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Phase 1 flashcards > GI > Flashcards

GI Flashcards

1
Q

which cells line the intestines?

A

enterocytes

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2
Q

where does the voluntary phase of swallowing occur?

A

mouth

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3
Q

describe the voluntary phase of swallowing

A

food is chewed and pushed into the oropharynx

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4
Q

describe the pharyngeal phase of swallowing

A

nasopharynx closed
hyoid elevated
epiglottis closed
pharynx shorter and wider (longitudinal muscle)
involuntary

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5
Q

is the pharyngeal phase of swallowing involuntary or voluntary?

A

involuntary

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6
Q

which sphincter lies between the oesophagus and stomach?
what is it’s function

A

lower oesophageal sphincter
prevent oesophageal reflux of acid

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7
Q

what is the oesophageal phase of swallowing?

A

pharynx sequentially contracts (circular muscle)
peristaltic waves along oesophagus towards the lower oesophageal spinchter
hyoid depressed, epiglottis opens, nasopharynx opened

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8
Q

which sphincter prevents oesophageal reflux of acid?

A

lower oesophageal sphincter

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9
Q

what is reflux into the oesophagus called?

A

GORD

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10
Q

what can cause acid reflux?

A

pregnancy, big meals

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11
Q

which sphincter is at the bottom of the stomach?

A

pyloric sphincter

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12
Q

blood supply to the stomach

A

coeliac trunk and its branches
a branch of abdominal aorta at T12

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13
Q

branches of the coeliac trunk

A

common hepatic artery
left gastric artery
splenic artery

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14
Q

blood supply of the lesser curvature of the stomach

A

left and right gastric arteries, which anastomose

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15
Q

blood supply of the greater curvature of the stomach

A

left and right gastroepiploic arteries, which anastomose

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16
Q

where does the left gastric arise from?

A

coeliac trunk

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17
Q

where does the splenic artery arise from?

A

coeliac trunk

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18
Q

branches of the splenic artery

A

left gastroepiploic artery
short gastrics
pancreatic branches

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19
Q

appearance of splenic artery

A

tortuous

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20
Q

sole arterial supply to liver

A

common hepatic artery

and then also hepatic portal vein supplying venous blood from the GI tract

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21
Q

terminal branches of the common hepatic artery

A

proper hepatic artery
gastroduodenal artery

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22
Q

branches of the proper hepatic artery

A

right gastric
right and left hepatic
cystic

last two are intuitive because the proper hepatic artery travels right, towards the liver and obviously gallbladder

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23
Q

branches of the gastroduodenal artery

A

right gastroepiploic
superior pancreaticoduodenal

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24
Q

blood supply of the fundus

A

splenic artery - intuitive, as the spleen is near the fundus of the stomach

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25
Q

folds on the stomach lining

A

rugae

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26
Q

function of rugae

A

allow expansion of the stomach after the consumption of foods and liquids

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27
Q

differences in the vasa recta and arterial arcades between jejunum and ileum

A

jejunum
- longer vasa recta, fewer arterial arcades
ileum
- more arterial arcades, shorter vasa recta

vasa recta - straight arteries coming off from arcades in the mesentery of the jejunum and ileum, and heading toward the intestines
arterial arcades - loops of arteries around the jejunum and ileum

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28
Q

function of the colon

A

absorb water

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29
Q

function of the small intestine

A

absorb nutrients

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30
Q

retroperitoneal organs

A

SAD PUCKER

Suprarenal (Adrenal) gland, Aorta and IVC, Duodenum, Pancreas, Ureter, Colon, Kidney, Esophagus, and Rectum

or DADPOK

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31
Q

do mesenteries allow movement?

A

yes
‘m’ for motile

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32
Q

where do the omenta hang?

A

off the greater and lesser curvature of the stomach

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33
Q

what is the only natural communication between the lesser and greater sac?

A

epiploic foramen of Winslow

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34
Q

foregut

A

mouth to proximal half of duodenum

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35
Q

midgut

A

distal half of the duodenum to proximal two thirds of the transverse colon

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36
Q

hindgut

A

distal third of transverse colon to rectum

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37
Q

what does ‘GORD’ stand for?

A

gastro-oesophageal reflux disease

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38
Q

consequences of GORD

A

metaplasia
Barret’s oesophagus
epithelium change from stratified squamous non keratinising epithelium (of the oesophagus) to simple columnar (of the stomach)
causes pain, as less protection due to change in epithelium

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39
Q

which cranial nerves are involved in the gag reflex?
which is sensory, and which is motor in this response?

A

CN IX and CN X
glossopharyngeal (sensory) and vagus (motor)

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40
Q

how much saliva is produced a day?

A

800ml - 1500ml

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41
Q

what does saliva contain?

A

water, mucus, antibodies, enzymes e.g amylase

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42
Q

functions of saliva

A

lubricant, taste (by dissolving), cephalic digestion, mouth hygiene

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43
Q

name the three major salivary glands

A

parotid, submandibular and sublingual

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44
Q

which is the largest salivary gland?

A

parotid

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45
Q

which salivary gland are continuous?

A

submandibular and sublingual

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46
Q

which salivary gland must be stimulated for secretions to occur?

A

parotid

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47
Q

what type of secretions does the parotid gland secrete?

A

serous

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48
Q

which duct does saliva from the parotid gland leave?

A

Stensen’s duct

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49
Q

innervation of the parotid gland

A

CN IX - glossopharyngeal

not CN XII (facial), this only passes through and divides into 5 terminal branches in the parotid

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50
Q

which cranial nerve passes through the parotid gland?

A

facial
CN VII

facial DOES NOT innervate the parotid gland

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51
Q

name structures passing through the parotid gland

A

external carotid artery
retromandibular vein
facial nerve - remember the parotid is not actually innervated by the facial nerve however

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52
Q

is the submandibular gland continuous?

A

yes

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53
Q

is the parotid gland continuous?

A

no

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54
Q

is the sublingual gland continuous?

A

yes

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55
Q

where do secretions from the submandibular gland leave?

A

Wharton duct

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56
Q

what type of secretions does the submandibular gland secrete?

A

mixed serous and mucous

subMandibular for mixed

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57
Q

what can we see histologically in submandibular glands?

A

serous demilunes
serous acini form crescents around mucous

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58
Q

innervation of the submandibular gland

A

CN VII
7th cranial nerve
facial nerve

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59
Q

which is the smallest salivary gland?

A

sublingual

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60
Q

which type of secretions does the sublingual gland secrete?

A

mixed

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61
Q

where do secretions from the sublingual gland leave?

A

Wharton duct

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62
Q

innervation of the sublingual gland

A

facial nerve

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63
Q

where is the sublingual gland relative to the submandibular?

A

anterior

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64
Q

which is the only non mucous secreting (serous) minor gland?

A

von ebner

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65
Q

from which gland is the main salivary output when stimulated?

A

parotid

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66
Q

what percentage of salivary flow is by the three major glands?

A

80

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67
Q

here are minor salivary glands located?

A

submucosa of oral mucosa

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68
Q

what percentage of saliva is produced by minor salivary glands?

A

20% approx

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69
Q

compare the contents of serous and mucous secretions

A

serous
- water and alpha amylase

mucous
- water and glycoproteins

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70
Q

compare the histological appearance of serous and mucous glands

A

serous
- dark staining
- small central duct
- nucleus in basal third

Mucous
- pale and foamy appearance (Michael Palin - to remember)
- large central duct
- nucleus at base

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71
Q

what is xerostomia?

A

dry mouth

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72
Q

what can cause xerostomia?

A

cystic fibrosis
Sjorgen’s syndrome

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73
Q

what causes obstruction in salivary glands?

A

calcium and phosphate ions in saliva can form salivary calculi
most often in submandibular gland

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74
Q

which gland swells up significantly in mumps?

A

parotid - capsule does not allow much enlargement

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75
Q

effect of parasympathetic stimulation on salivary glands

A

saliva stimulated - rest and digest

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76
Q

effect of sympathetic stimulation on salivary glands

A

saliva inhibited - fight or flight

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77
Q

layers of the GI tract, internal to external

A

mucosa
submucosa
muscularis externa
serosa

MSMS

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78
Q

name the two large plexuses of the enteric nervous system

A

submucosal plexus
myenteric plexus

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79
Q

where is the submucosal plexus?

A

submucosa of the gastrointestinal tract wall

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80
Q

how many layers does the muscularis externa of the stomach have? what are they?

A

three

inner oblique, intermediate circular, outer longitudinal

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81
Q

how many layers does the muscularis externa of the GI tract (minus the stomach) have? what are there?

A

two

inner circular, outer longitudinal

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82
Q

where is the myenteric plexus?

A

muscularis externa of GI tract

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83
Q

which cells are predominantly found in the cardia of the stomach and what do they produce?

A

foveolar
mucus - for protection

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84
Q

where are parietal cells predominantly found, and what do they produce?

A

fundus of stomach
HCl and intrinsic factor

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85
Q

what do parietal cells produce?

A

HCl and intrinsic factor

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86
Q

function of intrinsic factor

A

absorption of vitamin B12

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87
Q

what is pernicious anaemia?

A

vitamin B12 deficiency

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88
Q

where are chief cells predominantly found?

A

fundus of stomach

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89
Q

what do chief cells produce?

A

pepsinogen

(which is cleaved to pepsin)

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90
Q

what is a zymogen?

A

inactive precursor of an enzyme

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91
Q

where are ECL cells predominantly found?

A

fundus of stomach

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92
Q

what do ECL cells produce?

A

histamine

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93
Q

function of histamine in the stomach

A

signals the release of HCl for digestion

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94
Q

where are G cells primarily found?

A

pyloric antrum

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95
Q

what to G cells produce?

A

gastrin

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96
Q

function of gastrin

A

stimulates release of HCl into the stomach
directly and via histamine

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97
Q

where are D cells predominantly found? (gastric delta cells)

A

stomach, duodenum, pancreas

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98
Q

what do D cells produce?

A

somatostatin

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99
Q

where are I cells found?

A

duodenum

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100
Q

function of I cells

A

produce cholecystokinin - CCK

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101
Q

function of cholecystokinin

A

bile secretion

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102
Q

where are S cells found?

A

duodenum

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103
Q

what do S cells produce?

A

secretin

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104
Q

functions of the stomach

A

digests and sores food
activates enzymes
kill microbes
secrete intrinsic factor for the absorption of B12
protection and lubrication

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105
Q

in which cells is gastric acid produced?

A

parietal cells

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106
Q

describe gastric acid production, using equations where necessary

A

water and carbon dioxide combine within the parietal cell cytoplasm to produce carbonic acid
this is catalysed by carbonic anhydrase
carbonic acid spontaneously dissociates into a hydrogen ion and a bicarbonate ion
CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+

the hydrogen ion is transported into the stomach lumen via the H+-K+ ATPase ion pump. the pump uses ATP to exchange potassium ions into the parietal cells of the stomach with H+ ions

the bicarbonate ion is transported out of the cell into the blood via an anion exchanger which transports the bicarbonate ion out of the cell in exchange for a chloride ion

the chloride ion is then transported into the stomach lumen via a chloride channel

results in hydrogen and chloride ions being present within the stomach lumen. their opposing charges leads to them associating with each other to form hydrochloric acid

Cl- + H+ —> HCl

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107
Q

what is the pH of the stomach?

A

pH 2

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108
Q

name the three phases of digestion

A

cephalic phase, gastric phase, duodenal phase

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109
Q

does the cephalic phase of digestion always stimulate or inhibit gastric acid production?

A

increase
always stimulatory

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110
Q

does the gastric phase of digestion stimulate or inhibit gastric acid production?

A

first part
- stimulates
- stomach distends
- triggers gastrin release; activates histamine release
- increases number of H+-K+ ATPase pumps

second part
- low luminal pH
- decrease in gastrin and therefore histamine
- an increase in somatostatin

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111
Q

does the duodenal phase of digestion always stimulate or inhibit gastric acid production?

A

always inhibitory

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112
Q

what is the mechanism of gastric acid regulation?

A

an increase in the number of apical H+ K+ ATPase pumps on the parietal cell

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113
Q

what is the cephalic phase of digestion?

A

stomach responds to the mere sight, smell, taste, or thought of food

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114
Q

what is the gastric phase of digestion?

A

swallowed food and semi-digested protein ( peptides and amino acids) activate gastric activity

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115
Q

what is the duodenal (also known as intestinal) phase of digestion?

A

the duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes

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116
Q

describe the cephalic phase of digestion

A

vagus nerve uses Ach
induces parasympathetic stimulation of the GI tract
promotes gastrin secretion from G cells
increases histamine secretion from ECL cells
an increase in H+ K+ ATPase pumps

parasympathetic
sight, small, taste of food and chewing
vagus nerve
Ach release
Ach triggers release of gastrin and histamine
net effect is increased acid production

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117
Q

describe the gastric phase of digestion when gastric acid secretion is stimulated

A

triggered by gastric distension or presence of peptides and amino acids
gastrin release
gastrin acts directly on parietal calls
gastrin triggers release of histamine
histamine acts directly on parietal cells (and mediates effect of gastrin and ACh)
net effect is increased acid production

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118
Q

why do proteins stimulate gastric acid production?

A

proteins in the lumen act as a buffer and mop up H+ ions
pH rises
gastrin release stimulated
decreased secretion of somatostatin
more parietal cell activity - lack of inhibition

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119
Q

describe the gastric phase of digestion when gastric acid secretion is inhibited

A

low luminal pH
directly inhibits gastrin secretion
indirectly inhibits histamine release via gastrin
stimulates somatostatin release which inhibits parietal cell activity

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120
Q

what triggers the duodenal phase of digestion?

A

triggered by
distension of the duodenum
hypertonic luminal contents
a fall in pH
a rise in fatty acid concentration
a rise in amino acid concentration

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121
Q

describe the response in the duodenal phase of digestion

A

enterogasterones are released
secretin from S cells
- inhibits gastrin release
- promotes somatostatin release

choleocystokinin (CCK) from I cells
- stimulates bile release

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122
Q

what are peptic ulcers?

A

breaches in mucosal lining

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123
Q

what causes peptic ulcers?

A

H pylori bacteria
NSAIDS e.g ibuprofen
chemical irritants
gastrinoma

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124
Q

how do gastronomas cause ulcers?

A

excessive gastrin release attacks gastric mucosa

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125
Q

how does Helicobacter pylori cause peptic ulcers?

A

secretes urease
splits urea to carbon dioxide and ammonia
ammonia combines with h+ to form ammonium
damaged gastric epithelium

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126
Q

how do NSAIDS cause peptic ulcers?

A

inhibit Cox-1 which makes prostaglandins
prostaglandins stimulate mucus production

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127
Q

what pH does H pylori thrive at?

A

low

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128
Q

how are peptic ulcers caused by H pylori treated?

A

proton pump inhibitors increase pH so conditions are inhospitable to H pylori
antibiotics

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129
Q

how are peptic ulcers caused by NSAIDs treated?

A

prostaglandin analogues - misoprostol
reduce acid secretion

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130
Q

what do parietal cells produce?

A

HCl and intrinsic factor

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131
Q

what cell secreted pepsinogen?

A

chief cell

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132
Q

what two things activates the cleaving of pepsinogen to pepsin?

A

pepsin itself (positive feedback)
HCl

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133
Q

action of pepsin

A

protein digestion into peptides

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134
Q

do chief cells produce pepsin?

A

NO NO NO
they produce pepsinogen, which is converted to pepsin by a low pH and pepsin itself

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135
Q

what vitamin supplements may you need if your stomach is removed?

A

B12

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136
Q

where do peristaltic waves begin in the stomach? nature of these contractions

A

gastric body
weak contractions

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137
Q

are contraction in the gastric antrum stronger or weaker than in the body?

A

stronger

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138
Q

what causes mixing of the contents of the stomach?

A

antral contents are forced back towards the body

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139
Q

when is the conversion of pepsinogen to pepsin most efficient?

A

when pH is less than 2

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140
Q

what can irreversibly inactivate pepsin?

A

HCO3-

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141
Q

what percentage of total protein digestion is pepsin responsible for?

A

20%

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142
Q

how much chyme is released into the duodenum at a time? what happens to the rest?

A

3ml
retropulsed - pushed back

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143
Q

nervous control of peristalsis

A

parasympathetic nervous system acting on enteric nerve plexuses
coordination - afferent input via vagus nerve

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144
Q

what substances mediate receptive relaxation of the GI tract?

A

nitric oxide and serotonin released by enteric nerves

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145
Q

which cells mediate gastric motility by contracting?

A

interstitial cells of cajal

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146
Q

how many times does the GI tract contract a minute?

A

three

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147
Q

what slows gastric emptying?

A

a decrease in pH
an increase in fatty acids
an increase in amino acids
distension
hypertonicity - high concentration

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148
Q

what is dumping syndrome?

A

food moves into duodenum too quickly

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149
Q

which has a greater volume, stomach or duodenum?

A

stomach
rugae can stretch

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150
Q

describe the two responses that mediate the slowing of duodenal emptying

A

short pathway
- smaller response
- enteric local GI neurons

long pathway
- CNS
- bigger

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151
Q

what is gastroparesis?

A

too delayed duodenal emptying

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152
Q

water input into the GI tract per day

A

9000 ml

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153
Q

how much water is secreted and ingested into the GI tract per day?

A

7000ml secreted
2000ml ingested

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154
Q

where is water secreted in the GI tract?

A

intestines, saliva, stomach, bile, pancreas

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155
Q

what volume of water is secreted by intestines into the GI tract per day?

A

1000 ml

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156
Q

what volume of water is secreted in saliva into the GI tract per day?

A

1500 ml

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157
Q

what volume of water is secreted by the stomach into the GI tract per day?

A

2500 ml

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158
Q

what volume of water is secreted in bile into the GI tract per day?

A

500 ml

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159
Q

what volume of water is secreted by the pancreas into the GI tract per day?

A

1500 ml

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160
Q

what percentage of water is reabsorbed into GI tract, and what volume does this correspond to?

A

98%
8800 ml

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161
Q

what volume of water is excreted in stool?

A

200 ml

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162
Q

what does exocrine mean?

A

secretion into a duct

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163
Q

what volume of water is reabsorbed by the jejunum?

A

5500 ml

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164
Q

what volume of water is reabsorbed by the ileum?

A

2000 ml

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165
Q

what volume of water is reabsorbed by the colon?

A

1300 ml

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166
Q

which ion is most abundant in chyme?

A

Na+

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167
Q

in which part of the GI tract is iron absorbed?

A

duodenum

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168
Q

where are vitamin B and C absorbed?

A

jejunum
but not B12 even though it is water soluble

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169
Q

which are the water soluble vitamins?

A

B and C

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170
Q

what are the fat soluble vitamins?

A

ADEK

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171
Q

which vitamins does the ileum absorb?

A

A,D,E,K and B12
all fat soluble bar B12

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172
Q

which vitamins do the jejunum and ileum absorb?

A

jejunum - B and C
ileum - A,D,E,K,B12

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173
Q

digestion of starch

A

alpha amylase in the mouth
pancreatic amylase released at duodenum major duodenal papilla (95% digestion)
broken down into oligo/ disaccharides
membrane bound oligo/ disaccharidases at duodenum converted to monosaccharides

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174
Q

products of carbohydrate digestion

A

glucose, galactose, fructose
monosaccharides

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175
Q

products of carbohydrate digestion

A

glucose, galactose, fructose

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176
Q

absorption of glucose and galactose from duodenal lumen into lining cell

A

secondary active transport with Na+, SGLT-1

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177
Q

where are carbohydrates digested and absorbed?

A

duodenum

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178
Q

absorption of fructose from duodenal lumen into lining cell

A

facilitated diffusion using a GLUT 5 transporter

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179
Q

how do glucose, fructose and galactose leave the duodenum?

A

basolaterally
by GLUT2

diffuse into capillary then portal vein to liver

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180
Q

absorptive state

A

have eaten
glucose uptake by liver and stored as glycogen and in skeletal muscle

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181
Q

post absorptive state

A

fasted
glycogen stores broken down to glucose and consumed by skeletal muscle

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182
Q

what is metabolism?

A

the chemical processes that occur within a living organism in order to maintain life

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183
Q

protein digestion

A

stomach pepsin cleaves some bonds
in the duodenum, pancreatic endopeptidases
- acts mid chain
- e.g trypsin, chymotrypsin
in the duodenum, pancreatic exopeptidases
- acts on ends
- membrane bound aminopeptidases

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184
Q

protein absorption

A

secondary active transport with sodium
basolaterally into interstitial fluid then capillaries

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185
Q

fat digestion

A

starts in mouth with salivary lipase
emulsified by bile salts into small droplets - amphipathic so don’t reaggregate
lipase converts triglycerides to monoglycerides and 2 fatty acids
products packaged into micelles
contents released at intestinal brush border

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186
Q

fat absorption

A

monoglycerides + 2 FA converted to triglycerides in small intestine SER
packaged into vesicle with cholesterol
vesicles modified by Golgi into chylomicrons
exocytosed basolaterally into lacteals to the lymphatic circulation

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187
Q

where is vitamin A stored?

A

Ito cells of liver
and space of Diese

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188
Q

what vitamin do the words ‘rhapsodic’, ‘carotenoids’, ‘retinol’ refer to?

A

A

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189
Q

how is vitamin A absorbed?

A

as a lipid

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190
Q

function of vitamin A
presentation of vitamin A deficiency

A

vision
night blindness

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191
Q

source of vitamin A

A

carrots

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192
Q

what vitamin is ‘calciferol’?

A

D

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193
Q

what vitamin is required to absorb calcium and phosphate?

A

D

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194
Q

source of vitamin D

A

UV B

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195
Q

where is vitamin D stored?

A

liver

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196
Q

presentation of vitamin D deficiency

A

rickets
osteomalacia

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197
Q

source of vitamin E

A

nuts and seeds

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198
Q

where is vitamin E stored?

A

liver

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199
Q

function of vitamin E

A

antioxidant

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200
Q

function of vitamin K

A

activates clotting factors 10, 9, 7, 2 (remember - 1972)

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201
Q

source of vitamin K

A

synthesised by plants and present in food

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202
Q

presentation of a vitamin K deficiency

A

bleeding disorders

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203
Q

action of warfarin

A

inhibits vitamin K

204
Q

presentation of a lack of vitamin B12

A

pernicious anamia

205
Q

function of vitamin B12

A

cell metabolism
energy

206
Q

which vitamins does the liver store?

A

ADEK and B12
fat soluble vitamins and B12

207
Q

how is vitamin B12 absorbed?

A

in stomach, binds to R protein transcolbamin-1 which prevents it becoming cleaved
cleaved at duodenum and binds to intrinsic factor
absorbed in ileum as B12-IF complex

208
Q

source of vitamin B12

A

poultry and eggs

209
Q

source of vitamin C

A

fresh fruit and vegetables

210
Q

presentation of vitamin C deficiency

A

scurvy

211
Q

function of vitamin C

A

immune system, iron absorption, antioxidant

212
Q

where is iron stored? and how?

A

liver as ferritin

213
Q

how is iron absorbed into the blood

A

transferrin

214
Q

storage form of iron

A

ferritin

215
Q

where is copper stored?

A

liver

216
Q

name two minerals stored by the liver

A

copper and iron

217
Q

source sof calcium

A

dairy

218
Q

functions of calcium

A

muscle contraction and synaptic transmission

219
Q

source of iodine

A

seafood

220
Q

function of iodine

A

key component of thyroid hormone

221
Q

malnutrition

A

malabsorption of vitamins and minerals

222
Q

what is coeliac disease?

A

gluten intolerance
decrease surface area of intestinal brush border
damaged brush border

223
Q

equation for BMI

A

weight/ height2

224
Q

units of BMI

A

kg/m2

225
Q

units of BMR

A

kcal of energy expended /hr/m2

226
Q

blood supply of the foregut

A

coeliac trunk

227
Q

dorsal mesentery of the foregut

A

greater omentum
does not seem intuitive because dorsal means on top of

228
Q

ventral mesentery of the foregut

A

lesser omentum
does not seem intuitive because ventral means below

229
Q

sympathetic innervation of the stomach

A

greater splanchnic nerve
T5-T9

230
Q

where does the foregut extend to?

A

mouth to major duodenal papilla

231
Q

blood supply of the midgut

A

SMA

232
Q

sympathetic innervation of the midgut

A

T10 and 11
lesser splanchnic nerve

233
Q

where does the midgut extend to?

A

major duodenal papilla to proximal 2/3 transverse colon

234
Q

blood supply of the hindgut

A

IMA

235
Q

sympathetic innervation of the hindgut?

A

T12, least splanchnic nerve

236
Q

where does the hindgut extend to?

A

distal third of transverse colon to rectum

237
Q

compare intraperitoneal, primary retroperitoneal and secondary retroperitoneal

A

viscera with mesentery - intraperitoneal
viscera without mesentery - primary retroperitoneal
viscera that had a mesentery but now does not - secondary retroperitoneal

238
Q

which layers of the embryo are present in the GI tract?

A

endoderm - epithelial linings; mucosa
mesoderm - muscle and connective tissue

239
Q

how and when is the primitive gut tube formed during embryogenesis?

A

4th week
trilaminar disc folds medially and horizontally
endoderm fuses to form primitive gut tube

240
Q

how and when does the mouth form during embryogenesis?

A

end of 4th week
oropharyngeal membrane of primitive gut tube ruptures to form the mouth

241
Q

how and when do the anus and urogenital openings form during embryogenesis?

A

7th week
cloacal membrane at the caudal end of the primitive gut tube ruptures

242
Q

midgut tube development

A

elongation, herniation, rotation, retraction, fixation

243
Q

embryological development of the stomach

A

4th week - fusiform dilation
7th week - 90 degree clockwise longitudinal rotation, creates lesser sac
8th week - ventrodorsal rotation

244
Q

where do the pharyngeal arches run between?

A

oropharyngeal membrane to respiratory diverticulum

245
Q

when do the pharyngeal arches develop?

A

4th/ 5th week

246
Q

how many pharyngeal arches are there? which one regresses?

A

5: 1,2,3,4,6
5th regresses

247
Q

how are pharyngeal arches formed?

A

derived from connective mesenchymal tissue (mesodermal) invaded by cranial neural crest cells

248
Q

what does each pharyngeal arch contain?

A

its own blood and nerve supply

249
Q

which cranial nerve is contained in the first pharyngeal arch?

A

CN V3 (mandibular branch of the trigeminal)

250
Q

which muscles are associated with the first pharyngeal arch?

A

mastication, tensor tympani, diagastric, mylohyoid

251
Q

which bones are associated with the first pharyngeal arch?

A

maxilla, mandible, incus, malleus

252
Q

which nerve is associated with the second pharyngeal arch?

A

CN VII
facial

253
Q

which muscles are associated with the second pharyngeal arch?

A

facial expresson, stapedius, stylohyoid

254
Q

which bones are associated with the second pharyngeal arch?

A

stapes, styloid, lesser horn of hyoid cartilage

255
Q

which cranial nerve is associated with the third pharyngeal arch?

A

CN IX
glossopharyngeal

256
Q

which muscles are associated with the third pharyngeal arch?

A

pharyngeal stylopharyngeus

257
Q

which bones are associated with the third pharyngeal arch?

A

body and greater horn of hyoid cartilage

258
Q

which nerve is associated with the 4th pharyngeal arch?

A

superior laryngeal branch of CN X
vagus

259
Q

which muscle is associated with the 4th pharyngeal arch?

A

cricothyroid

260
Q

which bones are associated with 4th pharyngeal arch?

A

thyroid and epiglottic cartilages

261
Q

which nerve is associated with the 6th pharyngeal arch?

A

recurrent laryngeal branch of CN X
vagus

262
Q

which muscles are associated with the 6th pharyngeal arch?

A

all internal larynx muscles except cricothyroid

263
Q

which bones are associated with the 6th pharyngeal arch?

A

cricoid, arytenoid, cuneiform, corniculate cartilages

264
Q

functions of the stomach

A

secrete proteases
secrete intrinsic factor
kill microbes
store and mix food

265
Q

how much gastric acid is secreted a day?

A

2L

266
Q

why is gastric acid secretion energy dependent

A

it takes place against a concentration gradient

267
Q

which nerve regulates gastric acid secretion

A

vagus

268
Q

what does ACh release trigger?

A

release of gastrin and histamine

269
Q

action of gastrin and histamine

A

increased gastric acid production

270
Q

what acts directly but also mediates the effect of gastrin and ACh?

A

histamine

271
Q

what happens when there is a low luminal pH?

A

inhibits gastrin secretion
indirectly inhibits histamine release via gastrin
stimulates somatostatin release
parietal cell activity is inhibited

272
Q

what are enterogastrones, and give examples

A

released from duodenal mucosa
secretin and cholecystokinin

273
Q

which pump regulates gastric acid production?

A

H+/ K+ ATPase
proton pump

274
Q

which substances control control gastric acid production?

A

ACh
gastrin
histamine
somatostatin
secretin
CCK

275
Q

causes of pepetic ulcers

A

NSAIDs
H Pylori
Chemical irritants
- alcohol, bile salts
gastrinoma

276
Q

defences against ulcers

A

alkaline mucus
tight junctions between epithelial cells
replacement of damaged cells
negative feedback loops to prevent overproduction of acid

277
Q

how do bile salts cause peptic ulcers?

A

regurgitated bile strips away mucus layer

278
Q

what is an inactive form of an enzyme?

A

zymogen

279
Q

how is pepsin irreversibly inactivated?

A

in small intestine by bicarbonate

280
Q

is the stomach needed for digestion

A

no

281
Q

volume of empty stomach

A

50mL

282
Q

volume of full stomach

A

1.5L

283
Q

what is receptive relaxation?

A

smooth muscle in body and fundus relax
parasympathetic
vagus

284
Q

which substances mediate receptive reelaxation?

A

nitric oxide and serotonin

285
Q

where do peristaltic waves begin?

A

body

286
Q

which cells determine the frequency of peristaltic waves, and where are they located?

A

pacemaker cells in muscular propria

287
Q

frequency of peristaltic waves

A

3 per minute

288
Q

what increases the strength of peristaltic contractions?

A

gastrin
gastric distension

289
Q

what decreases the strength of peristaltic contractions?

A

duodenal distension
duodenal osmolarity
duodenal luminal pH
sympathetic nervous system action
parasympathetic nervous system action

290
Q

is the capacity of the stomach or duodenam greater?

A

stomach

291
Q

what is gastroparesis?

A

delayed gastric emptying

292
Q

are gastric motility and emptying regulated by the same fsctors that regulate HCL production?

A

pretty much

293
Q

what pH is saliva? what is the range

A

7.2
6.2 to 7.4

294
Q

saliva flow rate

A

0.3-0.7ml/ minute

295
Q

content of serous secretions

A

alpha amylase for starch digestion

296
Q

content of mucus secretions

A

mucins for lubrication of mucosal surfaces

297
Q

are the parotid, submandibular and sublingual glands serous, mucus or mixed?

A

parotid - serous
the other two are mixed

298
Q

factors affecting composition and amount of saliva

A

gender
diet
type and size of gland

299
Q

how does saliva contrribute to oral health?

A

lubrication
mechanical cleaning
buffering salts - neutralises acid
remineralisation - calcium and phosphate
proteins for defensive and digestive function

300
Q

oral defences

A

mucosa
palantine tonsils
salivary glands

301
Q

which salivary glands are continuous

A

submandibular, sublingual and minor glands

302
Q

which salivary gland must be stimulated?

A

parotid

303
Q

which epithelial tissues form the salivary glands?

A

acinar cells around ducts
have channels and transporters in the apical and basolateral membranes to enable transport of fluid and electrolytes

304
Q

how are interlobular ducts divided?

A

intercalated and striated
intercalated
- cuboidal cells
striated
- basal membrane highly folded into microvilli for hydrogencarbonate active transport against concentration gradient
- microvilli filled with mitochondria
- major site of reabsorbtion of NaCl

305
Q

function of acinar ducts

A

modify electrolyte composition
ducts secrete K+ and HCO3- and reabsorb Na+ and Cl-

306
Q

which muscle separates the lobes of thee submandibular?

A

mylohyoid

307
Q

what is glucose converted to in erythrocytes?

A

pyruvate or lactate

308
Q

what is the only metabolic process RBC use to gain energy and why?

A

glycolysis
anaerobic

309
Q

how do triglycerides enter lymphatics?

A

combine with triglycerides to form chylomicrons

310
Q

fed state

A

fuels are oxidised to energy
any excess is stored
triglycerides in adipose tissue
glycogen in liver and muscle

311
Q

what is gluconeogenesis?

A

forming new glucose from amino acids, lactate and glycerol

312
Q

how are fats used for energy?

A

lipolysis
broken down into glycerol and fatty acids

313
Q

how are the products of fat breakdown used for energy?

A

glycerol converted to glucose
fatty acids converted to ketones

314
Q

which hormones regulates fuel metabolism?

A

growth hormone somatostatin
thyroxine
adrenaline
noradrenaline
cortisol
insulin
glucagon

315
Q

is insulin anabolic or catabolic?

A

anabolic

316
Q

is glucagon anabolic or catabolic?

A

catabolic

317
Q

what processes does insulin stimulate?

A

glycogen storage, fat storage, protein synthesis

318
Q

which processes does glucagon stimulate?

A

glycogenolysis
gluconeogenesis
ketogenesis

319
Q

effects of cortisol on fuel metabolism

A

lipolysis
protein breakdown
gluconeogenesis
glycogen storage

320
Q

what is cortisol and where is it released from?

A

stress hormone
adrenal glands

321
Q

effect of thyroxine on fuel metabolism

A

glycolysis
cholesterol synthesis
glucose uptake
protein synthesis
sensitises tissues to adrenaline

322
Q

is thyroxine anabolic or catabolic?

A

normally anabolic but catabolic at high concentrations

323
Q

effect of growth hormone on fuel metabolism

A

gluconeogenesis
glycogen synthesis
protein synthesis
lipolysis
decreased glucose use

324
Q

which hormone increases appetite?

A

ghrelin

325
Q

which hormone decreases appetite?

A

leptin

326
Q

is leptin high or low with obesity?

A

high
leptin resistance

327
Q

which is the only anabolic hormone?

A

insulin

328
Q

what do the taste buds detect?

A

sweet, sour, salty, bitter, umami

329
Q

why is saliva hypotonic?

A

duct epithelium does not allow any water movement

330
Q

what keeps saliva alkaline?

A

bicarbonate buffering system

331
Q

what does sympathetic stimulation of salivary glands produce?

A

secretion of protein and glycoprotein

332
Q

innervation of the sublingual and submandibular glands

A

facial

333
Q

innervation of the parotid

A

CN V3

334
Q

are the minor glands continuous?

A

yes

335
Q

lipid microvesicles in saliva

A

exosomes

336
Q

boundaries of parotid gland

A

zygomatic arch
sternocleidomastioid
ramus of mandible

337
Q

muscles layers in the stomach, in to out

A

oblique, circular, longitudinal

338
Q

which substances stimulate gastric acid secretion?

A

gastrin
histamine

339
Q

which substance inhibits gastric acid production

A

somatostatin

340
Q

where in the stomach is intrinsic factor produced?

A

fundus
basically everything is produced in the fundus
the les and cardia and antrum and pylorus only produce bicarbonate and mucus

341
Q

stomach epithelium structure and function

A

invaginates into the mucosa to form tubular glands
upper portion secretes mucus HCL and pepsinogen
lower portion secretes endocrine molecules

342
Q

which cells are interspersed inthe stomach epithelium?

A

APUD cells

343
Q

produce mucus?

A

mucous neck cells

344
Q

causes of gastroparesis

A

idiopathic
abdominal surgery
MS
females

345
Q

mptoms of gastroparesis

A

nausea
GORD
abdominal pain

346
Q

what is the enterogastric reflex?

A

a nervous reflex whereby stretching of the wall of the duodenum results in inhibition of gastric motility and reduced rate of emptying of the stomach

347
Q

how to reduce stomach acid pharmacologically

A

proton pump inhibitors
H2 receptor agonists

348
Q

where is cholecystokinin released from?

A

I cells in duodenum, jejunum and less so from ileum

349
Q

function of choleocystokinin

A

stimulates release of pancreatic enzymes
increases bicarbonate secretion
liver and gallbladder - sphincter of oddi relaxation
- gallbladder contration

350
Q

endocrine functions of the pancreas

A

insulin and glucagon

351
Q

exocrine functions of the pancreas

A

bicarbonate secretion
enzyme secretion

352
Q

what do beta cells of the pancreas secrete?

A

insulin

353
Q

hat do alpha cells of the pancreas secrete?

A

glucagon

354
Q

which pancreatic cells are endocrine?

A

islet cells

355
Q

which pancreatic cells are exocrine?

A

acini cells

356
Q

function of centrocinar cells

A

produce bicarbonate

357
Q

function of pancreatic duct cells

A

exchange of bicarbonate and chloride

358
Q

what activates trypsinogen and chymotrypsinogen?

A

enterokinase

359
Q

what activates trypsinogen to trypsin?

A

trypsin (positive feedback) and enterokinase

360
Q

how are proteases released?

A

zymogens

361
Q

where is enterokinase present?

A

small intestine wall

362
Q

amylase function

A

hydrolyses starch to maltose and dextrin

363
Q

name other pancreatic enzymes

A

gelatinise, elastase, ribonuclease, deoxyribonuclease

364
Q

primary secretion from pancreas

A

NaHCO3

365
Q

secondary secretion from pancreas

A

bicarbonate exchanged for chloride

366
Q

what happens to the pancreatic fluid composition as flow rate increases?

A

richer in bicarbonate and lower in chloride
because the faster it flows, less exchange takes place

367
Q

function of acinar cells

A

secrete enzyme

368
Q

which comes first, intercalated or interlobular duct?

A

intercalated

369
Q

how much bicarbonate secreted per day

A

1L

370
Q

function of bicarbonate secretions

A

neutralises stomach acid and protects duodenal mucosa
buffers duodenal contents
optimises pH for enzyme digestion

371
Q

which ions are predominantly in resting flow bicarbonate secretions?

A

Na+ and Cl-

372
Q

which ions are predominantly in high flow bicarbonate secretions?

A

Na+ and bicarbonate

373
Q

what stimulates bicarbonate secretion from pancreas?

A

secretin and CCK

374
Q

what stimulates the reelease of ezymes from the pancreas?

A

CCK
ACh

375
Q

what stimulates CCK release?

A

HCl
proteins and fats in duodenum

376
Q

action of choleocystokinin

A

pancreatic enzyme and bicarbonate secretion
gallbladder contraction
inhibition of gastric acid secretion
delayys gastric emptying

377
Q

what stimulates secretin?

A

low duodenal pH

378
Q

where is secretin releaseed from?

A

upper small intestine

379
Q

action of secretin

A

bicarbonate secretion from pancreas

380
Q

what stimulates gastrin?

A

gastric distension and irritation

381
Q

where is gastrin produced?

A

G cells of stomach

382
Q

action of gastrrin

A

HCl secretion
enzyme release from acinar cells

383
Q

how much peptide does an adult need a day?

A

40-50g

384
Q

how many amino acids are used by the body?

A

20

385
Q

how many essential amino acids

A

8

386
Q

what is an essential amino acid?

A

cannot be manufactured in the body

387
Q

which form of amino acid does the body use?

A

L

388
Q

what is a zwitterion?

A

contains positive and negative groups on the same molecule

389
Q

ncentration of stomach acid

A

[H+] is greater than 150mM

390
Q

how much stomach acid is produced a day?

A

2L

391
Q

function of stomach acid

A

activate pepsinogen to pepsin

392
Q

stomach acid production energy dependent?

A

yes

393
Q

what stimulates gastrin?

A

amino acids/ peptides in stomach lumen
distension of stomach
activation of enteric nervous system
vagus nerve - cephalic reflex

394
Q

what inhibits gastrin?

A

decreased pH

395
Q

what breaks down peptides to amino acids?

A

peptidases from duodenum

396
Q

what breaks down proteins to peptides?

A

pepsin

397
Q

does pepsin break down proteins to amino acids?

A

no
to peptides

398
Q

what percentage of protein digestion is in the stomach by pepsin?

A

20

399
Q

types of peptidases in the duodenum

A

endopeptidases
exopeptidases

400
Q

action of endopeptidases

A

split polypeptide internal bonds

401
Q

name endopeptidases

A

trypsin, chymotrypsin, elastase

402
Q

function of exopeptidases

A

cleave amino acids off ends of polypeptides

403
Q

name exopeptidases

A

carboxyl dipeptidases, amino peptidases

404
Q

can peptides be proken down in cells? how

A

intracellular peptidases
yes

405
Q

where can peptides be digested?

A

intestinal lumen
brush border
intracellularly

406
Q

which enzyme activates other peptidases?

A

trypsin

407
Q

precursors for:
- colipase
- elastase
- carboxypeptidase A
- chymotrypsin
- trypsin

A

procolipase
proelastase
procarboxypeptidases
chymotrypsinogen
trypsinogen

408
Q

how are amino acids absorbed?

A

facilitated diffusion and cotransport
sodium potassium ATPase creates a Na gradient
amino acids are absorbed alongside Na+
peptides can be cotransported with H+

409
Q

which version of sugars can be used?

A

D isomer

410
Q

which is more branched, starch or glycogen?

A

glycogen

411
Q

which bonds does cellulose contain?

A

1-4 beta glycosidic

412
Q

which bonds do glycogen and starch have?

A

alpha 1-4 glycosidic and branching by alpha 1-6 glycosidic

413
Q

in lactose, do OH groups lie above or below the plane of the molecule?

A

above

414
Q

what are the constituents of sucrose

A

glucose and fructose

415
Q

constituents of lactose

A

glucose and galactose

416
Q

constituents of maltose

A

2 glucose

417
Q

carbohydrate digestion

A

starch degraded by ptyalin (alpha amylase in saliva)
small amount of digestion in the mouth
polysaccharides browken down into di and trisaccharides
further digestion by oligosaccharidases and disaccharidases

418
Q

does amylase produce monosaccharides?

A

no
oligosaccharides/ disaccharides only

419
Q

what are oligosaccharides?

A

several sugar molecules

420
Q

where is most starch digested?

A

small intestine especially duodenum

421
Q

what does alpha amylase break down?

A

alpha 1-4 linkages, not any others like alpha 1-6

422
Q

where are disaccharidases located?

A

intestinal brush border

423
Q

where are monosaccharides absorbed?

A

brush border membrane

424
Q

how are glucose and galactose absorbed?

A

active transport
Na+ dependent secondary secondary active transport process
low Na conc created intracellularly
monosaccharides cotransported with Na via a sodium glucose linked transported

425
Q

how is fructose absorbed?

A

facilitated diffusion
GLUT

426
Q

how are monosaccharides transported basolaterally from brush border?

A

facilitated diffusion using GLUT

427
Q

where does glucose travel from the capillaries in the brush border?

A

hepatic portal vein

428
Q

which organs store glucose as glycogen

A

skeletal muscle and liver

429
Q

what can glucose be converted into?

A

glycogen, fatty acids, alpha-glycerol phosphate

430
Q

which product of glycolysis is required for creation of alpha glycerol phosphate?

A

dihydroxyacetone phosphate

431
Q

how is fat made frrom glucose in the liver stored?

A

with proteins as lipoproteins

432
Q

how does fat made in the liver reach adipose tissue?

A

fatty acids from glucose are used to synthesise triglycerides
lipoproteins secreted by hepatocytes into the blood as VLDLs
lipoprotein lipase is present on blood facing surface of capillary endothelial cells, especially in adipose tissue
lipoprotein lipase hydrolyses triglycerides to monoglycerides and fatty acids
free fatty acids diffuse into adipocytes and combine with alpha glycerol phosphate to form triglycerides

433
Q

what are VLDLs?

A

very low density lipoproteins
contain more fat than protein, hence low density as fat is lighter

434
Q

daily fat intake

A

70-100g

435
Q

forms of fat

A

triglycerides, phospholipids, cholesterol

436
Q

name some fatty acids

A

palmitic acid, stearic acid, oleic acid

437
Q

where are proteins digested?

A

mouth, stomach, small intestine

438
Q

where are fats digested?

A

mouth, stomach and small intestine

439
Q

where are fats predominantly digested/

A

small intestine

440
Q

types of lipase

A

lingual, gastric and pancreatic

441
Q

what forms fat droplets?

A

bile salts - amphipathic

442
Q

what are bile salts synthesised from?

A

cholesterol

443
Q

action of colipase

A

cofactor for pancreatic lipase

444
Q

what do fats become once emulsified?

A

miscelles

445
Q

what is contained inside miscelles?

A

bile salts, fat soluble vitamins, cholesterol, fatty acids, monoglycerides and phospholipids

446
Q

where is bile reabsorbed?

A

ileum

447
Q

how much bile is excreted?

A

3%

448
Q

fate of reabsorbed bile

A

travels in blood to liver

449
Q

how many times a day is bile recycled?

A

8

450
Q

fat absorbtion and processing

A

bile salts from liver coat fat droplets
pancreatic lipase and colipase break down fats into monoglycerides and fatty acids stored in micelles
monoglycerides and fatty acids move out of micelles and enter cells by diffusion
chylomicrons are formed as the absorbed fats combine with cholesterol and proteins in the intestinal cell
chylomicrons are removed by the lymphatic system

451
Q

how are fats formed?

A

alpha glycerol and fatty acids

452
Q

systemic handling of fats after absortion

A

chylomicrons enter lacteals and into the lymphatic system
lymph enters systemic veins
lipoprotein lipase releases fatty acids into circulation
fatty acids diffuse into adipocytes to combine with alpha glycerol phosphate

453
Q

where is most water reabsorbed?

A

small intestine

454
Q

sodium absorbtion

A

Na/ K ATP ase pumps sodium out of cell to create a low intracellular concentration of Na+
glucose sodium transporter uptakes from luminal side
1 glucose to 2 Na+
glucose moved out via GLUT2

455
Q

how does luminal glucose enter the epithelial cell?

A

Na+/ glucose symport protein on the apical membrane

456
Q

how does enterocyte sodium enter the blood?

A

sodium potassium pump

457
Q

sodium secretion

A

Na/ K ATPase creates low intracellular concentration of Na+

458
Q

how does intestinal sodium enter the enterocytes?

A

Na+/ glucose symport protein

459
Q

how does enterocyte glucose enter the blood?

A

GLUT 2

460
Q

how is energy for movement supplied?

A

sodium and proton gradients

461
Q

movement of substances in between cells

A

paracellular pathway

462
Q

factors increasing intestinal absorption

A

number and structure of enterocytes
blood and lymph flow
nutrient intake
GI motility

463
Q

factors increasing intestinal secretion?

A

irritants
bile
bacterial toxins
neural and hormonal inputs to secretion and GI motility

464
Q

where can we find gluten?

A

wheat, rye, barrley

465
Q

which aspect of the intestines is damaged with coeliac disease?

A

villi

466
Q

effect of cholera on small intestine

A

toxin binds to interstitial cells
stimulates adenylate cyclase to produce more cAMP and increase expression of Cl- channels
dramatic efflux of ions and water
water diarrhoea

467
Q

what order are fats, carbohydrates and proteins used?

A

carrbohydrates first, proteins last

468
Q

how long do glycogen stores last?

A

12 hours

469
Q

how long do lipid stores last?

A

3 months

470
Q

which sources does brain use for energy?

A

glucose and ketone bodies

471
Q

can the liver use ketones for energy?

A

no

472
Q

energy in

A

food and drink

473
Q

energy out

A

BMR
diet induced thermogenesis (DIT)
activity

474
Q

when is weight stable?

A

energy in = enegy out

475
Q

what BMI is obese?

A

over 30 kg/m2

476
Q

what BMI is overweight?

A

25-30 kg/m2

477
Q

normal BMI range

A

18.5-25 kg/m2

478
Q

what BMI is underweight?

A

less than 18.5 kg/m2

479
Q

what is BMR?

A

basal metabolic rate
energy required to keep the body alive

480
Q

how is BMR measured?

A

oxygen consumption whilst awake, restful and fasted for 12 hours

481
Q

effect of glucose on VLDL levels

A

increases

482
Q

fate of glucose in erythrocytes

A

converted to pyruvate
pyruvate diffuses out of cell or converted to lactate
lactate released from cell

483
Q

types of lipoproteins

A

LDL - low density lipoproteins
HDL - high density lipoproteins
VLDL - very low density lipoproteins

483
Q

what processes does insulin stimulate?

A

glycogen storage, fat storage, protein synthesis

484
Q

what processes does cortisol stimulate?

A

lipolysis, protein brreakdown, gluconeogenesis, glycogen storage

485
Q

actions of adrenalise/ noradrenaline

A

glycogenolysis, gluconeogenesis, lipolysis

486
Q

actions of thyroxine

A

glycolysis, cholesterol synthesis, glucose uptake, protein synthesis, sensitises tissues to adrenaline

487
Q

which hormone controls metabolism?

A

thyroxine

488
Q

where is growth hormone produced?

A

pituitary

489
Q

actions of growth hormone

A

gluconeogenesis, glycogen synthesis, lipolysis, protein synthesis, decreased glucose use

490
Q

where is leptin released from?

A

adipocytes

491
Q

where is ghrelin released?

A

stomach

492
Q

what do leptin and ghrelin act on?

A

CNS

493
Q

what breaks down glycogen?

A

glucagon

494
Q

what substances are used for gluconeogenesis?

A

amino acids, lactate, glycerol

495
Q

where does gluconeogenesis occur?

A

liver

496
Q

how are the components of lipids used for energy?

A

glycerol transported to liver for gluconeogenesis
fatty acids produce ketones in the liver

497
Q

is the circular or longitudinal layer of muscle inner?

A

circular

498
Q

is the internal sphincter voluntary?

A

no
external is though

499
Q

physiology of defecation

A

basal
pre expulsive
expulsive
termination

500
Q

basal phase of defecation

A

segmental contractions of colon - mixing
rectum - motor complexes
tonic contraction of anal sphincter
puborectalis contracted - anorectal angle

501
Q

pre-expulsive phase

A

colon - high amplitude propagating contractions
mass movement of stool 8 times a day
gastro-colic reflex
rectum fills causing distension
rectal compliance - adaptive relaxation
EAS maintains contraction
reflex relaxation of IAS for stool sampling
puborectalis contracted

502
Q

expulsive phase

A

rectum contracts
3 muscles relax
valsalva manouvre aids emptying

503
Q

termination phase

A

traction loss causes sudden contraction of EAS
valsalva ceases

504
Q

function of pudendal nerve

A

motor control of external anal sphincter

Phase 1 flashcards (27 decks)

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