and what do they secrete?

A

-Parotid
-Sublingual
-Submaxillary

Secrete:
Lingual lipase (fat digestion)
Salivary amylase (carbohydrate digestion)

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14
Q

What is the purpose of the tongue and what are the 2 divisions of muscles that control it and what different functions do they control?

A

Assists mechanical digestion

Extrinsic muscles
-Gross movement of tongue

Intrinsic muscles
-Fine motor control and food movement

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15
Q

At what vertebral level does the trachea start?

A

C5-C6

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16
Q

At what vertebral level does the trachea finish?

A

T8

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17
Q

At what vertebral level does the diaphragm start?

A

T10

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18
Q

At what vertebral levels does the oesophagus start and end?

A

Starts at C5
Ends at T10

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19
Q

At what vertebral level does the aorta start?

A

T2ish

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20
Q

Function of the oesophagus

A

Conduit for food, drink & swallowed secretions from pharynx to stomach

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21
Q

Is the oesophageal epithelium keratinising?

A

It is non-keratinising

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22
Q

What is the oesophagus lubricated by?

A

Mucus and saliva

23
Q

What does the wear and tear lining nature of the oesophagus mean?

A

It is in the extremes of temperature and texture

24
Q

What kind of sphincters are present in the oesophagus and how are they controlled?

A

Upper oesophageal sphincter: Skeletal muscle
Lower oesophageal sphincter: Smooth and skeletal muscle

25
Q

What type of muscle is responsible for oesophageal peristalsis?

A

Circular muscle

26
Q

What is interesting about the association between gravity and the lower oesophageal sphincter?

A

The smooth muscle is tonically active- So is able to keep food from travelling back up the oesophagus when upside down

27
Q

What occurs in stage 0 in swallowing?

A

Oral phase:
Chewing & saliva prepare bolus
Both oesophageal sphincters constricted

28
Q

What occurs in stage 1 in swallowing?

A

Pharyngeal phase:
Pharyngeal musculature guides food bolus towards oesophagus
Both oesophageal sphincters open

29
Q

What occurs in stage 2 in swallowing?

A

Upper oesophageal phase:
Upper sphincter closes
Superior circular muscle rings contract & inferior rings dilate
Sequential contractions of longitudinal muscle

30
Q

What occurs in stage 3 in swallowing?

A

Lower oesophageal phase:
Lower sphincter closes as food passes through

31
Q

How does the epithelial structure change when passing the gastro-oesophageal junction?

A

Goes from stratified squamous to simple columnar

32
Q

What muscle is gastric reflux prevented by?

A

The diaphragm

33
Q

What is the purpose of the gastro-oesophageal epithelial transition

A

Transition from a largely musculature structure to a secretory structure

34
Q

3 major stomach functions

A

Breaks food into smaller particles (acid & pepsin)

Holds food, releasing it in controlled steady rate into duodenum

Kills parasites & certain bacteria

35
Q

What forms the stomach gel coating?

A

HCO3- trapped in the mucus gel

36
Q

What is secreted by the antrum?

A

Gastrin

36
Q

Where is stomach mucus secreted?

A

Cardia and pyloric regions

37
Q

What is secreted by the body and fundus?

A

Mucus, HCl, Pepsinogen

37
Q

What is the pH at the epithelial surface and in the lumen?

A

Epithelial surface: 6-7
Lumen: 1-2

38
Q

How much stomach acid is produced per day?

A

2L

39
Q

What are the 2 types of muscle contractions in the stomach, what do they each do and which nervous systems are needed for them to function?

A

Peristalsis - 20% of contractions
Propels chyme towards colon-more powerful as moves from LOS to pyloric sphincter
ANS essential

Segmentation - 80% of contractions
Weaker.
Fluid chyme towards Pyloric sphincter
Solid chyme pushed back to body
Stretching activates enteric NS

39
Q

What are gastric chief cells and what do they secrete?

A

Protein-secreting epithelial cell
Abundant RER
Golgi packaging and modifying for export
Masses of apical secretion granules
Secretes pepsinogen

40
Q

What are 3 cytoplasmic components of gastric parietal cells?

A

Many mitochondria (requires lots of ATP)

Internal canaliculi (secretory surface)

Cytoplasmic tubulovesicles (contain H+/K+ ATPase)

41
Q

What occurs to gastric parietal cells when in secreting state?

A

Microvilli project into canaliculi

Tubulovesicles fuse with membrane

42
Q

How do gastric parietal cells produce/secrete stomach acid?

A

K+ is drawn into the parietal cell through the basal membrane, releasing Na+ through an antiporter

K+ moves through another channel directly into the cannaliculi

Carbonic Anhydrase catalyses the reaction between CO2 and H2O to produce HCO3-, which is antiported with Cl-, Cl- travels into the cannaliculi through another direct channel

H+ moves into the cannaliculi through an ATPase H+/K+ antiporter

H+ and Cl- combine in the gastric lumen to form HCl - stomach acid

43
Q

What occurs to pepsinogen when reacted with HCl?

A

Converts to pepsin to break down proteins

44
Q

What is the function of gastrin and what prompts its secretion?

A

Produced from G-cells in the pyloric antrum

G cells stimulated by distension, produces gastrin which then stimulates parietal cells to produce HCl

45
Q

What are the 3 phases of gastric secretion?

A

Cephalic
Gastric
Intestinal

45
Q

What occurs in the cephalic phase of gastric secretion?

A

Vagus innervation of the stomach to produce HCl

46
Q

What occurs in the gastric phase of gastric secretion?

A

Food enters the stomach, still innervated by the vagus nerve leading to production of HCl and pepsin

47
Q

What occurs in the intestinal phase of gastric secretion?

A

Chyme is produced in duodenum

When ph<2 or lipids are present in duodenum gastric inhibitory peptides like cholecystokinin and secretin inhibit gastric secretion(HCl/pepsin).

48
Q

What occurs in the excitatory intestinal phase of gastric secretion?

A

Protein concentration in duodenum stimulates gastric secretion

49
Q

SUMMARY OF GASTRIC SECRETORY PHASES

A