Lecture 21: The Stomach and Pancreas Flashcards

1
Q

What is peristalsis?

A

The contraction of muscle to move food to the stomach

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2
Q

What the oesophageal hiatus?

A

The hole in the diaphragm that the oesophagus passes through to get to the stomach

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3
Q

What is the lower oesophageal sphincter (including its function)?

A

The sphincter passing through the stomach that prevents reflux of food back up the oesophagus

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4
Q

What are the four main parts of the stomach called?

A

Cardia
Fundus
Body
Pylorus (pyloric antrum)

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5
Q

Which part of the stomach does the oesophagus open up into?

A

the cardia

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6
Q

What is the significance of the fundus part of the stomach?

A

there are lots of gastric glands here and it is where all the gases collect

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7
Q

What is the significance of the pylorus part of the stomach?

A

it contains the pyloric sphincter for regulating the movement of luminal contents into the duodenum of the small intestine

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8
Q

What is an omentum?

A

a double layer of peritoneum that connects one organ to another

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9
Q

What does the lesser omentum connect?

A

the stomach to the liver

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10
Q

What does the greater omentum connect?

A

the stomach to the transverse colon

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11
Q

What does the lesser omentum contain?

A

blood vessels

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12
Q

What does the greater omentum contain and what are the roles of these things?

A
  • fat tissue to provide padding for the abdomen

- has clusters of immune cells to destroy pathogens in the peritoneal cavity

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13
Q

The four layers of the gut tube are mucosa, submucosa, muscularis and adventitia. How has the structure of the muscularis changed in the stomach and why?

A

The muscularis has been modified for motility and mixing to mechanically breakdown food and drive it towards the small intestine.
In the stomach, there is three layers (inner oblique, middle circular, outer longitudinal layer) instead of just the circular and longitudinal layers.

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14
Q

How does the thickness of the of the pyloris differ from the thickness of the fundus and why?

A

It is thicker in the pyloris because the stomach needs to mechanically breakdown food distally, closer to the small intestine.

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15
Q

What are rugae and what is their advantage?

A

they are temporary folds that allow for the expansion of the stomach
this is important to expand to accomodate more food

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16
Q

What is the role of sphincters in storage?

A

they control whether the food leaves the stomach or not and therefore they can keep food in the stomach for digestion.

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17
Q

Which layer of the gut wall are the rugae in and why?

A

the submucosa because the connective tissue in the submucosa allows them to flatten out

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18
Q

The four layers of the gut tube are mucosa, submucosa, muscularis and adventitia. How has the structure of the mucosa changed in the stomach and why?

A

The simple squamous epithelium has changed to simple columnar epithelium which invaginate down into the lamina propria to form glands.
This increases the surface area for secretion

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19
Q

Are glands in the mucosa of the stomach permanent

A

Yes

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20
Q

What four things do we need to be secreted from the glands?

A
  • Acid and enzymes for digestion
  • mucus for protection
  • hormones for regulation
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21
Q

What is present in glands that allows them to secrete mucus, and where are these located in the gland?

A

There are lots of goblet cells on the surface and in the neck of the gland

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22
Q

What is present in glands that allows them to secrete acid, and where are these located in the gland?

A

There are parietal cells deep in the gland which secrete HCl

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23
Q

What is present in glands that allows them to secrete hormones, and where are these located in the gland?

A

There are G cells which produce hormones deep in the gland

24
Q

Give an example of a hormone secreted by a G cell and what its role is

A

Gastrin is secreted which is for motility and secretion

25
Q

What is present in glands that allows them to secrete enzymes, and where are these located in the gland?

A

Chief cells located deep in the gland

26
Q

Give an example of an enzyme secreted by chief cells and what the role is

A

pepsinogen is the precursor of pepsin which is used for protein digestion

27
Q

Chief cells produce enzymes. What is it about their structure that allows them to carry out this function?

A

enzymes are proteins so they need a lot of rough endoplasmic reticulum to produce them
there is also apical zymogen granules to transport the enzymes to the apical surface
basal nucleus due to the zymogens being at the apical surface

28
Q

Parietal cells produce acid. What is it about their structure that allows them to carry out this function?

A

They need ion pumps to pump H+ ions and this requires energy. Therefore there is a lot of mitochondria to produce lots of energy
There is also a central nucleus and lots of folds to increase the surface area to maximise secretion

29
Q

How are the stomach functions regulated?

A

endocrine control

neural control

30
Q

Describe the endocrine control which regulates stomach function

A
  • endocrine cells in the mucosa secrete hormones to regulate function
  • gastrin and ghrelin are secreted into the bloodstream
31
Q

Describe the neural control which regulateds stomach function

A

enteric nervous system has local reflexes for primary control such as the myenteric plexus regulating motility events and the submucosal plexus regulating secretory events

32
Q

What is the role of ghrelin?

A

it is the hunger hormone

33
Q

What is chyme?

A

partially digested food

34
Q

What is the role of the pyloric sphincter?

A

to contract to stop movement of chyme from stomach to the duodenum of the small intestine but it can relax when this movement is required

35
Q

As the chyme enters the small intestine, further digestion is required. What is required in the duodenum to allow for this to happen

A
  • enzymes

- protection from acidic chyme through mucous and bicarbonate

36
Q

Where does the mucous come from in the duodenum?

A

It is provided by glands in the submucosa of the duodenum

37
Q

Where do the enzymes and the bicarbonate come from in the duo

A

from the pancreas

38
Q

How does the enzymes and the bicarbonate get from the pancreas to the duodenum?

A

through the pancreatic duct

39
Q

The pancreas is retroperitoneal. What does this mean?

A

It is behind the peritoneum as it doesn’t need to move

40
Q

What organ produces bile and which organs stores it?

A

The liver produces it and the gallbladder stores it.

41
Q

How does the bile get from the liver/gallbladder to the pancreatic duct?

A

Via the bile duct

42
Q

Where do the bile duct and the bile duct meet up?

A

in the hepatopancreatic ampulla

43
Q

What is the duodenal papilla?

A

Contents from the bile duct and pancreatic duct meet at the hepatopancreatic ampulla and they empty into the duodenum via the duodenal papilla

44
Q

How is the release of bile and contents from the pancreas into the duodenum controlled?

A

by the hepatopancreatic sphincter

45
Q

the pancreas has both ________ and _________ functions

A

endocrine and exocrine

46
Q

What are the exocrine secretions of the pancreas?

A
  • the acinar cells secreting digestive enzymes

- the duct cells secrete bicarbonate

47
Q

What is the structure of the pancreatic acinar cells?

A
  • apical zymogen granules
  • basal nucleus
  • abundant rough ER
48
Q

What is the purpose of the acinar cells?

A

secrete enzymes to break down proteins, carbohydrates and fats

49
Q

One acinus is made up of lots of

A

acinar cells

50
Q

The secretions of the acinar cells travel down _____ and combine with bicarbonate from _____ ______

A

ducts

duct cells

51
Q

What is it in the pancreas that produces the enzymes?

A

the acinar cells

52
Q

What is it in the pancreas that produces the bicarbonate?

A

the duct cells

53
Q

What two structures allow storage in the stomach?

A
  1. sphincters

2. rugae

54
Q

What three things do you need in the stomach for mechanical digestion?

A
  1. smooth muscle;
  2. the additional oblique layer in the stomach
  3. sphinctors
55
Q

What two things are needed for chemical digestion?

A
  1. secretion of strong chemicals (acids and enzymes)

2. protective epithelium