Week 1 Flashcards
(177 cards)
1
Q
4 roles of the GI system
A
Digestion
Absorption
Secretion
Motility
2
Q
What are the accessory components of the gI tract
A
Teeth tongue salivary glands (parotids, sublingual, submandibular) Pancreas liver gallbladder
3
Q
How many meters long
A
8
Small intestine is 7
4
Q
What acid in stomach and why
A
HCL to sanitise
5
Q
What is in the large intestine
A
Colon rectum and Anus
6
Q
Where are the most nutrients absorbed and most digestion then
A
Small intestine
7
Q
Two ways that’s nutrients are absorbed
A
Diffusion or active transport
8
Q
4 layers throughout GI tract are
A
Adventia
Submucosa
Muscularis propria
Mucosa
9
Q
What from saliva breaks long carbs to sugars
A
Amylase from saliva
10
Q
How long can digestion take
A
5 hours
11
Q
What is adventitia
A
Thick fibrous connective tissue
12
Q
The muscularis externa layer of the GI system contracts automatically. Yes or no
A
Yes
How food moves
13
Q
What are the two layers of the muscularis externa and purpose
A
Inner circular = contract behind food
Outer longitudinal = relaxes and lengthens to pull food forward
14
Q
Inner circular layer and outer longitudinal layer of the muscularis externa layer in GI system: working together what is this called
A
Peristalsis
15
Q
Where might the inner circular layer of the muscularis externa thicken? And why?
A
At oesophageal sphincters (looks like waves) because remember, inner circular layer contracts to push. Needs extra push in the wave/bump/sphincter
Think that circular = a ball pushing things along
16
Q
What’s between the circular and longitudinal muscle layer?
A
Plexus of nerves to coordinate contraction called the myenteric plexus
17
Q
So what happens when the myenteric plexus (between muscles layers of the muscularis externa) is activated?
A
Smooth muscle relaxation
18
Q
Where is the blood and lymphatics in the layers in the GI tract?
A
Sub mucosa
19
Q
So it’s: Adventitia, muscularis externa, sub mucosa, then what?
A
Mucosa (muscularis interna)
20
Q
What are the three layers of the mucosa/ muscularis interna
A
Muscularis mucosa
Lamina propria
Epithelial
21
Q
What does the epithelial layer of the GI tract do( part of the mucosa /muscularis interna).
A
It secrets mucus for digestive enzymes
22
Q
What does the muscularis mucosa of the mucosa (interna) layer of gi tract do
A
It’s smooth muscle for breaking down food
23
Q
Lamina propria of the mucosa/ muscularis interna does what?
A
Contains blood and lymph nodes
24
Q
Where is the EsophaGeal sphincter?
A
At entrance to stomach
25
Is the muscularis externa at the esophageal thick or thin?
Thick. Think- it’s the circular and longitudinal muscle layers that push food. Vs the mucosa
26
What is the sphincter at the end of the stomach called
Pyloric sphincter
27
The lining of the stomach included what
Gastric pits that release gastric secretions
28
What three parts of the gastric secretions?
HCL, pepsin enzyme which chops up proteins, and mucus which protects the stomach.
29
Three parts of the small intestine. Dude judge I’ll
Duodenum
Jejunum
Ileum
30
Describe surface of the stomach and why
Villi for absorption
31
What’s chyme
Fluid that passes from stomach to the small intestine, consisting of gastric juices and partly digested food
32
Where does the liver sit?
Under the right dome of the diaphragm.
33
Purpose of liver in food stuff
Provides bile salts for digestion/ absorption of fats in small intestine
34
Purpose of pancreas
Digestive enzymes for digestion of fats, carbs, and proteins
35
Purpose of gall bladder
Stores and concentrates bile of the liver
36
Is water absorption of small or large intestine
Large
37
Is chemical digestion small or large intestine
Small intestine
38
Where is the bacterial fermentation?
In the large intestine
39
So does any nutrient absorption occur in the large intestine?
No, only small
40
What’s the second name for the Adventitia?
Serosa. What it’s called in the peritoneal cavity
41
What part of the mucosa results in the secretion of and synthesis of digestive enzymes
The epithelium
42
The oesophagus and the rectum attaches to surrounding structures via what layer/tunic
The adventitia
43
Which nervous system for the submucosal and myenteric plexuses
Enteric nervous system (independent control of gut function)
44
Sympathetic or parasympathetic increases secretion and motility?
Parasympathetic increases secretion and motility OBVIOUSLY
45
Sympathetic for gut is what nerve
Splanchnic nerve
46
Parasympathetic for gut is what nerve
Vagus nerve
47
Arterial supply to the GI tract comes from where?
Descending abdominal aorta
48
So obviously we have the 3 edges of the colon, ascending transverse then descending, but which is on the right and which is on the left?
Ascending is on the right and decanting is on the left
49
What’s the part of the colon by the rectum called?
Sigmoid colon
50
What are the 4 signalling types?
Para auto Endo exo
51
What’s paracrine signalling (2)
Short distance chemical message , locally coordinate activities
Think paranoid about neighbours
52
What’s autocrine signalling and when’s it important to consider?
Cell signals to itself, releasing ligand to bind receptors to its own surface
Reinforce its cell purpose- cancer
53
What type of cell signalling are hormones involved with?
Endocrine
54
If salivation occurs parasympathetic, surely that’s the vagus nerve?
No
Salivation comes from facial and glossopharyngeal nerves
55
Off the descending aorta, two main arteries/ groups of arteries that feed GI and liver?
Hepatic artery and digestive tract arteries
56
The hepatic artery feeds what
The liver
57
What comes from the liver to feed the IVC?
Hepatic vein
58
What vein travels from GI tract to go through liver?
Hepatic portal vein. Not to be confused with hepatic vein, which is after. Think hepatic portal to enter the liver- portal first
59
What’s the arterial supply of GI tract from abdominal aorta? (3)
Celiac
Superior mesenteric artery
Inferior mesenteric artery
Think celiac as in stomach, and it’s all messy and bloody (artery) down there
60
Celiac trunk supplies what (4)
Liver
Pancreas
Small intestine
Stomach
61
Superior mesentery artery (vice versa for the vein) supplies what
Small intestine
Of large intestine:
Caecum
Ascending
Transverse Colon
62
Inferior mesentery artery feeds what (vice versa for the vein)
Descending colon
Sigmoid colon
Rectum
63
Inferior
64
What veinous drainage for stomach and what for pancreas?
Gastric veins for stomach
Splenic vein for pancreas
Both stomach and pancreas fed from celiac trunk
65
So what are the breakdown products of carbs?
Hexose sugars/ monosaccharides like glucose, galactose and fructose
66
At what breakdown point are carbs absorbed by the small intestine?
At hexose sugar level, so like monosaccharides like glucose, galactose, fructose
67
Are there any issues absorbing monosaccharides by the small intestine?
No
68
When can the small intestine absorb disaccharides?
When they’ve been broken down into monosaccharides
69
Where and how are disaccharides broken down in the small intestine?
By brush border enzymes in the brush border (made of microvilli)
70
The brush border of intestinal lining is the site of what
Terminal carbohydrate digestion
71
If there is deficiency in disaccharidases, produced by the intestinal brush border, what could this result in?
Well: this interferes with the breakdown and absorption of carbohydrates, so may result in abdominal pain gas bloating diarrhoea
72
What would lactose be broken down by?
An enzyme called lactase, so it would become glucose and galactose
73
When sucrose is broken down by sucrase what does it become?
Sucrose = glucose and fructose.
Think that ‘s’ is the big sound. And then glucose and fructose are more glutular
74
Where is glucose stored?
As glycogen, in our liver or in our muscles
75
What enzyme is starch degraded by?
Starch is degraded into glucose by amylase
76
Where is amylase present?
In saliva, and in pancreatic juices.
(So starch can be degraded in mouth and in the duodenum)
77
Can humans digest cellulose?
No
78
What can cellulose be degraded by?
Certain bacteri
79
Why is cellulose important?
Assists digestive system by keeping food moving through the gut thus preventing constipation
80
How does cellulose prevent constipation?
Can’t be degraded so helps food move, adds bulk and therefore hastens passage
81
If cellulose cannot be degraded by humans then why does the enzyme cellulase exist?
Because that’s the enzyme that certain bacteria can produce
82
What’s the problem in lactose intolerance?
A problem with the enzyme lactase. So it’s either not there or there is a defect with it.
83
Why is there diarrhoea in lactose intolerance?
Lactose builds up, creating an osmotic pressure. So then water wants to go inside the intestine from the blood. So diarrhoea
84
So if lactose is just sitting there in the large intestine, what happens to it?
Bacteria starts to ferment/degrade it and therefore form acids therefore irritation and gastric discomfort
85
What are the three ways nutrients are absorbed?
1) trans cellular = through the cell
2) para cellular = through tight junctions
3) vectorial transport = needing a pump
86
How does protein digestion work?
It happens in the stomach with HCL and protease enzymes, broken into amino acids, which then move to the small intestine.
87
Amino acids are absorbed how?
Vectorial transport.
88
All digested fat is in the form of what
Triacylglycerol
89
Where does fat digestion occur?
Small intestine
90
Digestive process steps of fats to tri- and monoglycerides
1) Bile salts emulsify because your triglyceride is insoluble, and attaches fats to the microvilli for absorption
2) bile organises fat into micelles of lipids and bile acids
3) while lipase converts the triglycerides in the micelles and breaks them into glycerol and fatty acids.
4)these can go through the small intestinal epithelial and into the lymphatics
91
Why must ingested fats be emulsified? (3)
Triglyceride is insoluble, so must be emulsified by bile salts
Also makes smaller and stops them from reforming
Smaller = better for lipase to convert into glycerol and fatty acids
92
Emulsification requires what
Mechanical disruption of large lipid droplets into small droplets by muscularis externa of stomach and or intestines
93
What does the liver do
Make bile
94
How does body know to release bile?
Chyme stimulates a hormone from epithelial of small intestine which travels to hall bladdsr
95
How does the body know to release lipase enzyme (which converts triglycerides of micelles into fatty acids and glycerol)?
Because chyme stimulates epithelial cells of small intestine to secrete hormone into the blood, which travels to pancreatic duct into duodenum
96
What does lipase do
Travels from pancreas down pancreatic duct to the duodenum, grabs the triglycerides in micelles and converts it to fatty acids and glycerols which can go through lymphatics
97
What enzymes break down peptide chains into single amino acids?
Peptidases
98
What happens to stuff that isn’t absorbed in the small intestine? Eg fiber
Into the colon of the large intestine. When the chyme hits the Cecum of the colon, it’s met by the bacteria of the large intestine called the gut microbiome.
99
Bowel = what
Intestines
100
What’s peristalsis?
Wave like muscle contractions that move food through the digestive tract- starts in the esophagus until anus
101
What happens to water as chyme moves via peristalsis through the large intestine?
Excess water absorbed from chyme, until feces are in the rectum.
102
What triggers the defecation reflex? How do we balance being ready to defecate Vs actually defecating?
When the rectum is filled and stretched, signals travel to parasympathetic neurons in the spinal cord, initiating the defecation reflex.
So rectum contracts (to push out) but internal anal sphincter relaxes.
Meanwhile signals are sent to the brain stem and thalamus, so you can choose when to allow the external anal sphincter to relax
103
How many anal sphincters are there?
Internal and external sphincters
104
Are fat micelles absorbed?
No
Lipase digests fat into monoglycerides, and fatty acids (aka lipase digestion products) which can then be absorbed by the small intestine…
105
So when exactly are fatty acids and glycerols converted to tricyglycerols
When they enter epithelial cells, and are in the process of being absorbed. When they enter the smooth endoplasmic reticulum and become tricyglycerols, and processed through the Golgi apparatus, and exocytosed into extracellular fluid that way.
106
fat droplets aka chylomicrons can’t pass through the capillary basement membrane of a blood vessel, so where do they go?
Into lacteals between endothelial cells
107
What’s a lacteal?
A lymphatic vessel of the small intestine, which absorb digested fats.
108
Fat soluble vitamins eg EKAD follow what route
Same route as fat molecules
109
Absorption route of water soluble vitamins? (E.g. b,c etc.)
Passive diffusion or carrier mediated transport
110
How is vitamin b12 absorbed?
1) HCL in stomach, separates vitamin B12 from the protein it’s attached to.
2) freed vitamin b12 combines with a protein made by stomach called intrinsic factor and then absorbed
111
Why is vitamin b12 important?
Helps make DNA, and keeps body’s blood and nerve cells healthy
112
What happens when there is vitamin B12 deficiency?
Pernicious anaemia (failure of red blood cell maturation)
113
How much of daily ingested iron will actually go across the intestine into the blood?
Only like 10%
114
What’s a cell of the intestinal lining called?
Enterocyte
115
What is a Micelle made of
Bile salt and monoglycerides and fatty acids and phospholipids
116
What produces intrinsic factor? (Needed for vitamin b12 absorption)
Parietal cells of the stomach
They also produce HCL
117
How long does pernicious anaemia occur?
3 years
118
Stents for stable angina patients prevent how many heart attacks and extends the lives of patients how much
Prevents zero heart attacks. Nobody that’s having a heart attack needs a stent.
(Stents May improve chest pain in some patients, albeit briefly)
119
Good blood pressure and what might be bad;
Good = 120/80
At risk = more than that
Bad = 140/90
120
Relative risk reduction vs absolute risk reduction. Eg chance of heart attack = 80%. Add stent and risk of heart attack reduces by 20% so..
Relative risk = 25% reduction
Absolute risk = 20%
121
High score of ASSIGN score? (Chance of developing cardiovascular disease).
20 or higher.
Remember that it doesn’t include lifestyle factors.
122
High ASSIGN score = do what? (Other than lifestyle of course)
Low dose aspirin to reduce the risk of blood clots (thrombosis)
Statin tablets to reduce cholesterol levels
123
What do statins do
Lower cholesterol
124
How long stay on statins for
Life usually, LDL cholesterol can return to high levels within weeka
125
Quote from Jacob Bigelow about suffering and over involvement of doctors.
The amount of death and disease suffered by mankind would have been less if all disease were left to itself
We’re seeking hope- society wants advice from doctors, rather than accepting the inevitable limitations of our short lives. Yet some treatments offer no value. And overdiagnoses
126
How often is chronic kidney disease picked up incidentally on routine blood tests, where patients remain symptomatic?
Often.
Labels are powerful! Diagnoses does result in annual monitoring of bloods and blood pressure. Implication on certain medications they can be prescribed
127
Do sleeping tablets actually work?
Like 7/100 sleep better, marginally. But most people have no effect AT ALL, and even more people have side effects
128
Hypertension definition was dropped form what to what
160 to 140
129
What are the 4 questions to ask at a doctors appointment?
Benefits
Risks
Alternatives
Nothing
130
What’s a portal systemic anastomoses?
Well whilst the hepatic portal collects nutrient rich, oxygen poor blood it’s all gotta connect somehwo
131
What are the 4 sites of the portal-systemic anastomoses?
Azygous to esophageal vein with the left gastric vein
Rectal veins of the portal system and inferior and superior veins of the systemic system
Superficial epigastric veins with the para- umbilical veins of the abdominal wall
At colon, colic veins (portal system) with retriperitoneal veins (systemic system)
132
Left gastric vein goes to where
Stomach
133
Why anastomoses
Alternative route if blockage in liver and portal vein- veinous blood from gastro can still reach IVC
134
Each organ has its own group of what
Lymph nodes
135
Pre aortic nodes Vs para-aortic
Para = if vessels protrude either side of the aorta, pre = if vessel comes out anteriorly
136
Celiac trunk comes out anteriorly to aorta for the foregut. So, all lymph will drain to what type of nodes at t12?
Pre-aortic nodes
137
Plexus surrounding bifurcation of the aorta?
Superior hypogastric plexus
138
Where is the inferior hypogastric plexus
Internal iliac arteries
139
Most nerves from the spinal cord will synapse at the sympathetic chain. What about the nerves supplying abdominal organs?
Will go straight through the sympathetic chain without synapsing
140
Where do nerves supplying abdomen synapse?
Pre aortic ganglia eg at
Celiac trunk ganglia
S and I mesenteric trunk ganglia
141
Fibres from where that go the celiac trunk ganglion,what fibres what come from where
Sympathetic fibres coming from T5-9, I.e greater splanchnic nerve
142
The greater splanchnic nerve is what and synapses where
T5-T9
Celiac ganglion
Then follows arteries off the trunk to the foregut
143
What nerve supplies the foregut
Greater splanchnic nerve
144
What fibres go the the superior mesenteric ganglion, as the lesser splanchnic nerve
T10 and T11
Goes to
NB. There is also the least, which is 12
145
How many splanchnic nerves are these
Greater 5-9
Lesser 10 and 11
Least 12
146
Which nerves go to the superior mesenteric ganglion
Least and lesser splanchnic
147
Inferior mesenteric ganglia receives from what nerve
Lumbar splanchnic nerve, L1-3
148
So the lumbar splanchnic nerve (and other ones) synapse with what type of fibre
A post synaptic fibre
149
Hindgut mid and fore = what nerve
Greater splanchnic 5-9
Lesser and least 10,11 and 12
Lumbar l1-3
150
What are the two PARA sympathetic nerves of the abdomen?
Vagus and pelvic splanchnic nerve
151
Where does the vagus nerve enter the abdomen
EsophaGeal opening
152
Wher does the vagus nerve (uniquely) synapse ?
Not in a ganglion
But in the wall of the target organ
So VERY short post synaptic fubre
153
Vagus nerve also joins what plexus after foregut
Superior mesenteric plexus of midgut
154
Pelvic splanchnic nerve (sympathetic) goes where
Ascends with hypogastric nerves to the superior hypogastric plexus to inferior mesenteric plexus towards hindgut
155
What’s vagotomy
Medical intervention to interrupt signals from the vagus nerve
156
Effect of vagotomy on gastric secretion?
Reduces gastric secretion therefore treatment for peptic ulcers?
157
Foregut, mid gut and Hindgut tends to refer pain to where
Epigastral region
Umbilical region
Suprapubic region
158
Lumbar plexus is in which muscle
Psoas muscle
159
What artery supplies the hall bladder?
Cystic artery, comes off hepatic artery
160
How many layers of smooth muscle are in the muscular externa layer in the stomach?
3
Whereas usually 2 - circular muscle, longitudinal muscle
161
Lining of the stomach when empty is thrown up into what folds?
Rugae
162
What is the extra layer of the muscularis externa (which is usually) circular (inner) and external longitudinal layer?
An even inner layer of oblique muscle
163
Peyers patches are lymph nodules present within the mucosa of the small intestine… which part?
Ileum
164
Role of peyers patch in the ileum mucosa
Immune
165
What type of epithelium is in the anal canal?
Stratified squamous - this is protective. (Vs columnar like rest of GI.)
166
What type of epithelium is in the rectum?
Columnar like rest of the GI tract
167
We use the TNM classification for cancer. What unique staging do we use for colorectal cancer?
Duke’s staging
168
What’s the biggest treatment for colorectal cancer?
Surgery is the biggest
80% of patients will go through surgery
169
Surgical treatment for colorectal cancer is undergone how?
Via the laparoscopic method
170
Mainstay is surgery for colorectal cancer, and that is undertaken via laparoscopic method. When could cancer be resected endoscopically instead?
Very early cancers
171
(Simple question). When would a partial hepatectomy occur in colorectal cancer?
When the cancer has metastasised to the liver. Significantly improves survival.
172
When to do radiotherapy and chemo in colorectal cancer?
Before surgery in order to downstage the lesion
173
Majority of cancer occurs where in the colon.
Affects screening how?
Left side
So often when we’re screening we can undertake a colonoscopy, or just the left side of the colon with by means of a sigmoidoscopy
174
FAP is a risk factor for colorectal cancer. What is it?
Familial adenomatous polyposis
Where like multiple adenomas occur throughout the colon (sometimes even hundreds). Start at young age like 15, nearly everyone by 35
Chromosome 5
Most patients will develop colorectal cancer by the age of 40 unless untreated.
175
Why prophylactic proctocolectomy by my ageish for FAP’s? (Familial adenomatous polyposis).
Most patients will develop colorectal cancer by the age of 40 unless untreated.
176
Why do you do faecal elastase for pancreatic insufficiency?
Because elastase is a digestive enzyme for breaking down fats, carbs and proteins. If pancreas is working well you’ll have elastase in your stool.
177
Arterial supply of the oesophagus?
Thoracic region = branches from thoracic aorta, and inferior thyroid artery
Abdominal region = left gastric artery and left inferior phrenic artery
