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Histology -- Zach H. > Lecture #32: Upper GI Histology I > Flashcards

Lecture #32: Upper GI Histology I Flashcards

1
Q

Other than at either end, what type of epithelium makes up most of the length of the GI tract?

A

Simple Columnar Epithelium

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2
Q

True or False:

Glands are found along most of the length of the GI tract?

A

True

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3
Q

What type of musculature is found at either end of the GI tract, including the upper esophagus?

A

Skeletal Muscle

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4
Q

What type of muscle is found throughout most of the length of the GI tract?

A

Smooth Muscle

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5
Q

What 3 peptide neurotransmitters are found in the GI tract?

A
  • bombesin
  • motilin
  • vasoactive intestinal peptide
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6
Q

What do unicellular endocrine cells of the GI tract secrete?

A

neuropeptides

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7
Q

What are unicellular endocrine cells derived from?

A

endoderm

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8
Q

What are intrinsic nerve fibers of the GI tract derived from?

A

neural crest

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9
Q

What type of lymphoid tissue is found in the GI tract?

A

MALT (mucosal associated lymphoid tissue)

- referred to as GALT (gut associated lymphoid tissue) in the gut tube.

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10
Q

Describe the mucous membrane lining the oral cavity.

A

The oral cavity is lined with a mucous membrane lying on a vascular FECT layer; this mucosa consists of:

 - stratified squamous epithelium 
 - basement membrane 
 - lamina propria
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11
Q

List the three structures derived from the epithelial bud.

A

> enamel organ

> dental papilla

> dental sac (follicle)

**The enamel organ forms enamel, which caps the dental papilla **

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12
Q

Discriminate between the dental papilla and the enamel organ with regard to their embryonic origin and their derivatives.

A

> ectoderm forms the enamel organ:

 - consists of cells committed to formation of enamel 
 - formed from ectoderm under influence of mesoderm and neural crest

> Neural crest and mesoderm give rise to dental papilla:
- forms dentin, cementum, and pulp as well as surrounding connective tissue and periodontal pulp

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13
Q

What is the dental papilla derived from and what does it form?

A

Derived from neural crest and mesoderm.

Forms:

  • dentin
  • cementum
  • pulp
  • surrounding CT and periodontal pulp
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14
Q

What is the enamel organ derived from?

A

ectoderm

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15
Q

What is the dental lamina?

A

The internal limb

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16
Q

Describe the histology and specific functions of the odontoblasts.

A

> Forms:

  • dentin matrix throughout the life of the tooth
  • single layer of cells lining pulp cavity

> Tomes’ dentinal fibers (odontoblastic processes):

  • cytoplasmic extension of the odontoblasts continuing through the predentin and dentinal layers to the dentin-enamel junction
  • they occupy space in the dentin matrix known as dentinal tubules

> Increment lines (of Ebner and Owen)

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17
Q

Describe the histology and specific functions of the ameloblasts.

A

> Forms:
- enamel which covers only the tooth crown
*enamel is the hardest substance in the body
*enamel is laid down in prisms
*each prism is formed by 1 ameloblast
secreting apical domains = Tomes’ processes
increment lines of Retzius are periods of rhythmic growth
enamel is 96% inorganic salts, about 90% of which is calcium phosphate in the form of apatite crystals and 4% organic matter and water

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18
Q

Describe the histology and specific functions of the cementoblasts.

A

> Cementum:

 - cells of the dental sac differentiate into cementoblasts which deposit cementum on the dentin of the root from neck to apex. 
 - Cementum has coarse collagen fibers (Sharpey's) in a bone-like calcified matrix.
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19
Q

What type of epithelium is found at either end of the GI tract for protection and resisting friction?

A

Stratified Squamous Epithelium

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20
Q

Describe the histology and functions of the periodontal membrane.

A

> CT formed from dental sac with fibroblasts, osteoblasts, cementoblasts, collagen fibers, blood vessels, and nerve fibers.

> Highly metabolically active tissue

> Binds cementum to bony socket

> Sharpey’s fibers extend from cementum to alveolar wall via the membrane

> Allows limited movement

> Absorbs pressures of mastication and prevents this pressure from damaging alveolar bone

> Affected by diseases such as diabetes and scruvy

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21
Q

What is the sulcus terminalis?

A

Sulcus Terminalis -> the anterior two-thirds (2/3) of the upper oral portion of the tongue is separated from the posterior one-third (1/3) by the sulcus terminalis.

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22
Q

What are the 4 different lingual papillae found on the tongue?

A

> filiform papillae

> fungiform papillae

> foliate papillae

> circumvallate papillae

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23
Q

What is the most numerous lingual papillae found on the tongue?

A

Filiform Papillae

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24
Q

True or False:

Filiform papillae are evenly distributed over the entire oral upper potion of the tongue.

A

True

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25
Q

Fill in the Blank:

Unlike the fungiform papillae, the filiform papillae lacks __________.

A

Taste Buds

26
Q

Where are taste buds only present on fungiform papillae?

A

taste buds are present only on the oral surface of the epithelium.

27
Q

Compare the difference in where the taste buds are located between the fungiform and circumvallate papillae.

A

Taste buds are present only on the oral surface of the epithelium in contradistinction to the position of the taste buds on the circumvallate papillae whose taste buds are primarily located in the lateral walls.

  • *Circumvallate Papillae -> lateral walls
  • *Fungiform Papillae -> oral surface of epithelium
28
Q

Where are circumvallate papillae located on the tongue?

A

located along the sulcus terminalis as projections surrounded by a moat (circular furrow).

29
Q

True or False:

Fungiform papillae are interspersed singly among the parallel rows of filiform papillae.

A

True

30
Q

Fill in the Blank:

Foliate papillae are ________ in humans, but well developed in lower animals.

A

rudimentary

31
Q

True or False:

In foliate papillae, the pharyngeal portion is free of papillae but contains the lingual tonsils.

A

True

32
Q

You know that circumvallate papillae are located along the sulcus terminalis as projections surrounded by a moat, but what type of ducts open into this moat?

A

Ducts of von Ebner’s glands (serous) open into the moat.

33
Q

Which 2 cell types make up taste buds?

A

Sustentacular cells and Taste cells

34
Q

What are sustentacular cells?

A

Spindle-shaped support cells that are arranged like barrel-staves to surround the inner taste pore a the base.

35
Q

True or False:

Taste buds contain two types of cells derived from a single stem cell?

A

True

36
Q

Do taste cells possess apical microvilli with taste receptors?

A

YES

37
Q

What does the basal part of taste cells release?

A

Neurotransmitters

38
Q

What is a taste cell?

A

Each cell is long and slender with an elongated central nucleus that terminates as a short taste hair which projects into the external opening called the outer taste pore.

39
Q

True or False:

Except for bitter taste, taste sensations utilize various signal transduction pathways that result in depolarization of the taste cell.

A

True

40
Q

What does sour and salt taste sensation utilize ionic transport for?

A

Salt and sour utilize ionic transport as a signal transduction mechanism.

41
Q

What ion does sour block to cause depolarization?

A

Sour involves hydrogen ion blockage of potassium ion channels to cause depolarization.

42
Q

What kind of taste involves a hypopolarized state and what type of taste involve a hyperpolarized state?

A

Bitter Taste -> involves a hypopolarized state
(similar to retinal cell signal transduction)

Sweet Taste -> involves a hyperpolarized state

43
Q

What are the 4 layers of the digestive tube?

A

Mucosa

Submucosa

Muscularis Externa

Outermost Layer

  • serosa
  • adventitia
44
Q

What are the layers of the mucosa (innermost) layer?

A

> Epithelium

> Lamina Propria

> Muscularis Mucosa

45
Q

What type of epithelium makes up the mucosa and lines the digestive tube? Also, what are its 3 functions?

A

Stratified squamous transitioning to simple columnar.

May have secretory, absorptive, and/or protective functions.

46
Q

What makes up the lamina propria in the mucous layer?

A

> loose areolar CT associated with epithelium

> contains various glands and GALT

47
Q

How many layer of smooth muscle make up the muscularis mucosa?

A

made up of 1 -3 layers of smooth muscle

48
Q

What kind of connective tissue makes up the submucosa layer of the digestive tube? Also, is it vascularized or not?

A

Dense, irregular connective tissue

Vascularized

49
Q

What nerve plexus does the submucosa layer of the digestive tube have?

A

Meissner’s plexus (submucosal plexus)

50
Q

Fill in the Blank:

The inner layer of smooth muscle in the muscularis externa layer is __________ and the outer layer is _________.

A

Circular; Longitudinal

51
Q

What nerve plexus is found in the muscularis externa layer of the digestive tube?

A

Myenteric (Auerbach’s) nerve plexus lies between the two layers of muscle tissue.

52
Q

What are the functions of the muscularis externa?

A

> regulates the size of the lumen (circular layer of smooth muscle)

> regulates rhythmic movement of the GI tract (longitudinal layer of smooth muscle)

53
Q

What are the two sub-components of the outermost layer of the digestive tube?

A

Serosa and Adventitial

54
Q

What kind of CT is the serosa layer composed of?

A

Composed of dense irregular CT

55
Q

True or False:

The serosa layer consists of a mesothelial lining and a layer of submesothelial connective tissue.

A

TRUE

56
Q

What layer of the digestive tube forms the visceral peritoneum?

A

Serosa layer

57
Q

Which portion of the abdominal organs is covered by the serosa layer?

A

Covers intraperitoneal

58
Q

What kind of connective tissue makes up the adventitia?

A

Dense irregular CT with adipose tissue

59
Q

Which layer of the digestive tube covers the retroperitoneal portions of the digestive system?

A

adventitia

60
Q

What kind of innervation does the digestive tube have?

A

Sympathetic and Parasympathetic

Histology -- Zach H. (21 decks)

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