GI/LIVER Flashcards
1
Q
what are the three phases of swallowing?
A
oral
pharyngeal
oesophageal
2
Q
of the phases of swallowing which are voluntary?
A
the oral phase is voluntary
3
Q
of the phases of swallowing, which are involuntary?
A
the pharyngeal and oesophageal phases are involuntary
4
Q
what can the oral phase of swallowing be broken down into?
A
the preparatory phase and the transfer phase
5
Q
what happens during the preparatory phase of swallowing?
A
food mixes with saliva and a bolus is formed
during this stage, chewing, mastication and sucking all occur
6
Q
what happens during the transfer phase of swallowing?
A
- the tip and sides of the tongue contract against the hard palate and the bolus passes into the oropharynx
- the soft palate lifts up to close off the nasopharynx
- the posterior pharyngeal wall begins contracting downwards and the soft palate also moves down
- the tongue contracts to close off the oral cavity and so the bolus is propelled into the oropharynx
7
Q
what happens during the pharyngeal phase of swallowing?
A
- the tongue seals off the oropharynx and the airway is sealed off
- the vocal cords and arytenoids close off the larynx and the epiglottis swings down to prevent aspiration
- the larynx moves up and out
- the pharynx widens and shortens
- the upper oesophageal sphincter elevates
- food is propelled into the oesophagus and pharyngeal peristalsis occurs
8
Q
what happens during the oesophageal phase of swallowing?
A
- oesophagus and lower oesophagus relax
- the bolus enters the oesophagus
- part of the bolus may enter the stomach - this is aided by gravity
- the residual bolus is then cleaved by peristaltic wave into the stomach
- a solid bolus generally requires contraction, rather than gravity alone
9
Q
how long does it take for food to travel through the pharynx after chewing?
A
roughly 1 second
10
Q
how long does it take for food to travel through the oesophagus?
A
roughly 5 seconds
11
Q
what are mucous cells, what do they secrete and what is the function of their secretion?
A
mucous cells are gastric cells found in the cardia and pylorus of the stomach. they secrete mucin which helps lubricate and protect the mucosa
12
Q
what are parietal cells, what do they secrete and what is the function of their secretion?
A
parietal cells are gastric cells found in the fundus and body of the stomach. they secrete:
- HCl which aids digestion, cleaves pepsinogen into pepsin and kills pathogens
- intrinsic factor which aids absorption of B12 at the terminal ileum
13
Q
what are chief cells, what do they secrete and what is the function of their secretion?
A
chief cells are gastric cells found in the fundus and body of the stomach. they secrete the zymogen pepsinogen
pepsinogen is then cleaved into pepsin
14
Q
what are ECL cells, what do they secrete and what is the function of their secretion?
A
ECL cells are gastric cells located in the gastric pits. they secrete histamine which stimulates the secretion of HCl
15
Q
what are G cells, what do they secrete and what is the function of their secretion?
A
G cells are gastric cells and are most commonly found in the pyloric antrum. they secrete gastrin which stimulates the secretion of HCl and histamine
16
Q
what are D cells, what do they secrete and what is the function of their secretion?
A
D cells are gastric cells found commonly throughout the GI tract. they secrete somatostatin which inhibits HCl secretion
17
Q
how is pepsin produced?
A
pepsin comes from the zymogen pepsinogen which is secreted by chief cells
pepsinogen is converted to pepsin by HCl
this conversion is most efficient at a pH of less than 2
18
Q
what are some of the protective mechanisms of the mucosa?
A
- alkaline mucous (on luminal surface)
- tight junctions between epithelial cells
- rapid cell replacement of damaged cells by stem cells in the base of gastric pits
- feedback loops which regulate the secretion of HCl
19
Q
what are the consequences of insufficient protective mechanisms of the mucosa?
A
the formation of peptic ulcers
20
Q
what causes peptic ulcers?
A
H. pylori
NSAIDs
chemical irritants
gastrinoma’s
21
Q
what are the three phases of gastric acid secretion?
A
- cephalic phase
- gastric phase
- intestinal phase
22
Q
what happens during the cephalic phase of gastric acid secretion?
A
- the cephalic phase of gastric acid secretion occurs in response to stimuli (e.g tase, smell, sight of food). this is a reflex mediated by the vagus nerve
- gastric juice is secreted in response to vagal stimulation and can occur either directly (via electrical impulses) or indirectly (via stimuli received through the senses)
23
Q
what happens during the gastric phase of gastric acid secretion?
A
- the gastric phase of gastric acid secretion is mediated by the vagus nerve and the release of gastrin
- gastrin stimulates the release of HCl and histamine
- the acidity of the stomach is buffered to remain at a pH of 3 for roughly 90 minutes
- HCl continues to be secreted in response to distension and the presence of amino acids digested due to proteases
24
Q
what happens during the intestinal phase of gastric acid secretion?
A
NOTE: this is complex!
- amino acids and small peptides that promote gastric acid secretion are infused into circulation
- meanwhile, chyme inhibits acid secretion
- gastrin secretion is inhibited when pH is below 2.5
- hormones that are released due to digestion (i.e glucagon, secretin) suppress HCl secretion
essentially the intestinal phase is the phase in which gastric acid secretion stops
25
what is the volume of the stomach when empty?
roughly 50ml
26
what is the maximum volume of the stomach?
1500ml
27
how does the stomach increase in volume?
the muscles in the body and fundus of the stomach relax
| this is mediated by acetylcholine (parasympathetic innervation from vagus nerve) and nitric oxide + serotonin (enteric)
28
when does peristalsis occur?
in response to the presence of food in the stomach
29
what happens during peristalsis?
1. a ripple movement begins in the body of the stomach
2. a more powerful wave occurs at/in the antrum
3. the pyloric sphincter closes which means that little chyme can enter the duodenum
4. the antral contents are forced back into the body and mixing occurs
30
what mediates peristalsis?
the interstitial cells fo Cajal
| these determine the frequency of peristaltic contractions
31
how many peristaltic contractions happen per minute
3
32
what can increase the strength of peristaltic contractions?
- gastrin
| - distension of the stomach
33
what can decrease the strength of peristaltic contractions?
- duodenal distension
- increase in duodenal fat/osmolarity
- decrease in duodenal pH
- increased sympathetic stimulation
- decreased parasympathetic stimulation
34
what is BMI?
weight/height^2
| kg/m^2
35
what is an underweight BMI?
below 18.5
36
what's a healthy weight range BMI?
between 18.5 and 24.9
37
what's an overweight range BMI?
between 25 and 29.9
38
what's an obese range BMI?
between 30 and 39.9
39
define BMR?
the basal metabolic rate is the amount of energy needed to stay alive at rest
it is approximately 24 kcal/kg/day
40
what increases BMR?
- being overweight
- being male
- being pregnant
- caffeine
- hyperthyroidism
- exercise
- low temperatures
41
what decreases BMR?
- increase in age
- being female
- being underweight
- malnutrition/starvation
- hypothyroidism
42
what vitamins are fat soluble?
A, D, E, K
43
where and how are fat soluble vitamins absorbed?
they are absorbed along with fat, in micelles in the ileum
44
what are the water soluble vitamins?
B, C
45
where are water soluble vitamins absorbed?
in the jejunum
46
where is B12 absorbed?
in the terminal ileum, attached to intrinsic factor
47
what is the function of vitamin A?
cellular growth and differentiation, vision, lymphocyte production, skin and mucous membranes
48
what are some sources of vitamin A?
liver, dairy, fruit&veg. oily fish, margaine
49
what can a vitamin A deficiency cause?
night blindness, growth retardation, increased susceptibility to infection, impaired: hearing, taste + smell
50
what is the function of vitamin B12?
erythrocyte formation, DNA synthesis, brain development
51
what are some sources of vitamin B12?
meat, fish, eggs, milk
52
what can a vitamin B12 deficinecy cause?
pernicious anaemia (fatigue, shortness of breath, tingling)
53
what is the function of vitamin C?
collagen synthesis, antioxidant, absorption of non-haem iron
54
what are some sources of vitamin C?
citrus fruit, green veg, potatoes
55
what can a vitamin C deficiency cause?
scurvy, bleeding gums
56
what is the function of vitamin D?
calcium absorption in the gut and its reabsorption in the kidneys
57
what are some sources of vitaminD?
```
D3 = plants, mushrooms, UV light
D2 = fish oils, egg yolks
```
58
what can a vitamin D deficiency cause?
frequent bone fractures, muscle weakness, bone pain
59
what is the function of vitamin E?
antioxidant, protects cell walls
60
what are some sources of vitamin E?
nuts, seeds, vegetable oils
61
what can a vitamin E deficiency cause?
muscle weakness, degeneration of retina
62
what is the function of vitamin K?
the formation of clotting factors: 2, 7, 9, and 10 in the liver
63
what are some sources of vitamin K?
leafy green veg, beef liver, chicken, soy oils
64
what can a vitamin K deficiency cause?
clotting factor deficiencies, bleeding, poor bone development
65
how is vitamin B12 absorbed?
vitamin B12 is a very large and charged vitamin that is ingested orally
it is absorbed bound to intrinsic factor because in this complex it is fat soluble
this intrinsic factor-B12 complex binds to specific sites on the epithelium of the terminal ileum.
it is here that B12 is then absorbed by endocytosis
66
what are carbohydrates?
sugars and starches found in food
67
what enzyme breaks down starch and glycogen?
salivary alpha-amylase
68
what breaks down maltose? what is it broken into?
the enzyme maltase. it breaks down into two glucose molecules
69
what breaks down sucrose
the enzyme sucrase
| it breaks down into one glucose and one fructose molecules
70
what breaks down lactose?
the enzyme lactase
| it breaks down into one glucose and one galactose molecule
71
what are the stages of carbohydrate absorption and digestion?
1. digestion begins in the mouth as saliva from serous parotid glands contains alpha amylase which begins breaking down starches
2. the vast majority of absorption/digestion occurs in the small intestine. pancreatic alpha amylase breaks polysaccharides down into disaccharides
3. enzymes on the luminal membranes of epithelial cells of the small bowel break disaccharides into monosaccharides
4. these monosaccharides can then be absorbed into the bloodstream
72
what are the stages of protein absorption?
1. stomach stage
2. small intestine stage
3, final digestion
73
what happens to proteins in the stomach ?
proteins denature in the stomach and become polypeptides
| the optimum pH for this to occur is 1.6-3.2
74
what happens to proteins in the small intestine?
polypeptides are further fragmented by pancreatic enzymes
| endopeptidases such as trypsin, chymotrypsin, elastase and carboxypeptidase are all found here
75
what happens to proteins during final digestion?
polypeptides are broken into amino acids by exopeptidases
there are:
- amino peptidases found on the luminal membrane of epithelial cells
- intracellular peptidases then break fragments into single amino acids
the single amino acids an then be absorbed into the blood stream
76
what is chyme mostly made of?
water
77
how much fluid passes through the GI tract daily?
roughly 9 litres
78
where does 80% of water absorption occur?
in the small intestine
79
what absorbs most water?
the jejunum
80
how much of total fluid is reabsorbed?
98%
81
how much fluid is lost per day in stools?
roughly 200ml
82
how is sodium absorbed?
by active transport
it is co-transported with glucose and amino acids
water then follows sodium!
83
why is sodium an important ion?
it helps maintain the fluid balance, is needed for muscle contractions and helps with nerve signalling
84
how is potassium absorbed?
by passive diffusion
85
what can cause a loos of potassium ions?
diarrhoea
86
why is potassium an important ion?
it keeps blood pressure levels stable, regulates heart contracts and helps with muscle functions
87
how is chloride absorbed?
by active transport - it is exchanged for bicarbonate
| this makes the intestinal contents more alkaline!
88
why is chloride an important ion?
it helps maintain fluid balance, helps maintain proper blood pH and is needed to make stomach acid
89
at what stage of development does the liver begin forming?
at week 3
90
what is the liver a derivative of?
the foregut
91
what do hepatocytes arise from?
the endoderm
92
at what stage does the liver start producing bile?
roughly at week 12
93
what do mesenchymal tissue and Kuppfer cells arise from?
the mesoderm
94
what important role does the liver play in the foetus?
it plays an important role in foetal haematopoiesisi
95
what is the arterial blood supply to the liver?
it comes from the hepatic artery proper and the hepatic portal vein
96
how much blood is supplied by the hepatic artery proper?
roughly 25%
97
how much blood is supplied by the hepatic portal vein?
roughly 75%
98
what is the venous drainage of the liver?
via the hepatic veins which then drain into the inferior vena cava
99
what does the hepatic artery proper carry?
oxygen rich blood
100
what does the hepatic portal vein carry?
nutrient rich blood
101
what is the functional unit of the liver and what does it contain?
the lobule is the functional unit of the liver. it is hexagonal in shape and has a central vein with the portal triad branches forming at each corned
102
what does hepatic sinusoid contain?
hepatic sinusoid is a form of fenestrated epithelium that contains oxygen rich blood from the hepatic artery proper and nutrient rich blood from the hepatic portal vein
103
what separates sinusoids from hepatocytes?
the space of Disse
104
what key substances are commonly stored in the liver?
iron - stored as ferritin
copper
glycogen
vitamins (A,D,E,K + B12)
105
how is iron transported?
in the plasma, bound to transferrin
106
how is copper transported?
in the plasma, bound to ceruloplasmin
107
what is the function of copper?
it helps to form erythrocytes and aids in iron absorption
108
what are the three types of protein produced in the liver?
plasma proteins
clotting proteins
complement proteins
109
what are some examples of plasma proteins?
- albumin
- fibrinogen
- globulin
110
what are some clotting proteins?
```
clotting factors (except 3,4+8)
- vitamin K dependent ones! (2,7,9,10)
```
111
what is albumin and what are its functions?
albumin is the most common plasma protein
it is involved in maintaining osmotic pressure
it binds to and transports large hydrophobic molecules
112
what molecules does albumin transport?
```
fatty acids
calcium
bilirubin
hormones
drugs
heavy metals
some steroid hormones
plasma tryptophan
```
113
what are xenobiotics?
foreign chemicals that are not normally found or produced in the body and cannot be used to produce energy
114
what is the aim of liver detoxification?
to transform a substance to be less toxic/more water soluble so it can be excreted
115
what is the purpose fo a phase 1 liver detoxification reaction?
to transform a substance from one type to another using oxidation/hydrolysis reactions
often enzyme cytochrome p450 used
116
what happens during phase 2 reactions of liver detoxification?
- glucorinidation (addition of glucuronic acid)
- conjugation (addition of a chemical group to a substance)
- excretion - often in bile/urine
example: lipophilic molecule becomes hydrophilic
117
what is the purpose of the glucose-alanine cycle?
to move proteins from muscle to the liver when glycogen is low
118
what can be used to measure liver health?
alanine aminotransferase (ALT)
119
what happens during the glucose alanine cycle?
- excess alanine is transferred to the liver and converted to pyruvate (by transamination)
- pyruvate can be used to produce glucose in gluconeogenesis (provides carbon)
- glucose enters the blood and is then used by muscles (glycolysis)
- this also removes excess ammonia
120
how is excess ammonia removed in glucose-alanine cycle?
- glutamate becomes ammonium by oxidative deamination
- this then dissociates to ammonia
- the ammonia is then converted to urea via the urea cycle
121
what is the function of the urea cycle?
to dispose of excess nitrogen
| - to remove excess ammonia (to make urea less toxic)
122
what does arginine + arginase form?
urea and ornithine
123
what does ornithine + ammonia + carbon dioxide form?
citrulline
124
what does citrulline + ammonia form?
arginine
125
what are the stages of the urea cycle?
arginine --> orthinine (urea made)
orthinine + CO2 + ammonia --> citrulline
citrulline + ammonia --> arginine
126
why is it important to excrete ammonia?
it is neurotoxic, it can cross the blood brain barrier and cause damage
without the urea cycle, it would require a lot of water to excrete which would lead to dehydration
127
what are micelles?
molecule produced by combination of lipids and bile salts
128
how are free triglycerides formed?
by the reaction of lipids with pancreatic lipase
129
how are lipids metabolised?
1. fatty acids and monogylcerides are emulsified by bile salts to form micelles
2. fatty acids enter the epithelial cells and link to form triglycerides
3. triglycerides combine with proteins inside the Golgi body to form chylomicrons
4. chylomicrons enter the lacteal and are transported away from the intestine
5. from lacteal they enter the blood stream
6. they are transported to the liver and are stored as very low density lipoproteins
7. VLDL are used to transport lipids from the liver to the adipose tissue
130
what are low density lipoproteins?
lipoproteins formed in plasma that enable cholesterol delivery to all cells in the body
131
what are high density lipoproteins?
lipoproteins formed in the liver that remove excess cholesterol from blood + tissues via excretion in bile
132
what are very low density lipoproteins?
lipoproteins synthesised in hepatocytes
| they deliver triglycerides from the liver to adipocytes
133
what is the purpose of fatty acid beta-oxidation?
it is the catabolism of fatty acids to produce energy
134
where does fatty acid beta-oxidation occur?
in the mitochondria of hepatocytes
135
what does the fatty acid beta-oxidation cycle lead to?
the production of CO2 and also ATP via the Krebs cycle
136
where is bile produced?
in the liver, by hepatocyes
137
what journey does bile go on to enter the duodenum?
1. bile is produced by hepatocytes in the liver
2. bile flows into the left and right hepatic ducts
3. the left and right hepatic ducts join to form the common hepatic duct
4. the common hepatic duct goes on to form the cystic duct
5. bile can now flow in/out of the gallbladder
6. the cystic duct then becomes the common bile duct
7. the common bile duct and pancreatic duct join to form the hepatopancreatic ampulla of Vater
8. bile then empties into the 2nd part of the duodenum (by the Sphincter of Oddi), at the major duodenal papilla
138
what happens in bile production?
bile is produced in the liver and is continuously secreted by hepatocytes
it is released in response to increased fatty acid concentration in the duodenum - this is mediated by CCK
139
what are the function of bile?
to emulsify fats and excrete certain drugs and toxins
140
what is bile made of?
- bile salts
- phospholipids (lecithin)
- bicarbonate
- cholesterol
- bile pigments (bilirubin)
141
what is bilirubin?
a pigment found in bile
142
what occurs during bilirubin metabolism?
1. old/damaged red blood cells are ingested by macrophages
2. the haemoglobin from these cells in broken down into haem + globin
3. the globin is used to generate new RBC's in bone marrow
4. haem breaks down into biliverdin and Fe2+ (this is catalysed by heme oxygenase)
5. biliverdin is converted to unconjugated bilirubin by biliverdin reductase
6. unconjugated bilirubin is then transported to the liver by albumin
7. unconjugated bilirubin is toxic + lipid soluble and so must be metabolised and excreted
8. glucuronidation occurs by UDPGT to produce conjugated bilirubin
9. conjugated bilirubin becomes bile which then enters the biliary system
10. bile travles to the duodenum
11. bile enters the terminal ileum and becomes urobilinogen
143
what happens to urobiliogen?
10% of it is reabsorbed and recycled to bile
| 90% is oxidised to stercobilin which is then excreted in the faeces
144
what makes urine yellow?
the presence of urobilin
145
what makes faeces brown?
the presence of stercobilin
146
what does the pancreas originate as embryologically?
2 buds:
- dorsal bud
- ventral bud
147
what does the dorsal bud of the pancreas make up?
the neck, body, tail + part of the head
148
what does the ventral part of the pancreas make up?
the uncinate process and part of the head
149
what happens to the dorsal and ventral buds?
they undergo clockwise rotation so that the pancreas sits in the 'C' shape of the duodenum
150
what are the exocrine and endocrine cells of the pancreas formed from?
the endoderm
151
what is the mesenchymal tissue formed from?
the mesoderm
152
when does insulin secretion begin?
at roughly 20 weeks of gestation
153
what do alpha cells from the islets of Langerhans secrete?
glucagon
154
what do beta cells from the islets of Langerhans secrete?
insulin
155
what do delta cells from the islets of Langerhans secrete?
somatostatin
156
what is the exocrine secretion pathway of the pancreas?
acini --> interlobular ducts --> pancreatic ducts --> pancreatic sphincter --> Sphincter of Oddi
157
what lines the ducts found in the pancreas?
simple columnar epithelium
158
which cells secrete pepsin?
NONE OF THEM!
| chief cells secrete the zymogen pepsinogen which is cleaved to pepsin by HCl
159
what is the main enzyme involved in phase 1 detoxification reactions in the liver?
cytochrome P450
160
what are the 5 anatomical regions of the stomach?
- cardia
- fundus
- body
- antrum
- pylorus
161
what are the two sphincters of the stomach?
the cardiac and pyloric sphincters
162
what are rugae?
muscular ridges of the stomach that enable distension
163
what part of the duodenum has smooth mucosa?
the superior part
164
what parts of the duodenum have plicae circularis?
the descending, inferior and ascending parts
165
what are the four parts of the large intestine?
1. ascending colon
2. transverse colon
3. descending colon
4. sigmoid colon
166
what is the arterial supply to the ascending colon?
the right colic artery from the superior mesenteric artery.
167
what are 5 functions of the liver?
production of clotting factors (2,7,9+10)
production of bile
storage of glycogen
detoxification
production of proteins (plasma, clotting, complement)
168
name two metals that the liver stores
copper and iron
169
where are red blood cells broken down?
in the spleen and in the liver
170
what is unconjugated bilirubin bound to in blood?
albumin
171
what is the main exocrine function of the pancreas?
the production of digestive enxzymes
this occurs at the acini of the pancreas
the enzymes are then released via the pancreatic duct to the duodenum
172
what are the 4 histological layers of the intestine?
mucosa
submucosa
muscularis mucosa
serosa
173
give two histological descriptions of the duodenal epithelium
there are Brunner's glands and few goblet cells
174
what is key to activating zymogens?
enterokinase
175
what stimulates the release of digestive enzymes?
cholecystokinin (CCK)
176
what inhibits the release of digestive enzymes?
somatostatin
177
why does the pancreas secrete bicarbonate ions?
to help neutralise chyme in the duodenum
178
what stimulates the release of bicarbonate?
its stimulated by secretin release
| bicarbonate is secreted into the lumen of the small intestine via the Cl-/HCO3- exchanger
179
how is Cl- recycled back into the lumen after its been used in the Cl-/HCO3- exchanger?
by the CFTR channel
| this is faulty in cystic fibrosis
180
which of the following statements is false in regards to GI tract embryology?
A. the muscularis layer of the gut wall is formed by the mesoderm
B. endoderm forms the epithelial layer of the gut lining
C. the junction between the foregut and midgut is the proximal 2/3 of the transverse colon
D. the nerves that supplies the same embryological area of the gut as the inferior mesenteric artery has the nerve root T12
E. the structures formed from layers of the ectoderm and endoderm, the buccopharyngeal membrane and cloaca, form structures similar to the mouth and anus, respectively
C
181
Where is vitamin E stored?
in non-adipose cells such as the liver and plasma cells and in adipose cells
182
where is visceral pain of the hindgut felt?
in the suprapubic region
183
where does the rectum start?
at the point where the circular muscle and longitudinal muscle coalesce
184
where does the midgut embryologically start?
halfway along the duodenum, just distal to the entrance of the bile duct - the 3rd + 4th parts of the duodenum are the midgut
185
where does the embryological midgut end?
at the junction of the proximal 2/3 of the transverse colon with the proximal 1/3
- the first 2/3 of the transverse colon are midgut
186
where does the embryological hindgut start?
at the last 3rd of the transverse colon
187
where does the embryological hindgut end?
at the upper 1/3 of the anal canal
188
where does the embryological foregut start?
at the distal aspect of the oesophagus
189
where does the embryological foregut end?
halfway along the duodenum - the first + second parts of the duodenum are foregut
190
where do the ducts for the submandibular glands open into the mouth?
below the tongue
191
what sympathetically innervates the midgut?
the lesser splanchnic nerve
192
what sympathetically innervates the hindgut?
the least splanchnic nerve and the lumbar splanchnic nerves
193
what sympathetically innervates the foregut?
the greater splanchnic nerve (T5/6-T9)
194
what role does glucose play in erythrocytes?
it is used as a direct energy source by RBC's as they do not have a mitochondria and so can't make their own ATP
195
what parasympathetically innervates the hindgut?
the pelvic splanchnics
196
what parasympathetically innervates the midgut?
the vagus nerve
197
what parasympathetically innervates the foregut?
the vagus nerve
198
what mediates the cephalic phase of gastric acid secretion?
the hypothalamus and medulla (to stomach) via the vagus nerve
199
what is the role of the sympathetic nerves in the colon?
they slow down gut action
200
what is the role of the parasympathetic nerve supply to the colon?
it stimulates GI motility and certain hormones which make you poo
- mainly arises from vagus nerve
201
what is the role of insulin in the liver?
it increases the uptake of glucose
202
what is the rate limiting step of lipogenesis?
acetyl-CoA to malonyl-CoA
| this is catalysed by Acetyl-CoA carboxylase
203
what is the nerve supply to anterior 2/3 of the tongue?
general sensation = mandibular branch of the trigeminal nerve
taste sensation = facial nerve
muscle = hypoglossal nerve
204
what is the most common cause of a peptic ulcer?
reduced mucosal defence
205
what is the intrinsic nerve supply to the colon?
Meissners and Auerbach's plexus
act as the bowels pacemakers
complete peristaltic waves
AND increase blood supply + absorption to the colon
206
what is the gastro-colic reflex?
the stretching of the stomach and presence of food in the jejunum leads to the mass movement of the colon
207
```
what is the first layer of the anterior abdomen, excluding the skin?
A. Scarpa's fascia
B. Camper's fascia
C. external oblique
D. peritoneum
E. transversus abdominus
```
B - camper's fascia
208
what is the first branch of the abdominal aorta?
```
A. coeliac trunk
B. superior mesenteric artery
C. renal artery
D. inferior phrenic artery
E. gonadal artery
```
D - inferior phrenic
209
what is the definition of an ulcer?
a breach in the mucosal surface
210
what is the arterial supply to the hindgut?
inferior mesenteric artery
211
what is the arterial supply to the midgut?
superior mesenteric artery
212
what is the arterial supply to the foregut?
coeliac trunk
213
what is the anatomy of the colon?
| DETAILED
ileocaecal valve
- appendix
- caecum
- ascending colon
- hepatic flexure
- transverse colon
- splenic flexure
- descending colon
- sigmoid colon
- rectum
- anus
214
what is the anatomical surface location of the appendix commonly referred to as?
```
A. Broca's area
B. Wernicke's area
C. McBurney's point
D. Space of Disse
E. Traube's space
```
C - McBurney's point
215
what hormone is essential for gylcogenolysis?
glucagon
216
visceral pain of the foregut is felt where?
in the epigastric region
217
```
If:
1 = greater splanchnic nerve
2 = lesser splanchnic nerve
3 = least splanchnic nerve
4 = vagus nerve
5 = hypogastric plexus
```
which of the following statements is true regarding the innervation of the stomach?
A. the stomach receives input from 2 and 4
B. the stomach receives input from 4 and 5
C. the stomach does not receive input from 1, 4 or 5
D. the stomach receives input from 2 and 4
E. the stomach receives input from 1 and 4
E - the stomach receives input from 1 and 4
218
which stomach cell produces the zymogen that helps break down protein in the stomach and what is the name of the zymogen?
```
cell = chief cell
zymogen = pepsinogen
```
219
which cells are responsible for triggering the peristaltic contraction of the stomach and where do these contractions begin?
interstitial cells of Cajal
| the location of the contractions is the gastric body
220
why is the action of pepsin terminated once it enters the duodenum?
the high pH of the duodenal lumen causes it to denature
221
what percentage of water is absorbed in the small intestine?
80%
222
how frequently does the large intestine contract?
every 30 minutes
223
how long does ingested food stay in the large intestine before its excreted?
18-24 hours
224
what sphincter can be voluntarily controlled to prevent defecation?
the external anal sphincter
225
define and give examples of insensible water loss
insensible water loss = water lost through means that cannot easily be measured
examples = faeces, sweat, breathing
226
which artery, sympathetic nerve and parasympathetic nerve supply the midgut
artery - superior mesenteric
sympathetic = lesser splanchnic
parasympathetic = vagus
227
name the structures lying on Addison's plane at the level of L1
- gallbladder
- pancreas
- pylorus
- duodeno-jejunal flexure
228
which embryological structure forms the ligamentum teres?
the umbilical vein
229
which cells produce the following hormones:
A. gastrin
B. somatostatin
C. histamine
A. G cells
B. D cells
C. ECL cells
230
how many litres of water pass through the GI tract everyday?
9
231
why are pancreatic enzymes produced in the form of zymogens?
to prevent auto digestion
232
which cells produce bile?
hepatocytes
233
in which organ is haemoglobin from red blood cells broken down into haem and globin?
the liver
| the spleen
234
which enzyme is responsible for converting haem into biliverdin?
haemoxygenase
235
what feature of the epithelium of the gallbladder allows it to concentrate bile and what type of epithelium is it?
```
feature = microvilli
epithelium = columnar
```
236
what hormone causes the gallbladder to contract and release the bile stored within in and what stimulates this hormone to be secreted?
```
hormone = cholecystokinin
stimuli = amino acids, acetylcholine
```
237
when bilirubin enters the terminal ileum it is reduced by bacteria. what is the first (main) molecule it obtains?
urobilinogen
238
which molecule, derived from bilirubin, is responsible for the brown colour of faeces?
stercobilin
239
what are the functions of saliva?
- it is a lubricant for mastication /swallowing/speech
- important for oral hygiene
- involved in maintaining oral pH
- releases digestive enzymes
- is an aqueous solvent necessary for taste
240
what is the flow rate of saliva?
0.3-7 mL per min
241
what is the daily secretion of saliva?
800-1500mL
242
what are the three major pairs of salivary glands?
parotid, submandibular and sublingual
243
what salivary glands are continuously active?
the submandibular, sublingual and minor glands are always active
244
when does the parotid gland become the main source of saliva?
when it is stimulated
245
what activates the salivary glands?
they are activated by the thought or smell of food
