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Cell And Tissue Biology > Digestive System > Flashcards

Digestive System Flashcards

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1
Q

What is the general structure of the digestive tract?

A

This is a hollow tube where all regions have a certain structural feature in common

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2
Q

The wall of the GI tract is made up of four main layers. What are these layers named in order?

A

Mucosa
Submucosa
Muscularis system
Serosa Adventitia

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3
Q

Explain the mucosa, the first layer of the GI tract and its 3 subdivisions.

A

The mucosa is a mucus membrane that functions as protection, absorption, and secretion.

This is divided into 3 components:

I—> epithelium
II—> Lamina Propria, loose CT that supports epithelium . Rich in blood, in GI tract, contains lymphatic tissue (GALT AND MALT)
III—> Muscularis Mucosae, smooth muscle allows for movement

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4
Q

Explain the submucosa, the second layer of the GI tract.

A

This contains a dense irregular CT.

  • supports large blood vessels and lymphatic vessels
  • contains the submucosal plexus (meissners plexus)
  • contains some glands in area of GI tract and may contain lymphatic tissue
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5
Q

Explain the muscularis externa, the third layer of the GI tract and its 2 subdivisions.

A

This usually consists of 2 layers of smooth muscle.

  • there is a layer of SM running in opposite planes that aids in peristalsis.
  • myenteric plexus (Auerbachs plexus) innervates smooth muscle
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6
Q

Explain the Serosa Adventitia, the fourth layer of the GI tract and its 2 subdivisions.

A

This either has a serosa, or an adventitia.

A serosa: thin layer of CT with outer covering of mesothelium and a serous membrane continuous with mesentery

An adventitia: CT that merges with surrounding tissue, not a free surface (no mesothelium)

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7
Q

What is the esophagus? What are the three types of lawyers within this wall?

A

The esophagus is a muscular tube that transports swallowed material to the stomach.

Consists of:

Mucosa—> epithelium, stratified squamous. Lamina propria and esophageal glands that are limited to a small region near the cardiac portion of the stomach. Produces neutral mucous.

Submucosa—> esophageal glands. More numerous, produces slightly acidic mucous which lubricates and protects mucus

Muscularis Externa—> swallowing begins with voluntary muscle and ends with involuntary peristalsis.
(1/3 skeletal, 1/3 mixed Smooth and Skeletal, 1/3 Smooth)

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8
Q

What is the function of the stomach? What a are the four regions?

A

This dilates and allows for food to become broken down.

  1. Cardiac stomach/region (cardia)
  2. Pyloric Stomach/region (Pylorus)
  3. Fundic Stomach/region (fundus)
  4. Body (similar to fundus)
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9
Q

What is chyme?

A

When acid comes in contact with food to create a viscous mass. This mass is chyme

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10
Q

What is Rugae?

A

This is where the mucosa and submucosa are thrown into a large longitudinal fold. Allows for distension as stomach fills with food.

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11
Q

Provide a description of the mucosa in the stomach

A

This is basically epithelium. Simple columnar. This invaginates deeply into the lamina propria forming millions of gastric pits which lead into gastric glands

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12
Q

What are surface mucous cells?

A

These line the lumen and gastric pits. Theses secrete thick viscous insoluble mucous layer rich in bicarbonate (alkaline)/ this protects against abrasion from chyme and stomach acid

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13
Q

What are gastric glands?

A

These can be given a more specific name based on their location

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14
Q

What is the fundus of the stomach? Provide its 4 type of cell types (do not describe)

A

The fundus has fundus glands. This is a long tubular body.

This houses 4 types of cells:

  1. Mucous neck cells
  2. Parietal cells
  3. Chief cells
  4. Enteroendocrine cells (argentaffin cells)
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15
Q

What are the mucous neck cells of the fundus?

A

These are in the upper portion of the stomach. These secrete a soluble mucous, slightly acidic.

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16
Q

What are the parietal cells of the fundus?

A

These produce HCL. They are also an intrinsic factor (a glycoprotein that is required for the protection and uptake of VITAMIN B12)

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17
Q

What are chief cells of the fundus?

A

These secrete pepsinogen, which in an acidic environment gets converted to pepsin, as well as gastric lipase.

(Pepsin is a protease and breakdown proteins)
(gastric lipase breaks down lipids)

18
Q

What are the enteroendocrine cells (argentaffin cells) of the fundus?

A

These are most prevalent at the base of the gland. Theses secrete various peptide hormones (serotonin) and increase gut motility, specifically gastrin (promotes acid production)

19
Q

Provide a description of the Cardia and Pylorus of the stomach.

A

These are similar in morphology. These two contain tubular glands with long pits branching into gastric glands.

Cardiac and pyloric glands composed of mostly mucous secreting cells (no chief or parietal)

20
Q

What are the three layers of the cardia and Pylorus?

A

Outer longitudinal
Middle circular
Inner oblique

21
Q

What do the three layers of the muscularis externa of the cardia and Pylorus (of the stomach) eventually form? What is its purpose?

A

They thicken and form the pyloric sphincter. This controls the release of chyme into the duodenum

22
Q

What is the purpose of the small intestines? What are the three segments of this?

A

This is where digestion is completed and nutrients are absorbed.

The three segments consist of duodenum, jejunum, and ileum

23
Q

The small intestines contain goblet cells, what are these?

A

These are mucous producing cells that are found in mucosa and increase throughout the GI tract.

24
Q

Explain the folds of the mucosa and submucosa within the small intestines

A

These are thrown into permanent circular folds called plicae circulares. These increase surface area

25
Q

With regards to the small intestines’ mucosa, explain what “Villi” is and its function

A

These are finger like projections that are covered by the epithelium with a core of lamina propria. It’s function is to increase surface area of mucosa for absorption.

26
Q

With regards to the small intestines’ mucosa, explain the type of epithelium it has and its function.

A

The small intensities has simple columnar and contains the following:

Entrocytes—> absorptive cells that contain thousands of microvilli in order to increase SA

Goblet cells—> interspread among the entrocytes

27
Q

With regards to the small intestines’ mucosa, explain what “lamina propria” is and its function/contents

A

These contain a central lacteal, which is a highly permeable blind ended lymphatic vessel which is important for absorption of lipids.

28
Q

With regards to the small intestines’ mucosa, explain what and where the crypts of lieberkuhn are, and their contents.

A

These are found between villi short tubercular glands. These crypts are lined with mainly entrocytes and goblet cells.

They also have a special paneth cell—> basal portion of crypt that secretes antimicrobial substances

29
Q

With regards to the small intestines’ mucosa, explain what “entroendocrine cells” are and where they’re found?

A

These produce various peptides such as cholescystokinin (I cells) and promotes pancreatic enzyme secretion and gallbladder contraction.

These inhibit secretin ( S cells)

30
Q

Where is bruners gland found? What is its function?

A

This is found within the submucosa of the duodenum and produces alkaline mucus, which neutralizes acid containing chyme and produces optimal pH for pancreatic enzyme

31
Q

What is the purpose of the jejunum of the digestive system?

A

This is identified by the lack fo submucosal glands and lack of peyers patches (ilieum)

32
Q

What is the purpose of the ileum within the digestive system?

A

This produces mucosa, lamina propria, and submucosa. These all contain peyers matches

33
Q

What are peyers patches?

A

These are permanent lymphatic nodules (that differ from MALT and GALT) which is transient

34
Q

What is the function of the large intestines?

A

This is responsible for absorption of electrolytes of water and eliminates undirected food and waste.

35
Q

What are the three parts of the large intestines? Explain each of them

A

Cecum—> short piece, forms a blind pouch from which appendix projects

Colon—> subdivided into ascending, transverse, and descending, and sigmoid

Rectum—> dilated distal portion, stores feces prior to evacuation

36
Q

What is special about the Mucosa layer of the large intestine?

A

This does not have a plicae circularis or villi

37
Q

What is the epithelium type within the mucosa of the large intestines?

A

Simple columnar with many goblet cells and enterocytes which have microvilli

38
Q

What does the lamina propria of the mucosa have?

A

This contains crypts of lieberkhun (intestinal glands)

39
Q

explain the type of layers the colon has and it’s importance

A

The colon within the large intestines has an outer layer of condensed bands called teniae coil (these contract length wise and assist in peristalsis)

40
Q

Explain the epithelium type of the anal canal

A

This is simple columnar epithelium, it shifts to stratified squamous at the anus

Cell And Tissue Biology (4 decks)

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