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BMS109 Phys/Pharm > GI Tract > Flashcards

Flashcards in GI Tract Deck (90)
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1

Constituents of the GI tract

Mouth oesophagus, stomach, duodenum, jejunum, ileum, colon, rectum anus

2

Which regions make up the small intestin

Duodenuim, jejunum, ileum

3

Which regions make up the large intestin

Colon rectum anus

4

Accessory structures

Parotid, sub-mandibular, sublingual, pancrease, liver, gallbladder, tounger

5

What is the GI tract function

Breakdown of ingested food which can be taken up into the body tissues

6

What are the two aspects the the role of the GI tract

Digestion and absorption

7

How is the GI tract organised structurally

Mucosa, sub mucosa, muscularise and serosa

8

Which is the innermost layer of the Gi tract and what does it consist of

Mucosa - Consists of mucous epithelium, lamina propria and muscularis mucosae

9

What two layers make up the muscularis

Circ muscle layer
Longitudinal muscle layer

10

Which layer is referred to as the peritoneum and consists of connective tissue

Serosa

11

What is meant by the pylorus

Opening form stomach into duodenum

12

What are the main roles of the stomach

Storage
Mechanical digestion

13

What region does most absorption occur

Small intestin

14

What is special about the jejunum and ileum

3 strata of folding, no definable boundary

15

Define chyme

Semifluid mass of partially digested food that is expelled from the stomach into the duodenum

16

Describe the chyme found in the large intestin

Very little nutrients

17

What is the roel of the large intestin

Absorb of salt, water and sugar

18

Name the regions of the colon

Caecum, ascending, transverse, descending and sigmoid

19

Main control mechanisms of the GI tract

ANS - symp inhib digestion, para stim
Enteric - Independent from the CNS
Gut peptides - paracrine or hormonal

20

What are the nerve plexus involved in enteric nervous control of the GI tract

Myenteric and sub mucosal plexus

21

What are the roles of the nerve plexus

Sense luminal contents and controls muscles and glands

22

Where are gut peptides secreted from

Enteroendocrine cells in the mucosa

23

Name some gut peptides

Gastrin
Secretin
Cholecystokinin

24

What is motility and secretion controlled by

Reflexes

25

Main differences between intrinsic and extrinsic control reflexes

Int - Short - local stim - local nerve circuits
Ext - Long - ext stimuli - CNS involvement

26

What are enteroendocrine cells

Single cells scattered throughout the GI tract

27

What is the role of EE cells

Detect luminal contents and respond by releasing peptide transmitteres

28

How do EE cells act

Humourally or paracrine

29

What stimulates peristalsis

Distension of the GI tract by bolus

30

What structure mediates peristalsis

Myenteric plexus

31

What are the aspects of peristalsis

Oral contraction followed by aboral relaxation

32

If the bolus is moving away from the anus

Vomitting

33

Does peristalsis require CNS input

No

34

What is Hirchsprungs disease

Congenital disorder due to the absent development of the myenteric plexus, lack of GI innervation, enlarged colon requires surgical removal

35

What is the role of saliva

Solvent or taste
Cleans/protects teeth LUbrication
Antimicrobial

36

What is the role of the parotid gland

Secretion of saliva into the parotid duct

37

What is the name of the gland that secretes below the tounge

Sub lingual

38

Which salivary gland located below the mandible

Sub mandibular

39

What are the component parts of slaiva

Water, mucous, a-amylase, lipase

40

Which enzyme secreted by the parotid gland

A amylase

41

Which enzyme secreted by the sub lingual

Lipase

42

Descibe salivary gland structure

12+ aciniar cells around central lumen

43

Describe the process of slaivation

Acinar cells produce primary saliva and secrete it into the intercalated duct. The saliva then travels through the striated duct where the ductal cells modify it by reabsorbing Na+ and Cl- and secreting HCO3-. After the striated duct the saliva then passes into the excretory duct where myoepithelial cells contract following nervous system stimulation to bring the saliva into the mouth

44

What are zymogen granules, why are they useful

Zymogen granules are vesicles containing inactive proenzymes that are to be secreted. Only once secreted are these proteins cleaved to their active forms. These prevent damage to our own cells by the protease activity of some of the enzymes.

45

Defiene swallowing

Process by which food passes from mouth to stomach

46

What are the phases of deglutination

Oral, pharyngeal and oesophageal

47

NS 1 peri wave

ANS

48

NS 2 peri wave

ENS

49

What are the four roles of the stomach

Motilitiy, digestion, protection and absorption

50

3 types of motility by the stomach

Accomodation
Trituration
Emptying

51

Which bio mole does the stomach digest

Protein

52

What is absorbed in the stomach and how

Alcohol and fat soluble drugs
By diffision

53

What are the components of gastric juice

Water
Ions HCL
Pepsinogen
Intrinsic factor
Mucus
Gastrin

54

Role of HCL secreted

Lower pH to prevent bacterial grouth and catlayses pepsinogen to pepsin

55

What is the function of pepsinogen

Proenzyme of pepsin

56

What role does intrinsic factor play

Prevent vit B12 breakdown so it can be absorbed in the ileum

57

What does the cephalic phase of gastric secretion represent

Sight, thought, smell of food triggers secretion of acid, mucus and enzymes as well as increased gastric motility

58

what initiates the cephalic phase

PARA - vagus fibres

59

What does the gastric phase of secrection represent

Food entering stomach causes streching and tiggers secretion and motility

60

What initiates gastric pahse

Long vagal fibres and short myenteric reflexes

61

What does the intestinal phase of gastric secretion represent

Food in the intestine induces the release of hormones that inhibit motility

62

What initiates the intestinal phase

Hormones

63

30. Which cells in the gastric pit are responsible for secreting mucus and HCO3-?

Mucus neck

64

Which cells secrete acid and intrinsic factor

Parietal cells

65

Which cells secrete gastrin

G-enteroendocrine

66

Which cells secrete pepsinogen

Chief

67

Which cells secrete somatostatin

D-enteroendocrine

68

What does gastrin do

Stimulate acid secretion

69

What does somatostatin do

Unhibit gastrin secretion and acid secretion

70

37. What is the pH of the lumen of the GI tract compared to that of the mucus gel

Lumen - 1.5
Mucus-gel neutral zone 7.0

71

What is gastric/peptide ulcer disease

Breakdown in the mucus gel neutralisation barrier causing damage to the lining of the stomach/small intestine

72

The parietal cells exchnge what ions

K in H out

73

Why do pariental cells contain many mitochondria

active transport of H+ against steep gradient

74

How is acid secretion controlled by the NS

ACh from vagus causes secretion

75

How can acid secretion be controlled by the paracrine system

Histamine released from from nearby cells can stimulate acid secretion

76

What causes G enteroendocrine cells to secrete gastrin

Detection of increased protein levels

77

What causes D enteroendocrine cells to release somatostatin

Acidity of the stomach becomes too low

78

Which type of cells releases histamin

Enterochromaffin-like cells

79

What are symptoms of gastric/peptic ulcer disease

Abdo pain
Bloating
Nause/vomiting
Haemorrhage

80

Give an example of an endogenous cause of peptic ulcer diease

Stress- leads to decrease of HCO3- and thinning of the mucus layer

81

How can alcohol and coffee lead to gastric ulcer disease

Stimulate parietal cell leading to increasing in acidity

82

How can NSAIDs lead to gastric ulcer disease

Secretion of proteases and endotoxins that degrade tissue of the stomach

83

How can peptic ulcer disease be treated

Antacids - neutralise stomach acid, histamine antagonists - ranitide, cimetidine, proton pump inhibitors - omerpraxole, antibiotics, - kill H

84

Name given to the functions regions of the stomach, how do they differ

Reservoir – top 2/3, tonic contractions, relax during gastric accommodation to store increased volume of food. Antral Pump – bottom 2/3, phasic contractions, trituration of food

85

Which sphincter allows food into the stomach

Lower oesophageal sphincter

86

What happens when food enters the stomach

Accommodation by receptive relaxation of corpus and fundus

87

Describe peristalsis in the stomach

Muscle contraction pushes food toward the pylorus mixing in the antrum

88

Retropulsion

During peristalsis in the stomach food is pushed up against the closed pyloric sphincter resulting in being pushed back away

89

Descibe antral systole

Peristaltic waves pushed contents of the stomach back towards the body – trituration. Some chyme enters the duodenum where cells detect what is coming out of the stomach

90

Descibe the intestinal phase of gastric motility

Arrival of food in the duodenum triggers the release of the hormones CCK and secretin