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Flashcards in Ch5-P143-153Reverse Deck (20):
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  1. Epithelial – tissue composed of layers of closely spaced cells that cover organ surfaces, form glands, and serve for protection, secretion and absorption (Epidermis, Inner lining of digestive tract, Liver and other glands)
  2. Connective – tissue with usually more matrix than cell volume, often specialized to support, bind and protect organs (Tendons and ligaments, Cartilage and bone, Blood)

  3. Nervous – tissue containing excitable cells specialized for rapid transmission of coded information to other cells (Brain, Spinal cord, Nerves)
  4. Muscular – tissue composed of elongated, excitable muscle cells specialized for contraction [Skeletal muscles, Heart (cardiac muscle), Walls of viscera (smooth muscle)]

Name 4 Primary Tissue Classes and explain a bit about each as an introduction

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  • Layers of closely adhering cells with little extracellular matrix
  • One or more cells thick
  • Upper surface usually exposed to the environment or to an internal space in the body
  • Avascular (no room between cells for blood vessels) relies on the diffusion of nutrients and gases from vessel-rich underlying CT layer
  • Rests on a basement membrane (which is between the CT layer and epithelia) which anchors epithelia to underlying CT
  • High rate of mitosis with cells closest to the CT layer (allows for rapid repair)

CT = connective tissue

Epithelium is the name given to the cells that line a surface. The outer surface of the body is lined by an epithelium called the epidermis.

Structural properties of epithelial tissue:

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  1. Protecting underlying structures – e.g. the outer layer of skin and epithelium of the oral cavity protect underlying structures from abrasion
  2. Secretion of substances – e.g. mucous glands, sweat glands, enzyme-secreting portions of pancreas all composed of epithelial cells
  3. Absorption – e.g. absorption of nutrients across epithelium of small intestine
  4. Filtration – e.g. kidney epithelia in glomeruli filter out wastes from blood capillaries
  5. Sensation – e.g. epithelial structures with sensory nerve endings are found in the skin, nose, ears and eyes

5 functions of epithelial tissue

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  1. Simple – single layer of cells with all cells attached to basement membrane
  2. Stratified – more than one layer of cells where only the basal layer attaches to basement membrane
  3. Pseudostratified – type of simple epithelium where epithelium appears to be stratified but is not. Some cells don’t extend to free surface

The basement membrane is between an epithelium and the underlying connective tissue.

Epithelial tissues are classified according to the number of cell layers and the shape of the cells. Name the three major types of epithelia tissue based on layers.

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  1. Squamous – cells are flat and scale-like
  2. Cuboidal – cells are cube-shaped , about as wide as they are tall
  3. Columnar – cells are taller than they are wide like a column

Epithelial tissues are classified according to the number of cell layers and the shape of the cells. Name the three major types of epithelial tissue based on shape

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1. Simple Squamous Epithelium

2. Simple Cuboidal Epithelium

3. Simple Columnar Epithelium

4. Pseudostratified Epithelium

5. Keratinized Stratified Squamous

6. Non-keratinized Stratified Squamous

7. Stratified Cuboidal Epithelium

8. Transitional Epithelium

Name the 8 types of epithelia

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  • Single row of flat cells
  • Permits diffusion of substances
  • Secretes serous fluid
  • Alveoli, glomeruli, endothelium, and serosa

1. Simple Squamous Epithelium

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  • Single row cube-shaped cells with microvilli
  • Absorption and secretion, mucus production
  • Liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules

2. Simple Cuboidal Epithelium

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  • Single row, tall, narrow cells
  • Oval nuclei in basal half of cell
  • May possess microvilli
  • Absorption and secretion; mucus secretion
  • Lining of GI tract, uterus, kidney and uterine tubes

3. Simple Columnar Epithelium

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  • Single row of cells some not reaching free surface
    • nuclei give layer stratified look
  • Often with goblet cells and ciliated
  • Secretes and propels respiratory mucus
  • Typically found in trachea

4. Pseudostratified Epithelium

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  • Keratinized epithelium has surface layer of dead cells
  • Multilayered epithelium covered with dead squamous cells, packed with a tough protein  called keratin
  • Retards water loss and barrier to organisms
  • Found in epidermal layer of skin where abrasion is high

5. Keratinized Stratified Squamous

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  • Multilayered surface epithelium forming moist, slippery layer
  • Without surface layer of dead cells
  • Resists abrasion
  • Tongue, oral mucosa, esophagus, anal canal and vagina

6. Non-keratinized Stratified Squamous

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  • Two or more cell layers; surface cells square
  • Secretes sweat; produces sperm and hormones
  • Sweat gland ducts; ovarian follicles and seminiferous tubules

7. Stratified Cuboidal Epithelium

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  • Multilayered epithelium surface cells that change from round to flat when stretched
    • allows for filling of urinary tract
    • Lining of urinary bladder and ureter

8. Transitional Epithelium

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in areas where diffusion of materials across  the membrane is important like the alveoli in lungs and capillary walls.  Stratified epithelium here would be counterproductive

Simple squamous epithelium is typically found 

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a barrier is needed and where abrasion is present like the epidermis and oral cavity.  Simple epithelium here would soon wear away

Stratified epithelia are found in areas where 

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lining the intestinal lumen ↑ the surface area (SA) available for absorption of nutrients, squamous cells or cuboidal cells would not offer as much SA

Columnar cells with microvilli are found 

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protein keratin which also retards water loss, stratified non keratinized areas like vagina and anus must still resist abrasion but need to be moist to reduce friction

Stratified keratinized epithelia (epidermis) are durable due to the 

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when tissues move to surface then finally die and flake off. Their separation from the surface is called exfoliation.

  exfoliation is?

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  1. Most abundant and variable tissue type
  2. Widely spaced cells that are not close together like epithelial tissue
  3. The cells of the CT type are responsible for producing the extracellular matrix
  4. Extracellular matrix consists of ground substance and fibres
  5. Variability in vascularity between CT types (loose CT vs. cartilage)
  6. Multitude of different cell types (e.g. fibroblasts/fibrous CT, osteoblasts/bone, chondrocytes/cartilage
  7. Ground substance consists of water and large molecules like hyaluronic acid and proteoglycans
  8. Types of fibres in the matrix include collagen, reticular & elastic

Structural properties of CT (connective tissue), there are 8 points.