GI Flashcards
(322 cards)
1
Q
What are the implications of the external environment?
A
- You have to ingest food, digest food, absorb food and egest what not needed
- Stop toxin/infection entering
- Very thin epithelium
- Need water in gut lumen for chemical reactions and cant lose to external world
2
Q
What are the waste products that are not ingested in the gut?
A
- Bilirubin
- Cholesterol
3
Q
What are the areas of mechanical disruptions in the GI tract?
A
- Mouth/Teeth
- Stomach
4
Q
What are the muscular actions of the stomach?
A
- Vigorous contractions of the stomach cause food to be liquefied.
- Upper area create basal tone (tonic)
- Lower area has powerful peristaltic contractions that effectively grind food and mix stomach contents. Every 20 seconds proximal to distal
- Has additional inner oblique layer of muscle
5
Q
How does the stomach resist rise in intraluminal pressure?
A
Eat quicker that digest
- Stomach can distend due to rugae (temporary folds)
- Receptive relaxation occurs to allow food to enter stomach without raising intragastric pressure to much and prevents reflux of stomach content during swallow
- Vagally stimulated relaxation
6
Q
What is the purpose of the colon?
A
- Contents are only evacuated several times a day
- Acts as a temporary storage
- Gastrocolic reflex
- Mass movements to rectum which is normally empty
- Final water absorption
- Final electrolyte absorption
7
Q
What are the contents of the stomach for chemical digestion?
A
- Acid
- Pepsin
8
Q
What are the defences of the GI tract?
A
- Saliva
- HCl
- Liver (kupffer cells)
- Peyer’s Patches (Lymphoid follicles, Submucosa, mainly in terminal ileum)
9
Q
What are broad functions of the oesophagus?
A
- Rapid transport of bolus to stomach through thorax
- Upper oesophageal sphicnter prevents air from entering GI tract
- Lower oesophageal sphincter prevents reflux into the oesaphagus
10
Q
What are broad functions of the the stomach?
A
- Storage facility
- Produce chyme
- Infections control (HCL)
- Secrete intrinsic factor (Vit B12)
11
Q
What are broad functions of the the stomach?
A
- Storage facility (receptive relaxation)
- Produce chyme
- Infections control (HCL)
- Secrete intrinsic factor (Vit B12)
12
Q
What are the broad functions of the duodenum?
A
- Start of small intestine
- Neutralisation/osmotic stabilisation of chyme (HCO3 secretions)
- Digestion wrapping up (pancreatic secretions, bile)
13
Q
What are broad functions of Jejunum/ileum?
A
- Final digestion
- Nutrient absorption mainly in the jejunum
- Water/electrolyte absorption mainly in ileum
- Bile recirculation in ileum
- B12 absorption in the terminal ileum
14
Q
What is the structure of the peritoneum?
A
- Parietal peritoneum in contact with abdomen
- Visceral in contact with organs
- Space between parietal and visceral peritoneum with fluid
15
Q
How is the gut controlled?
A
- Autonomic nervous system
- Enteric nervous system
- Hormones and paracrine
16
Q
What presynaptic nerves formed by the sympathetic nervous system to supply the Gut?
A
- Greater splanchnic nerve (T5-T9)
- Lesser splanchnic nerve (T10-T11)
- Least (T12)
17
Q
What is the purpose of the splanchnic nerves?
A
-Synapse with pre-vertebral ganglia
(Coeliac, Renal, superior mesenteric, inferior mesenteric and others)
-Mainly innervate blood vessels
-Generally inhibits GI function
-Post ganglionic fibres extend to myenteric and submucosal plexus and release norepinephrine
-Reduces motility
18
Q
What are the nerves from he parasymapthic nervous system to the gut?
A
- Vagus nerve
- Pelvic splachnic nerves (S2-S4)
19
Q
What does the right and left vagus become in the gut?
A
- Right vagus becomes posterior vagal trunk
- Left vagus becomes anterior vagal trunk
20
Q
What is the functions of the parasymapathetic system on the gut?
A
- Pre ganglionic fibres (long) synapse in walls of the viscera
- Post ganglionic fibres (short) release Acetylcholine and peptides (GIP and VIP)
- Innervate smooth muscle/endocrine and secretory
21
Q
Which parts of the GI tract does the Pelvic nerve innervate?
A
- Transverse colon
- Anal canal
22
Q
Which parts of the GI tract does the vagus nerve innervate?
A
- Oesaphagus
- Transverse colon
23
Q
What are the features of the enteric nervous system?
A
- Divisions of the nervous system
- Can operate completely independently
- Exists from the oesophagus to anus
- It has 2 main plexuses: Submucosal and Myenteric
24
Q
What is another name for the submucosal plexus?
A
-Meissner’s Plexus
25
What is another name for the myenteric plexus?
-Auerbach's
26
What is the function of the submucosal and myenteric plexuses?
Submucosal
- Secretions
- Blood flow
Myenteric
-Motility
27
What is the route that hormones take in the GI tract?
- Released from endocrine cells
- Pass into portal circulation
- Pass through the liver
- Enter systemic circulation to end up close to their release point
28
How is Hal production inhibited?
Somatostatin
- Released by D cells in antrum of stomach and pancreas
- Stimulated by H+ (low pH) on stomach lumen. Food is buffer so when it leaves the stomach pH drops
- Inhibits G cells
- Stomach distension reduces due to reduced vagal activity
- Inhibits histamine release
29
What is the action of Gastrin in the gut?
- Acts on G cells in antrum of stomach
| - Increase gastric acid secretion
30
What is the action of cholecystokinin?
- I cells in duodenum and jejunum
| - Increases pancreatic/gallbladder secretions
31
What is the control of the release of CCK?
- Stimulated by fat and protein
- Gall bladder contracts
- Pancreas stimulated
32
What is the action of secretin?
- Increases HCO3 from pancreas/gallbladder
| - Decrease gastric acid secretion
33
What is the control of release of secretin?
- Release stimulated by H+ and fatty acids
| - Released from S cells in the duodenum
34
What is the action of GIP?
- Increases insulin
| - Decreases gastric acid secretion
35
What is the control of GIP release?
- Cells in the duodenum and jejunum
| - Stimulated by sugars, amino acids and fatty acids
36
Why does appendicitis present with central abdominal pain initially?
- Visceral peritoneum involved
| - Visceral afferents accompany sympathetic motor fibres back to spinal sensory ganglia
37
Why does pain localise to the Right iliac fossa (suprapubic region)?
- Involvement of the parietal peritoneum
- Due to somatic sensory pain
- Pain is localised
38
Where can visceral pain from foregut, midgut and handout structures be felt?
Foregut - Epigastric
Midgut - Periumbilical
Hindgut - Suprapubic/hypogastric
39
Which muscles in the GI tract are not smooth muscle and instead skeletal muscle?
- Pharynx
- Upper 1/3 of oesaphagus
- External anal sphincter (voluntary control)
40
What are the types of motility that occur in the GI tract?
Peristalsis
- Contraction proximal to contents and relaxation distal
- Propels contents in one direction
Segmentation
- Contraction splits contents then releaxes
- To and fro movement that mix contents
Mass movement
- Occurs in distal colon
- Rapid movement of contents into rectum
- Gastrocolic reflex
41
What is paralytic ileus?
Loss of GI contractility
| -Can occur following GI surgery
42
What is achalasia?
Failure of LOS to relax
43
What is Hirschsprung's disease?
- Lack of myenteric and submucosal plexus
| - Results in function obstruction
44
What is secreted in the GI tract?
- Water
- Acid
- Alkali
- Enzymes
- Mucus
- Waste products
- Emulsifiers
- Intrinsic factor
45
Where do secretion come from in the GI tract?
- Saliva (acini of salivary glands)
- Gastric (gastric glands)
- Intestinal (Brunner's glands, intestinal glands, Goblet cells)
- Liver (hepatocytes)
- Pancreas (exocrine pancreas)
46
What are the purposes of stomach acid?
- Innate barrier to infection
- Prepares proteins for digestion
- Activate enzymes
47
What are the emulsifiers in the GI tract and their purpose ?
- Bile salts
- Increase surface area of lipids
- Aids digestion by lipases
- Allows lipid breakdown products to be transported in the gut
48
What is the purpose of mucus in the GI tract?
- Protects against chemical damage due to acidic environment in stomach
- Protects against bacteria in small intestine
- Habours bacteria in large intestine
- Lubricates to reduce friction
- Forms physical barrier against bacterial inflammation
49
What are the principles of absorption in the GI tract?
- Movement across enterocyte
| - Movement paracellularly
50
How is the large surface in the Gi tract created?
- Plica circulares (Permanent folds in small intestine)
- Villi
- Microvilli
51
What are the effects of disrupting surface area in the gut?
- Diarrhoea
- Malnutrition
- Anaemia (Crohn's, Coeliac)
52
What is absorbed in the GI tract?
- Nutrients (carbohydrates, proteins, lipids, fat soluble vitamins, Vitamin B12, Bile salts, Ca2+, Fe2+)
- Electrolytes
- Water
53
How is water reabsorbed in the GI tract?
Passive
-After a meal, water uptake is driven by nutrients coupled with Na+ (sodium co-transporters)
In between meals
-Na+ and Cl- absorbed (sodium/hydrogen & chloride/bicarbonate exchangers)
In colon
-Additional mechanism so that stool can be desiccated (ENaC)
54
What are the layers of the gut tube?
- Mucosa
- Submucosa
- External muscle layers
- Serosa
55
What are the regions of the mucosa?
Epithelial layer
- Selectively permeable barrier
- Facilitate transport and digestion of food
- Promote absorption
- Produce hormones
- Produce mucus
Lamina propria
- Lots of lymphoid nodules and macropahes
- Produces antibodies to protect against bacteria/viral invasion
Muscularis mucosa
-Layer of smooth muscle in different direction to help keep crypt contents dynamic and epithelium in contact with gut contents
56
What are the contents of the submucosa?
- Contains dense connective tissue, blood vessels, glands, lymphoid tissue
- Contain submucosal plexus (Meissner's)
57
What are the contents inner circular muscle?
-Myenteric plexus
58
What are the contents of the serosa?
- Blood and lymph vessels and adipose tissue
| - Continuous with mesenteries
59
What are the epithelial regions of the gut?
- Stratified squamous in oesaphagus and distal anus
| - Everything in between is simple columnar
60
What is an enterocyte?
- Simple columnar epithelial that absorbs
- Predominant cell of small intestine and colon
- One cell thick
- Has microvilli
- Blood vessels/lymphatics lie immediately below the basolateral membrane of the enterocyte
61
What is the purpose of the enterocyte?
- Apical membrane (faces the lumen)
| - Basolateral membrane (faces blood vessels)
62
What is the structure of the goblet cells?
- Has a wide top and pushed down base nucleus
- Has a terminal bar, mucus droplet and basal nucleus
- Produces mucus to protect the epithelia against pathogens and keeps some bacteria alive
- Scattered in between enterocytes in intestinal epithelia
63
What the defences of the stomach?
- Surface mucus cells line gastric mucosa/gastric pits in stomach and secrete mucus/HCO3 that forms thick alkaline viscous layer that adheres to stomach epithelium acid to protect the stomach and keep the epithelial surface at a higher pH
- High turnover of epithelial cells to help keep epithelia intact
- Prostagladins to maintain mucosal blood flow to supply epithelium with nutrients
64
What are crypts of lieberkuhn (intestinal gland) and what do they contain?
Intestinal glands
- Stem cells
- Paneth cells
- Enteroendocrine cells
65
What is the purpose of the cells in the crypts of lieberkuhn?
Stem cells
- Constantly divide to replace epithelia (2-4 days)
- Mature as they migrate to surface
Paneth cells
- Located at base of crypts
- Secrete antibacterial proteins to protect stem cells
Enteroendocrine cells
- Secrete hormones to control functions of the gut
- Hormones such as gastrin, CCK and secretin
66
What are the effects of inflammatory bowel disease on crypts?
- Crypt alteration
- Cryptitis (inflammation of wall)
- Crypt abscess (neutrophils in lumen)
67
What do the acini glands tend to secrete?
- Serous (+enzymes) secretions
- Tubules tend to secrete mucous (Brunner's glands)
*salivary glands can be mixed
68
What is ulceration in the GI tract?
- Erosion through muscularis mucosae
| - Failure of protective merchiasnm such as mucus production
69
What is coeliac disease?
- Inability to tolerate gliadin found in gluten.
- Gluten is found in wheat, rye and barley
- Results in immune response which damages the mucosa leading to poor digestion and malabsorption
- Causs absence of intestinal villi and causes lengthening of intestinal crypts.
- Lymphocytes infiltrate epithelium
70
What are the layers of the abdominal wall?
- Skin
- Fascia/Fat (superficial and deep)
- 3X anterolateral muscles
- Peritoneum
71
Which muscle is enveloped by the aponeurosis of the lateral muscles?
Rectus abdominus
Forms the rectus sheath
72
What are the 3 anterolateral muscles?
- External oblique
- Internal oblique, transverse abdominis, Rectus abdominis)
- Transversalis fascia
73
What is the arcuate line?
- Lower limit of the posterior layer of rectus sheath
- Point at which inferior epigastric vessels pierce rectus abdominus
- Roughly half way between umbilicus and pubic crest
74
What is mesentery?
Double fold of peritoneum that teaches the viscera to the posterior abdominal wall
Contains blood vessels, lymph vessels, nerves and fat
75
What are the organs that are connected by mesentery?
- Jejenum
- Ileum
- Appendix
- Transverse Colon
- Sigmoid Colon
- Rectum
76
What is the peritoneal ligament?
Double fold of peritoneum that connect two viscera together
or
Double fold of peritoneum that connects viscera to the abdominal wall
77
What are the examples of peritoneal ligaments?
- Gastrocolic ligament (Stomach to transverse colon)
- Gastrosplenic ligament (Stomach to spleen)
- Falciform ligament (liver ot anterior abdominal wall)
- Triangular ligaments (liver to diaphragm)
78
What are the omenta?
- Double folds of peritoneum
- Greater omentum hangs off the greater curve of the stomach and folds back up and attaches to the anterior surface of the transverse colon
- Lesser omentum connects lesser curve of the stomach to the liver
79
What is the blood supply to the GI tract?
Arterial is from branches of the aorta
- Coeliac trunk
- Superior mesenteric artery
- Inferior mesenteric
Venous drainage goes to the liver via the Hepatic Portal Vein
-Portal system
80
What is the composition of saliva?
- Mostly water (Hypotonic)
- Rich in potassium and bicarbonate
- Mucins to help with lubrication
- Enzymes: Amylase, Lingual lipase
- Diversity of immune proteins
81
What are functions of saliva?
- Creation of bolus
- Initaite process of digestion
- Oral hygiene
- Transmitting disease
- Protection of mouth
- Speech
- Solvent for taste
82
What is xerostomia?
-Dry mouth
Can lead to dental cavities, mouth ulcers, bad breath and oral thrush
83
What are the 3 pairs of salivary glands?
- Parotid gland
- Sub lingual gland
- Sub mandibular gland
84
What is the oral preparatory phase?
- Voluntary
- Pushes the bolus towards the pharynx
- Once bolus touches the pharyngeal wall, pharyngeal phase begins
85
Describe the structure of the oesophagus and outline its functions
- Muscular layers
| - Transport of bolus from oral cavity to the stomach by peristalsis
86
Outline the pharyngeal phase of swallowing?
- Involuntary
- Soft palate seals of the nasopharynx
- Pharyngeal constrictors push bolus downwards
- Larynx elevates closing epiglottis
- Vocal cords duct to protect the airway and breathing temporarily ceases
- The upper oesophageal sphincter opens
87
Outline the anatomical relationships of the oesophagus
- Originates in the neck at 6th cervical vertebrae
- Sits posteriorly the larynx and trachea
- Closely related to the aorta (right hand side)
- Pierces the diaphragm at T10 (oesophageal hiatus)
88
What are causes of dysphagia?
Dysphagia is difficulty swallowing
Causes are
- Stroke that affect nerves controlling swallowing
- Oesophageal tumour (solid are a problem)
- Hardening of muscular layers
89
Describe the anatomical mechanisms that prevent gastro-oesophageal reflux.
- Lower oesophageal sphincter (diaphragm)
- Intra-abdominal oesophagus which gets compressed when intra-abdominal pressure rises
- Mucosal rosette at cardia to prevent back flow
- Acute angle of entry of oesophagus
90
Give an overview of the control of saliva production.
-Autonomic control
-Mainly parasympathetically controlled to stimulate salivary secretion
-Sympathetic also causes small amounts of saliva
secretion and can also vasoconstrict blood vessels
91
What is the structure of a salivary cell?
- Acinus line with acinus cells
- Ductal portion with ductal cells
- Myoepithelial cells
92
Outline the production of saliva.
- Acinus produces initial saliva which is isotonic and releases it into the ductal portion
- Ductal cells modify the initial solution to produce hypotonic saliva.
- Myoepithelial cells which help move saliva from the structure into the mouth
93
What is the purpose of kallikrein released in the saliva?
-Helps to produces bradykinin to vasodilate in the mouth in periods of maximum activity to allow blood flow to get to salivary glands
94
How does saliva flow rate affect its modification by duct cells?
- Increased flow rate of saliva results in less modification
- Decreased flow rate of saliva results in more modification by duct cells
*Bicarbonate gets excreted more at higher flow rates as an exception
95
How do duct cells form hypotonic saliva?
- Exchanging increased amounts of sodium, chloride from the saliva in the lumen into the cell compared to excreting bicarbonate and potassium back into the lumen.
- This results in a hypotonic solution
96
What are the nervous supply for the submandibular and sublingual?
-Parasympathetic from the facial nerve
97
What is the nervous supply fo rate parotid gland?
- Parasympathetic fibres from the glossopharyngeal fibres
| - Increases production of saliva
98
Which drugs could have an effect of the parasympathetic innervation of the salivary glands?
- Anti muscurinic
| - Can cause xerostomia
99
Outline the oesohaphgeal phase of swallowing?
- Involuntary
- Closure of the upper oesophageal sphincter
- Peristaltic wave carries bolus downwards into oesophagus
100
Outline the neural control of swallowing and the gag reflex?
- Mechanoreceptors in wall of pharynx detect the bolus
- Glossopharyngeal nerve carries sensory impulses to medulla
- Vagus nerve carries impulses to the Pharyngeal constrictors which contract to cause an effect
- Pushes the bolus inferiorly
*Gag reflex works the same. Psychological possibly
101
What are the narrowings found in the oesophagus?
- Tightest narrowing is the junction between the pharynx and oesophagus
- Second narrowing is when the arch of aorta crosses the oesophagus
- Third narrowing is when the left main bronchus crosses the oesophagus
- Final narrowing is when oesophagus passes through diaphragm (T10)
102
Outline some of the clinical consequences of free gastro-oesophageal reflux.
-Barrett's oesaphagus
103
Describe the protective mechanisms of the nasal cavity and the larynx during swallowing.
- The nasal cavity is protected by elevation of the soft palate
- The respiratory tract is protected by elevation of the larynx (which closes epiglottis) and adduction of the vocal cords.
104
Describe areas of potential weakness in the abdominal wall
- Inguinal canal
- Femoral canal
- Umbilicus
- Previous incisions
105
What is the inguinal canal and where does it pass in males and females?
Oblique passage through lower part of the abdominal wall
Males
-Structures pass through abdomen to testis
Females
-Round ligament goes through Uterus - Labium majus
106
Distinguish direct and indirect inguinal hernias
Indirect
- Lateral to the inferior epigastric vessels
- Goes through deep ring, inguinal canal and superficial ring
Direct Inguinal Hernia
- Bulges through Hesselbach's triangle
- Medial to inferior epigastric vessels
- Goes through the inguinal canal and superficial ring
107
Where can the deep and superficial ring be found?
- Deep ring in the posterior wall of inguinal canal
| - Superficial ring in the anterior wall of inguinal canal
108
Describe the structure of a hernia
Sac - Pouch of peritoneum
Contents of the Sac - Commonly loops of bowel, omentum but other structures as well
Covering of the Sac - Layers of abdominal wall through which the hernia has passed.
109
What can occur if the processus vaginalis doesn't close after the gubernaculum causes the testis to descend?
- Inguinal hernia (indirect)
| - Scrotal hernia
110
What are the borders of the inguinal canal?
Floor
- Inguinal ligament
- Lacunar ligament medially
Roof
- Internal oblique
- Transverse abdominus
Posterior wall
- Transversalis fascia
- Conjoint tendon medially
Anterior wall
-Aponeurosis of external oblique
111
Why are femoral hernias more common in females?
- Pelvic anatomy different. Femoral ring entrance is bigger in females
- Can get easily stuck
- If Stuck, can lead to strangulation of the hernia due to loss of blood supply. Ischaemia can result.
112
What are the borders of the femoral canal?
Medial border – Lacunar ligament.
Lateral border – Femoral vein.
Anterior border – Inguinal ligament.
Posterior border – Pectineal ligament, superior ramus of the pubic bone, and the pectineus muscle
113
What is an omphalocele?
- Congenital umbilical hernia
- Content herniate into umbilical cord
- Has peritoneal covering
114
What an acquired infantile hernia?
- Type of umbilical hernia
| - Contents herniate through weakness in scar of umbilicus
115
What is an acquired adult hernia?
- Type of umbilical hernia
- Herniation through linea alba in region of umbilicus
- More in females than males
116
What is an epigastric hernia?
- Occurs through linea alba
- Occurs between Xiphoid process to umbilicus
- Usually start with small hernia
- Chronic straining forces more fat out which can eventually pull peritoneum through
117
What are symptoms of hernias?
Varied. Based around what happens if loops of bowel get trapped
- Pain
- Vomiting
- Sepsis
118
What cell cover the surface of the stomach and extend into gastric pits/glands?
- Parietal cells
- Mucous cells
- Chief cells
- G cells
119
How does the stomach continue digestion?
Acidic conditions
- Helps unravel protein
- Activates proteases (pepsinogen to pepsin)
- Disinfects stomach contents
120
What does the stomach secrete?
- HCl
- Intrinsic factor
- Mucus/HCO3-
- Pepsinogen
121
What are the regions of the stomach proximal to distal?
- Cardia (below LOS)
- Fundus (Upper region)
- Body
- Pylorus
122
How is HCl production in the stomach controlled?
Parietal cells stimulated by
- Gastrin
- Histmaine
- ACh
123
How is gastrin production controlled?
G cells in antrum stimulated by
- Peptides/amino acid in stomach lumen
- Vagal stimulation by acetyl choline and GRP
124
What are examples of things that breach stomach defences?
- Alcohol dissolves the mucus layer
- Helicobacter pylori which can cause chronic active gastritis
- NSAIDS inhibit prostaglandin
125
What is gastrooesophageal reflux disease?
-Reflux of stomach contents into the oesophagus
126
What are the symptoms of gastro-oesophageal reflux?
- Heart burn
- Cough
- Sore throat
- Dysphagia
127
What are causes of gastro-oesophageal reflux?
- Lower oesophageal problems
- Delayed gastric emptying
- Hiatus hernia
- Obesity
128
What are complications that arise from gastro-oesophageal reflux disease?
- Barrett's oesophagus which is metaplasia of squamous epithelium to columnar. Increased risk of developing adenocarcinoma
- Oesophagitis
- Strictures
129
What is the treatment for gastro-oesophageal reflux disease?
-Lifestyle modifications
Pharmacological
- Antacids
- H2 antagonists (block histamine)
- Proton Pump Inhibitors
Surgery(rare)
130
What is acute gastritis?
Acute mucosal inflammatory process. Caused by:
- Heavy use of NSAIDS
- Lots of alcohol
- Chemotherapy
- Bile reflux
131
What are the symptoms of acute gastritis?
Asymptomatic most of the time but can present with
- Pain
- Nausua
- Vomiting
- Occasionally bleeding
132
What are the common causes of chronic gastritis?
Bacterial
-H pylori infection
Autoimmune
- Antibodies to gastric parietal cells
- Can lead to pernicious anemia
Chemical/reactive (minimal inflammation)
- Chronic alcohol abuse
- NSAIDS
- Reflux of bile
133
What are symptoms of chronic gastritis caused by H.pylori?
Asymptomatic or similar to acute gastritis
| -Symptoms may develop due to complications (peptic ulcers, adenocarcinoma, MALT lymphoma)
134
What are symptoms of chronic gastritis caused by an autoimmune disorder?
- Symptoms of anaemia
- Glossitis
- Anorexia
- Neurological symptoms
135
What is peptic ulcer disease?
Defects in gastric/duodenal mucosa that extend through the muscular mucosa
-Commonly in first part of duodenum and lesser curve of the stomach
136
What are the causes of peptic ulcer disease?
- Stomach acid
- H pylori
- NSAIDS
- Smoking
- Massive physiological stress
137
What are the symptoms of peptic ulcer disease?
Epigastric pain
- Burning/Gnawing
- Follows meal times
- Often at night
Serious symptoms
- Bleeding/anaemia
- Satiety (early)
- Weight loss
138
What is functional dyspepsia?
- Symptoms of ulcer disease
- No physical evidence
- Diagnosis of exclusion
139
What are the methods used to diagnose gastric pathology?
- Upper GI endoscopy (biopsies)
- Urease breath test
- Erect chest X-ray (perforation)
- Blood test (anaemia)
140
What is the treatment for peptic ulcer disease?
- Eradicate H-pylori
- Stop NSAIDS
- Endoscopy for bleeding ulcers and follow up fro treated gastric ulcers
- PPIs
141
How do H2 blockers work?
-Stop histamine components which stimulate parietal cells
142
Describe the pathogenesis of helicobacter-pylori?
- Spread via faecal-oral route
- Helix shaped gram negative
- Produces urease which covers urea to ammonium to increase local pH
- Has flagellum for good motility. It lives in mucus layer/adheres to gastric epithelia
143
How does helicobacter pylori cause problems?
- Relase cytotoxins to cause direct epithelial injury
- Expresses urease which can form ammonia which is toxic to epithelium
- Possibly degrades mucus layer
- Promotes inflammatory response which can cause self injury
144
What is the pathological result of the location of H-pylori colonisation?
In antrum
-Duodenal ulceration
In antrum and body
-Asymptomatic
Predominantly in body
-Can lead to cancer
145
What are causes of stress ulceration?
- Severe burns
- Raised intracranial pressure
- Sepsis
- Severe trauma
- Multiple organ failure
146
Describe the key properties of chyme leaving the stomach
- Hypertonic
- Low pH
- Partially digested
147
List the secretions of the exocrine pancreas
Acini
- Amylases
- Lipases
- Proteases (trypsin, chymotrypsin, Elastase, Carboxypeptidase
Duct cells
- Aqueous compenent
- Bicarbonate
148
What stimulates pancreatic and biliary secretions?
Secretin
CCK (enzymes)
Autonomic (PNS stimulates, SNS inhibits)
149
Describe the mechanism of secretion of alkaline juice
- Stimulated by secretin
- Release of aqueous bicarbonate component of pracretuc secretions by duct cells to neutralise chyme. Also released as part of bile
150
Describe how the microscopic structure of the liver relates to its functions
- Hexgonal arrangement
- Triad of structures at each corner (portal vein, hepatic artery, bile duct)
- Substance brought liver start at periphery and work towards middle
- Central vein in the middle
- Blood enter lobule via hepatic artery and portal vein
- Blood flows toward central vein via sinusoids (low pressure)
- Bile flows out alone canaliculi then bile duct into duodenum
151
Why are pancreatic proteases release in inactive forms?
- Inactive protease enzymes (zymogen) produced within acinar cells and are concentrated and stored in zymogen granules
- The enzymes are converted to active forms where they need to be used
152
Describe the digestive functions of the liver and the components of bile
Liver secretes bile into duodenum to emulsify fat so they can be readily digested by lipases secreted by pancreas
Bile consists of
- Bile acids and bile pigments
- Alkaline solution
153
The liver acinus is divided in zone 1, 2, 3 starting from the periphery towards the centre. Where is toxic and ischaemic damage likely to have a greater effect?
Toxic
-Zone 1. Last region to receive blood supply
Ischaemic
-Zone 3. Last region to receive blood supply
154
Describe the function of the gall bladder and the relationship to the formation of gallstones
- Bile is stored in the gallbladder
| - Concentrates bile which can lead to gallstones
155
Describe the secretion of bile acids and the entero-hepatic circulation of bile acids
-CCK stimulates bile release by causing gallbladder contraction
156
What are bile salts?
Two primary acids
- Cholic acid
- Chenodeoxycolic acid
Bile salts are bile acids conjugated with amino acids
157
Why are bile acids conjugated?
- Not always soluble at duodenal pHs
| - Bile salts have amphipathic structure so can fact at oil/water interface
158
Describe the mechanisms of digestion of fats
- Lipids tend to form large globules by time reached duodenum which results in small surface area for enzymes to act
- Bile salts emulsify fat into smaller units to increase surface area and allow lipases to act
- Bile salts then create micelles with product of lipid breakdown
- Micell transports digested lipids to luminal membrane of enterocyte
- Lipids diffuse into intestinal epithelial cells
159
What is the enter-hepatic circulation of bile acids?
- Bile salts remain in gut
- Reabsorbed in terminal ileum
- Returned to liver in portal blood
Liver recycle bile acids
160
How are digested fat transported to the blood circulation?
- Inside the enterocyte, lipid molecules are built back up again into triglycerides, phospholipids and cholesterol
- Lipids packed with apoproteins within enterocyte into chylomicrons
- Chylomicrons exocytosed from basolateral membrane of enterocyte ad enter lymph capillaries into thoracic duct
161
What is steatorrhoea?
- Certain pathologies may cause bile acids or pancreatic lipases to not be secreted in adequate amounts
- Undigested fat appears in faeces. It is pale, floating and foul smelling
162
What are the symptoms of coeliac disease?
- Diarhoea
| - Flatulence
163
How does chyme becomes isotonic as it leaves the duodenum?
- Stomach is impermeable to water
- Duodenum is relatively permeable to water
- Hypertonic chyme draws movement of water from ECF/circulation into duodenum
164
What are the key points of carbohydrate digestion?
- Carbohydrates are chains of sugars (Polysaccharides, Disaccharides, Monosaccharides)
- Only monosaccharides can be absorbed (Fructose, Galactose, Glucose)
- Final breakdown occurs in brush border by brush border hydrolases
- Glucose can only enter with Na+
- Fructose can enter from lumen through GLUT-5
165
How is starch digested?
- Amylase
- Break in the middle results in maltose. Maltase can digest maltose
- Break at the end results in glucose
- Isomaltase can disrupt branching chains to form glucose from alpha dextrin
166
How are monosaccharides absorbed?
- Na+/K+ ATPase on basolateral membrane maintains aa low intracellular Na+
- SGLT1 bind to Na+. Allows glucose to bind which allows Na+ and glucose to move into cell
- GLUT2 transports glucose out of enterocyte as the basolateral membrane. Diffuses down gradient into capillary blood
167
What are the principles of oral rehydration?
- Uptake of Na+ generate osmotic gradient and water follows
- Glucose uptake stimulate Na+ uptake
- Mixture of glucose and salt will stimulate maximum water uptake
168
What are the principles of protein digestion in stomach?
- Only amino acids, dipeptides and tripeptides absorbed
- Pepsinogen released from chief cells which gets converted to pepsin by HCl
- Pepsin acts on protein to form oligopeptides /amino acids which move to the small intestine
169
What are the principles of protein digestion in small intestine?
- Pancreas release proteases as zymogens
- Trypsinogen conver to trypsin by enteropeptidase. Trypsin then activates other proteases
- Endopeptidases (Trypsin, Chymotrypsin, Elastase) produce shorter polypeptides
- Exopeptidases (carboxypeptidase A & B) produce dipeptides and amino acids
170
How are protein product absorbed?
- Amino acids are transported into cell by Na+-amino acid co-transporters (neutral, acidic, basic, imino)
- Dipeptides/tripeptides moved by H+ co-transporter called peptide transporter 1 into the cell where they are converted to amino acids by systolic peptidases
171
Describe the basis of electrolyte and water uptake in the GI tract?
- Na+ moved by activ transport of the cell on basolateral membrane
- Na+ diffuses into epithelial cells
- Osmoic gradient from all bsoritpn leads to uptake of water. The fluid absorbed is isoosmotic
172
What are the similarities and differences in electrolyte/water uptake in small intestine vs the large intestine?
-Both have Na+-K+ ATPase on basolateral membrane
Apical membrane
- Na+ is co-transported in the small intestine
- Na+ channels in the large intestine which is induced by aldosterone (ENaC)
173
Describe uptake of calcium in the intestine?
When calcium intake is low
- Active transcellular absorption so it enters cell via facilitated diffusion
- Ca+ ATPase removes Ca+ from basolateral membrane
- Process requires Vitamin D and is stimulated by parathyroid hormone.
When calcium intake is normal/high
-Passive paracellular absorption
174
Describe the uptake of iron in the GI tract?
- Mostly in haem/Fe2+
- Gastric acid is important in the process
- Iron absorbed across apical membrane. This is via co-trasnport with H+
- If iron levels are low, iron binds to transferrin to be transported to stores
- If iron levels are high, iron contained in ferritin complexes and trapped in cells. Lost when enterocyte is replaced
175
How are water soluble vitamins absorbed?
Absorbed by Na+ co-transport (Vitamin C/B)
-Vitamin B12 absorbed in terminal ileum bound to intrinsic factor which is secreted by gastric parietal cells. Removal of terminal ileum and gastritis can cause B12 deficiency
176
What investigations done for coeliac disease?
- Upper GI endoscopy and biopsies. Checks for mucosal pathology and whether villli are reduced or absent
- Bloods (Serology, Electrolyte imbalances and Anaemia)
- Treatment (diet)
177
Describe red cell breakdown.
- 120 days
- Occurs extravascularly in macrophages in spleen and liver
- Bilirubin released by heme breakdown. It is hydrophobic and therefore bound to albumin before being carried to the liver
- Bilirubin conjugated with glucoronic acid by UDP glucoronyl transferase
- Conjuaged bilirubin is water soluble and secreted by hepatocyte into bile canaculi
178
Describe bilirubin transport?
- Conjuagted bilirubin is converted to urobiligoen in the intestine and kidney
- In the intestine urobilinogen is converted to stercobilin
- In the kidneys urobilinogen is converted to urobilin which is light yellow
179
How do we measure liver dysfunction?
- Failure of anabolism (albumin, glycogen, numerous coagulation factors, Haematopoiesis in fetus)
- Failure to catabolise and excrete (drugs, hormones, haemaglobin, poisons, can take over removal of aged red cells after splenectomy)
- Markers of hepatocyte damage
180
What is the results of failure of anabolism?
- Prolonged prothrombin time (inr)
- Signifies serious liver damage
- Hypoalbuminaemia reflects severe liver dysfunction
- Signs of severe liver damage
181
What is pre-hepatic jaundice?
-Too much bilirubin
| Caused by haemolytic anaemia for example
182
What is intra-hepatic jaundice?
-Failure of hepatocytes to conjugate and/or secrete most of the bilirubin presented to them. Stasis within the liver is called cholestasis.
Caused by hepatitis, cirrhosis for example
183
What is post-hepatic jaundice?
-Failure of the biliary tree to convert the conjugated bilirubin to the duodenum.
Caused by biliary tree obstruction such as gallstones or carcinoma of the head of pancreas
184
What is result of increased serum levels of conjugated bilirubin?
-Water soluble so will be excreted in the urine and turn the urine dark yellow. Can be measured with a dipstick
185
What is the result of increased level of urobilinogen?
Will not noticeable colour the urine but can be measured with a dipstick
186
Why does pruritus occur in post-hepatic jaundice?
-Inability to secrete bile salts leading to itching
187
What are the signs of pre-hepatic jaundice?
- Dark stools
- Normal urine colour
- Mild jaundice
- No prurities
188
What are the signs of intra-hepatic jaundice?
- Moderate jaundice
- Stools normal
- Urine is dark
- No pruritus usually
189
What are features of post-hepatic jaundice?
- Raised serum bilirubin
- Decreased urinary urobiliogen
- Conjuagted bilirubin present in urine
190
What are features of intra-hepatic jaundice?
- Raised serum biliruibin
- Normal urinary urobiliogen
- Conjugated bilirubin present in urine
191
What are features of pre-hepatic jaundice?
- Raised serum bilirubin
- Increased urinary urobiliogen
- No conjugated bilirubin present in urine
192
What are signs of post-hepatic jaundice?
- Severe jaundice
- Stools pale
- Urine is dark
- Pruritis
193
What are markers of liver damage?
- ALT
- AST
- Alk Phos
- Gamma GT (alcohol induced so can indicate alcoholism)
194
What are the causes of increased Alk Phos?
Bone disease
- Bone metastases
- Bone fracture
- Osteomalacia
- Hyperparathyroidism
- Paget's disease of bone
Liver disease with cholestasis
- Biliary obstruction
- Cirrhosis
- Liver metastases
- Drugs
*Normally high in growing bone
195
What are causes of Raised ALT?
Hepatitis
- Viral
- Acute alcohol intake
- Fatty liver disease
- Drugs/toxins
196
What are causes of raised Gamma GT?
- Biliary duct obstruction
- Cirrhosis
- Liver metastases
- Drugs
- Alcoholism
197
What are common liver and bile duct disease?
- Hepatitis
- Cirrhosis
- Gallstones and biliary tract obstruction
- Liver metastases
198
What is pathology underlying hepatitis?
-Inflamed and/or necrotic hepatocytes that cannot function normally
199
What are the implications of liver failure?
- Increased susceptibility to infections (bacterial mostly)
- Increases susceptilibit to toxins and drugs
- Increased blood ammonia due to failure to clear ammonia via urea cycle
- Ammonia is produced by colonic bacteria and deamination of amino acids. this can causes hepatic encephalopathy
200
What are symptoms of hepatitis?
- Feeling generally unwell
- Anorexia
- Fever
- Right upper quadrant pain
- Dark urine
- Jaundice
201
What are typical blood test findings in acute hepatitis?
- Normal albumin and INR
- High serum bilirubin
- Conjugated bilirubin present in the urine
- Very high serum ALT
- Normal/Silghtly raised Alk Phos
- Normal/Silghtly raised Gamma GT
202
What is liver cirrhosis and causes?
-Liver fibrosis producing a shrunken hard nodular liver
Caused by alcohol, Viral hepatitis, Fatty liver disease and Idiopathic
203
What are the effects of liver fibrosis?
- Pressure and occlusion of the hepatic sinusoids leads to portal hypertension which leads to portosystemic shunting, including oesophageal varices, diverting nutrient-carrying blood away from the liver.
- Pressure on the bile canaliculi and therefore reduced ability to excrete toxins, bilirubin.
- Replacement of hepatocytes by fibrous tissue which leads to reduced albumin and clotting factor production
204
What are the sites of portosystemic anastomoses?
- Anorectal juction
- Ligamentum teres of falciform ligament
- Oesophagogastric junction
205
What are symptoms of cirrhosis?
- Fatigue/Weakness
- Bleeding and bruising early
- Swollen abdomen
- Swollen legs
- Weight loss
- Jaundice
- Haematemesis and/or malena
- Confusion, drowsiness and slurred speech
206
How can cirrhosis be treated?
- Not possible to reverse
- Treatment aimed at dealing with complications
- Only cure is liver transplantation
207
What is cholangitis?
Life threatening complication of bile duct obstruction as a result of infection in the bile ducts. Commonest bacteria is E.Coli
-Obstruction is common due to to gall stones in common bile duct
208
What is a biliary colic?
- Not a true colic. Pain is constant
- Pain in the right upper quadrant that radiates to the tip of the right scapula/shoulder due to irritation of diaphragm
- Often precipitated by eating a fatty meal and can last up to 6 hours
209
What is acute cholecystitis?
- Gallstone obstructs the cystic duct then there is stasis of the gallbladder contents which is an infection risk
- Infecting organism is E.Coli
210
What are the symptoms of acute cholecystitis?
- Severe gall bladder pain
- Systemically unwell and toxic
- Pyrexial
- Tender over gall bladder
211
What is acute pancreatitis?
-Premature activation of pancreatic proteases in the pancreas itself rather than the duodenum. Protease then auto digest the pancreases and retroperitoneum
212
What is chronic pancreatitis?
- Rare and due to repeated low grade pancreatitis that causes pancreatic fibrosis.
- Due to alcohol abuse
- Pancreas become calcified and patients suffer severe epigastric and back pain that leads to opiate addiction and not infrequently suicide.
213
What is the aetiology of acute pancreatitis?
- Alcohol alters the balance between proteolytic enzymes and protease inhibitors thus triggering enzyme activation, auto digestion and cell destruction
- Gallstones blocking the ampulla of vater lead to outflow obstruction with pancreatic duct hypertension and a toxic effect of bile salts contribute to activation of pancreatic proteases.
214
What are symptoms of acute pancreatitis?
- Epigastric pain that goes through the back
- Vomiting
- Dehydration
215
How is acute pancreatitis diagnosed and treated?
Investigations
- Raised serum amylase or serum lipase
- CT scan may be used in moderate/severe cases to look for pancreatic necrosis/pseudocyst. Necrosed pancreas is non-enhancing with contrast
Treatment of acute pancreatitis
- No specific treatment
- Analgesis, supportive treatment
- Fluid resuscitation as patient can sequester litres of fluid in their retropeiritoneum
216
What is clinical presentation of pancreas cancer?
- Anorexia, Malaise, Fatigue
- Significant weight loss
- Epigastric and/or back pain
- Dark urine
- Pale Stools
- Pruritis
217
What is clinical presentation of an AAA?
- Sudden death
- Sudden onset of severe abdominal and back/loin pain
- Sudden collapse
- Presents to the emergency department with shock. 83% mortality. Most patient die of multi-organ failure on the ITU
218
What are 2 common types of inflammatory bowel disease?
- Crohn's disease
| - Ulcerative colitis
219
What are the gross pathological features of Crohn's disease?
- Affects anywhere in the GI tract. Ileum in most cases
- Skip lesions
- Cobblestone appearance
- Transmural inflammation
- Fistulae
- Mucosal oedema
- Discrete superficial ulcers
- Thickening of bowel wall
- Narrowing of lumen
220
What are the gross pathological features features of ulcerative colitis?
- Begins in rectum
- Can extend to involve entire colon
- Continuous pattern
- Mucosal inflammation
- Loss of haustra
- Pseudopolyps
221
What are the causes of intestinal inflammation and infection?
- Genetic
- Gut organism
- Immune response (Triggered by Antibiotics, Infections, Diet, Smoking)
222
What is the presentation of Crohn's disease?
- Weight loss
- Right lower quadrant pain
- Joint pains
- Young patient
- Tender mass
- Mild perianal inflammation/ulceration
- Low grade fever
- Mildly anaemic
223
What is the presentation of Ulcerative Colitis?
- Bloody stool
- Mucus in stool
- Weight loss
- Mild lower abdominal pain/cramping
- Painful red eye
- Mildly tender abdomen
224
What are microscopic features of Crohn's disease?
-Granuloma formation
225
How is Crohn's disease investigated?
- Bloods (Anaemia)
- CT/MRI scans (Bowel wall thickening, Obstruction, Extramural problems)
- Barium enema/follow through (Used less, Strictures/fistulae, Colonoscopy)
226
What are microscopic features of Ulcerative colitis?
- Crypt abscesses
- Crypt distortion
- Goblet cells
- Chronic inflammatory infiltrate of lamina propria
227
How is ulcerative colitis investigated?
- Stool cultures
- CT/MRI – less useful in diagnosing uncomplicated UC
- Plain abdominal radiographs
- Bloods (Anaemia, Serum markers)
- Barium enema (mild cases only)
- Colonoscopy
228
What are radiological features of Crohn's and Ulcerative Colitis?
Crohn's
-String sign of cantor. Normal size lumen that becomes thinner due to strictures
ULcerative colitis
- Lots of ulceration between contrast
- Loss of haustra leading to featureless colon. Lead pipe colon
229
What are the medical treatment options of inflammatory bowel diseases?
- Aminosalicylates
- Corticosteroids
- Immunomodulators
230
What are the surgical treatment options of inflammatory bowel diseases?
Crohn’s
- Not curative
- Strictures/fistulae
- As little bowel removed as possible
Ulcerative colitis
- Curable (colectomy)
- Inflammation not settling
- Pre-cancerous changes
- Toxic megacolon
231
What is the nerve supply of the peritoneum?
- Parietal peritoneum is supplied by the same nerve that supply skin of abdomen. Perceives inflammation as pain at the site of the inflammation
- Visceral peritoneum is supplied by the nerve supply of the viscera it invests. This produces referred pain
232
What are the symptoms of peritonitis?
- Severe pain all over abdomen which may refer to the shoulder tips
- Rigid abdomen as diaphragmatic and abdominal wall movement greatly increases pain.
- Shallow rapid breathing
- Very tender on examination of abdomen
- Rebound tenderness may occur in early stages
233
Describe the common life threatening events occurring in the abdominal cavity
Blood loss
- Into the gut
- Into the retro-peritoneum (AAA, patients on anticoagulants may bleed from torn retroperitoneal veins)
- Into the peritoneal cavity
Perforation of a viscus
-Allows the outside world to enter the peritoneal cavity causing inflammation, hypovolaemia and sepsis
Autodigestion of the retroperitoneum due to acute pancreatitis
Acute cholangitis
Acute gut ischaemia
234
What is the clinical presentation of bowel perforation?
- Severe generalised abdominal pain
- Patient lies still, shallow breathing
- Patients will be hypovolemic
- Patient may be septic
Symptoms of peritonitis
235
What is the clinical presentation of bowel ischaemia?
- Severe abdominal pain
- Tender over ischaemic gut
- Becomes rapidly toxic and hypotensive
- Very high white cell count
236
What is the clinical presentation of pancreatitis?
- Significant dehydration due to vomiting and fluid sequestration in retroperitoneum
- Raised serum amylase
237
What is the clinical presentation of cholangitis?
```
Charcots triad
-Jaundice
-Fever
-Right upper quadrant pain
May also have Reynold pentad
-Hypotension
-Confusion
-Rigors
```
May develop septic shock due to the bile duct being blocked by bacteria. This leads to canaliculi backing up into the central vein and this is a huge area of contact between the infected area and the blood.
238
What is the underlying pathology in relation to abdominal aortic aneurysm?
-Sudden Blood loss
239
What is the underlying pathology in relation to bowel perforation?
- Perforated peptic ulcer can leads to chemical peritonitis. 10% mortality
- Perforated diverticular disease can lead to peritoneal sepsis and septicaemia. 50% mortality
- Posterior perforation of gastric ulcer initially allows gastric contents to enter the lesser sac. Thereafter the fluid can track into the greater sac via the epiploic foramen.
- Faecal peritonitis can occur with perforation of large bowel
240
What is the underlying pathology in relation to bowel ischaemia?
-Embolism (atrial fibrillation)
241
What is the clinical presentation of bleeding oesophageal varices?
- Haematemesis
| - Malaena
242
What is the clinical presentation of bleeding peptic ulcer disease?
- Haematemesis
| - Malaena
243
What is the clinical presentation of bleeding diverticular disease?
-Bright red bleeding per rectum (haematochezia)
244
What is malaena?
- Melaena is due to alteration of blood by digestive enzymes and can occur with bleeding from anywhere from the mouth to caecum
* Patients taking oral iron can have black stools. The smell reveals the difference
245
What is haematemesis?
Vomiting blood
246
What is the significance of urea measurement for GI bleeds?
- Bleeding from the stomach or oesophagus presents with a large protein meal to the small bowel.
- The protein is converted by the liver into urea.
- Rise in blood urea in patient with oesophageal/gastric bleeding will help indicate (if the creatinine is normal) source of bleeding and size of the bleed
247
1. describe the key features of the gut immune response to infection, including the Gut-associated lymphoid tissue (GALT)
2. describe the importance of the gut microbiome and the role of commensal organisms
6. Describe an approach to a patient presenting with traveller’s diarrhea and
consider protozoa such as Giardia and Entamoeba
ggggg
248
Describe an clinical approach, with regard to history, examination and investigation of a patient presenting with gastroenteritis
- History
- Physical examination of hydration status
- Abdominal examination
- Take appropriate samples and request right test
249
What is the main example of a viral cause of gastroenteritis?
- Norovirus
- PEak incidence in the winter and affects all ages
- Immunity is short-lived and reinfections can occur
- Resits freeing, disinfection with alcohol and temperature up to 60 C
250
How is norovirus transmitted?
- Faeco-oral person to person transmission
- 24 hour incubation period
- Viral particles shed in stool and vomit and fomites can contaminate environment
251
What is route of infection for shigella infection?
- Faecal oral route
| - Direct person to person
252
Describe Shigella.
- Gram negative facultative anaerobic
- Rod shaped
- Non-spore forming
- Non motile
253
What are the virulence factors of Shigella?
- Plasmid
| - Shinga toxin (exotoxin)
254
How does shigella cause diarrhoea?
- Enters the interstitial epithelial cells by endocytosis
- Escapes from the endocytic vesicle and multiplies inside the cell
- Mucosal abscesses from leading to cell death and this results in diarrhoea with blood and mucus
255
Describe the key features of Cryptosporidium
-Microscopic parasite
256
What is the route of infection for cryptosporidium?
-Faecal oral route
257
How can salmonella cause gastroenteritis?
- Salmonella invade epithelial cells of the small intestine.
- Disease may remain localized or become systemic, sometimes with disseminated foci.
- The organisms are facultative, intracellular parasites that survive in phagocytic cells
258
Describe salmonella
- Gram negative baccili
- Spore forming
- Motile
259
What are some virulence factors of salmonella?
- Endotoxins
| - Fimbraie
260
Recognise and describe the importance of infection prevention and infection
control measures with regard to GI infections
- Handwashing
- Isolation
- Environmental cleaning
- 48 hour rule especially for healthcare professional, childcare, schools and food handlers
261
How are GI infections treated?
- Fluid resuscitation
- Antibiotics if immunocompromised
- Treatment of underlying conditions
262
Describe how G.I. cancers may spread within the body
- Blood stream
| - Lymph
263
What are risk factors of oesophageal carcinomas?
- Smoking
- Obesity
- Barrett's
264
What are histological features of malignancies in the oesophagus?
- Squamous cell carcinoma
| - Lower third can develop adenocarcinoma from Barretts
265
What is the incidence of GI cancer from most common to least common?
1. Bowel
2. Pancreas
3. Oesophagus
4. Stomach
5. Liver
266
What is the clinical presentation of Gastric Cancer?
- Similar pain to peptic ulcer
| - 50% have palpable mass
267
What are risk factors of Gastric Cancer?
- Smoking
- High salt diet
- Family history
- Chronic inflammation (chronic gastritis by H.Pylori)
268
What is the most important environment factor for stomach cancer?
-H.Pylori
269
Which part of the GI tract is the most common site for a primary gastrointestinal lymphoma?
- Stomach
- MALT tissue
- Most associated with H.Pylori
- Similar presentation to gastric carcinoma but prognosis better
270
What are the histological features of stomach cancers?
- Adenocarcinomas
- Arise from chronic gastritis common or metaplasia.
Stomach ulcers potentially malignant
271
Why does gastric cancer have a poor prognosis?
-Present late and are therefore advanced
272
How does pancreatic cancer present?
Head
- Painless jaundice (Interferes with biliary flow into duodenum. )
- Persistent pain
- Weight loss anorexia
- Fatigue
Body/Tail
-Symptoms more vague
273
What are the risk factors for pancreatic cancer?
- Family history
- Smoking
- Chronic pancreatitis
- Men more than women
- Incidence increases with age. Typical over 60 years
274
What is the histological features of pancreatic cancer?
- Commonly (80%) are ductal adenocarcinomas
| - Commonly affects head of pancreas
275
What is the clinical presentation of small bowel cancer?
- Per rectum bleeding
- Change in bowel habit (frequency, consistency, discomfort)
- Weight loss
- Abdominal pain
276
What are risk factors of small bowel cancer?
- Inflammatory bowel disease
- Coeliac disease
- Familial adenomatous polypoids
- Diet
277
What are risk factors of large bowel cancer?
- Family history
- Inflammatory bowel disease
- Polyposis syndromes (FAP)
- Diet and lifestyle
278
What the histological features of small bowel cancer?
Rare!
- Stromal
- Lymphoma
- Adenocarcinoma
- Sarcoma
- Carcinoid tumours
279
What are the histological features of large bowel cancer?
-Adenocarcinoma (mostly in rectum and sigmoid colon)
Most can be viewed with sigmoidoscope
280
What is the basis for most colorectal cancer?
- Adenomas are the basis of most colorectal cancers.
- Demonstrated by
familial adenomatous polyposis, an inherited condition where invariably the
numerous adenomas present will undergo malignant change.
281
What genetic events are coleorectal cancers related to?
- Activation of oncogene
- Ineffective DNA repair
- Loss of tumour suppressor genes
282
What are the features of rectal cancers?
Usually ulcerating and therefore give PR bleeding. They
can also produce the symptom of tenesmus due to distension of the rectum.
283
What is the clinical presentation of left sided colon cancer?
- Weight loss
- Bowel obstruction (Contents are more solid on left side)
- Tenesmus
- Early change in bowel habit
- Less advanced disease at presentation
- Rectal bleeding
- Abdominal pain
- Mass in left illiac fossa
284
What is the clinical presentation right sided colon cancer?
- Weight loss
- Anaemia
- Occult bleeding
- Mass in right iliac fossa
- Disease more likely to be advanced at presentation
- Caecum and colon are more distensible so obstruction doesn't occur early
285
Describe the adenoma-carcinoma sequence
Benign growth derived from genetic changes
- Become hyperplastic
- Abnormal differential leads to dysplasia of the cells
- Dysplastic cells have potential to become cancerous
286
What are the contents of the external muscle layers?
- Inner circular muscle
| - Outer longitudinal muscle
287
What are the ligament of the liver and their attachments?
Falciform ligament
-Attaches the anterior surface of the liver to the anterior abdominal wall. Free edge contains the ligamentum teres
Coronary ligament
-Attaches the superior surface of the liver to the diaphragm
Right and Left Triangular ligament
-Attaches the superior surface of the liver to the diaphragm
Inferior vena cava – Secures to the posterior surface of the liver through hepatic veins and fibrous tissue
Lesser omentum
288
What are the parts of the lesser omentum
Hepatic duodenal ligament which extends form the duodenum to the liver
Hepatogastric ligament which extends from the stomach to the liver
289
What are the macroscopic features of the liver?
4 lobes
- Divided into right and left lobes by the falciform ligament
- Caudate lobe on the upper aspect of the visceral surface. Lies between inferior vena cava and a fossa produced by the Ligamentum Venosum
- Quadrate lobe located on the lower aspect of the visceral surface. Lies between gallbladder and a fossa produced by the Ligamentum Teres
290
What are the main branches of the coeliac trunk and their path?
- Left gastric which travels along the lesser curve of the stomach where it anastomose with the right gastric artery
- Splenic artery which travels towards the spleen running posteriorly to the stomach and along the superior margin of the pancreas. Terminates to supply the spleen
- Common hepatic arteries which travels past the superior aspect of the duodenum
291
What are the branches of the splenic artery and area of supply ?
- Pancreatic branches which supply the body and tails of the pancreas
- Left gastroepiploic which supplies the greater curvature of the stomach
- Short gastric which supplies the fundus of the stomach
292
What are the branches of the common hepatic artery and path?
- Proper hepatic artery ascends through lesser omentum
| - Gastroduodenal artery descends posterior o the superior portion of the duodenum
293
What are the branches of the gastroduodenal artery and area of supply?
- Right gastroepiploic which supplies the greater curvature and greater omentum
- Superior pancreatoduodenal artery which supplies the head of the pancreas
294
What are the branches of the proper hepatic artery and their area of supply?
- Right gastric to supply the pylorus and lesser curvature of the stomach
- Right and left hepatic artery which divide inferior to porta hepatis to supply the respective lobes of the liver
- Cystic which is a branch of the right hepatic which supplies the gallbladder
295
What are the regions of the peritoneal cavity?
- Greater sac (larger portion)
| - Lesser sac
296
What are the areas of the greater peritoneal sac separated by?
Transverse colon
- Supracolic
- Infracolic
297
How are the colics connected by?
Paracolic gutters
298
Where does the lesser peritoneal sac lie?
- Lies posterior to the stomach
- Known as omental bursa
- Allows stomach to move freely against the structures inferior and posterior to it
299
What connect the greater and lesser sac?
-Epiploic foramen which lies posterior to the ligamentum teres
300
Where does the rectovesical pouch lie?
Double folding of peritoneum between the rectum and the bladder. The peritoneal cavity is completely closed in males.
301
Where does the pouch of Douglas lie?
Rectouterine Pouch
Double folded extension of the peritoneum between the rectum and the posterior wall of the uterus.
302
Where does the vesicouterine pouch lie?
The vesicouterine pouch is a double fold of peritoneum between the anterior surface of the uterus and the bladder.
303
What are the primarily retroperitoneal organs?
- Oesophagus
- Rectum
- Kidneys
304
What are the secondarily retroperitoneal organs?
- Ascending colon
| - Descending colon
305
Describe the surface anatomy of foregut organs on the abdominal wall.
Stomach - Epigastrium
Duodenum - Epigastrium
Liver – Lies in the dome of the right diaphragm. Right hypochondrium and epigastric region
Pancreas – Lies in C shape of duodenum. Behind the stomach. Tail in left Hypochodnrium
Spleen – Lies near 10th rib and posterior
306
Describe the surface anatomy of the midgut organs on the abdominal wall.
Jejunum - Left lumbar and umbilical regions of abdomen
Ileum – terminate in right inguinal region and mainly lower portion of abdomen
Caecum – Appendix arise here. Right inguinal region
Ascending Colon – Arise from right inguinal region to right lumber region
307
Describe the surface anatomy of the hindgut organs on the abdominal wall.
Transverse colon – Arise from the ascending colon and travels transversely across abdomen
Descending colon – Left lumber region to Left inguinal
Sigmoid colon – Arises from left inguinal
Rectum
308
What is formed by the aponeuroses of all the flat muscle in the midline?
Linea alba
309
Which muscle is located in the middle of the abdominal wall?
- Rectus abdominus
- Split into 2 by the linea alba
- Lateral border is the linea semilunares
- Tendinous intersections form the six pack
310
What forms the anterior wall of the rectus sheath?
-Aponeuroses of the external oblique and half of the internal oblique
311
What forms the posterior wall of the rectus sheath?
-Aponeuroses of half the internal oblique and transverse abdoniums
At Arcuate line the apoenurses all become anterior
312
What is the path of the superior mesenteric artery?
- Arises at L1 anteriorly to the abdominal aorta
- Descends down the posterior aspect of the abdomen.
- Supplies the midgut
313
What are the anatomical relations with the superior mesenteric artery?
Anterior to the SMA
- Pyloric part of the stomach Splenic vein
- Neck of the pancreas
Posterior to the SMA
- Left renal vein
- Uncinate process of the pancreas – hooks around the back of the SMA
- Inferior part of the duodenum
314
What are the major branches of SMA?
Inferior Pancreaticoduodenal – Inferior region of the dad of the pancreas, uncinate process, duodenum
Right colic – Supplies the ascending colon
Illeocolic artery – Ascending colon, Appendix, Caecum, Ileum
Middle colic artery – Supplies the transverse colon
Jejununal arteries – Supplies the jejunum. Smaller number of arterial arcades but longer vasa recta than illegal arteries
Ileal arteries – Supplies the ileum
315
What is unique about the superior mesenteric artery blood supply?
Formation of arcade to supply the parts of the GUT
316
What is the path of the inferior mesenteric artery?
Arise at L3 near the inferior border of the duodenum
Depends anteriorly then moves to the left side and it is a retroperitoneal
Supplies the hindgut
317
What are the major branches of the inferior mesenteric artery?
Left colic artery
- Ascending branch which supplies the distal 1/3 of the transverse colon, and the upper aspect of the descending colon.
- Descending branch – moves inferiorly to supply the lower part of the descending colon. It anastamoses with the superior sigmoid artery.
Sigmoid arteries - supply descending colon and the sigmoid colon
Superior Rectal artery -
318
What is the marginal artery?
Continuous arterial circle along the inner border of the colon. Straight vessels arise form the artery to supply the colon.
319
What makes up the marginal artery?
- Illeocolic, right colic and middle colic of superior mesenteric artery.
- Left colic and sigmoid branches of the inferior mesenteric artery
320
What is the arc of riolan?
Anastomosis between the middle colic branch of superior mesenteric artery and left colic branch of inferior mesenteric artery.
321
Which artery can a horseshoe kidney hook onto?
Inferior mesenteric artery
322
What is the venous drainage of the gut?
Hepatic portal vein
