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Misc. Notes Year 1 > GI Physiology Document notes > Flashcards

GI Physiology Document notes Flashcards

1
Q

What are the 4 layers of the digestive tract

A

Mucosa
Submucosa
Muscularis Externa
Serosa (bock)

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2
Q

What 5 things are in the mucosal layer

A 
epithelial cells, 
exocrine cells, 
endocrine cells, 
lamina propria, 
muscularis mucosa
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3
Q

What 3 things are in the submucosal layer

A

connective tissue,
lymph tissue,
submucous (meissner’s) plexus

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4
Q

What 3 things are in the muscularis externa layer

A

circular muscle,
myenteric (Auerbach’s) plexus,
longitudinal muscle

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5
Q

What is in the serosa bock

A

connective tissue

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6
Q

The mucosa is the outermost layer

True or False

A

False

that would be the serosa bock

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7
Q

Where does the primary salivary secretion come from

A

Acinar cells

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8
Q

Which cells are responsible for the secondary modification of the primary saliva secretion

A

Ducts cells

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9
Q

What do the duct cells do to the primary secretion

A

Remove Na & Cl

Add K & HCO3

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10
Q

Parasympathetic saliva is…

A

Large volume
Watery
Enzyme rich

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11
Q

Sympathetic saliva is…

A

Low volume
Thick
Mucus rich

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12
Q

Parasympathetic control of saliva is mediated by which receptors and which NT

A

M1/M3 Ach receptors

VIP

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13
Q

Sympathetic control of saliva is mediated by which receptors and which NT

A

α and B1-adrenoceptors

Doesn’t say but probes noradrenaline?

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14
Q

What is the unconditioned (simple) salivary reflex

A

Activation of chemo/pressure receptors when food is in mouth leads to saliva production

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15
Q

What is the conditioned (acquired) reflex

A

Saliva production due to thinking of, seeing or smelling food

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16
Q

Which organ stores food before passing it to the small intestine

A

The stomach obviously

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17
Q

What is chyme

A

The mixture of gastric secretions and partially digested food - formed in the stomach

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18
Q

What gastric factors favour gastric emptying

A

Increased volume of chyme.

Finely divided chyme.

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19
Q

What duodenal factors go against gastric emptying

A

High volume of fat in duodenum.
High volume of acid in duodenum.
Distension of duodenum.
Lots of products of carbohydrate/protein breakdown in duodenum.

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20
Q

Which cells secrete HCL and where are they located

A

Parietal cells located in oxyntic mucosa

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21
Q

What, apart from, HCl do parietal cells secrete and what is it’s function

A

Intrinsic factor

Binds to B12 to allow absorption in terminal ileum

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22
Q

What are the 3 functions of HCL

A

Denatures proteins
Activates pepsinogen to pepsin
Kills micro-organisms

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23
Q

Which cells secrete pepsinogen and where are they found

A

Chief cells

oxyntic mucosa

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24
Q

What is pepsinogen

A

Inactive precursor of pepsin, activated by HCL

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25
Q

Which cells secrete histamine and where are they located

A

Enterochromaffin like cell

Oxyntic mucosa

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26
Q

What is the function of histamine

A

Stimulates HCL production

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27
Q

Which cells secrete gastrin and where are they located

A

Secreted by G cells (duh)

Pyloric Gland Area

28
Q

What is the function of gastrin

A

Stimulates HCL production

29
Q

Which cells secrete somatostatin and where are they located

A

Secreted by D cells

Pyloric Gland Area

30
Q

What is the function of somatostatin

A

Inhibits HCL production

31
Q

What does vagal stimulation do in terms of acid secretion

A

Increases secretion of substances which stimulate acid production

32
Q

Name 4 mechanisms protecting mucosa from HCL and pepsin

A

Hydrophobic monolayer
Bicarbonate secretion
Elimination of H+ in exchange for Na+
Locally produced prostaglandins which reduce acid secretion

33
Q

How do NSAIDs cause gastric ulceration and bleeding

A

NSAID’s reduce prostaglandin formation by COX 1 INHIBITION; can lead to gastric ulceration and bleeding

34
Q

Name 2 drugs which affect acid secretion

A

Protein Pump Inhibitors (PPI’s)

H2 receptor antagonists

35
Q

How do PPI’s work and give an example

A 
Inhibit active (membrane inserted) proton pumps
omeprazole
36
Q

How do H2 receptor antagonists work and give an example

A

Competitively antagonise H2 receptors
Completely block histamine mediated acid secretion
Ranitidine

37
Q

Name the two types of pancreatic secretions

A

Endocrine
Exocrine
well done

38
Q

Name the 2 endocrine secretions and where they are secreted

A

Insulin
Glucagon
secreted into bloodstream

39
Q

Name the 2 exocrine secretions and where they are secreted to

A

Digestive enzymes
Sodium bicarbonate
Secreted into duodenum as pancreatic juice

40
Q

Where are pancreatic digestive enzymes secreted from

A

Acinar cells

41
Q

Where is sodium bicarbonate secreted from

A

Duct cells

42
Q

What is the function of the sodium bicarbonate that is secreted from pancreatic duct cells

A

Neutralises acid chyme thus protecting mucosa and providing optimum pH for pancreatic enzymes

43
Q

Which cells secrete secretin and what does it do

A

S cells funnily enough

Increases secretion of aqueous NaHCO3 solution into duodenum

44
Q

What cells secrete CCK and what does it do

A 
i cells (not C cells) 
Increases secretion of digestive enzymes into duodenum
45
Q

Where is bile secreted from

A

Bile duct cells

Hepatocytes

46
Q

The presence of what stimulates gallbladder SM to contract

A

Presence of chyme in the duodenum

47
Q

What is the function of bile

A

Aids in the digestion of fat

48
Q

Name 3 features of the small intestine which make it well adapted for absorption

A

Circular folds
Villi
Microvilli

49
Q

What are the two types of starch

A

Amylose

Amylopectin

50
Q

What is the difference between the two types of starch

A

Amylose only has α 1-4 bonds

Amylopectin has α 1-6 and α 1-4 bonds

51
Q

Does glycogen have α 1-6 bonds

A

Yes

but more commonly than amylopectin (1 in 10 rather than 1 in 30 like amylopectin)

52
Q

What does salivary α amylase do

A

attacks 1-4 glycosidic links

53
Q

What breaks down sucrose

A

Sucrase

wow

54
Q

What breaks down lactose

A

Lactase

na wa

55
Q

What is sucrose made up of

A

GLUCOSE + FRUCTOSE

56
Q

What is lactose made up of

A

GLUCOSE + GALACTOSE

57
Q

How are proteins broken down in the stomach

A

HCl denatures proteins, pepsin cleaves proteins into peptides.

58
Q

How are proteins broken down in duodenum

A

pancreatic enzymes split peptide bonds between amino acids, brush border enzymes cleave amino acids from amino end of molecule.

59
Q

Hydrophilic amino acids are absorbed by passive diffusion

True or False

A

False

HydroPHOBIC amino acids are absorbed by passive diffusion

60
Q

How does bile affect lipids

A

Emulsifies them to allow a larger surface area for pancreatic lipase to act

61
Q

What is the co-factor that allows pancreatic lipase to do it’s job

A

Co-lipase

incredible

62
Q

What are free fatty acids and how are they absorbed

A

Short-medium length chains

Absorbed by passive diffusion

63
Q

How are long chain fatty acids and mono-glycerides absorbed

A

Resynthesised into triglycerides in the ER and incorporated into chylomicrons

64
Q

What are lacteals

A

lymphatic vessels of the small intestine

65
Q

Which protein surrounds a chylomicron before it is incorporated into a lacteal

A

Apolipoprotein

ApoB-48

66
Q

What is a chylomicron that isnt bound to ApoB-48 called

A

Nascent chylomicron

67
Q

Where do chylomicrons drain to and via which vessel

A

Left venous angle

via thoracic duct

Misc. Notes Year 1 (13 decks)

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