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Flashcards in The Gastrointestinal System Deck (113)
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What does the gastrointestinal tract consist of?

- Oral Cavity
- Oesophagus
- Stomach
- Small Intestine
- Large Intestine
- Rectum


What is the gastrointestinal tract associated with?

- Liver
- Gall Bladder
- Pancreas


Throughout its length the GI tract is lined with different types of ___1___. Each functionally distinct area is lined with a type that reflects its function in the processing of ___2___.

1. Epithelium
2. Food


Describe the following epithelium: Simple.

= 1 layer


Describe the following epithelium: Stratified.

= >1 layer


Describe the following epithelium: Pseudostratified.

= 1 layer that pretends to be 2


Describe the following epithelium: Squamous.

= Flat cells


Describe the following epithelium: Columnar.

= Column like cells


The mouth is the gateway to the ___1___, it is the access point not only for food but also for ___2___. The mechanisms of the mouth are designed to deal with both digestion and pathogen defence.

1. GI tract
2. Pathogens


What type of epithelium are the mouth and tongue covered by?

Stratified squamous epithelium.


Below the epithelia of the mouth and tongue there is an underlying submucosa containing what?

Salivary glands.


Food must be broken down into smaller pieces to increase its ____ 1 ____ for the action of digestive enzymes.
In the mouth the ___2___ divide up food. The muscles of the tongue and ___3___ aid pulverisation and bolus formation.
The muscles of mastication move the ___ 4 ___, bringing its teeth into contact with the teeth of the ____ 5 ____.
All the muscles elevate the jaw but ___6___ is the major effector.
___7___ elevates and protrudes the lower jaw.
The pterygoids create ___8___ movement of the lower jaw.

1. Surface area
2. Teeth
3. Cheeks
4. Lower jaw
5. Upper jaw
6. Temporalis
7. Masseter
8. Lateral


Name the 3 main salivary glands.

- Parotid
- Submandibular
- Sublingual


What do the submandibular glands secrete?

Both serous and mucous saliva.


What do the parotid glands secrete?

Serous saliva.


What do the sublingual glands secrete?

Mucous saliva.


Saliva is produced in the ___1___ of saliva glands by ____ 2 ____ of ions from blood and has a similar composition to extracellular fluid.

1. Acini
2. Active filtration


Where and why is the composition of saliva modified?

In the ducts within a gland. To make it appropriate for requirements.


Autonomic stimulation of the glands changes the composition and volume of saliva secreted.
Describe what sympathetic and parasympathetic stimulation does.

- Sympathetic stimulation produces a small amount of mucous saliva

- Parasympathetic stimulation produces a large volume of watery saliva.


List the functions of saliva.

- Lubrication due to mucin content
- Digestion due to presence of α-amylase
- Protection of oral mucosa through lubrication, rinsing action and alkaline pH
- Antibacterial through actions of antimicrobial thiocyanate.
- Thirst stimulation
- Speech
- Absorption in the mouth


Name and describe the 3 layers of mucosa.

Epithelium - This thin layer lines the lumen of the tube, it may be simple or stratified, squamous or columnar. It forms a selective barrier that digested molecules must cross. It may contain mucous secreting goblet cells and endocrine cells secreting digestive hormones.

Lamina propria - This is a layer of loose connective tissue. It has a good blood supply and as it often contains lymphatics and numerous white blood cells, it is the first immunological barrier to pathogens in the GI system.

Muscularis mucosa - A thin layer of smooth muscle cells. This causes localised contractions in the mucosa.


The walls of the digestive tract consists of the same 4 layers throughout its length. Name them.

- Mucosa
- Submucosa
- Muscularis externa
- Serosa


What is the submucosa?

A layer of dense connective tissue that contains the submucosal plexus.


What controls secretion and blood flow and also relays information from the gut epithelium and stretch receptors in the wall, in the submucosa?

The submucosal plexus.


The submucosal plexus is a part of the ______ nervous system



The enteric nervous system is a branch of the ___1___ nervous system.
It is not part of the sympathetic or parasympathetic nervous systems but entirely separate.
Unlike the other ___1___ systems, the enteric system can operate independently of the ___2___.

1. Autonomic
2. Cental Nervous System


The enteric nervous system consists mostly of two major plexi within the GI wall. Name them and give their old names in brackets.

- Myenteric plexus (Meissner’s plexus)
- Submucosal plexus (Auerbach’s plexus)


What does the Muscularis externa consist of?

2 layers of smooth muscle; an inner circular and outer longitudinal layer.


Waves of contraction and relaxation along the layers of the Muscularis externa force food along the digestive tract, an action known as what?



Which nerve plexus of the enteric NS lies between the 2 layers of the Muscularis externa? What is this plexus involved in?

The myenteric plexus.
This plexus is involved mainly with the control of GI motility.