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Histology/Embryology > Lesson 6 - Part 2 > Flashcards

Lesson 6 - Part 2 Flashcards

1
Q

Describe the anatomy of basic tissue

A
  1. Cells with similar characteristics of form and function are grouped together to form a tissue.
  2. A tissue is a collections of similarly specialized cells that will then form into organs.
  3. Tissue types are categorized according to four basic histological types - epithelium, connective tissue, muscle, and nerve tissue
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2
Q

What are the 2 types of epithelium?

A
  1. Simple - squamous, cuboidal, columnar, pseudostratified
  2. Stratified - squamous ( keratinized/nonkeratinized) cuboidal, columnar, transitional
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3
Q

List the 4 types of connective tissue

A
  1. Solid soft - connective tissue proper, specialized (adipose, fibrous, elastic, reticular)
  2. Solid firm - cartilage
  3. Solid rigid - bone
  4. Fluid - blood, lymph
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4
Q

List the 2 types of muscle tissue

A
  1. Involuntary - smooth, cardiac
  2. Voluntary - skeletal
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5
Q

List the 2 types of nerve tissue

A
  1. Afferent - sensory
  2. Efferent - motor
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6
Q

It is during prenatal development that __________ differentiate into the various basic embryological tissue types—ectoderm, mesoderm, and endoderm—that will later form the basic ___________.

A
  1. embryonic cell layers
  2. histological tissue types of the body
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7
Q

Most tissue of the body can be _________ as the individual cells die and are removed from the tissue. The _________ is the time it takes for the newly divided cells to be completely replaced throughout the tissue. It differs for each of the basic tissue types, as well as for specific regions of the __________.

A
  1. renewed
  2. turnover time
  3. oral cavity
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8
Q

Describe the epithelium

A
  1. Epithelium is the tissue type that covers and lines both external and internal body surfaces, including vessels and small cavities.
  2. protective covering or lining
  3. tissue absorption
  4. secretion
  5. sensory
  6. specialized functions
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9
Q

Describe the histology of the epithelium

A
  1. Epithelium generally consists of closely grouped polyhedral cells surrounded by very little or no intercellular substance or tissue fluid.
  2. Capable of rapid turnover
  3. Epithelium is highly regenerative: deeper germinal cells are capable of reproduction by mitosis.
  4. Epithelial cells usually undergo cellular differentiation as they move from the deeper germinal layers to the surface.
  5. Epithelial cells are tightly joined by intercellular junctions: desmosomes, except in the more superficial layers.
  6. The epithelial cells are also tightly joined in to nearby noncellular surfaces by hemidesmosomes - I.e. basement membrane
  7. Epithelium is avascular, having no blood supply of its own.
  8. Cellular nutrition consisting of oxygen and metabolites is obtained by diffusion from the adjoining connective tissue, which is usually highly vascularized, providing its own source of nutrition.
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10
Q

Describe the basement membrane of the epithelium

A

The basement membrane is located between most epithelium and deeper connective tissue, such as skin and oral mucosa, and is produced by both the epithelium and the adjoining connective tissue.

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11
Q

Epithelium is classified based on cell __________

A

Shape

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12
Q

Simple epithelium consists of __________ layer(s) of epithelial cells

A

a single

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13
Q

Describe simple squamous epithelium and where it is found

A
  1. Simple squamous epithelium consists of flattened platelike epithelial cells
  2. Found in the lining blood and lymphatic vessels, heart, and serous cavities as well as interfaces in the lungs and kidneys.
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14
Q

Describe simple cuboidal epithelium and where it is found

A

Simple cuboidal epithelium consists of cube‑shaped cells that line the ducts of various glands, such as certain ducts of the salivary glands

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15
Q

Describe simple columnar epithelium and where it is found

A

Simple columnar epithelium consists of rectangular or tall cells, such as in the lining of salivary gland ducts, as well as the inner enamel epithelium, whose cells become enamel‑forming ameloblasts.

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16
Q

Describe pseudostratified columnar epithelium

A
  1. Pseudostratified looks like many layers, but all cells touch basement membrane
  2. This type lines the upper respiratory tract, including the nasal cavity and paranasal sinuses
17
Q

Describe stratified epithelium

A

Stratified epithelium consists of two or more layers of cells, with only the deepest level lining up to contact the basement membrane.

18
Q

Interdigitation of the outer epithelium with the deeper connective tissue, having a basement membrane between them, appears on two-dimensional microscopic section as the ___________.

A

rete ridges (or rete pegs)

19
Q

Stratified squamous epithelium can be ___________ or __________

A
  1. keratinized
  2. nonkeratinized
20
Q

Describe keratin

A
  1. Keratin is a tough, fibrous, opaque, waterproof protein that is impervious to pathogenic invasion and resistant to friction
  2. Keratin is produced during the maturation of the keratinocyte epithelial cells as they migrate from near the basement membrane to the surface of the keratinized tissue, which occurs in certain regions of the oral mucosa found in the oral cavity.
21
Q

Give an example of keratinized stratified squamous epithelium

A

An example of keratinized stratified squamous epithelium is epidermis, which is the superficial layer of the skin

22
Q

Describe the epidermis

A
  1. The epidermis overlies a basement membrane and the adjoining deeper layers of connective tissue (dermis and hypodermis, respectively.
  2. The skin has varying degrees of keratinization depending on the region of the body.
23
Q

Describe turnover and repair of epithelium

A
  1. Turnover of epithelium occurs as the newly formed deepest cells migrate superficially from their formation near the basement membrane.
  2. The turnover time is the time taken for a cell to divide and pass through the entire thickness of tissue.
  3. In order to migrate, the cells release and then regain their desmosomal connections from their intercellular junctions in the more superficial location.
  4. The turnover time is higher for all types of epithelium as compared to connective tissue.
  5. This higher turnover time is a result of the higher level of mitosis in those deepest dividing cells near the basement membrane.
  6. Thus the older, superficial epithelial cells are being shed or lost at the same rate as the deeper germinal cells are dividing into more cells.
  7. These overall higher turnover times vary slightly for the different types of epithelium.
  8. The epithelium of the oral mucosa generally has a higher turnover time than the epidermis of the skin.
  9. The differences of turnover time are especially noted during repair or healing of the tissue after injury.
24
Q

Describe connective tissue

A
  1. Connective tissue is derived from the somites during prenatal development.
  2. Connective tissue has many functions: it is involved in support, attachment, packing, insulation, storage, transport, repair, and defense.
25
Q

Describe somites

A

Differentiated mesoderm gives rise to the somites that will give rise to muscle tissue. Somites are located on the sides of the developing central nervous system

26
Q

Describe the histology of connective tissue

A
  1. Compared with epithelium, connective tissue is usually composed of fewer cells spaced farther apart and containing larger amounts of matrix.
  2. Matrix - intercellular substance, fibers
  3. Most connective tissue is renewable - Cells capable of mitosis
  4. Most cells can produce their own matrix of intercellular substance and fibers.
  5. Connective tissue is vascularized (except cartilage)
  6. The most common cell in all types of connective tissue is the fibroblast.
  7. Other cells found in connective tissue include migrated WBCs - from the blood supply, such as monocytes (macrophages), basophils (mast cells), lymphocytes (including plasma cells), and neutrophils.
27
Q

What do fibroblasts synthesize?

A
  1. protein fibers
  2. intercellular substance needed to sustain the connective tissue.
28
Q

Describe collagen fibers

A
  1. Collagen fibers are composed of the protein collagen, great tensile strength
  2. Collagen fibers are the main connective tissue fiber type found in the body
  3. All collagen fibers are composed of smaller subunits: fibrils; which are then composed of microfibrils
29
Q

How many types of collagen are there?

A

4 - I, II, III, IV

30
Q

Describe type 1 collagen protein

A
  1. Dermis, lamina propria, bone, tendons
  2. Cells that produce type 1 - Fibroblasts, odontoblasts & osteoblasts
31
Q

Describe elastic fibers

A
  1. Elastic fibers:, composed of microfilaments embedded in the protein elastin, which makes it a very elastic type of tissue
  2. This tissue has the ability to stretch and then to return to its original shape after contraction or extension.
  3. Certain regions in the oral cavity, such as the soft palate, contain elastic fibers in the lamina propria to allow this type of tissue movement.
32
Q

Describe the 4 classifications of connective tissue ( soft, firm, rigid, fluid)

A
  1. Soft connective tissue - includes the tissue found in the deeper layers of the skin and oral mucosa, such as a connective tissue proper
  2. Firm connective tissue consists of different types of cartilage
  3. Rigid connective tissue consists of bone
  4. Fluid connective tissue consists of blood with all its components and lymph
33
Q

Describe connective tissue proper

A
  1. The connective tissue proper is found deep to the epithelium and basement membrane, in the deeper layers of the skin and oral mucosa.
  2. The connective tissue proper in the skin - Dermis (loose CT & dense CT); Hypodermis (Hypodermis: loose connective tissue and adipose connective tissue,(specialized CT), glandular tissue, large blood vessels, and nerves)
34
Q

Describe loose connective tissue

A
  1. The superficial layer of both the dermis of the skin and lamina propria of the oral mucosa is composed of loose connective tissue
  2. In the dermis or lamina propria, this layer of loose connective tissue is also considered the papillary layer
  3. The papillary layer has connective tissue papillae, which are interdigitations of loose connective tissue with the epithelium: rete pegs
35
Q

Dense connective tissue

A

Deep to the loose connective tissue in the deepest layers of the dermis or lamina propria is a dense layer ::dense connective tissue.

36
Q

Describe connective tissue turnover and repair

A
  1. Turnover of the connective tissue proper in skin or oral mucosa occurs as a result of the production of fibers and intercellular substance by the fibroblasts.
  2. The overall turnover time for a connective tissue proper is slower than its adjacent epithelium; it also demonstrates individual variance from region to region.
  3. When injured, the connective tissue proper in the skin or oral mucosa goes through stages of repair that are related to the events in the more superficial epithelium.
  4. After a clot forms and an inflammatory response is triggered with WBCs, fibroblasts migrate to produce an immature connective tissue deep to the clot and newly forming epithelial surface.
  5. This immature connective tissue is considered granulation tissue and has few fibers and an increased number of blood vessels.
  6. Granulation tissue appears as a redder, soft tissue that bleeds easily.
  7. Later, during the repair process, this temporary granulation tissue is replaced by paler and firmer scar tissue in the area.
  8. Scar tissue contains an increased number of fibers and fewer blood vessels.
37
Q

Describe aging and the skin

A
  1. By age 20, the skin begins to deteriorate, and by the age of 50 the skin is in a rapid state of degradation.
  2. Collagen fibers begin to fall apart, elastic fibers stiffen and thicken, wrinkling the skin.
  3. Oil glands in skin cease production, and melanin production decreases, leading to more pallid skin color and gray hair.
  4. Keratin cells also cease production and so become thin and stiff.
  5. Skin begins to heal poorly after being injured (see earlier discussion).
  6. Skin also becomes susceptible to disease states that include inflammation (such as with dermatitis), infection (such as with herpes zoster), and cancer (such as with basal cell carcinoma).
38
Q

What accelerates aging in the skin?

A
  1. Exposure to ultraviolet light
  2. Increased environmental toxicity (excessive alcohol and tobacco use).

Histology/Embryology (14 decks)

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