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41 Cards in this Set

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What are the three parts of the digestive system?
1) The Oral Cavity
2) The Alimentary Canal:
-The Esophagus
-Large and Small Intestines
3) Accessory Digestive Glands:
-Salivary Glands
What are the functions of the digestive system?
-Elimination: Pooping

What are the four parts of the Oral Cavity?
What are the components of the Oral Cavity?
-Lined by an Oral Mucosa (secretes mucus):
-Made of stratified squamous nonkeratinized epithelium
-Parts that are lightly keratinized: Gingiva, Palate, Dorsal surface of the tongue.

-Contains the ducts of major salivary glands.

The anterior border is the lips
The posterior border is the palatoglossal folds.

The connective tissue here is the lamina propia.
What do the lips do and what are they made of?
Guard the entrance to the oral cavity

Their core is made of skeletal muscle, called: orbicularis oris
What are the 3 different regions of the lips?
-External Aspect: has thin skin, sweat glands, hair and sebaceous glands

-Vermilion Zone: Reddish pinkish zone has thin skin with NO hear or sweat glands but some sebaceous glands

-Mucous Aspect: Always wet, epithelium overlies dense CT with glands
What are the two sets of teeth?
1) 20 Deciduous Teeth which are baby teeth

2) 32 Permanent Teeth- 20 succedaneous teeth and 12 molars
Study this image
Note the different parts of the tooth:

Clinical crown- white enamel that you see see
Anatomical crown- where the enamel extends below the gumline
Pulp chamber- filled with loose mesenchymal tissue. Lots of blood vessels and nerves

Neck - is between the root and crown

Aleveolus- what the tooth is embedded in

Nerves and blood vessels enter and leave at the Root canal

Cementum- locks the tooth in place and connects it to the periodontal ligament
What are the nine parts that make up a tooth anatomy?
1) Alveolous (Tooth socket):
Made of all primary bone and no lamellae.
2) Periodontal Ligament:Region between cementum and alveolus. Very vascular. Made of dense, irregular connective tissue.
3) Gingiva: Gums. They are a specialized part of oral mucosa around neck of tooth.
4) Root: The portion of the tooth embedded in alveolus
5) Crown: The portion of tooth visible in oral cavity. Two types of crown: Clinical and Anatomical. The clinical is visible above the germ line. The anatomical is the portion covered by enamel
6) Neck or Cervix: Portion between root and crown.
7) Pulp: soft gelatinous connective tissue filling central Pulp Chamber
8) Root Canal: Communication channel between pulp chamber and periodontal ligament
9)Apical Foramen: Opening into root canal
What are the mineralized components of teeth?
1) Enamel: highly calcified (96% hydroxyaapatite) Produced by ameloblasts

2) Dentin: 65% Hydroxyapatite. Produced odontoblasts.

3) Cementum: 45-50% hydroxyapatitie. Produced by cementoblasts and cementocytes.
How does a tooth develop?
Find that odontoblasts secrete up and stay in the same place.

While ameloblasts secrete down and migrate up.
What is the tongue and what is it made of?
Tongue is a big mass of muscle covered with oral mucosa. It is the largest structure in the oral cavity.

It is mobile due to a large amount of skeletal muscle: Intrinsic and Extrinsic muscles.

Has a rough dorsal surface. The anterior 2/3 is separated from posterior 1/3 by V shaped groove.
What does this image show?
Cross-Section of a Tongue (Cat)
What does this image show?
Skeletal muscle in the tongue.

Notice how the mass of skeletal muscle is organized in 3 different ways.
What papilla sit on the dorsal surface of the tongue?
Circumvallate papilla
Filiform Papillae
Fungiform Papillae
What is the lingual papillae?
Lies anterior to sulcus terminalis on dorsal and lateral surfaces. Made of:

1) Filiform papillae: Slender conical scrapers has no taste buds

2) Fungiform papillae: resembles a mushroom has taste buds on dorsal aspect

3) Circumvallate Papillae: Has taste buds on lateral surface. They are large papillae. THey are submerged into tongue surface. Have serous glands secreting fluid. (Known as Ebners Glands)
What does this image show?
Filiform Papilla. It is keratinized and is the most common. Roughest part.
What is shown in this image?
Fungiform Papilla. It is mushroom shape and lightly keratinized.
What is shown in this image?
Circumvallate Papilla.
Are Larger and recessed into base of tongue. The clearish structure are taste buds.
What von Ebner's glands?
They are seruos glands that secrete Lingual lipase which prevents the development of hydrophobic layer on tongue surface.

The lipase also digests 30% of lipids in the stomach and cleans the surface of taste buds.
What are taste buds?
They are intraepithelial sensory organs. We have about 5000 taste buds. They are histologically paler than surrounding epithelial cells.

The opening to the surface is called the taste pore.
What are the five different basic tastes?

What does taste discrimination depend on?
Salty, Sweet, Sour, Bitter and Umami

Depends on taste buds in the oral cavity and the olfactory apparatus in the nasal cavity and brain.
What does the alimentary canal do?
It is the esophagus to the anus

It functions in fragmentation, digestion, absorption and elimination. FADE.
How does the muscular tube aid in digestion?
By mechanical breakdown of ingested food and moves food through by muscular action. (Controlled by autonomic nervous system)
What is the structure of the alimentary canal?
The muscular tube is lined by mucous membrane.

Made of four distinct layers:
-Muscularis Externa
-Adventitia (If just connective tissue) or Serosa (if lined with mesothelium on outside)
Study where the different structures are on this image
Structure of the Alimentary Canal
What are the 3 distinct histological layers of the mucosa?
1) Lining Epithelium
2) Lamina Propia (underlying loose connective tissue)
3) Muscularis Mucosae
What are the properties of the lining epithelium in the alimentary canal?
It differs throughout the alimentary canal.

It is specifically adapted to function at each location and provides valuable histological clues.

The main function of the lining epitheliul is to :

Absorptive:Small Intestine
Secretory: Stomach
Absorptive/Protective: Large Intestine
Protective: Esophagus
What are the properties of the lamina propria?
Has underlying loose connective tissue.

May have a substantial amount of immune system cells including recognizable nodules.

Contains most of the specialized glands of the digestive tract.
What are the properties of the muscularis mucosae?
It is the deepest layer of mucosa (between the mucosa and submucosa)

Made of smooth muscle arranged in two layers:
-Inner circular
-Outer Longitudinal

Contraction here produces local movements
What are the properties of the submucosa?
Made of moderately dense, irregular connective tissue.

Contains the largest blood and lymph vessels that send branches into mucosa.

May contain specialized mucous glands.

Has an accumulated cell bodies of unmyelinated nerve fibers called Meissner's Plexus---> controls contraction of muscularis externa.
What are the properties of muscularis externa?
It has layers of smooth and skeletal muscle. Both oriented at right angles to each other.

Typically inner circular and outer longitudinal.

The action of this muscle is based on peristalsis.

It contains networks of unmyelinated nerve fibers and ganglion cells known as Auerbachs' plexus.
How can you determine if the muscular tube is covered in adventitia or serosa?
- If the section of the tube is retroperitoneal, meaning the connective tissue binds the tube to body wall it is covered in --> Adventitia

If the section of the tube is intraperitoneal,, then connective tissue is covered by mesothelium so covered by serosa.
What does this image depict and what parts do you see?

Note the :
-Muscularis mucosa
-Circular muscle
-Longitudinal muscle
What is the esophagus and what does it do?
It is along muscular tube and connects the oral pharynx with the stomach.

Its function is to convey food bolus to stomach. Material is only in the tube fore one second.

Rough diet can lightly keratinize the esophagus
What is the esophageal mucosa made of?
1) Epithelium:
-Stratified squamous nonkeratinized epithelium
-Only cells in the deepest layers are mitotic
-Cells near the lumen accumulate glycogen so they appear paler
Have Langerhans cells present here (APCs)

2)Lamina Propria
Made of loose cellular connective tissue, have mucosal glands present called esophageal cardiac glands. They produce a neutral mucus.

3) Muscularis Mucosae: have a single layer of longitudinal smooth muscle. They are particularly well developed in the bottom third.
What does this image show?
Mucosal and Submucosal Glands
What are the properties of esophageal submucosa?
Made of loose connective tissue.

Contains Esophageal Glands Proper. Which has both mucous and serous cells.
Mucous cells produce slightly acidic mucus. Serous cells produce pepsinogen and lysozyme.

Has Meissner's Plexus
What are the properties of muscularis externa?
Has two layers: An inner circular and outer longitudinal

Type of muscle differs:
-in the upper third has two layer of skeletal muscle
-in the lower third has two layers of smooth muscle
-in the middle third has a mixture of both smooth and skeletal muscle.

Has Auerbachs' plexus
What does this image show?
Muscularis Externa
WHat part of the alimentary canal is covered by adventitia vs serosa?
Above the diaphragm: Adventitia
Below diaphragm: Serosa