Small intestine

Question 1

What three substances are secreted into the duodenum and where do they come from?

Answer 1

Chyme - stomach
Bile - gall bladder
Pancreatic juice - Pancreas

Question 2

What three things increase the surface area of the small intestine?

Answer 2

Circular folds
Villi
Microvilli

Question 3

What juice is secreted by the small intestine itself?

Answer 3

Succus entericus

Question 4

What hormones are released from the small intestine and where are they released into

Answer 4

Systemic Circulation:
CCK
Gastrin
GLP-1
GIP
Secretin
Motilin
Ghrelin

Question 5

What is included in the succus entericus and where are they released from?

Answer 5

Mucous - goblet cells at top of villi

Aqueous salt - dips between villi

Question 6

Where is chlorine excreted from and to and which ion channel is involved in the second part of this?

Answer 6

From the lumen of the GI tract across the mucosa and into systemic circulation - through CTFR ion channel (CF)

Question 7

What is segmentation for and how does it occur?

Answer 7

Mixing of food in the small intestine by contraction of smooth muscle

Question 8

What are the two types of peristalsis that occur between meals?

Answer 8

Localised peristaltic contractions

Migrating motor complex (MMC) - sweeps from top to bottom of GI tract

Question 9

How is segmentation affected by feeding?

Answer 9

It increases

Question 10

What are the two parts of the pancreas and what do they each secrete?

Answer 10

Exocrine - digestive enzymes + alkaline fluid

Endocrine - insulin + glucagon

Question 11

What is secreted in the pancreatic juice?

Answer 11

Digestive enzymes

Bicarbonate rich solution (neutralises acidic chyme from stomach)

Question 12

What are the three types of digestive enzyme released from the pancreas and what do they each digest?

Answer 12

Proteases - protein (not activated until in small intestine as would auto digest the pancreas)
Amylases - carbohydrates
Lipases - fat

Question 13

What are the 3 phases of pancreatic secretion?

Answer 13

Cephalic
Gastric
Intestinal

Question 14

What are the two types of digestion and where are the enzymes from?

Answer 14

Luminal digestion - enzymes from pancreas

Membrane digestion - enzymes on brush border of membrane

Question 15

What is the overall process of absorption and digestion called?

Answer 15

Assimilation

Question 16

What is the process of digestion of carbohydrates (luminal/membrane digestion)?

Answer 16

Starch –> oligosaccharides (luminal digestion)

Oligosaccharides –> monosaccharides (membrane digestion)

Question 17

Why is lactase so important?

Answer 17

Is is the only enzyme that can break down lactose into glucose

Question 18

What form must carbohydrates be in to be absorbed?

Answer 18

Monomers

Question 19

Where does absorption of carbohydrates occur?

Answer 19

Duodenum + jejeunum

Question 20

What are the three types of intestinal failure?

Answer 20

Type 1: self-limiting
Type 2: prolonged with complications
Type 3: long term, stable

Question 21

What is enteral and parenteral nutrition?

Answer 21

Enteral: Feeding directly into the small intestine
Parenteral: feeding directly into systemic circulation

Question 22

What are the four parts of the duodenum?

Answer 22

Superior (with duodenal cap),
Descending,
Horizontal,
Ascending

Question 23

Where does the duodenum start and end and what are these parts?

Answer 23

Starts: pyloric sprinter - anatomical sphincter controlling release of chyme into the stomach (parasympathetic)
Ends: duodenaljejunal flexure - change in the small intestine

Question 24

Describe + name the parts and path of the biliary tree?

Answer 24

Left + right hepatic duct
==> common hepatic duct
common hepatic duct + cystic duct
==> common bile duct

Question 25

What is the name of the blood supply to the gall bladder?

Answer 25

Cystic artery

Question 26

Name the 4 parts of the pancreas

Answer 26

Head, Neck, Body, Tail

Question 27

What types of cell are in the pancreas?

Answer 27

Acinar cells

Question 28

Is the pancreas parasympathetic or sympathetic?

Answer 28

All glands = parasympathetic

Question 29

What drains the cells of the pancreas and what 'hole' does it pass through at the end?

Answer 29

The main pancreatic duct | Major duodenal papilla

Question 30

What do the main pancreatic duct and the common bile duct pass through into the duodenum and what sphincter is associated with this?

Answer 30

``` Hepatopancreatic ampulla (of Vater) Sphincter of Oddi ```

Question 31

Which hormone stimulates opening of the sphincter and release of digestive enzymes and bile into the duodenum?

Answer 31

CCK

Question 32

Which arteries supply the pancreas and how do they join?

Answer 32

Superior pancreaticduodenal artery and inferior pancreaticduodenal artery Anastomose

Question 33

Does the pancreas have foregut or midgut blood supply

Answer 33

Both The superior pancreaticduodenal artery is foregut (from the coeliac trunk) and the inferior pancreaticduodenal is midgut (off the superior mesenteric artery)

Question 34

Which parts of the small intestine are fore or midgut organs?

Answer 34

Foregut: duodenum Midgut: jejunum + ileum (DJ ileum)

Question 35

What are the differences between the jejunum and the ileum?

Answer 35

``` Jejunum = thicker Jejunum = more vasculature Jejunum = more circular folds Jejunum = more red Ileum = more fat (responsible for fat absorption) ```

Question 36

Which arteries supply the jejunum and ileum?

Answer 36

Superior mesenteric artery via jejunal and ill arteries

Question 37

What is the venous drainage of the jejunum and ileum?

Answer 37

Jejunal and Ileal veins into the superior mesenteric vein and the hepatic portal vein

Question 38

At which vertebrae does the superior mesenteric artery leave the aorta?

Answer 38

L1

Question 39

What does pepsin do?

Answer 39

Cleave protein to peptides

Question 40

How do di-, tri- + tetra- peptides enter the cell?

Answer 40

PepT1 transporter - uses the proton gradient due to acidic microenvironment at brush border

Question 41

What is the issue to digestion caused by fats?

Answer 41

They are insoluble/very limited solubility so must be emulsified to break into smaller particles for lipase action

Question 42

What lipases are active where?

Answer 42

Gastric lipase in the stomach (stimulated by gastrin release - denatured by higher pH in the duodenum) Pancreatic lipase in the duodenum (stimulated by CCK release - aided by bile salts from gall bladder)

Question 43

What prevents lipid salts coalescing?

Answer 43

``` Bile salts (have -ve charges which repel each other) Hydrophobic/hydrophilic coat ```

Question 44

How are free fatty acids absorbed?

Answer 44

Passive diffusion

Question 45

Which circulation are short and long chain fatty acids transferred into?

Answer 45

``` Short = systemic Long = lymphatic ```

Question 46

How is cholesterol absorbed?

Answer 46

Invagination of the apical membrane when bound to a specific protein

Question 47

Describe the foregut blood supply

Answer 47

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