GI Flashcards

1
Q

What happens in the stomach?

A

Acetylcholine>gastrin>histamine

Protein increases ph so secretion of somatostatin inhibited so more parietal cell activity

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2
Q

How is acid secretion in stomach turned off

A

Duodenal distension low luminal ph hypertonic contents trigger real ease of secretin (inhibits gastrin release and promotes somatostatin release) ach reduces too

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3
Q

What happens with protein in the stomach

A

Pepsinogen(as zymogen) released by chief cells and turned into pepsin in the stomach by low ph

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4
Q

Wht mediates receptive relaxation in stomach?

A

NO and serotonin released by enteric nerves mediate relaxation

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5
Q

How does acid from parietal cells work?

A

Diagram

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6
Q

What are the functions of he stomach

A
Storage
Mixing food
Dissolve and continue digestion
Secrete and activate proteases
Etc
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7
Q

What’s is the blood supply to the stomach?

A

Diagram

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8
Q

What are the folds in the small intestine called?

A

Plicae circulares

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9
Q

What immune type things are located in the ileum an not the jejenum and why?

A

Peters patches- submucosal lymph nodules. Found in ileum as most absorption taken place in jejenum so bacteria more conc

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10
Q

Where does the large intestine start?

A

Ileo-caecal valve

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11
Q

What arê components of the large intestine?

A
Taenia coli 
Mucosa 
Submucosa
Mesocolon
Appendix epiploica
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12
Q

What is the blood supply to the jejenum and ileum and how do they differ in structure

A

Superior mesenteric artery
Jejenum-single row of arcades then vasa recta
Ileum- several rows of arcades then vasa recta

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13
Q

What are the landmark parts to the duodenum?

A

1st-posteriorly related gastroduodenal artery and portal vein anteriorly to liver and gall bladder

2nd-bile duct and pancreatic duct enter duodenal papilla

3rd- runs horizontally to left crossing vena cava and aorta

4th- ascends vertically and turns abruptly to end as duodenojejunal flexure.

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14
Q

Blood supply to large intestine from top left down

A

Inferior mesenteric- left colic

Marginal , sigmoid

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15
Q

What are the parts of the stomach

A

Fundus, cardia, body, Antrum

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16
Q

How are carbohydrates digested

A

Start in mouth by alpha amylase (ptyalin) in saliva

Most in small int by pancreatic amylase into disaccharide maltose and other branches chain glucose molecules. Further digested by brush border ogliosacaridases eg maltase

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17
Q

How are carbs absorbed?

A

Glucose/na symporter channel (also does galactose)

Fructose- facilitated diffusion

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18
Q

How is protein digested?

A
Pepsinogen--->pepsin=stomach
Proteolitic enzymes (peptidases) small intestine
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19
Q

How are proteins absorbed?

A

Small peptides-co-transport with h+
Amino acids-absorbed into cytosol by cotransport with na+ them cross basolateral membrane by fac dif and then into capillary through pores

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20
Q

Outline fat digestion and absorption

A
Micelles 
Chylomicron>lateal
Blood
Lipoprotein lipase
Fatty acids enter cells
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21
Q

What are the lipid soluble vitamins?

A

A,d,e,k absorbed in the same way as fats

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22
Q

What are the water soluble vits?

A

C, b12, b6

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23
Q

What’s the function of vit a,c and b12

A

A-cellular growth and differentiation
C-synthesise collage and neurotransmitters, absorption of iron
B12-DNA synthesis, brain development

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24
Q

How is b12 absorbed?

A

Bound to intrinsic factor

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25
Outline the B-oxidation pathway of fatty acids
``` CoA binding to fatty acid Dehydrogenation Hydration Oxidation Removal of acetyl-CoA Repeats until fatty acids is left as to acetyl-CoA's Thea acetyl CoA's enter the kerbs cycle ```
26
How are sodium and water absorbed in the small intestine?
Water-osmosis or aqua porins ( both solute driven) Na-actively transported into cell of intestine (often coupled with glucose) then pumped into the blood by na/k ATPase Glucose absorbed from intestinal cell into blood via GLUT-2 channel
27
What is the distribution of iron in the body?
Utilised- muscle (myoglobin) and bone marrow to make rbcs Storage-liver, reticulo-endothelial macrophages
28
Explain the absorption of iron
Food iron split into heme and fe3+(non heme iron) Heme- passes into cell via heme transporter. Then stored as ferritin and exported out of the cell into the blood through ferroporin channel. Non heme- passes into cell through DMT1 channel then stored as ferritin and passes into blood via ferroporin 1 channel. Once in the portal blood fe3+ bound to plasma transferrin and taken to the liver or bone marrow
29
Where are the parietal cells in the stomach?
Body and fundus
30
Outline the absorption of vitamin B12
Binds to r factor in stomach then r factor Removed by pancreatic enzymes in duodenum and binds to IF produced by parietal cells. Then absorbed in terminal ileum and taken in portal circulation to the liver
31
What is the role of b12 and folate. What effect can it have in pregnancy?
B12-rbcs Folate-help rbcs mature an involved in development of fetal ns Spina bifida
32
Outline the lysosomal degradation of proteins in the liver
Carries out by the reticulo-endothelial system. Sinusoids remove proteins through sieve plates. Kupffer cell phagocytose particulate matter.
33
Outline the non-lysosomal degradation of proteins in the liver
For proteins that are defective. Bind to protein called ubiquitous which is a recognition site for cellular executioner proteosome which breaks down the protein
34
What sorts of times is the body in positive nitrogen balance?
Pregnancy Body builders Patients recovering from illness or surgery
35
When is the body in negative nitrogen balance,
Malnutrition-severe wasting due to lack of calorie intake Multiple trauma or extensive trauma
36
Outline the development of the pancreas
Develops at two separate outgrowths-ventral and dorsal bud. Ventral bud rotates around and fuses with the dorsal pancreas. The two ducts fuse to form main pancreatic duct.
37
Why are the exocrine functions of the pancreas?
Acinar cells- release enzymes in their inactive form (zymogen) eg trypsinogen inform activated to trypsin by enterokinase and trypsin. Duct cells- release bicarbonate in the same way as hcl in stomach but reversed direction
38
What is the blood supply to the pancreas?
Mainly coeliac trunk but also a bit to the head from the superior mesenteric
39
What hormones control enzyme secretion in the pancreas?
Secretin-watery bicarbonate part | CCK-enzyme part
40
What is the role of bile?
Bile salts emulsify fats. Bile slats synthesised from cholesterol in the liver
41
What is the blood supply to the gallbladder
Cystic artery. No venous drainage as drains directly into the liver
42
What makes up the portal triad?
Hepatic portal vein Hepatic artery Bile duct
43
What do Kupffer and stellate cells do?
Kupffer-liver resident macrophages | Stellate- produce extra cellular matrix
44
What happens to the bile once made in the liver?
Passes down left and right hepatic duct and as the sphinchter of oddi into the duodenum is closed pushed down the cystic duct into the gallbladder where bile is concentrated by adding na and cl. When food enters duodenum at CCK is released from duodenum the gallbladder contacts and sphinchter of oddi opens so bile can move into the duodenum.
45
Where are bile salts reabsorbed and how much?
Start to be reabsorbed in the jejenum with greatest amounts being reabsorbed in the terminal ileum. 90% is retained
46
Explain what happens to bilirubin
Bilirubin being fairly water soluble is conjugated to glucuronic acid and excreted into bile. In the intestine action if bacteria reduces this to urobilinogen and most of this is passed in the faeces. Although some is reabsorbed into portal circulation and either ends up in urine (yellow tinge) or is recycled into bile
47
What are the lobes and ligaments of the liver
Right, left, caudate, quadrate. | Falciform, teres, left coronary, right coronary, left and right triangular
48
Describe haemoglobin and bilirubin metabolism
Reticulo endothelial system of spleen breaks down old rbcs. Heme oxygenated to biliverdin then reduced to unconjugated bilirubin. Not water sol so passes in the blood attached to album to the liver. In the liver it is conjugated with glucaronic acid making it water sol. Conjugated passes into colon where urobilinogen is formed due to bacteria. Thai can be oxidised into urobilin and sterobilin (giving stool brown colour). Urobilin is reabsorbed into enterohepatic circulation where it is transported to liver and re-excreted into bile or processed by the kidneys into urine.
49
What are the classification of the causes of jaundice
Pre-hepatic- increased rate in haemolytic so raised unconjugated bilirubin Hepatic-cell necrosis reduces liver ability to metabolise and excrete bilirubin so raised unconjugated bilirubin Or impairment of excretion so raised conjugated bilirubin Post hepatic- failure of canicular excretion so raised conj bilirubin. No urobilirubin as can't pass into small intestine
50
Outline the development of the duodenum
During rotation of the foregut hanged to c-shaped loop and swings to the right side of the body. Pancreas grows rapidly and fills the con cavity. In this process dorsal mesoduodenum fuses with peritoneum on posterior abdo wall and become retroperitoneal
51
What are the stages of the development of the midgut?
``` 1-elongation 2-physical umbilical herniation 3-rotation 4-retraction 5-fixation ```
52
What is the space of disse?
Between hepatocyte and sinusoid. In these spaces lymph is collected and delivered to lymphatic capillaries. Lymph is collecting in hepatic duct outside the liver.
53
Where does the liver develop?
Outgrowth from the distal part of the foregut
54
How does the liver develop in the body?
Hepatic cells proliferate and penetrate ventral mesentery. The connection between liver diverticulum and duodenum narrows forming the bile duct. Further growth if liver bud allows cords to intermingle with umbilical and cute line veins forming sinusoids. The liver cords form hepatocytes and ventral mesoderm forms hemopoietic cells, Kupffer cells and connective tissue cells
55
What do the islets if langergans in the pancreas do?
Beta cells-produce insulin Alpha cells- produce glucagon Delta cells- produce somatostatin
56
Outline the glucose alanine cycle
Liver- alanine>pyruvate>glucose | Muscle- glucose>pyruvate>alanine
57
What happens to glutamine in the liver?
Converted into glutamate (by glutminase) which then is made into a ketoglutarate which can be fed into kerbs cycle. This is catalysed by ADP.
58
What bounds the caudate and quadrate loves of the liver?
Caudate-Ivc and fissure holding ligamentum venosum | Quadrate- bounded by gallbladder and groove for ligamentum teres
59
What is the porta hepatis?
Transverse fissure of right lobe of liver. Separates caudate and quadrate lobe. Portal triad lies in it
60
What are the relations of the liver?
Anterior- anterior abdo wall and ribcage Superior- diaphragm Posterior-oesophagus,stomach,gallbladder, first part of duodenum
61
What are the parts of the gallbladder?
Fund us Body Neck
62
What is the innervation to the gallbladder?
Celiac plexus- sympathetic | Vagus-parasympathetic