GI Flashcards
(305 cards)
0
Q
What does the mucosa consist of?
A
Epithelia
Lamina propria
Muscularis mucosa
1
Q
What is the general layers of the GI tract?
A
Mucosa
Submucosa
Muscularis externae
Adventitia
2
Q
What does the submucosa consist of?
A
Loose connective tissue
Blood vessels
Lymphatics
3
Q
What does the Muscularis externa consist of?
A
Inner circular layer
Outer longitudinal layer
4
Q
What is the adventitia?
A
Supporting tissue lining the external surface
5
Q
What epithelia is in the oesophogus?
A
Stratified squamous
6
Q
How is reflux of food prevented from the stomach to the oesophogus?
A
Diaphragm pinch cock
Angle of his
Lower oesophogeal spinchter
Intra abdominal pressure collapses the oesophogeal wall
7
Q
What epithelium does the stomach have and where does it start?
A
Simple columnar
Gastro-oesophogeal junction
8
Q
What is there to allow chyme to pass through to the duodenum?
A
Pylorus spinchter
9
Q
What specialised adaptations does the small intestine have?
A
Villi
Microvilli
Plicae circulares
Inner and outer muscular layers
10
Q
Where does the common bile duct enter the duodenum?
A
Ampulla
Second part of the duodenum
11
Q
What specialisations does the large intestine have?
A
Inner and outer layers
Mucous secretions
Taeniae coli - 3 distinct bands of outer muscle
12
Q
What epithelium is below the pectin ate line?
A
Stratified squamous
13
Q
Why is there a change between upper and lower pectinate lines?
A
In embryo the mesoderm cells died off to make a hole for the anus
14
Q
What specialised features are below the pectinate line?
A
Sebaceous glands
Sweat glands
15
Q
Name the processes of the GI Tract
A
Digestion
Absorption
Excretion
16
Q
Name where the sequence events occur in order
A
Mouth Saliva Pharynx Oesophogus Stomach Duodenum Small intestine Large intestine Anus
17
Q
Where does the most amount of absorption occur?
A
Small intestine
18
Q
What is chyme?
A
Food turns into this in the stomach Neutral Low pH Hypertonic Sterile
19
Q
Describe where fluid is added to GI
A
1l in 1kg food each day 1.5l saliva 2.5l gastric secretions 9l isotonic and neutral 12.5l absorbed on small intestine 1.35l absorbed in large intestine Remaining in faeces
20
Q
What controls the GI system?
A
Enteric nervous system
21
Q
What function does the mouth have?
A
Disrupts food to form a bolus
Allowing swallowing food without choking
22
Q
Why does the mouth require protection?
A
Teeth
Microbes
Mucosa
Stratified squamous epithelium
23
Q
What is mastication?
A
The disruption of food by teeth
24
What is the main muscle involved in mastication?
Masseter
25
What nerve innervates the masseter?
Trigeminal nerve
26
What are the 3 salivary glands?
Sub mandibular glands
Sublingual
Parotid
27
How much saliva is used every day?
1.5l
28
What is the function of saliva?
```
Make a food bolus
Keeps the mucosa wet
Protects against microbes
Washes the teeth
Maintains an alkaline environment
High calcium for teeth
Digestion of carbohydrates
```
29
What is xerostomia?
Inability to produce saliva due to nerve damage or a tumour.
Microbes grow and teeth and mucosa degenerate and they also cannot swallow so results in dysphasia
30
What are the main consistuents of saliva?
```
Water
Electrolytes
Enzymes
Alkali
Mucous
Bacteriostats
```
31
What type of glands are the salivary glands?
Paired tubuloacinar compound exocrine
32
What are the glands composed of?
Tubes which are blind ended with acini at the end which secrete merocrine secretions
They have myoepithelia which contract and push saliva down the duct
33
What are serous demilunes?
Shrinkage artefacts that salivary glands appear as when fixed because they are capable of mucous and serous secretions
34
How much does the sublingual glands contribute and what do their secretions consist of?
5%
No enzymes
Mucous
35
How much does the sublmandibular glands contribute and what do their secretions consist of?
25% mostly serous secretions
36
How much does the parotid glands contribute and what do their secretions consist of?
75% serous and mucous secretions
37
What is saliva mostly when resting?
Mucous
38
What is saliva mostly when stimulated?
Serous
39
What is the volume of saliva controlled by?
Acinar cells
40
What is the composition of saliva determined by?
The ducts
41
What are the 3 properties of chyme?
Hypertonic
Partially digested
Acidic
42
What is bile made from?
Acid independent - mainly alkali juice
Acid dependent - bile acids,bile pigment, cholesterol
Water, phospholipids
43
What are the 2 main bile acids?
Cholic acid
| Chenodeoxycholic acid
44
Where is the bile dependent secreted from?
Canaliculi
45
Where is the bile acid independent secreted from?
Ducts
46
Describe the structure of the liver
It has lobules surrounding central lobes
The hepatic arteries and hepatic portal vein enter the central vein via sinusoids which are surrounded by hepatocytes
Hepatic triad - bile duct, artery, vein
47
Describe the entero-hepatic circulation of bile acids
Gastric emptying stimulates cck which causes gall bladder to contract and bile acids to be secreted
They come out of the ampulla of vater and enter the duodenum and the terminal ileum is where they are actively reabsorbed through the epithelium on entering the hepatic portal vein
They are then secreted into the canaliculi
48
Are all bile acids reabsorbed again?
No, some are unconjugated by bacteria and lost
49
Describe the function of the gall bladder
The gall bladder stores bile acids and it contracts on stimulation of cck
They are concentrated and therefore sodium and chloride diffuse in and therefore so does water
50
Explain the formation of gall stones
Gall stones are formed due to the water and salt entering the epithelium, this can lead to precipitation which can form gall stones.
They can be symptomatic but if in the neck or on gall bladder contraction they can lead to billary cholic and cholecystits
51
Name the secretions from the exocrine pancreas
```
Lipases
Anylases
Proteases:
- elastin
- carboxypeptidase
- chymotrypsin
- trypsin
```
52
Explain the function of acini of the pancreas
They secrete enzymes into vacuoles as zymogens granules which are then cleaved in the intestine to their active form.
Acinar secretions are Stimulated by cck, released from APUD duodenal cells and stimulated by hypeprtonicity and fats
53
Explain the function of the ducts in the pancreas
Secrete an alkaline juice.
| Stimulated by secretin, released from jujenal cells in response to a low pH
54
Describe the mechanism of the secretion of alkaline juice
Na-K-ATPase sets up a concentration gradient
Na-H and H+ binds with HCO3- in the ECF to make water and carbon dioxide which is transported back into the cell and reforms as H+ and HCO3- which is then secreted across the lumen
55
Describe the digestion of fats
The bile acids are in a miscelle configuration and this allows fatty acids to enter the hydrophobic entity. They are then transported and once they go through the unstirred layer they diffuse slowly into epithelia cells where they then become triaclglycerols and can be transported in the lymphatics by chylomicrons into the systemic veins
56
What is steatorrhoea?
An inadequate amount of bile salts are produced and therefore fat appears in the stools and they are pale and float and very foul smelling
57
What is jaundice?
Bilirubin accumulates in the body as it cannot be excreted as there is a problem, giving rise to jaundice.
58
What does the upper stomach secrete?
Acid and pepsinogen
59
What does the lower third of the stomach secrete?
Mucous and gastrin
60
What anatomy makes up the stomach?
2 spinchters - lower oesophogeal and pyloric
Antrum, body, cardia, pylorus, fundus, lesser curvature, greater curvature
Mucous bicarbonate barrier
61
What epithelium lines the stomach?
Simple columnar
62
What is a hiatus hernia?
A little bit of the stomach gone above the diaphragm
63
What are the preventative measures of stopping gastric contents refluxing back into the oesophagus?
```
Angle of his
Diaphragm acts as a pinch cock
High intra abdominal pressure compresses the oesophagus
The lower oesophogeal spinchter
Gravity
```
64
Some reflux is normal, how is this dealt with?
Gravity, salivary bicarbonate, peristaltic waves
65
When do the clinical features of gastro-oesophogeal reflux disease occur?
Prolonged contacts of stomach with the oesophagus
| Anti reflux mechanisms fail
66
What are the clinical features of GORD?
Dyspepsia - heartburn
| Worse lying down, bending over and drinking hot drinks
67
What investigations would you usually do for GORD?
None usually unless you suspect cancer or hiatus hernia then you would do an endoscopy
But you can usually diagnose based on history.
68
How do you manage GORD?
Raft antacids which sit on top of stomach contents
Simple antacids such as calcium carbonate
PPIs eg omeprazole
H2 antagonists eg, ranitidine
Both lower inhibit acid secretion
Diet and lifestyle - stop eating fatty foods/alcohol/smoking/lose weight
69
What is a major complication of GORD?
Barrett's oesophagus - a metaplastic change of oesophageal epithelium converted to gastric epithelium
70
What is a peptic ulcer?
A break in the superficial epithelia cells penetrating down into the muscularis mucosa of the stomach or the duodenum
71
What are the causes of peptic ulcers?
H pylori
NSAID's
Alcohol
72
How does the use of NSAIDs cause gastric ulcers?
They inhibit prostaglandins which prevents the production of the unstirred layer
73
What is the epidemiology of peptic ulcers?
Decreasing in young, esp men
Increasing in elderly, esp women
10% of population (duodenal, 3x more common than gastric)
Decreased h pylori cause and increased NSAIDs cause in developed world
74
What are the clinical features of peptic ulcers?
Recurrent, burning epigastric pain, nausea, vomitting, weight loss, anorexia, back pain, severe persistent pain
75
What investigations would you do for peptic ulcers?
H pylori by C13 urease test
See if on NSAIDs
Endoscopy in the elderly
76
Management of peptic ulcers
Stop NSAIDs (if on)
Antibiotics (if h pylori) - amoxicillin or clarythromycin
PPI
H2 antagonist
77
What are some complications of peptic ulcers?
Haemorrhage
Perforation
Gastric outlet obstruction
78
What type of bacterium is h pylori?
Helical
Gram negative
Urease producing
Aerobic
79
How does h pylori cause pud?
```
Invades epithelium releasing ammonium to get through unstirred layer and causes a neural environment
Release cytotoxins causing apoptosis
Affects gastrin secretion
In Antrum - DU
Antrum and body - a symptomatic
Body - GU
```
80
How do you detect H pylori?
C13 urea breath test as it produces urease which breaks down to form co2
IgG detected in serum
Gastric sample and culture
81
What is gastritis?
Inflammation of the stomach
| Chronic causes chronic hypergastraemia due to increased gastrin and increased Gastrin production
82
What is gastric cancer survival like?
5 year survival has not changed much over 40 years
Late diagnosis usually
Poor survival rates
83
What are the functions of the stomach?
Disinfection
Store food
Break down food into chyme
84
What product does parietal cells produce?
Acid - HCL
85
What product does chief cells produce?
Enzymes
86
What product does neck cells produce?
Mucous
| Alkali
87
What do G cells produce?
Gastrin
88
Where do secretions of the stomach come from?
Gastric pits
89
How is stomach acid secreted?
Mitochondria of partial cells
Splitting water
Proton pumps which pump H+ onto the canaliculi and then these H+ sit on top of the bicarbonate layer of the stomach so that the epithelia is protected
90
Why are the proton pumps of the canaliculi key targets for drug action?
Because this will inhibit the production of stomach acid
91
How is gastric acid secretion controlled?
Ach
Histamine
Gastrin
92
Explain the mechanism of Ach controlling acid secretion
Ach is released from the gastric distension. They act on muscurinic receptors of parietal cells. Stimulated by the parasympathetic nervous system.
93
Explain how gastrin controls stomach acid release
Gastrin is stimulated by peptides and disinhibited by neutral pH
It acts on parietal cells to stimulate the release of gastrin
Stimulated by Ach additionally.
Intrinsic factor is also stimulated by gastrin which is important for absorption of vitamin B12 for production of RBC
94
Explain how histamine controls stomach secretion
Acts as a second messenger pathway, acts on h2 receptors of parietal cells and then acid secretion is done via c-amp
Released from mast cells
Amplified by gastrin and Ach as these stimulate mast cells
95
What are the 3 phases of gastric control?
Ceohalic
Gastric
Interstitial
96
Explain the cephalic phase of gastric secretion
Your body responds to the sight and smell of food by releasing Ach
Also responds to swallowing
Stimulates parietal cells directly
97
Explain the gastric phase of acid secretion
At first, gastrin is inhibited by the food neutralising the stomach
The distension of the stomach releases Ach
The release of peptides releases gastrin
98
Explain the interstitial phase of gastric secretion
Once chyme has entered the duodenum, CCK and gastric inhibitory peptide are released to inhibit gastrin
Low ph inhibits gastrin as food is no longer buffering the stomach
This low pH Inbetween meals can lead to stomach ulcers and the no buffering action of food at night is why they are so painful
99
How can gastric acid secretion be inhibited by drugs?
PPI which stops the production of acid
Eg. Omeprazole
H2 receptor antagonists such as cimetidine which removes the signal from gastrin and Ach
100
Describe the stomachs defences to acid
Mucous - sticky, bicarbonate layer with acidic layer on top and the acid cannot pass through
Mucous and hco3- are produced by prostaglandins acting on neck cells
101
Name some ways in which the stomach cells can be breeched
Alcohol - dissolves
H pylori - cytotoxins and neutralise
NSAIDs - get into the epithelia layer and cause apoptosis
Inhibit prostaglandins
102
What does breaching of the stomachs defences result in?
Peptic ulcers
103
Describe receptive relaxation
In order for us to be able to eat big meals, we have to reduce the stomachs pressure and so it does this via the vagus nerve causing the relaxation of the stomach
104
Describe the contractions of the stomach
Peristaltic waves are produced which allows the mixing of the stomach contents with chyme. Allows chyme to go to the bottom and larger particles to stay on top. Chyme leaves via the pyloric spinchter and the contractions relate to the stomach emptying and are usually 3 per minute.
105
Describe the control of gastric emptying
Controlled via:
Peristalsic waves
Squirt volume affected by rate of digestion
Low ph, fat and hypertonicity slow gastric emptying
106
What's the 4 muscles in the abdominal wall?
External oblique
Internal oblique
Transversalis abdominis
Rectus abdominis
107
What are the next layers in the abdomen?
Transversalis fascia
Peritoneum
Greater omentum
108
What is the function of the greater omentum?
To stop the spread or the infection in appendicitis
109
What is the significance of Douglas line?
It's where the rectus sheath disappears underneath the umbilicus and pubic symphysis
Important for caesarians - phannestiel incision
110
What is a patent urachus?
Where the urachus has become again and you excrete urine out of your umbilicus
111
What is a patent vitellointestinal duct?
Diverticulum of small intestine, reminent of yolk stalk, can excrete pancreatic enzymes
Occurs in 2% of pop, 2 inches long, 2 feet away from ilicoecal valve, 2 tissues involved
112
How would you diagnose a patent urachus and patent vitellointestinal duct?
MRI and see if dye comes out of the GI or the urinary tract - they present the same and are hard to diagnose
113
What tissue are sutures usually done through in the abdomen?
Linea alba because it is strong.
Cannot do through muscle or it will just rip through it
Or transverse incision where you suture the external oblique aponeurosis
114
At what anatomical landmark do you perform an Appendicecromy?
McBurney's point which is 2/3 way between umbilicus and ASIS
Grid on incision
115
Define referred pain
Pain which is perceived at a distant site from that causing it
116
Define somatic referred pain
Pain caused by a noxious stimulus to the proximal part of the somatic nerve that is perceived in the distal dermatome of that nerve
117
What is the dermatomal level of the umbilicus?
T10
118
What is the dermatomal level of the pelvis?
T12
119
Give 2 examples of somatic referred pain
Shingles - RIF pain but a lower back rash
| Right lower lobe pneumonia - RIF
120
Causes of pain in the abdomen
Inflammation
Ischaemia
Stretching
Abnormally strong muscle contractions
121
Why can't you feel touch, burning, cutting or crushing in your abdomen?
No reason as there is no protective mechanism
122
Where do you get pain for foregut derivatives?
Epigastric
123
Where do you get pain for midgut derivatives?
Peri umbilical
124
Where do you get pain for hindgut derivatives?
Supra pubic
125
Explain phrenic nerve referred pain
C3, C4, C5 innervate the shoulder too so pain from your diaphragm standing up presents as shoulder pain on lying down
126
Explain where you get cardiac pain
Either side of mouth, left ear, either side of neck, right shoulder, left arm, epigastric
127
Where is the arcuate line?
1/3 way between pubis and umbilicus
128
What are the 4 common types of abdominal hernia?
Inguinal
Umbilical
Femoral
Incisional
129
Where do direct inguinal hernias occur?
Through Hesselbach's triangle
Supra inguinal ring
Through muscle
130
What are the borders of Hesselbach's triangle?
Inferior epigastric vessels inguinal ligament, rectus abdominis
131
Where does an indirect inguinal hernia occur?
Through the deep inguinal ring, within the transversalis fascial sling
132
Explain the epidemiology of femoral hernias
More common in women
More likely to strangulate
Bowel obstruction
Through the femoral canal
133
List the 4 types of hernia in order of prevalence with most prevalent first
Inguinal
Incisional
Umbilical
Femoral
134
What is a Richters hernia?
Where only part of the bowel is strangulated through the abdomen
Does not present with bowel obstruction
Through the femoral canal
135
What is a Spigelian hernia?
An area of weakness vaguely in the abdomen
Presents with a lump
Lateral border of rectus muscle and arcuate line
136
What does incarnated mean?
Stuck, not strangulated
137
Where is the mid point of the inguinal ligament?
Palate for the femoral artery
138
Where is the mid inguinal point?
Between the ASIS and the pubic symphysis
139
Where is the femoral canal?
Below the inguinal ligament and next to the femoral vein
140
Why would you operate on a hernia?
Worrying
Strangulation
Bowel obstruction
Painful or aching
141
Name the range of toxins that the GI tract and the liver may be exposed to
```
Chemical
Bacteria
Worms
Viruses
Protozoa
```
142
How much of the worlds population do not have access to clean water?
1 billion
143
What are the physical/innate defences of the GI tract?
```
Sight/smell
Memory
Mucous
Anaerobic conditions
Peristalsis
Stomach acid
Small intestine secretions
```
144
What are the cellular innate defences of the GI tract?
```
Eosinophils
Tissue mast cells
Natural killer cells
Macrophages
Neutrophils
```
145
What is a guinea worm?
Goes from the duodenum to the foot
Wants to get back into water
Need to wind it out each day with a match stick
Causes a lot of suicides
146
What are the adaptive defences of the GI tract?
B lymphocytes which present antigens
T lymphocytes which deal with intracellular organisms
GALT
147
Explain what happens when salivary defences fail
Xerostima which is the inability to produce saliva and causes mucous destruction, bacterial overgrowth
Parotitis caused by staph aureus which has a 25% mortality rate
148
What happens when you have a decrease in acid production?
More susceptible to cholera, salmonella and shigelosis
| In a hosp environment, patients on PPI are more susceptible to clostridium difficile
149
Which organisms are resistant to stomach acid?
```
Norovirus
TB
Hep A
Polio
Coxsackie
```
150
Is H pylori resistant to stomach acid?
No it produces ammonia which neutralises the stomach acid
151
What do mast cells do?
```
Release histamine
Cause major dehydration
Vasodilation and decreases in blood volume
Rice stools
Washer woman's hands
```
152
What are the causes of appendicitis?
Lymphoid hyperplasia
Faecal obstruction
Chickenpox
Worm
153
What is mesenteric adenitis caused by and what is it commonly mistaken for?
Right iliac fossa pain mistaken for appendicitis
| Coxsackie or adenovirus
154
Why is there a lot of lymphoid tissue in the gut?
To protect from bacteria as the iliocaecal valve allows bacteria into the small bowel
155
What can gut Ischaemia be causes by?
Hypotension
Arterial disease
Venous thrombosis
156
What are the causes of liver failure?
```
Hepatitis
Alcohol
Drugs
Mushrooms
Industrial solvents
```
157
What does hepatic fibrosis lead to?
Portal hypertension
Portosystemic shunting
Oesophogeal varicies, haemorrhoids, caput medusa
Toxin shunting
158
What are the functions of the liver?
```
Carb metabolism
Lipid metabolism
Detoxification
Vit d metabolism
Storage of vitamins
Produces bile
```
159
At what bilirubin concentration is jaundice?
>40 micromol/L
160
What is the normal bilirubin concentration?
<22 micromol/L
161
What blood proteins does the liver produce?
Clotting factors
Thromboprotein
Amino acid synthesis
Albumin
162
What proteins are used for liver function tests?
Bilirubin
Albumin
ALTS/ASTS
Alkaline phosphatase
163
What are the effects of jaundice?
Yellow sclerae
Yellow mucous
Yellow skin
164
What is the definition of pre hepatic jaundice?
Excessive bilirubin production, usually due to an increased breakdown of RBC
Liver is unable to cope with excess bilirubin
165
What are the lab findings with pre hepatic jaundice?
Anaemia
Unconjugated bilirubin
Reticulolysis
Increased LDH
166
What are the causes of pre hepatic jaundice?
```
Gilbert's syndrome
Crigler Najjar syndrome
Dublin Johnson syndrome
Immune
Mechanical
Drugs
Infections
Burns
```
167
What is hepatic jaundice?
A reduced capacity of liver cells to secrete conjugated bilirubin
Dysfunction
168
What are the lab findings of hepatic jaundice?
Increased ALT
Swollen cells
Abnormal clotting
Mixed unconjugated and conjugated bilirubin
169
What are the causes of hepatic jaundice?
```
Gilbert's syndrome
Crigler Najjar syndrome
Viral
Autoimmune hepatitis
Alcohol
Wilson's disease
Cirrhosis
Hepatic tumours
```
170
What is post hepatic jaundice?
Obstruction to drainage of bile, causing a back up of bile acids into the liver
Can be intra hepatic or extra hepatic
Conjugated bilirubin passage is blocked
171
What are the lab findings of post hepatic jaundice?
Urine is dark
Increased liver enzymes
Pale stools
Increased Canalicular enzymes
172
What are the causes of post hepatic jaundice?
```
Drugs
Hepatitis
Cirrhosis
Biliary colic
Gallstones
Pancreatitis
Carcinoma
```
173
What are the causes of hepatitis?
```
Viral: hep ABCD, yellow fever, EBV
Autoimmune
Hereditary - alpha 1 antitrypsin deficiency
Drugs
Alcohol
```
174
What are the symptoms of hepatitis?
Decreased albumin
Decreased clotting factors
Jaundice
Raised liver enzymes
175
Describe the key features of alcoholic liver disease
Fatty liver
Cirrhosis
Alcoholic hepatitis
Complications such as liver failure, carcinoma etc
176
What are the causes of cirrhosis of the liver?
Wilson's disease
Alcohol
Alpha 1 antitrypsin deficiency
Hepatitis
177
What are the clinical features of cirrhosis?
```
Liver dysfunction
Jaundice
Palpable liver
Anaemia
Bruising
Palmar erythema
Portal hypertension
```
178
What would you find on investigation with cirrhosis?
```
Low albumin
Decreased clotting
Raised liver enzymes
Raised bilirubin
Decreased sodium
```
179
What is portal hypertension defined as?
Hypertension of >20mmHg
Intra hepatic or extra hepatic
Obstruction of portal vein or an obstruction in liver
180
What is Ascites?
Increased tension in portal veins and then this causes less fluid in the circulation and for it to back up in the abdomen
181
How can splenomegaly occur?
Subsequent increased BP in spleen
182
Where are the main sites of Porto-systemic anastomoses?
Oesophagus
Anus as haemorrhoids
Caput medusa near the umbilicus
183
What is fulminant hepatic failure?
Hepatic encephalopathy within 2 months of liver failure diagnosis
184
What is hepatic encephalopathy?
Confusion
Reversible
Tremor, personality changes, intellectual deterioration
185
What are the causes of pancreatitis?
```
Gallstones
ECRP
Trauma
Steroids
Mumps
Autoimmune
Scorpion bite
Hyperlipidaemia
Ethanol
Drugs
```
186
What are the symptoms of acute pancreatitis?
```
Pain
Nausea/vomiting
Oedema or haemorrhage
Dehydration
Shock
```
187
What are the symptoms of chronic pancreatitis?
Calcification fibrosis
Pain
Malabsorption
Jaundice
188
What percentage of cancer deaths do pancreatic tumours account for?
5%
| Mostly ductal
189
What are the causes of pancreatic tumours?
Smoking
Benzedrine
Familial pancreatitis
Beta napthylamine
190
How does the duodenum make chyme less acidic?
HCO3- is added to it from the pancreas, liver and mucosa
191
How does the duodenum deal with chyme being hypertonic?
Water reabsorpbed through the duodenum wall
192
How does the duodenum deal with chyme being partially digested?
It digests it via enzymes from the mucosa and bile acids from the liver
193
What properties does the small intestine have for absorption?
Microvilli
Brush border
High surface area
194
What properties does the large intestine have?
Teniae coli which is 3 muscular layers
| Run the length of the intestine
195
What is the function of the large intestines?
It absorbs water and any remaining nutrients
| Stores faeces
196
What does the duodenum secrete?
```
Bile acids
Water
HCO3-
Proteases, carbohydrase
Secretin, gastrin, cholecystokinin
```
197
What does the duodenum absorb?
Iron
198
What does the Jujenum secrete?
Carbohydrase, proteases, cholecystokinin, secretin, gastrin
199
What does the Jujenum absorb?
```
Carbohydrates
Fatty acids
Amino acids
Vitamins
Minerals
Electrolytes
Water
```
200
What does the ileum secrete?
Proteases, carbohydrase, gastrin, secretin, cholecystokinin
201
What does the ileum absorb?
Bile
Remaining nutrients
B1
202
What does the large intestine secrete?
Nothing
203
What does the large intestine absorb?
Water
Anything remaining
Bacteria vitamins - k, b12, thiamine, riboflavin
204
What bonds does amylose have?
Alpha 1,4
205
What bonds does amylopectin have?
Alpha 1,6
206
What do alpha amylases act upon?
1,4 bonds
Yield glucose and maltose from amylose
Alpha dextri a from amylopectin
207
What does isomaltase do?
Breaks down branched molecules at alpha 1,6 bonds
208
What does maltase do?
Breaks down maltose into glucose
209
What does sucrase do?
Breaks down sucrose into glucose and fructose
210
What does lactase do?
Breaks down lactose into glucose and galactose
211
Explain how glucose is absorbed
Na-K-ATPase driving force
Sglut1 on apical membrane
Glut2 on basolateral membrane
212
What does pepsin do?
Breaks down peptides near aromatic AA side chains
213
What does chymotrypsin do?
Breaks down peptides near AA aromatic chains
214
What does trypsin do?
Breaks down peptides near basic AA chains
215
What does carboxypeptidase do?
Breaks down peptides near basic AA chains
216
What specialisation do neonates have in terms of proteins in the gut?
Absorb whole proteins as their gut is open
Allows passage of immune system proteins so innate immune system is set up
Passive immunity
217
How are amino acids absorbed?
Na+ co transporter
| Na-K-ATPase
218
How are fats absorbed?
Bile salts ingest them into their miscelle
| Then once though epithelia they go into triacylglycerols so can be transported by chylomicrons
219
How is NaCl absorbed?
Diffusion into cell
Active transport by Na-K-ATPase and chloride follows
Sets up an osmotic gradient
220
How is calcium absorbed?
Vitamin d binds to it in the gut
Stimulated by parathyroid hormone
Enters by facilitated diffusion and pumped out by ca-ATPase
221
How is iron absorbed?
Has to be absorped as ferrous form (2+)
Gastric acid makes it ferrous, and gastroferrin keeps it ferrous
Absorbed via transferrin endocytosis and then splits and then binds to transferrin in the blood again
222
What type of vitamins are c and b and how are they absorbed?
Water soluble
| Passive diffusion
223
How is vitamin b12 absorbed?
Co factor - intrinsic factor which keeps it soluble
224
What occurs with vitamin b12 deficiency?
Pernicious anaemia - damage to stomach and intrinsic factor is not secreted
225
What is oral rehydration therapy?
Uptake of Na creates an osmotic gradient
Glucose uptake stimulates Na uptake
Osmotic gradient also
Stimulates maximum water uptake and this is oral rehydration
226
What is segmenting?
The intestines move slowly to move the food along and agitation for absorption
Must move very slowly
Each section of small intestine has a pacemaker and an interstitial gradient
More mixing rather than moving along
227
What is haustral shunting?
Shuffles the contents of the large intestine back and forth for slow reabsorption and formation of faeces
228
What is mass movement?
1-2 times a day, especially when you've eaten, the faeces moves along the transverse and ascending colon to the rectum, producing the urge to defecate
229
What are the 2 anal spinchters?
Internal which is smooth muscle and involuntary
| External which is skeletal muscle and voluntary
230
Explain the excretion of faeces
The spinchters relax which creates a high pressure
| Forces faeces out
231
What are the different types of IBD?
Crohns
Ulcerative colitis
Diversion colitis
Diverticular colitis
232
Explain ulcerative colitis
Superficial
Bleeding, diarrhoea
Continuous and starts off in the rectum
TH2 cells which produce TGF and IL5
233
Explain Crohn's disease
Transmural
Patchy
Anywhere between mouth and anus
TH1 cells which produce IL2 and IFN gamma
234
What are the presentations of Crohn's?
Upper GI: nausea, indigestion, small bowel obstruction, anorexia, loose stools
Colonic GI: diarrhoea passage of blood
Terminal ileum: anaemia
235
What are the causes of Crohn's?
```
Genetic
NSAIDs
Diet
Smoking
Acute infections
```
236
Explain common methods used for IBD
```
Colonoscopy
Stool analysis
Barium radiographs
Ct scan
X ray
```
237
What are the macroscopic changes with Crohn's?
Thickened
Ulcers
Fissures
Cobblestone
238
What is the macroscopic appearance of uc?
Reddened mucosa
Bleeds easily
Polyps
239
What are the microscopic changes of Crohn's?
Lymphoid hyperplasia
| Granulomas
240
What are the microscopic changes with uc?
Crypt abscesses
| Goblet cell depletion
241
What is CUTE?
Colitis of undetermined type and aetiology
242
What is the treatment for Crohn's?
```
Oral or IV glucosteroids
Nutrition
anti TNF antibodies
Methotrexate, azathiorpine
Ciprofloxacin or metronidazole
Surgery
```
243
What is the treatment for uc?
Corticosteroids
Anti TNF antibodies
Surgery
244
What are the functions of the normal flora in the GI tract (5)?
synthesise vitamines (thiamine, b12, k)
produce GALT in peyers patchers and cecum
prevent colonisation
kill non indigenous bacteria
stimulate production of natural antibodies
245
What are obligate aerobes and give an example?
Die without O2
| pseudomonas and myobacterium TB
246
What are obligate anaerobes and give an example?
Die in the presence of O2
| Clostridia, bacteriodes fragillis
247
What are facultative anaerobes and give an example?
Prefer O2 but can live without it
| eg. E. coli
248
Where are the anaerobic zones of the GI tract?
Mouth - deep in taste buds and tongue, gingival crevices
Small bowel
Colon
249
Give some examples of bacteria in the mouth and what they can cause
Streptococci - strep mutans causes dental cavities/gingivitis
Staphylococci aureus - parotitis
Candida albicans (fungi) causes oral thrush
Lactobacillus
Enterococcus
250
What is noma/cancrum oris?
This is tissue degradation in the mouth which is caused by streptococcus and staphylococcus especially in immunocompromised, malnourished and dehydrated patients
251
What bacteria is particularly known for being in the nose?
MRSA (1 of 3 screening sites)
staphylococcus
streptococcus
252
What bacteria in the throat are present in 100% of people?
strep viridians
staphylococci
neisseria meningitidus
253
Name some throat bacteria and what they can cause?
```
Strep pyogenes - tonsillitis
Candida albicans - oral thrush
Haemophillus influenza - pneumonia
Strep pneumonia - pneumonia
Strep viridians - bacteraemia after dental procedures
Corneybacterium Diptheriae
```
254
What is the ratio between viral causes of tonsillitus and bacterial and what organisms are responsible?
70% viral - adenovirus, rhinovirus, EBV
| 30% bacterial - strep pyogenes
255
What organisms are present in the stomach and what can they cause?
H pylori
| Causes stomach ulcers, duodenal ulcers and gastritis
256
Give some examples of colonic bacteria
```
Bacteriodes fragilis
Bacteriodes oralis
Bacteriodes melaninogenicus
E coli
Enterococcus faecialis
```
257
Name some colonic bacteria that aren't very common
```
Pseudomonas
Campylobacter
Salmonella
Shigella
Vibrio cholera
Proteus
```
258
What is 'dirty surgery'?
When there may be small bowel bacteria
Most surgery opening the small bowel is dirty surgery
Treat with prophylactic antibiotics such as metronidazole and gentamicin
259
Explain faecal peritonitis
This is when bacteria from the abdomen gets into the peritoneum which can cause peritonitis and this has a high mortality even in the fit and healthy
260
Explain perianal abscesses
These are formed when the glands in the anus which produce lubrication for expulsion of faeces get infected, forming an abscess
261
Explain the development of vaginal thrush and how this is usually presented
Lactobacilli usually prevent thrush by excreting an acid, this is part of vaginal normal flora. When this is depressed, candida albicans can grow to form thrush. Antibiotics can do this
262
Where is the perineal skin?
Below the anus
263
What organisms can survive in the perineal skin?
E coli
Enterococcus faecialis
Lactobacillus
264
What are the common organisms causing urinary tract infections?
E coli
Enterococci faecialis
Gram negative enterococci
265
What are the 3 common clostridia organisms and what do they cause?
Difficile - diarrhoea - endospores which spread through hospital. can be associated with antbiotics
Tetani - cause tetanus (lock jaw) especially in women who bite the umbilical cord and elderly women who prune their roses
Perfingens - causes gas gangrene -> cardiac arrest
266
What does norovirus cause?
Vomitting and diarrhoea
267
What is gastroenteritis?
Food poisoning
D+V, stomach cramps
Caused by raw food or contaminated water
salmonella, campylobacter, listeria, clostridium, staphylococcus all common
268
What is cholera?
Generally from contaminated water from vibrio cholera, causes rice water stools, severe dehydration, diarrhoea
269
Give some examples of interstitial parasites
Giardia and cryptosporidium cause gastroenteritis
| Hemlinth causes malabsorption
270
What is the difference between bacteraemia and septicaemia?
Bacteraemia is just the presence of bacteria in the blood
| Septicaemia is this with the clinical presentation
271
What is the common cause of travellers diarrhoea?
ETEC (enterotoxinogenic E coli)
Heat stable or labile toxins produced from this
Severe cholera like watery diarrhoea
272
What does the gram stain consist of?
Crystal violet and iodine
273
What are the common GI malignancies?
```
Oesophagus
Stomach
Large Intestine
Pancreas
Liver
```
274
What is the epidemiology of oesophogeal carcinoma?
2% of malignancies in the UK
Males more than females
Low incidence in USA
High incidence in China
275
What are the most common GI malignancies?
```
Oesophogeal
Stomach
Large intestine
Pancreatic
Liver
```
276
Explain the prevalence of oesophogeal cancers
2% of UK population
| High incidence in China
277
What are the clinical features of oesophogeal cancer?
Dysphagia, starting off with dry food
| Weight loss
278
How can you investigate oesophogeal cancer?
Endoscopy
Barium swallow
Biopsy
279
What are the 2 types of oesophogeal cancer and where do they occur?
Squamous cell carcinoma - anywhere, most common
| Adenocarcinoma - lower third of the oesophagus, associated with Barrett's oesophagus
280
What is the prognosis of oesophageal cancer?
presents at an advanced stage
5% 5 year survival
direct spread through oesophogeal wall means that only 40% are operable
many patients have a tube down through the tumour to allow passage of food and drink
281
What is the prevalence of gastric cancer?
```
15% of worldwide cancer deaths
associated with H pylori
Poor prognosis
<20% 5 year survival
More common in men
More common in Japan, Finland and Columbia
Associated with gastritis
More common in blood group A
```
282
What are the clinical features of gastric cancer?
```
Dysphagia
Dyspepsia
Weight loss
Vomiting
Anaemia
Epigastric pain
```
283
What investigations would you do for gastric cancer?
Biopsy
Barium swallow
Endoscopy
284
What are the macroscopic features of gastric cancer?
Fungating
Ulcerating
Linitis plastica
Early
285
What are the microscopic features of gastric cancer?
Variable degree of gland formation
| Single cells - signet ring cells
286
What is the prognosis for gastric cancer?
If caught early, the prognosis is good
If caught late, there is a 10% 5 year survival
Late - spread through bowel wall, to liver, to lymph nodes and possibly ovaries
287
Explain gastric lymphoma
```
It is the most common GI lymphoma
Starts as a low grade lesion
Prognosis better than gastric cancer
Strong association with h pylori
Can potentially be cured by antibiotics because H pylori maintains control over the tumour and therefore you can technically cure it with antibiotics but realistically it slows it
```
288
Explain a little about gastro-intestinal stromal tumours
Relatively uncommon, derived from the interstitial cells of Cajal
CD117 mutation
Highly specific treatment
Unpredictable behaviour - pleomorphisms, mitoses, necrosis
289
Name the tumours of the large intestine
Adenoma
Adenocarcinoma
Polyps
Anal carcinoma
290
Explain intestinal adenomas
Present as polyps which stick out into the lumen
Macroscopic - sessile or pedunculated
Microscopic - variable degree of dysplasia - all large bowel adenomas are dysplastic
Definite malignant potential
Increases with age, FAP, Gardeners syndrome
291
Explain colorectal adenocarcinomas
```
60-70% are retrosigmoid
Fungating
Stenotic
Can usually see the pectinate line
Signet cells, mucinous
```
292
Explain how colorectal adenocarcinomas spread
Through bowel wall to organs
Via hepatic portal system to liver
Via lymph nodes
High risk of metastasis
293
What staging is used for colorectal cancer?
Dukes OR TNM
Dukes - A confined to bowel wall
B - through bowel wall
C1/C2 - lymph nodes involved
TNM - considers peritoneum
294
What is the incidence of colorectal cancer?
60-70
High UK/USA
polyposis syndromes
UC
295
What genetic factors increase the risk of colorectal cancer?
FAP
RAS
DCC deletion
p53 loss
296
What are the outcomes of colorectal cancer?
Decrease in survival with an increase in Duke's staging
Liver metastasis is common in advanced stages and taking out bits of liver can prolong life
Local radiotherapy
Bowel cancer screenings
297
What are some other rare tumours of the GI tract?
Carcinoid tumour
Lymphoma
Smooth muscle/stromal tumour
298
Explain a little about pancreatic tumours
Early symptoms are vague
| Presents with Jaundice, weight loss, trousseaus sign
299
Explain the histology of pancreatic tumours
80% ductal
well formed glands
some acinar cells with zymogen granules
+/- mucins
300
What is the prognosis for pancreatic cancer?
Poor
301
Explain about a carcinoma of the ampulla of Vater
Dilation of gallbladder
Presents with jaundice
Tumour blocks the bile duct
Pale stools, dark urine
302
Name some islet cell tumours
Insulinoma
Glucagonoma
VIPoma
Gastinoma
303
Name some benign tumours of the liver
Hepatic adenoma
Bile duct adenoma
Haemangioma
304
Name some malignant tumours of the liver
Hepatocellular carcinoma
Cholangiocarcinoma
Hepatoblastoma
