Block 3 - The Gastrointestinal System Flashcards
1
Q
What are the three accessory organs to the upper GI?
A
Liver
Gallbladder
Pancreas
2
Q
What aids the release of salivary enzymes from the mouth
A
The smell of the food
3
Q
What division of the nervous system innervates the salivary glands?
A
Parasympathetic
4
Q
What division of the nervous system innervates the salivary gland capsules?
A
Somatic nervous system
5
Q
What are the 4 borders of the parotid gland?
A
Anterior: Posterior mandible
Inferior and Posterior: Sternomastoid muscles
Superior: Anterior ear
6
Q
Where do the parotid ducts run?
A
Run along the mastered muscle
Pierce the buccinator
Enter the mouth at the upper 2nd molar
7
Q
What fluid does the parotid duct have?
A
Serous
8
Q
Where does the submandibular duct run?
A
Along the outside of the mylohyoid muscle and enters underneath the tongue either side of the sublingual papilla
9
Q
What is the difference between the sublingual frenulum and the sublingual papilla?
A
Sublingual frenulum: attaches the tongue
Sublingual papilla: a bump where the sublingual frenulum ends
10
Q
What fluid does the submandibular gland have?
A
Serous and mucus
11
Q
Where does the sublingual gland exit?
A
Above the submandibular glands
12
Q
What fluid does the sublingual gland release
A
Mucus fluid
13
Q
What nerve supplies the maxillary teeth
A
Maxillary nerve
14
Q
What nerve supplies the mandibular teeth
A
Mandibular nerve
15
Q
What bone does the mandibular bone pass through
A
The mandibular bone
16
Q
What is the blood supply to the mandibular teeth
A
Inferior alveolar artery
17
Q
What is the blood supply to the maxillary teeth?
A
The maxillary artery
18
Q
What is the condyle?
A
A bone at the top of the mandibular which articulated with the upper joint surface of the cranium at the temporomandibular joint
19
Q
What nerve innervates the muscles of mastication?
A
The mandibular branch of the trigeminal nerve
20
Q
What is the arterial and venous supply for the muscles of mastication
A
Maxillary artery
Superficial temporal veins
21
Q
What are the four muscles of mastication
A
Temporalis muscle
Masseter muscle
Lateral Pterygoid
Medial Pterygoid
22
Q
Does the lateral pterygoid or medial pterygoid close the mouth
A
Lateral closes
Medial opens
23
Q
2 types of muscles in the tongue
A
Intrinsic and extrinsic
24
Q
What are the four muscles in the tongue and their postitions
A
Genioglossus: genial spine on mandible –> glossus
Hyoglossus: hyoid –> glossus
Styloglossus: styloid –> glossus
Palatoglossus: palatoglossal folds –> glossus
25
What nerve supplies the muscles in the tongue?
| Which muscle is the 'odd one out'
Hypoglossal nerve
| Palatoglossus by the Vagus nerve
26
What is the arterial and venous blood supply for the tongue muscles?
Lingual artery and veins
27
What is the landmark for the anterior 1/3 and posterior 2/3 of the tongue?
Circumvallate papilla
28
What is the general and special sensory nerve supply to the posterior tongue?
Glossopharangeal nerve
29
What is the general sensory nerve supply to the anterior tongue?
Lingual nerve (mandibular division of trigeminal)
30
What is the special sensory nerve supply to the anterior tongue?
Facial nerve
31
Why is the special sensory nerve supply important?
It tells you if the bolus is ready
32
What level of the vertebrae does the pharynx end at?
C6
33
What are the three stages of the swallowing reflex?
Oral
Pharyngeal
Oesophageal
34
Explain what happens during the pharyngeal
The uvulua and levator veli muscles pull the soft palate up.
The vocal folds and epiglottis close.
The larynx raises and the upper oesophageal sphincter opens
35
What are the four anatomical constrictions of the oesophagus and where are they found?
Upper oesophageal sphincer
Tracheal bifurcation and Left atrium: T4/5
Lower oesophageal sphincter
36
How long is the oesophagus
25cm
37
What vertebral levels does the oesophagus run from and to?
C6-T10
38
What happens to the oesophagus at the level of T 10?
It enters the diaphgram
39
What are the two muscles in the oesophagus which contract in peristalsis waves
Circular and longitudinal
40
Which constrictor muscle makes the upper oesophageal sphincter
Inferior constrictor muscle
41
What is the sensory and motor nerve supply to the oropharynx
Sensory: Pharyngeal pleux (formed by pharyngeal branches of the glossopharangeal nerve)
Motor: Vagus nerve
42
What is the epithelium in the oesophagus
Stratified Squamous
43
What is the epithelium in the stomach
Simple Columnar
44
What is the junction between the epithelium of the oesophagus and stomach called?
The squamo-columnar junction
45
Is the stomach, retro-peritoneal or peritoneal?
Peritoneal
46
What is the blood supply to the stomach?
Coeliac Trunk
47
What is the lymph supply to the stomach?
Coeliac Nodes
48
What is the nerve supply to the stomach and what 2 things does this lead to?
Vagus nerve
| Peristalsis and secretory action
49
Is the left vagus nerve anterior or posterior?
Left: Anterior
Right: Posterior
50
How long is the duodenum?
25cm
51
What are the four parts of the duodenum called and are they peritoneal or retro-peritoneal?
D1: Superior (Peritoneal)
D2: Descending (Retro-peritoneal)
D3: Horizontal (Retro-peritoneal)
D4: Descending
52
What 2 things are posterior to the superior duodenum?
Common bile duct and gastroduodenal artery
53
How does fluid from the gallbladder and pancreas enter the duodenum?
The ducts join at the MAJOR DUODENAL PAPILLA and empty into the duodenum at the HEPATOPANCREATIC AMPULLA (OF VATER)
54
What 2 things are anterior and 2 things are posterior to the horizontal dudenum?
Anterior: Superior mesenteric artery and vein
Posterior: Inferior vena cava and aorta
55
What is the curvature of D4 supported by?
The ligament of Treitz
56
What are non-dietary loads?
Water and saliva
57
How much water is absorbed and consumed daily?
800ml absorbed
| 1200ml consumed
58
What are the 4 components of saliva (apart from enzymes)
Water, ions, amylase and lysosomes
59
Name the three phases of gastric secretion
Cephalic
Gastric
Intestinal
60
What are the 5 cells in the stomach?
Mucous, Parietal, Chief, Stem and Enteroendocrine
61
What are the roles of parietal cells and where are they found?
Secrete HCl and intrinsic factor
| Gastric, fundus and pyloric sphincter
62
What is the role of chief cells and where are they found?
```
Secrete pepsinogen (precursor of pepsin) and digestive enzymes
Cardiac and fundus
```
63
What is the role of enteroendocrine cells and where are they found?
Secrete protein hormones
| Gastric
64
What cells release histamine and what does the histamine do?
ECL cells
| Bind to H2 receptors to active adenylate cyclase --> cAMP
65
What cells release gastrin and what does the gastrin do?
Secreted from G cells
| Bind to CCK receptors to activate phospholipase C --> release cytostolic Ca --> indirect histamine release
66
What is the role of Ach in the stomach?
Binds to M 2 receptors to increase intracellular calcium and cAMP to activate downstream protein kinases and the proton pump
67
What three substances lead to activation of the H+/K+ ATPase and lead to acid secretion
Histamine, Gastrin and Ach
68
When and where is the hormone gastrin secreted?
| What is its role?
Secreted by the stomach in response to protein
Stimulates secretion of acid and pepsinogen
Prevents gastric emptying by increasing gastric motility
69
When and where is the hormone secretin secreted?
| What is its role?
Secreted by the duodenum in response to acid
Inhibits gastric acid production
Increases secretion from the pancreas and bile duct
70
When and where is the hormone CCK secreted?
| What is its role?
Secreted by the duodenum in response to fat
Inhibits gastric secretion and motility
Increases secretion from the pancreas and bile duct
71
When and where is the hormone somatostatin secreted?
| What is its role?
Secreted from D cells in the stomach and duodenum in response to acid
Inhibits gastric secretion
72
What does swelling of the stomach cause in regards to acid secretion?
Inhibition of gastric secretion
73
What is glucose-dependent insulinotropic peptide?
Stimulates insulin secretion when glucose increases
74
What condition does Heliobacter Pylori cause?
Gastritis
75
8 enzymes released from the small intestine
Chymotrypsin, Dipeptidases, Disaccharides, Elastase, Lipase, Pancreatic amylase, Phospholipase, Trypsin
76
Where in the small intestine does digestion and absorption occur?
Jejumum: Continuting digestion
Ileum: Absorption
77
What is the leftover chyme fermented to in the large intestine
Acetate, propionate, butyrate
78
Where is water absorbed from?
Large intestine
79
What is the venous draining from the small intestine?
Hepatic portal vein
80
What is the lacteal drainage from the small intestine
Thoracic duct
81
```
What are the precursors for:
Pepsinogen
Chymompsinogen
Pro-elastase
ProCarboxypeptidases
Pro-aminopeptidases
```
```
Pepsinogen: Pepsin
Chymompsinogen: Chymotrypsin
Pro-elastase: Elastase
Pro-carboxypeptidases: Carboxypeptidases
Pro-aminopeptidases: Aminopeptidases
```
82
How long do cells take to migrate up the crypt
48 hours
83
What is the region of the crypt which separates the under-developed cells from the developed ones?
The proliferate region
84
What happens to dipeptides in the enterocytes?
They are converted to cytoplasmic peptides then amino acids
85
Which specific fatty acids are absorbed by chylomicrons?
Ones with more than 12 carbon atoms
86
Another name for non-starch polysaccharides
Dietary fibre
87
Define glycemic index
Relative ability of carbohydrate to increase blood glucose levels.
Increased index = absorbed faster = increase levels faster
88
What is an increase in glucose related to?
Insulin secretion
89
What are the 2 roles of bacteria in the colon?
Regulate metabolites and secrete small chain fatty acids
90
What are the names of the small chain fatty acids released by bacteria in the gut and what are their roles?
Acetate
Propionate: Inhibits appetite and intake
Butyrate: Protects against colorectal cancer
91
4 benefits of non-starch polysaccharides
Absorbs and clears bile acids, cardiogens and cholesterol
Bacterial fermentation in the colon
Increases viscosity of the gut leading to slower absorption
92
What is lactylose broken down into in the gut? (2)
Hydrogen and methane
93
What is the role of neck cells and where are they found?
They produce mucus
| Cardia, pylorus and fundus
94
How is stomach acid made?
CO2 + H20 --> HCO3- + H+
HCO3- is returned to the blood in exchange for Cl-
H+ is pumped into the stomach in exchange for K+
95
How does Heliobactor Pylori cause inflammation?
Urease --> Ammonia + Carbonic acid
96
What does the pH of the stomach need to be to initiate healing?
Above 3
97
What type of response is vomiting?
Reflex response
98
6 examples of internal nausea
Abdomen, headache, heart attack, pain, pregnancy, viral infection
99
4 examples of external nausea
Motion sickness, alcohol/food poisoning, medication
100
4 pathways that lead to the vomiting centre in the medulla and the triggers for these pathways
Cerebral cortex: Anxiety and raised intracranial pressure
Peripheral: Gastric stasis, radiation and chemotherapy
Chemo-receptor trigger zone: Drugs and hyperglycaemia
Vestibular input: Vestibular neuritis
101
What receptors are found in the vomiting centre in the medulla?
Ach (M), H1, 5HT2, mu, NK1
102
What is the blood supply to the foregut, midgut and hindgut?
Foregut: Celiac artery
Midgut: Superior mesenteric artery
Hindgut: Inferior mesenteric artery
103
What organs are in the foregut (6), midgut (5) and hindgut (5)
Foregut: Oesophagus, stomach, liver, gallbladder, pancreas, proximal duodenum
Midgut: Distal duodenum, jejunum, ileum, ascending colon, 2/3 of transverse colon
Hindgut: 1/3 of transverse colon, descending+sigmoid colon, rectum, proximal anal canal
104
What are the 5 layers of the anterolateral abdominal wall
Skin --> fatty superficial fascia (Camper's) --> membranous superficial fascia (Scarpa's) --> Abdominal muscles --> Transversalis fascia --> parietal peritoneum
105
```
External Oblique:
Where does it originate?
Where do the fibres run?
What does it insert onto? - what is this?
What makes up the bottom of it?
```
Origin: Inferior 8 ribs
Fibres: Inferomedial fibre orientation
Insertion: Linea alba (a white fibrous band from the xiphoid process to the pubic sympysis)
Bottom: Inguinal ligament
106
```
Internal oblique:
Where does it originate?
Where do the fibres run?
What does it insert onto and how?
What ribs does it attach to?
```
Origin: Lumbar fascia and iliac crest
Fibres: Superomedial fibre orientation
Insertion: Joins the inguinal ligament, linea alba and pectin pubis via the conjoint tendon
Ribs: Attaches to the 10-12 ribs
107
```
Transverse abdominis:
Where does it originate?
Where do the fibres run?
What is its relationship with the internal oblique
What does it insert onto?
```
Origin: Lumbar fascia and iliac crest
Fibres: Transverse fibre orientation
Internal oblique: Joins the inguinal ligament with it and helps to form the conjoint tendon
Insertion: Xiphisternum, linea alba and pubic crest
108
Rectus abdominis:
Where does it originate?
What does it insert onto?
How does it form a '6 pack'?
Origin: Pubic crest and symphysis
Insertion: 5-9 costal cartilages and xiphisternum
6 pack: Due to 3 tendinous insertions
109
When do the muscles become aponeurotic?
At the 9th costal cartilage
110
What is different about the layering of the muscles above and below the arcuate line?
Above: External oblique anterior to rectus abdominis; internal oblique splits around it and transverse abdominis posterior
Below: All three are anterior to the rectus abdominis
111
What are the borders of the inguinal canal?
Floor: Inguinal ligament from external oblique (Medial = Lacunar ligament)
Anterior: Aponeurosis external oblique (Lateral = internal oblique)
Roof: Transversus abdominis, internal oblique and transversalis fascia
Posterior: Transversalis fascia
112
What type of membrane is peritoneum?
Serous membrane
113
Define intraperitoneal
Inside peritoneal cavity and surrounded by visceral peritoneum
114
Define retropertioneal
Behind parietal peritoneum
115
Define infraeritoneum
Below the cavity
116
Define mesentary
Double fold of peritoneum which attaches intestines to the posterior abdominal wall to allow blood to reach the organs.
117
Define omentum
Fold of peritoneum that attaches the intestines to other organs; covers the abdominal contents, has a blood supply and fat deposits
118
What is the epichoric foramen
A hole that connects the greater and lesser omentum
119
What are the 4 muscles in the posterior abdominal wall
Diaphragm, quadratus, ilicais and psoas major
120
What is the epithelium in the small intestines?
SIMPLE COLUMNAR
121
What is the nerve and blood supply to the small intestine
Vagus nerve
| Superior Mesenteric Artery
122
How long are the small intestines?
3-5m
123
Jejunum:
```
How much of the intestine does it make up?
What stomach quadrant is it found in?
What are the walls and calibre like?
What are the folds on the inside called?
What is the blood supply?
```
```
Proportion of intestine: Upper 2/5
Quadrant: ULQ
Walls and calibre: Thick
Folds: Pilicae Circularis
Blood: Less arterial arcades and more vasa recta
```
124
Ileum:
```
How much of the intestine does it make up?
What stomach quadrant is it found in?
What are the walls and calibre like?
What 3 things are absorbed?
What is the blood supply?
```
```
Proportion of intestine: Lower 3/5
Quadrant: R hypogastric region
Walls and calibre: Thin
Absorption: B12, bile salt and lipids
Folds: Pilicae Circularis
Blood: More arterial arcades and less vasa recta
```
125
What is the Meckel's Diverticulum and where is it found?
Remnant of the vitelline duct
| 2 feet from the ileocaecal junction
126
How long is the large intestine
5 feet
127
What type of peritoneal organ is the large intestine?
Intraperitoneal: Caecum, transverse and sigmoid
Retroperitoneal: Ascending and descending
128
What are the three characteristic features of the large intestine?
Taeniae coli: 3 longitudinal muscular strands that contract to move the faeces
Haustra: Bulges to keep the shape
Appendices epiploicae: Fat deposits
129
What are the two openings for the appendix?
| What does the appendix open into?
Ileo-caecal valve and orifice of the appendix
| Opens 2cm inferior to the ileocaecal valve into the posteromedial canal
130
Where is the appendix situated?
6-9cm behind the caecum/ileum
131
What is the appendix's mesentary?
Mesoappendix
132
What is the blood supply to the appendix?
Appendicular artery
133
Where is the rectum situated?
Between S2 and the pelvic floor
134
Where does the rectum end?
The anorectal junction
135
Where is faeces stored?
In the rectal ampulla on top of the transverse rectal folds
136
What peritoneum is the rectum made from?
Upper 1/3: Parietal peritoneum
Mid 1/3: Parietal peritoneum anteriorly
Lower 1/3: Infraperitoneal
137
How long is the anus
4cm
138
What is the epithelium of the anus?
Stratified squamous
| Keritanised below the pectinate line
139
Is the anus made from endoderm or ectoderm?
Endoderm above pectinate line
| Ectoderm below pectinate line
140
What is the blood supply to the anus?
Above the pectinate line: Superior rectal artery + vein
| Below the pectinate line: Inferior and middle rectal arteries
141
Parasympathetic and sympathetic nerve supply to the smooth muscle of the anus and the vertebral origin of these nerves
Parasympathetic: Pelvic splanchnic nerve (S234)
Sympathetic: Inferior hypo-gastric pleux (T11-L2)
142
What fibres trigger defecation?
Visceral sensory fibres
143
Nerve supply to the skeletal muscle of the anus
Inferior anal nerve
144
Explain the defecation reflex
Stretch receptor --> rectum contacts and shortens
| Voluntary control of external sphincter
145
What are the fat soluble vitamins?
A,D,E,K
146
What class of molecule are cholesterol and cholesterol esters?
Types of LIPIDS
147
What is the role of bile salts, amphiphatic lipids and cholesterol in lipid digestion?
Create a polar surface on small droplets to prevent them from re-combining with each other.
Amphiphatic lipids: Hydrophobic and hydrophilic aiding with transportation
148
What is the role of colipase?
Prevents lipase re-associating with the fat droplet
149
What is added to the triglyceride inside the enterocytes to make a cylomicron?
Apo(lipo)protein
150
What are the 3 lipid degrading enzymes?
Lingual lipase:Secreted from Ebner's glands on dorsal surface of tongue
Gastric lipase: Acid activated
Pancreatic Triglyceride lipase: Bile salt activated
151
How are bile salts made and what are they made from (12)
Cholesterol breakdown
Alkaline phosphatase, bile salts, bilirubin, cholesterol, fat, fatty acids, inorganic salts, lecithin, monoacylglycerol, monoacylphospholipases, mucin, pigments, phospholipids and water
152
How do bile salts get their polarity?
Added to glycine and taurine
153
Where is CCK released from?
Duodenal mucosa
154
What allows bile into the duodenum?
Sphincter of Oddi
155
What is triacylglycerol digested into?
Triacylglycerol --> Diacyclycerol (FAST)
| Diacyclycerol --> 2-monoacylglycerol (SLOW)
156
How is phosphatidylcholine digested?
Into lysophospharidylcholine by PLRP2
157
How are cholesterol esters digested?
Into cholesterol and fatty acids by cholesterol ester hydrolase
158
How are phospholipids digested?
Lysolipids and fatty acids
159
What are chylomicrons made from and where are they assembled?
Cholesterol, glycerides, phospholipids, proteins and vitamins
Endoplasmic reticulum and golgi apparatus
160
What is the role of peripheral apoproteins
Stabilises and stops accumulation of fat in enterocytes
161
What is the role of lipoprotein lipase?
Removes fatty acids from the cylomicron to allow them to diffuse into cells
162
What is beige adipose tissue
White adipose tissue that can turn brown under certain stimuli
163
10 roles of omega 3
Blood clotting; brain cell membranes; increases brain and joint function; decreases cancer, heart disease and diabetes risk; decreases inflammation; increases growth and development
164
3 main sources of omega 3 and foods they are found in
Alpha-linolenic acid: Walnuts, veg and soy beans
Eicosapenranenoic acid: Fatty fish and oil
Docosahexanoic acid: Fatty fish and oil
165
8 roles of omega 6
Regulates brain growth and development; regulates metabolism; increases inflammation; stimulates hair and skin growth; maintains bones; reproduction
166
3 main sources of omega 6 and foods they are found in
Linolenic acid: Corn, veg oil, soy beans and seeds
Gamma-linolenic acid: Veg and plant oils
Arachodonic acid: Wheat, poultry and egg
167
2 roles of omega 7
| 2 sources of omega 7
Decreased inflammation; insulin resistance
Produced by body or in foods with palmitic acid (e.g. nuts)
168
4 roles of omega 9
| 2 sources of omega 9
Decreased inflammation; increased joint health and healing; disease prevention
Produced by body or in foods with oleic acid (e.g. olive and veg oils)
169
Where is conjugated linoleic acid found?
What is its structure?
What is its role?
2 side effects
Cheese, milk and red meat
2 double bonds separated by a single bond
Increases fat metabolism and anticardiogenic
Side effects on pancreas and insulin resistance
170
Where is the liver in relation to the diaphragm?
Inferior and posterior
171
What type of gland is the liver?
Accessory digestive gland
172
What are the 8 functions of the liver?
```
Bile production
Decomposes RBC
Detoxification and breakdown of hormones and drugs
Metabolises nutrients for energy
Produces hormones
Regulates glycogen storage
Stores, fat, vitamins and minerals
Synthesises plasma proteins
```
173
What is the bare area of the liver?
A mesentary formed from the dorsal and ventral mesogastrum during embryonic development of the foregut
174
What is the peritoneal ligament?
A double fold of peritoneum which attaches the anterior abdominal wall and diaphragm to the liver
175
What is the lesser omentum?
| What is the hepatic duodenal ligament?
A ligament that connects the liver to the stomach
| On the lesser edge; separates the greater and lesser sac
176
What is the top and bottom surface of the liver called?
Top: Diaphragmatic
Bottom: Visceral
177
How are the coronary ligaments formed?
Formed due to the liver obliterating the parietal peritoneum so the parietal and visceral fuse.
Occurs as the falciform ligament and visceral peritoneum move backwards
178
What is the subphrenic recess?
A gap in the peritoneal cavity between the abdomen and liver
179
What is the hepatorenal recess also known as?
Where is it?
Why is it clinically significant?
The pouch of Morison
Under the liver and above the kidney
Deepest part of the peritoneal cavity when the patient is lying --> fluid collects here after injury
180
What is the ligamentum teres a remnant of?
The umbilical vein
181
What veins branch off the vena cava into the liver?
Right, middle and left hepatic veins
182
What order do vessels enter the porta hepatis?
Bile DUCT; Hepatic ARTERY proper, portal VEIN
183
What is the ligamentum venosum?
A remnant of the ductus venosus
184
Where do the bile ducts travel in the liver?
Within the hepatoduodenal ligament on the free edge of the liver (entry to the lesser sac)
185
What does the left hepatic artery, vein and duct supply?
The left lobe
| The caudate and quadrate (anatomical right)
186
How many segments of the liver are there?
8
187
What is the trans-pyloric plane?
| What does it contain?
```
An imaginary horizontal line across the body which contains:
Neck of pancreas
Pylorus of stomach
Hilum of kidneys
Fundus of galbladder
L1 vertebrae
Origin of portal vein + superior mesenteric artery
D2 (sphincter of oddi)
9th costal cartilages
```
188
2 functions of the pancreas
Digestive enzymes and hormones
189
What is the embryonic derivative of the spleen?
Mesoderm
190
What is the difference between the diaphragmatic and visceral surface of the spleen?
Diaphragmatic: Convex and smooth
Visceral: Convex ad irregular with notches
191
How can you repair a ruptured spleen?
Greater omentum used as a pressure pad
192
What ribs are in line with the spleen?
9th and 11th
193
Blood supply to the kidneys
Renal arteries and veins
194
What type of peritoneum organ is the kidney?
Retroperitoneal
195
What pathway do the lymphtics follow?
| What is the exception to this?
Same pathway as the coeliac and splenic nodes
Anterior liver drains into the phrenic lymph nodes
Posterior liver drains into the hepatic lymph nodes
196
3 parts of the gallbladder
Fundus, body and neck
197
What is the blood supply to the gallbladder?
Cystic and right hepatic artery
198
What does the hepatopancreatic sphincter of oddi receive fluid from?
The hepatopancreatic ampulla
199
What is ERCP?
Endoscopic reterograde cholandroancreatography
200
What marks the transition from foregut --> midgut
The hepatopancreatic sphincter of oddi
201
What hormone leads to Glycogenesis?
Insulin
202
What hormone leads to glycogenolysis?
Glucagon and Adrenaline (via second messenger)
203
How much cholesterol is produced every day?
1g
204
How is cholesterol produced
Acetyl CoA --A--> Isopentenyl --B--> Pyrophosphate --> Squalene --> Cholesterol
Enzyme A: Enzyme HMG-CoA reductase
Enzyme B: Enzyme X6
205
What do statins target?
Enzyme HMG-CoA reductase
206
What is the role of HDL?
Mops up excess cholesterol and lipids from tissues to bring it back to the liver
207
What happens during the condition 'hypercholesterolemia?
No LDL receptors --> a build up of fat in the blood
208
What 2 proteins are usually made in the liver?
Albumin and blood clotting factors
209
How is protein metabolised?
Protein --> Ammonia --> Urea --> Urine
210
How are erythrocytes broken down?
Haemoglobin --> Globulin --> Amino acids
| Haemoglobin --> Haem --> Iron + Bilirubin
211
What are the two phases of drug metabolism?
Phase 1: P450
| Phase 2: Glucoronide added and secreted
212
What is hepatitis?
What is hepatoma?
What is chirrhosis?
Hepatitis: Infection --> inflammation
Hepatoma: Tumour
Chirrhosis: Scar tissue due to overworked liver
213
What is another name for jaundice?
| 3 major causes
Hyperbilirubinemia
| Infectious hepatitis, bile duct obstruction and red blood cell destruction
214
2 liver function tests involving enzymes
| Where are these enzymes found?
```
Alanine Aminotransferase (ALT): Found in the cytosol of hepatoytes
Asperate Aminotransferase (AST): In the heart, liver, kidney, brain and skeletal muscle
```
215
2 liver function tests NOT involving enzymes
Albumin levels
| Prothrombin time: A coagulation factor that records the time it takes to clot blood
216
What happens during enterohepatic circulation?
The hepatic portal vein mops up unused bile
217
What is the structure of bile?
4 benzene rings and similar to cholesterol
218
How do bacteria make secondary bile salts?
Remove glycine/taurine which the liver had added to the bile salts to conjugate them
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4 functions of bile
Bilirubin excretion
Emulsifies fats
IgA antibodies
Neutralises stomach acid
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How is haemoglobin converted to bilirubin?
Haemoglobin --(A)--> Iron + Biliverdin --(B)--> Unconjugated bilirubin
Enzyme A: Haem oxygenase
Enzyme B: Biliverdin reductase
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What is the difference between unconjugated and conjugated bilirubin?
How is conjugated bilirubin made?
Unconjugated is insoluble so is bound to albumin
| It is conjugated (water soluble) in the liver by glucuronyl-bilirubin transferase
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What happens to conjugated bilirubin in the intesine and blood?
Bacteria convert conjugated bilirubin --> Sterobilin (excreted in faeces or absorbed by the blood)
In the blood converted to Uribilin (excreted in urine)
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How did Van Den Bergh find the difference between conjugated and unconjugated bilirubin?
Conjugated is water soluble and alcohol soluble so showed a colour change when a reagent was added in both of these mixtures.
Unconjugated is water INSOLUBLE but alcohol soluble so only showed a colour change when the reagent was added in alcohol
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Example of pre-hepatic, hepatic and post-hepatic disease
Pre: Haemolytic anaemia
Hepatic: Hepatitis
Post: Obstructive jaundice
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What is the difference between Cholelothasis and Choledocholithiasis?
Cholelothasis: Obstruction of the cystic duct
Choledocholithiasis: Obstruction of the entire bile duct
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What is ascending cholangitis?
Inflammation of the whole bile duct
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What is biliary colic?
A gallbladder attack
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What is inflammation of the gallbladder called?
Calculus cholecystitis
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What are the 3 conditions needed to produce gallstones?
Bile must be supersaturated with cholesterol
Cholesterol must precipitate as solid cholesterol mono-hydrate crystals
Crystals must aggregate with other elements
