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Foundations Of Medicine > 8.4 The Small Intestine, Pancreas, Liver & Gallbladder > Flashcards

8.4 The Small Intestine, Pancreas, Liver & Gallbladder Flashcards

1
Q

Describe segmental activity of the small intestine in relation to meal timing

A

Between: slight/absent
Immediately after: vigorous

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2
Q

Why does chyme gradually move throughout the intestine due to segmentation?

A

Because the frequency of small intestine contraction decreases distally

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3
Q

Describe the gastroileal reflex

A

Ileal begins segmentation while empty in response to gastrin secreted by the stomach in the presence of chyme

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4
Q

How is the MMC controlled? Why doesn’t it occur during eating?

A
  • Control by motilin: hormone secreted by endocrine cells of SI
  • Inhibited by feeding
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5
Q

What causes the ileocaecal valve to close/open?

A

Open: ileal contents pushes valve open
Close: Colon contents pushes valve closed (why is is important to keep colon contents out?)

REMEMBER: IC VALVE IS A SPHINCTER

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6
Q

How much intestinal juice is secreted per day? What does it contain, and why?

A
  • 1.5L/day
  • Aqueous salt and mucus solution; lubricates, protects, and enables hydrolysis (NO ENZYMES IN INTESTINAL JUICE)
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7
Q

Describe the secretion of intestinal juice

A

Secreted from enterocytes. Contains enteropeptidase, which is the enzyme necessary for activating trypsin (and the following cascade of reactions)

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8
Q

What are the three levels of folding of the small intestine?

A
  • Circular folds (3x)
  • Villi (10x)
  • Microvilli (20x)
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9
Q

Describe the structure of a villus

A
  • Epithelial cells joined by tight junctions
  • Have a luminal brush border with digestive enzymes
  • Capillary network
  • Central lacteal blind lymph vessel
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10
Q

Describe the actions of the crypts of liberkuhn

A
  • Invaginations on each side of the villus, in which water and electroytes are secreted
  • Mitotic activity of stem cells causes epithelial cells to migrate up toward tip and be shed into the lumen
  • Antimicrobial cells are produced in the Paneth cells at the base of the pit
  • Migration takes 3 days
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11
Q

What to paneth cells produce to safeguard stem cells?

A
  • Lysozymes
  • Defensins
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12
Q

Draw the process of digestion of carbohydrates, including relevant enzymes

A

Check diagram document

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13
Q

How do glucose and galactose enter the epithelial cells that line the small intestine

A

SGLT symporters; Na+ and energy dependent secondary active transport

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14
Q

How does fructose enter the epithelial cells that line the small intestine?

A

GLUT-5 Transporters

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15
Q

How do monosaccharides leave small intestine epithelial cells out of the stomach?

A

GLUT-2 Transporters

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16
Q

What enzymes work to break down proteins in the lumen of the SI? (precursors)

A
  • Trypsinogen
  • Chymotrypsinogen
  • Procarboxypeptidase
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17
Q

Describe how absorbed monoglycerides and fatty acids enter lymphatic circulation

A
  • Passively absorbed
  • Reform triglycerides
  • Coatted in lipoprotein from ER to form water-soluble chylomicrons
  • Exocytosis
  • Enter central lacteal (too big to pass through capilllaries)
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18
Q

True or false: the pancreas is derived from one tissue during embyronic development

A

False: endocrine and exocrine sections are derived from different tissues

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19
Q

True or false: the endocrine and exocrine regions of the pancreas have different functions but are under the same regulation

A

False: different functions, different regulation

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20
Q

The aqueous alkaline solution secreted from the ducts of the pancreas is rich in ___ which raises the pH, which is important for ____

A

Sodium bicarbonate. This is important for inactivating pepsin, which stops the duodenum from being digested.

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21
Q

Name three kinds of enzymes secreted from the acinar cells of the pancreas

A
  • Proteolytic enzymes
  • Pancreatic lipase
  • Pancreatic amylase
22
Q

List the three major pancreatic proteases

A
  • Trypsinogen
  • Chymotrypsinogen
  • Procarboxypeptidase
23
Q

Describe the activation of the three pancreatic proteases

A
  • Enterokinase from epithelial cells converts trypsinogen to trypsin
  • Trypsin converts chymotrypsinogen to chymotrypsin and procarboxypeptidase to carboxypeptidase
24
Q

Are pancreatic lipase and amylase secreted in active or inactive form? Why?

A

Active: no triglycerides or polysaccharides in acinar cells of pancreas

25
Q

What is the name of the condition that involves excess fat in faeces?

A

Steatorrhoea

26
Q

Draw a diagram of the substances exchanged into/out of a duct cell in the pancreas

A

Diagram document

27
Q

Draw the basic feedback loop that limits the acidity in the duodenum

A

Document

28
Q

What is the digestive role of the liver?

A

Secretion of bile salts

29
Q

Draw a map of the heart, the liver, the GI tract, and veins. What type of blood does the liver recieve from where?

A
30
Q

How are hepatic lobules arranged?

A
  • Hexagonal, with central vein in middle
  • On each corner, branch of hepatic portal vein, hepatic artery, bile duct
31
Q

Does blood move from inside to outside of hepatic lobule? How about bile?

A

Blood: Outside to inside
Bile: Inside to outside

32
Q

Does blood move from inside to outside of hepatic lobule? How about bile?

A

Blood: Outside to inside
Bile: Inside to outside

33
Q

What is the name of the specialised macrophages of the liver? What do they do

A
  • Kupffer cells
  • Break down old red blood cells
34
Q

Describe the passage of bile from hepatic lobules

A

Hepatocytes -> bile canaliculus -> peripheral bile duct -> common bile duct

35
Q

What are some components of bile?

A
36
Q

How is bile concentrated in the gall bladder?

A
  • Actively transports salt out
  • Water following
  • Volume decreases
37
Q

What are gallstones?

A

(AKA Choleliths); are cystalline bodies that have precipitated from bile components (most made of cholesterol)

38
Q

What sphincter connects to the ampulla of vater?

A

Sphincter of Oddi

39
Q

Where does bile travel to get to the liver from the common bile duct?

A

Cystic duct

40
Q

What is the diameter of a micelle? What comprises their hydrophilic components in the liver?

A
  • 3-10nm
  • Hydrophilic shell made of lecithin and bile salts
41
Q

In terms of micelles, how do gallstones form? Therefore, how can it be treated?

A
  • Fat-soluble cholesterol escapes core of micelle
  • Microcrystals form
  • Can be treated by ingesting bile salts
42
Q

Where are bile salts recycled in the GI tract? How do they return to the liver? How much escapes to faeces?

A
  • Reabsorbed in terminal ileum
  • Return via hepatic portal system
  • 5% escape to faeces
43
Q

What are choleretics?

A

Factors that increase bile secretion

44
Q

How can bile salt secretion be chemically stimulated

A

bile salts stimulate their own secretion when
returned to the liver during meal digestion

45
Q

How can bile salt secretion be hormonally stimulated?

A

Secretin stimulates an aqueous NaHCO3 bile
secretion to neutralise chyme

46
Q

How can bile salt secretion be neurally stimulated?

A

vagal stimulation of liver to increase bile flow
during cephalic phase plays a minor role

47
Q

Is bilirubin involved in digestion

A

No. It is a waste product secreted in bile

48
Q

How is bilirubin formed

A

Formed during the degradation of the heme (iron-containing) part of haemoglobin in RBCs

49
Q

If bilirubin is a yellow pigment, how does it make faeces brown?

A

Modified by bacterial enzymes in the intestines

50
Q

Why is urine yellow

A

Some bilirubin is reabsorbed and can be excreted in urine

51
Q

What are three potential causes of jaundice?

A
  • Obstruction
  • Liver problems
  • Haemolytic anemia, something wrong with blood
52
Q

What is cirrhosis?

A

Active liver tissue is replaced by connective tissue

Foundations Of Medicine (98 decks)

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