GI Tract: Fine-tuning revision Flashcards

1
Q

Does bile contain digestive enzymes

A

No

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2
Q

Does bile contain conjugated or unconjugated bilirubin

A

Conjugated ONLY

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3
Q

How does storage and concentration of bile in the gallbladder affect bile pH?

A

It DECREASES pH

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4
Q

Difference in the type of saliva secreted in serous and mucous glands

A

Serous is very WATERY (remember serous is a mixture of water and amylase)

Mucous is very thick and viscous (needed for lubrication)

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5
Q

Where is iodide mainly excreted

A

In the saliva

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6
Q

What cation can be found in the saliva

A

Calcium ions

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7
Q

What is the pH of saliva

A

6-7 (NEUTRAL)

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8
Q

What happens to the rate of saliva secretion when vomiting is about to take place

A

It increases in order to buffer the contents before it can cause any damage

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9
Q

Where is the swallowing reflex centre

A

Medulla oblongata

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10
Q

Is the swallowing reflex more effective standing or laying down

A

Standing because we then have the assistance of gravity

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11
Q

What needs to happen to iron before it can be absorbed at the duodenum

A

It needs to be reduced by HCL from trivalent ferric iron to divalent ferric iron

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12
Q

What cleaves pepsinogen to pepsin

A

HCL

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13
Q

Is vitamin C stored in the liver?

A

No

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14
Q

Where is vitamin C excreted

A

In the kidneys

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15
Q

How does ingestion of fibres influence bowel movement

A

It stimulates peristaltic waves by adding ‘bulk’ to the food residues

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16
Q

How are mucosal cells protected from gastric juices

A

Due to a coating of mucous which is IMPREGNATED with HCO3-

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17
Q

How will an increase in body fat affect body water volume

A

Will reduce it

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18
Q

Is saliva essential for digestion?

A

Nope, enzymes like ptyalin and HCL only assist digestion and can be carried out by chymotrypsin and trypsin in the duodenum

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19
Q

Where is calcium mainly absorbed

A

Duodenum

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20
Q

Do fatty acids get absorbed in the capillaries

A

They can do if they are small enough. Most will move in via lymphatics (lacteals) if they are too big and need to be esterified and packaged into chylomicrons

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21
Q

Where is cholesterol mainly excreted

A

In the bile (think HDL)

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22
Q

What factor will cause an increase in the risk of gallstone development

A

An increase in cholesterol: Bile salts and Cholesterol: Lecithin ratios

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23
Q

Will an increase in Bile salts: Cholesterol or Lecithin: Cholesterol increase the risk of gallstone formation

A

No, these favour micelle formation which reduces chances of gallstones forming

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24
Q

Can removal of the stomach impair iron absorption

A

Yes because it can only be absorbed at the duodenum as divalent ferric iron

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25
What symptoms can I expect to see in Hepatic Jaundice
Low prothrombic levels Low fibrinogen levels in the blood Low albumin levels
26
What papillae have no taste buds
FILLIFORM FUNGIFORM CIRCUMVALLATE FOLATE
27
Name the three branches of the coeliac trunk
- Left gastric artery - Common hepatic artery - Splenic artery
28
Is the duodenum retro or intraperitoneal
Retroperitoneal
29
Where is Meckel's diverticulum located
It is an appendix-like structure that is found at the ileum
30
Describe absorption of amino acids and glucose at the SMALL INTESTINES
They are moved into the intestinal epithelial cells by SECONDARY ACTIVE TRANSPORT with Na+
31
What ion moves into the intestinal epithelial cell with sodium ions
Cl-
32
How does Cl- enter the intestinal epithelial cell
Counter-transport with HCO3- ions
33
How does the Na+ and Cl- move out of the intestinal epithelial cells and into the interstitial
Na+/k+ ATPase Cl- ion channels
34
What other way does Na+ enter the intestinal epithelial cell
Na+/H+ ATPase
35
What two major ions are secreted in the large intestines and ileum
HCO3- and Cl-
36
Where is HCO3- absorbed , why and how
At jejunum and duodenum ``` H+ is exchanged with Na+ H+ reacts with HCO3- to give H2CO3 H2CO3 -> H2O + CO2 CO2 is re-absorbed and expired H20 remains in chyme ``` Prevents pH from becoming too high
37
Define Amphipathic
A compound that shows both lipophilic + hydrophilic properties
38
Where are meissner's plexus located
In gut submucosa
39
Where is Auerbach's plexus located
Between the two layers of the muscularis propria
40
What is the head of the pancreas supplied by
Inferior pancreaticoduodenal artery branch of the superior mesenteric artery
41
How does liver function affect the body if it fails
Increased size of male breasts as oestrogens and progesterones will not get conjugated Increased unconjugated bilirubin Increased tendancy to bleed
42
Why is dividing the vagal nerve supply to the stomach helpful for treating peptic ulcers
Less ACh released so less gastrin acidity
43
How will removing the pyloric antrum affect peptic ulcers
Reduce them as this removes a lot of the G cells in the stomach, reducing HCL release
44
What receptors do histamine bind to
H2 receptors
45
When does urobilin in the urine get darker
When exposed to light
46
Where are chymotrypsin and trypsin produced
Pancreas
47
Why can liver failure result in more salt and water retention
Because it is needed to conjugate aldosterone which won't be able to function at the liver properly otherwise
48
Can liver failure lead to oedema? If so, why?
Yes, because less albumin will be produced
49
What receptors does ACh bind to at the stomach
M1 - muscarinic receptors
50
How does portal hypertension affect vascular resistance through the sinusoids
Increases it
51
How does portal hypertension affect blood flow through the liver
Decreases it as blood flow will be diverted straight to the central vein as opposed to circulating around the sinusoids for a while
52
How will portal hypertension affect the volume of fluid in the peritoneal cavity
Increase it as there will be a higher hydrostatic pressure so more filtration will take place
53
What is D3 also known as
Cholecalciferol
54
What is D2 also known as
Ergocalciferol
55
What is the main source of vit D
UV rays
56
What do we have in our skin that starts off production of D3
7-Dehydrocholesterol
57
What is 7-dehydrocholesterol
Inactive precursor of D3
58
What happens to 7-dehydrocholesterol
It reacts with UV rays to produce cholecalciferol
59
What wavelength of UV is needed for activation of D3 to take place in the skin
270-300nm (optimal between 295 to 297nm)
60
Can we overdose from vit D with a lot of exposure from the skin?
Nope
61
Wht happens to vit D at the liver
converted to calcidiol
62
What happens to calcidiol at the kidney
Converted to calcitriol
63
What is the formula for calcidiol
25(OH)D
64
What is the formula for calcitriol
1,25(OH)2D
65
Where does vit D act
Intestines, Kidneys + Bone
66
Where is glucose absorped at the GI tract
Duodenum and small intestines
67
What part of the brain co-ordinates the vomiting reflex
Medulla Oblongata
68
What obstruction is vomiting indicative of
High intestinal obstruction
69
When does muscle tone in the oesophagus increase
Gastrin secretion to prevent reflux of gastric contents
70
When does muscle tone in the oesophagus decrease
During pregnancy - increases occurance of heart burn
71
What secretion causes disaccharides to be broken down
Intestinal secretions
72
What secretion causes triglycerides to be broken down
Pancreatic secretions
73
What secretions causes breakdown of nucleic acids
Pancreatic secretions
74
What compound causes contraction of the oesophageal-gastric sphincter
Gastrin
75
At what vertebral level is the gastro-oesophageal junction at
T11
76
What needs to happen to all carbohydrates before they can be absorbed by the body
They need to be broken down in to monosaccharides first
77
What happens to carbohydrates in the mouth
They are broken down by Ptyalin - an alpha amylase
78
What gland secretes ptyalin
Parotid Glands
79
What is the optimal pH that ptyalin works at
6.7
80
What happens to carbohydrates at the small intestines
The 1-4 glycosidic bonds of the carbohydrates are broken down but 1-6 glycosidic bonds are preserved
81
What are the end-products of digestion of the 1-4 glycosidic bonds in carbohydrates
- Maltose - Maltotriose - Alpha limit dextrins
82
What are alpha-limit dextrins
These are branched units with 8 units in total
83
What happens to maltose, maltotriose and alpha limit dextrins in the duodenum
They are broken down by oligosaccharidases in the microvilli: Maltase Lactase Sucrase Alpha-limit dextrase This produce monosaccharides
84
Name the three major monosachharides
- Glucose - Galactose - Fructose
85
How is Galactose absorbed
Galactose and glucose share the same SGLT co-transporter so compete with each other to be absorbed Galactose then moves from the intestinal epithelial cells into the interstitium via facilitated diffusion through GLUT channels
86
How does Fructose absorption differ from galactose absorption
Fructose has a different transporter - GLUT
87
Where are most carbohydrates absorbed
Duodenum
88
Where are these carbohydrates then moved from the duodenum
Into the hepatic portal vein and then on to the liver
89
What three things happen to glucose in the liver
- Glycogenesis - Production of glucose - Glycolysis
90
Why does glycolysis take place in the liver
- Production of alpha-glycerol phosphate and fatty acids that are needed to form triglycerides
91
How are alpha-glycerol phosphates produce from glycolysis of glucose
Reduction of dehydroxyacetone phosphate
92
What happens to triglycerides produced in the liver
They are placed into VLDLs
93
What are VLDLs
Lipoproteins that contain more fat than proteins
94
Why do lipoprotein lipases have to breakdown VLDLs as they circulate in the blood
Because they are too big to move through the capillary wall
95
How long do glycogen stores last for
12 Hours
96
How long do lipids last for in the body
3 months
97
When does protein become a source of energy
During prolonged starvation
98
How much of the body's total energy requirement is contributed to by the liver and the brain
40%