Digestive System Histology Overview
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Questions and Answers

What is the primary composition of the tongue?

  • Skeletal muscle (correct)
  • Adipose tissue
  • Smooth muscle
  • Cartilage

Which type of papillae are most numerous and do not contain taste buds?

  • Circumvallate Papillae
  • Filiform Papillae (correct)
  • Fungiform Papillae
  • Foliate Papillae

What is the function of serous glands found on the tongue?

  • Support skeletal muscle function
  • Secrete mucus
  • Secrete a fluid containing digestive enzymes (correct)
  • Generate taste sensations

Which type of papillae resembles mushrooms and contains taste buds?

<p>Fungiform Papillae (D)</p> Signup and view all the answers

Which type of papillae is poorly developed in humans and consists of parallel ridges?

<p>Foliate Papillae (D)</p> Signup and view all the answers

What is the role of minor salivary glands in the tongue?

<p>They secrete saliva containing digestive enzymes. (B)</p> Signup and view all the answers

Which type of papillae contains numerous glands that drain into the deep groove encircling each papilla?

<p>Circumvallate Papillae (B)</p> Signup and view all the answers

How many taste cells are typically found in a taste bud?

<p>50-100 cells (B)</p> Signup and view all the answers

What is the primary role of undifferentiated basal cells in taste buds?

<p>Replacing all cell types (B)</p> Signup and view all the answers

Which type of epithelium lines the pharynx near the nasal cavity?

<p>Ciliated pseudostratified columnar epithelium (B)</p> Signup and view all the answers

What type of receptors are associated with detecting bitter tastes?

<p>A family of about 40–80 members (A)</p> Signup and view all the answers

What is the primary mechanism for transporting food in the esophagus?

<p>Peristaltic contractions (C)</p> Signup and view all the answers

What surrounds the microvilli in the taste pore?

<p>Amorphous material from supportive cells (D)</p> Signup and view all the answers

What are the contributing muscles of the pharynx primarily responsible for?

<p>Constricting and relaxing during swallowing (B)</p> Signup and view all the answers

How do taste cells respond to tastants dissolved in saliva?

<p>By depolarizing and releasing neurotransmitters (B)</p> Signup and view all the answers

What role do esophageal glands play in the esophagus?

<p>Secreting mucus to protect the mucosa (A)</p> Signup and view all the answers

What type of muscle is primarily found in the structure of the tongue?

<p>Skeletal muscle (D)</p> Signup and view all the answers

Which papillae are primarily responsible for the sensory function of taste on the tongue?

<p>Circumvallate papillae (B), Fungiform papillae (C)</p> Signup and view all the answers

What type of epithelium covers the ventral surface of the tongue?

<p>Stratified squamous non-keratinized epithelium (A)</p> Signup and view all the answers

Which glands produce saliva that is secreted into the furrows between the papillae of the tongue?

<p>Minor lingual glands (A)</p> Signup and view all the answers

What is the primary function of the dermal papillae found on the tongue?

<p>To enhance blood circulation close to epithelial cells (D)</p> Signup and view all the answers

What type of epithelium makes up the specialized mucosa on the tongue's dorsal surface?

<p>Stratified squamous non-keratinized epithelium (D)</p> Signup and view all the answers

Which type of papillae are predominantly small and cover the anterior two-thirds of the tongue?

<p>Filiform papillae (A)</p> Signup and view all the answers

What defines the boundary separating the posterior one-third from the anterior two-thirds of the tongue?

<p>A V-shaped boundary (C)</p> Signup and view all the answers

Flashcards

Taste Pore

The circular opening at the apex of a taste bud.

Tongue Skeletal Muscle

Muscle bundles arranged in 3 directions for precise tongue movement.

Filiform Papillae

Numerous, cone-shaped papillae covering the tongue surface.

Fungiform Papillae

Mushroom-shaped papillae with taste buds, scattered amongst filiform papillae.

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Foliate Papillae

Ridged papillae on the tongue's sides; contain taste buds.

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Circumvallate Papillae

Large circular papillae in a V-shape at the back of the tongue, with glands.

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Taste Buds

Onion-shaped structures containing 50-100 cells, responsible for taste.

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Minor Salivary Glands

Glands throughout the tongue that secrete digestive fluids.

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Keratinized Gingiva

The tough outer layer of gum tissue. It's resistant.

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Lamina Propria Papillae

Finger-like projections in the gum tissue. They connect to bone.

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Tongue Muscle Structure

Striated muscle fibers in bundles, separated by tissue. It's layered.

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Tongue Papillae

Small bumps on the tongue's top surface.

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Tongue V-shaped Boundary

Divides the front and back sections of the tongue.

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Specialized Tongue Mucosa

Tongue lining with papillae and taste buds.

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Tongue's Dorsal Surface

The top (upper) surface of the tongue.

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Dermal papillae

Ridge-like structures in connective tissue, just beneath the epithelium. They reduce movement and bring vessels close to epithelial cells.

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Taste Bud Microvilli

Tiny projections from taste cells that extend through the taste pore, allowing them to interact with dissolved substances.

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Taste Bud Support Cells

Cells surrounding taste cells within the taste bud, providing structural support and secreting a fluid that surrounds the microvilli.

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Taste Bud Basal Cells

Undifferentiated cells at the base of the taste bud that continually divide to replace dying taste cells.

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Taste Cell Depolarization

The change in electrical charge across the taste cell membrane when a tastant binds to a receptor or ion channel.

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Taste Signal Transmission

Neurotransmitters released from a stimulated taste cell activate nerve fibers, sending taste information to the brain.

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Unique Taste Patterns

The brain distinguishes different tastes by interpreting the unique combinations of nerve signals from various taste cells.

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Taste Receptor Family

A group of proteins, like those for bitter tastes, that bind to specific tastants, initiating a signaling cascade.

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Pharynx Epithelium

The lining of the pharynx, varying from stratified squamous epithelium (near the esophagus) to ciliated pseudostratified columnar epithelium (near the nasal cavity).

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Study Notes

Digestive System Histology

  • The gastrointestinal tract (GIT) has a consistent structural design.
  • It's a hollow tube with a lumen (inner space) of varying diameter.
  • The tube wall is composed of four layers: mucosa, submucosa, muscularis, and serosa.

Mucosa

  • The mucosa forms the inner lining of the GIT.
  • It consists of an epithelial lining.
  • The lamina propria is a layer of loose connective tissue with blood vessels and lymph nodes.
  •  It also contains smooth muscle.
  • Glands are often present.
  • A muscularis mucosae layer separates the mucosa from the submucosa.
  •  The mucosa is sometimes called a mucous membrane.

Submucosa

  • The submucosa is a layer of dense connective tissue.
  • It contains blood vessels and lymph vessels.
  • It also has a submucosal nerve plexus.
  • Glands and lymph tissue may be present.

Muscularis

  • The muscularis has smooth muscle layers.
  • The inner layer is circular, while the outer layer is longitudinal.
  • A myenteric, or Auerbach's, nerve plexus lies between these two muscle layers.
  • It contains blood and lymph vessels.

Serosa

  • The serosa is a thin layer of loose connective tissue.
  • It has blood vessels and adipose (fat) tissue.
  • It contains simple squamous epithelium (mesothelium).
  • In the abdominal cavity, the serosa is connected to the mesenteries.

Oral Cavity

  • The oral mucosa lines the oral cavity.
  • It's either keratinized or nonkeratinized stratified squamous epithelium.
  • Keratinized areas are found where there's more friction or pressure.
  • Nonkeratinized areas line the rest of the oral cavity.
  • Areas that experience significant movement have a keratinized layer.
  • The lamina propria connects to the bony tissue.
  • The soft palate is covered by non-keratinized squamous epithelium.
  • The soft palate has skeletal muscle, mucous glands, and lymphoid nodules in its submucosa.

Tongue

  • The tongue is a mass of striated muscle covered by mucosa.
  • Muscle fibers are arranged in bundles separated by connective tissue enabling flexible movements.
  • The ventral (lower) surface is smooth.
  • The dorsal (upper) surface is irregular and has papillae.
  • The posterior third is separated from the anterior two-thirds by a V-shaped boundary.
  • Paired papillae types are found on the surface of the tongue
  • Filiform, Fungiform, Foliate, and Circumvallate.

Taste Buds

  • Taste buds are onion-shaped structures containing taste cells and supporting cells.
  • Taste cells have microvilli that protrude into the taste pore.
  • Undifferentiated basal cells are responsible for replacing old taste cells.
  • Tastants interact with taste receptors on the taste cells to generate signals.

Pharynx

  • The pharynx is lined with stratified non-keratinized squamous epithelium.
  • Areas near the nasal cavity are lined with pseudostratified columnar epithelium.
  • Mucus-secreting salivary glands are found in the lamina propria.
  • The constrictor and longitudinal muscles provide movement.

Esophagus

  • The esophagus is a muscular tube transporting food from the mouth to the stomach.
  • Peristaltic contractions allow food passage.
  • It has a nonkeratinized stratified squamous epithelium.
  • The submucosa has esophageal glands that aid digestion by secreting mucus.
  • The structure varies in different sections: mix of smooth and striated muscles in the middle.
  • Cardiac glands are present near the stomach, secreting mucus.

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Description

Explore the intricacies of the digestive system's histological structure with this quiz. Delve into the layers of the gastrointestinal tract, including the mucosa, submucosa, and muscularis, each vital to digestive functions. Test your understanding of their functions and histological features.

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