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Baz: Y1 Semester 2 > Nutrition and Digestion > Flashcards

Nutrition and Digestion Flashcards

1
Q

Main vessels entering and leaving the liver

A
  • Hepatic vein
  • Portal veins
  • Hepatic artery
  • Lymphatics
  • Hepatic ducts
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2
Q

Blood supply to liver?

A
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3
Q

What is a liver lobule and what is it’s shape?

A

It is the functional unit of the liver.

Approx 50’000-100’000 lobules

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4
Q

What does the portal triad consist of?

A
  1. Branch of hepatic artery
  2. Branch of portal vein
  3. Bile duct
  4. Lymph vessal (not included in the triad naming)
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5
Q

Try to draw out a lobule

A
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6
Q

What is a sinusoid?

A

It is a drainage channel where mixed oxygenated and nutrient rich blood from the portal triad can pass through the gaps in the endothelial lining to enter the space of disse and be taken up by the hepatocytes.

Further down towards the center of the hepatocyte blood containing stuff released by the hepatocytes drain back into the sinusoid form the space of disse where it drain into the central vein

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7
Q

What is a kupfer cell?

A

These are macrophages which gaurd the gaps between the sinusoid and the space of disse

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8
Q

What drains the other way out of the space of disse and back to the periphery (portal tracts)?

A

Lymph

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9
Q

What is produced by hepatocytes but drain back into the portal triad and not into the central vein?

A

Bile

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10
Q

What is the liver acinus?

A

As well as the classic lobule model some blood will perfuse from the edges of the hexagon (peripheral veins) of the lobule.

The liver acinus centers itself around one of these edges.

It is a way to divide up the hepatocytes in a lobule based on how much perfusion of blood from the portal triad they recieve.

Zone 1 gets the most perfusion and hence would become the most damaged from toxic substances in the blood.

Zone 3 gets the least perfusion and hence would suffer the most if the blood didn’t have enough oxygen.

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11
Q

What are the two types of faces on a hepatocyte?

A
  • Sinusoidal face - faces the sinusoid, takes in nutrients and toxin, releases other stuff
  • Lateral faces - faces other hepatocytes, some are modified to form the bile canaliculi
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12
Q

What are the bile channels within a lobule called?

What do they come together to form before the bile duct?

A

Bile caniliculi

Canal of hering

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13
Q

How is the lymph in a lobule formed?

A

By the filtration of plasma into the space of disse

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14
Q

Which three major vessels make up the portal vein?

A
  • Inferior mesenteric vein - from colon (large intestine)
  • Superior mesenteric vein - from small intestine
  • Splenic vein - from the spleen

Hint: inferior mesenteric comes formt he colon because the colon lies at the end (bottom) of the intestinal tract

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15
Q

Where does the hepatic artery come from and what is the other vessal that comes from the bifurcation?

A

It comes from the celiac trunk which forms both the hepatic artery and the splenic artery

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16
Q

Describe the glucagon-insulin cycle

A
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17
Q

What is bilirubin?

A

It is formed form the breakdown of haemoglobin at the end of a RBCs lifecycle

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18
Q

Describe the bilirubin cycle

A

Unconjugated bilirubin is toxic and must be removed from the blood.

This is done by the liver which turns it into conjugated bilirubin and excretes it into the biliary system. Conjugated bilirubin is then excreted directly in the faeces (brown colour) or converted into urobilinogen where it goes back through the liver and to the kidneys and excreted in urine

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19
Q

How does bile exit the liver?

A

Through the common bile duct where it combines witht eh pancreas’ bile and enter into the duodenum.

At the entrance to the duodenum there is a valve. If this shuts then refluxed bile goes to the gallbladder and is stored.

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20
Q

What are the general steps to liver detoxification?

A
  1. Fat soluable toxins enter liver
  2. Liver processes them using various vitamins and nutrients
  3. Water soluable toxins leave the liver
  4. Exit via bile and then to the bowel or to the kidney and urine
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21
Q

What is jaundice and what is it a sign of?

A

This is where the skin becomes yellow due to a build up of billirubin. It is a sign of liver damage or bile duct blockages

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22
Q

What would elevated bilirubin in a blood test signify?

A

Liver cirrhosis

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23
Q

What acid is stomach acid?

A

Hydrochloric acid

24
Q

What are the sphincters that prevent stomach acid from leaving the stomach?

A

Osophageal sphincter and Duodenal sphincter

25
Q

What protects the stomach from acid?

A

Mucosa

26
Q

What cells make stomach acid?

A

Parietal cells

27
Q

What cells in the stomach make gastrin

A

G Cells

28
Q

What cells in the stomach make somatostatin

A

D Cells

29
Q

What cells in the stomach make histamine?

A

Enterochromaffin cells

30
Q

What is gastrin?

A

Gastrin is a hormone primarily responsible for enhancing gastric mucosal growth, gastric motility (movement of food) and secretion of hydrochloric acid (HCl) into the stomach

31
Q

What cells int he stomach make mucus?

A

Mucus cells

32
Q

What cells in the stomach make pepsinogen (becomes pepsin which breaks down proteins in food)

A

Cheif cells

33
Q

What does amylase do and where is it made?

A
34
Q

What are proteases and what are the three main proteases?

A
35
Q

What are lipases?

A
36
Q

What do bile salts have to do with diarrhoea?

A

Bile salts are recyled from the small intestine intot he liver and back into bile

If they make their way to the large intestine they cause diarrhoea therefore diarrhoea can be a sign that somthing is up with the liver and bile salt recycling

36
Q

Three main types of enzymes?

A
  • Lipases
  • Amylase
  • Proteases
36
Q

What are bile salts?

A

The emulsify fats and allow lipases to act

37
Q

Describe the process of B12 absorption?

A

B12 is liberated from proteins by acid and pepsin int he stomach

Then binds to R-factors

Complex released by pancreatic proteases in the duodenum where it is bound to intrinsic factor (made by parietal cells)

It is then IF-B12 and can be absorbed in the terminal ileum

38
Q

What is the name of B-12 which can be absorbed?

A

IF-B12

intrinsic factor bound B12

39
Q

Main causes of B12 deficiency

A
  • Poor dietary intake
  • Small bowel disease (crohn’s / post surgery)
  • Pernicious anaemia (antibodies ot parietal cells)
40
Q

What disorder does S have and what is going on?

A

Pernicious anaemia

It is where you have antibodies to parietal cells therefore they don’t make intrinsic factor and you can’t absorb B12 reuslting in anaemia

This is overcoming by directly injecting B12 hence you can bypass the absorbtion issues

41
Q

Two types of dietary iron.

Where is each one found and which is better at being absorbed

A
  • Fe2+ - ferrous - found in heme from meats - well absorbed
  • Fe3+ - ferric - from vegetables - not well absorbed
42
Q

Stomach acid’s role and vit C in iron absorbtion?

A

Stomach acid and vit c can help reduce Fe3+ to Fe2+

43
Q

What is hepcidin and what is it’s role in ron metabolism?

A

It blocks iron absorbtion by degrading ferroportin (a way iron is stored before entering the blood)

High circulating iron is toxic so if iron in the blood plasma is high then hepcidin becomes high which impaires further iron absorbtion.

Hepcidin lasts for 48h therefor there is an argument to give iron supplimentation every 48h for optimum absorbtion

44
Q

What is the metabolic role of ATP (what does it achieve?)

A
45
Q

What is the metabolic role of NADPH? (what does it achieve?)

A
46
Q

What does the word “anabolic” refer to?

A

Tissue building or the sythesising of complex molecules from simple molecules

47
Q

What does the word catabolic refer to?

A

The breakdown of complex molecules into simple ones

48
Q

How do the roles of ATP and NADPH differ?

A

ATP is pure energy and can be used directly or for synthesis of complex molecules. NADPH is a reducing agent and is used in sythesis only

49
Q

Efficiency of glycolysis (anaerobic) vs TCA cycle and oxidative phosphorylation (aerobic)

A

2 ATP per glucose for anaerobic vs 30 ATP per glucose for aerobic

50
Q

What is Leptin and what is the effect of congenital Leptin deficiency

A

Leptin is a peptide hormone that is released by adipocytes.

Its circulating levels therefore correspond with body fat.

It’s effects are the suppression of appetite and increasing metabolism.

It is essentially a weight regulating hormone.

If someone is deficient in Leptin then they are particularly susceptible to obesity.

51
Q

What are gallstones and what is a common cause?

A

What causes gallstones? Gallstones are thought to develop because of an imbalance in the chemical make-up of bile inside the gallbladder. In most cases the levels of cholesterol in bile become too high and the excess cholesterol forms into stones.

52
Q

What is a common effect of pancreatitis

A

When the pancreas becomes damaged, pancreatic enzymes are not produced, and malabsorption results.

53
Q
A

Baz: Y1 Semester 2 (42 decks)

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