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First Year Term 1 > Epithelial Tissues > Flashcards

Epithelial Tissues Flashcards

1
Q

Define Epithelial Tissue

A

Epithelia cover and line internal and external surfaces of the body, forming barriers between other tissues of the body and the internal and external environments

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2
Q

What does this barrier act as

A

a defense barrier for underlying tissue and a surface where exchanges (secretion, absorption, excretion) can occur

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3
Q

List the features common to all types of epithelial tissue

A

a. totally cellular; i.e., no connective (support) tissue fibres holding the cells together; integrity depends on cell junctions.
b. no blood vessels (avascular)
c. stem cells lie within the epithelium (self-regenerating)
d. separated from underlying tissues by a basal lamina
e. always supported by an underlying layer of connective tissue (for mechanical support) containing blood vessels (for metabolic support). Epithelia can be divided into 2 main types: simple (single layer of cells) and stratified (multiple layers of cells).

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4
Q

How is the epithelial lining arranged?

A
  1. Apical Surface
  2. Epithelial cell
  3. Basal lamina (thin connective tissue called basement membrane)
  4. Connective tissue
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5
Q

What are the different types of cell junctions

A
  1. tight junction = act as a barrier- selective permeability of solute particles through neighbouring cells
  2. Desmosomes and hemidesmosomes which act as anchors to provide strength. D= cell to cell adherance. H= anchoring, structures that allow attachment of cell to basal surface.
  3. Gap junctions allow communication (movement between cells): like pores that allow transportation of solute particules between different cells
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6
Q

How do we classify Epithelia?

A
  1. Simple (single layer of cells)

2. Stratified (multi layer)

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7
Q

Name the types of simple epithelia

A
  1. Squamous - flat
  2. Cuboidal - cubes: height and width of cell is equal and centrally located nucleus
  3. Columnar- height longer than width
  4. Pseudostratified- single layer of cells but diff shape:. nuclei appear in different location. False multi layered appearance
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8
Q

Name the types of stratified epithelia

A
  1. Squamous - 3 subgroups
    a) Keratinised stratified squamous epithelium (skin)
    b) Parakeratotic stratified squamous
    c) Stratified Squamous
  2. Transitional (change shape according to environment or function. dedicated to excretory system. Ability to change shape according to function
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9
Q

Characteristics of simple squamous

A

> single layer
flattened cells with large surface area
thin
Hardly any cytoplasm (thin), nucleus buldges
irregular cell margins- no distinctive shape

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10
Q

Function of simple squamous

A
  • thin so idea for rapid transport (lungs)

- Smooth surface = low friction covering on internal organs that move against each other/ body walls

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11
Q

Where is Simple Squmous epithelial found which gives it a different name?

A

entire circulations (blood vessels and heart) system is lined: endothelial cells

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12
Q

Characteristics of simple cuboidal epithelial

A
  1. Single Layer
  2. Cell height and Width are the same
  3. Nucleus is centrally placed
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13
Q

Example of where simple cuboidal is found

A

lining the secretory part of an exocrine gland.
OR
In thyroid gland, lining secretory unit of individual follicles containing the thyroid hormone

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14
Q

what is a common fact for simple cuboidal and squmous?

A

they are restricted to internal protected surfaces as only a single layer of cells

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15
Q

Characteristics of simple columnar

A
  1. Height larger than width
  2. Elongated nuclei arranged in ordered layer towards the base of the cell
  3. contain more cytoplasm than simple cuboilad or squmous
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16
Q

Function of simple columnar and e.g.

A
  1. Absorption: lining of small intestine
  2. Secretion: lining of small intestine
  3. moving material over the surface of epithelium: cilia in airways
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17
Q

Why does Simple Columnar epithelium have higher cellular activity

A

Contain more cytoplasm

18
Q

characteristics of Pseudostratified Columnar epithelium

A
  1. Nuclei at different levels
  2. All cells still make contact with the basal lamina
  3. cilia on top to filter/ trap unwanted particles: line airways
19
Q

Characteristics of Stratified squamous epithelium

A
  1. Multiple layers
  2. basal layer cells roughly cuboidal, upper layer is squmous
  3. Tightly packed which is maintained by desmosomes between cells
  4. Rete pegs allow attachment to underlying connective tissue
20
Q

Function of Stratified Squamous

A

line oral cavity and oesophagus as thick layer provides defence against mechanical damage

21
Q

Characteristics of Keratinised Stratified Squmous Epithelium

A
  1. cuboidal to squmous shape
  2. accumulate granules of keratohyalin which stain dark blue with H&E
  3. In superficial layer all cellular detail is lost- layers of red-staining keratin
22
Q

Function of Keratinised stratified squamous epithelium

A

forms the epidermis as keratin is physically strong, chemically inert and semi-waterproof. This protects from mechanical and chemical damage and dessication

23
Q

Characteristics of Parakeratotic Stratified Squamous epithelium

A
  1. Similar to stratified squamous but superficial layer of cells shows CELLULAR detail AND KERATINISATION
24
Q

Function of PArakeratotic stratified Squamous Epithelium

A

Protects against coarse ingesta, allowing absorption of useful products of fermentation (e.g. VFA) in runimant stomach.

25
Q

Where is Keratinised Stratified Squamous epithelium found

A

ONLY in ruminant forestomach

26
Q

Characteristics of Transitional Epithelium

A
  1. Multi layer
  2. As move from base to upper cells become fatter and rounder- some may contain 2 nuclei
  3. DO NOT contain keratin!
27
Q

Functions of Transitional Epithelium and where found.

A

ONLY in urinary system as accomodates a variable volume (lateral stretching) of fluid without rupturing.
When stretched epithelium takes on squamous shape therefore must always examine the epithelium in the trough of FOLDS where it is relaxed so not to get confused

28
Q

Does Transitional Epithelium have rete pegs?

A

NO because not subject to shearing forces therefore no need for anchorage

29
Q

What type of epithelium lines the lungs and blood vessels

A

Simple suamous epithelium, also known as endothelium

30
Q

What type of epithelium lines the kidneys and lining of ducts

A

simple cuboidal epithelial

31
Q

What type of epithelium lines GI organising e.g. small intestine

A

Simple columnar epithelial

32
Q

What type of epithelium lines the trachea

A

Pseudostratified ciliated columnar epithelial tissue

33
Q

What type of epithelium lines the oesophagus

A

Stratified squamous epithelial tissue

34
Q

What type of epithelium lines salivary glands and sweat glands

A

Stratified cuboidal epithelial tissue

35
Q

What type of epithelium lines the bladder

A

Transitional epithelial tissue

36
Q

In a simple columnar epithelial cell section, if there are gaps what are these? why clear?

A
  1. don’t stain very well

2. goblet cells containing mucus

37
Q

What is a brush border and what type of epithelial

A

an type of epical specialisation = microvilli NOT CILIA = inc SA for absorption

38
Q

What is another type of specialisation within columnar?

A

Apical specialisation = cilia = airways = float on cell surface = function = trap particles on surface of epithelium to stop from going into lungs

39
Q

How do you identify if something is stratified?

A
  1. superficial most layer gives name to the epithelium. not basal!
40
Q

What is a retentions peg

A

invagination which anchors epithelial lining into underlying connective tissue. along with hemidesmosomes

41
Q

What is parakeratotic stratified squamous

A
  1. cell still maintains shape of normal squamous as nuclei are retained.
    ONLY ruminant forestoamch

First Year Term 1 (35 decks)

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