The tissue level of organization - Epithelia tissue Flashcards

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1
Q

Define tissues

A

Collections of specialized cells and cell products that perform specific functions

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2
Q

What is histology

A

is the study of tissues

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3
Q

What are the four types of tissue

A
  1. Epithelial
  2. Connective
  3. Muscle
  4. Nervous
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4
Q

Describe epithelial tissue

A

– Covers exposed surfaces
– Lines internal passageways
– Forms glands

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5
Q

Describe the connective tissue

A

Fills internal spaces
– Supports other tissues
– Transports materials
– Stores energy

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6
Q

Describe the muscle tissue

A

Specialized for contraction
– Skeletal muscle, heart muscle, and muscular walls of hollow organs

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7
Q

Describe the nervous tissue

A

– Carries electrical signals from one part of the body to another

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8
Q

Epithelial tissue includes

A

– Epithelia (singular, epithelium)
* Layers of cells covering internal or external surfaces
– Glands
* Structures that produce fluid secretions

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9
Q

What is the function of the epithelial tissue

A
  1. Provide physical protection
  2. Control permeability
  3. Provide sensation
  4. Produce specialized secretions
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10
Q

States some characteristics of epithelia

A

– Polarity (apical and basal surfaces)
– Cellularity (cell junctions)
– Attachment (basement membrane)
– Avascularity (avascular)
– Regeneration

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11
Q

Describe the specializations of epithelial cells

A
  1. Move fluids over the epithelium (protection)
  2. Move fluids through the epithelium (permeability)
  3. Produce secretions (protection and messaging)
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12
Q

Explain polarity

A

4-2 Epithelial Tissue
▪ Specializations of epithelial cells
1. Move fluids over the epithelium (protection)
2. Move fluids through the epithelium (permeability)
3. Produce secretions (protection and messaging)
▪ Polarity
– Apical surface
* Microvilli increase absorption or secretion
* Cilia on a ciliated epithelium move fluids
– Basolateral surface

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13
Q

Identify the structures of the epithelia

A
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14
Q

How is the integrity of the epithelia maintaned

A
  1. Intercellular connections
  2. Attachment to the basement membrane
  3. Epithelial maintenance and repair
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15
Q

What is the purpose for intercellular connections

A

– Support and communication
* Cell adhesion molecules (CAMs)
– Transmembrane proteins
* Proteoglycans act as intercellular cement
– Contain glycosaminoglycans such as hyaluronan (hyaluronic acid)

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16
Q

What is cell junctions

A

Form bonds with other cells or extracellular material

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17
Q

What are the types of cell junctions

A
  1. Gap junctions
  2. Tight junctions
  3. Desmosomes
18
Q

Describe gap junctions

A

– Allow rapid communication
– Cells held together by interlocking transmembrane
proteins (connexons)
– Allow small molecules and ions to pass
– Coordinate contractions in heart muscle

19
Q

Describe the tight junctions

A

– Between two plasma membranes
– Adhesion belt attaches to terminal web
– Prevent passage of water and solutes
– Keep enzymes, acids, and wastes in the lumen of the digestive tract

20
Q

Describe desmosomes

A

– CAMs and proteoglycans link opposing plasma
membranes
– Spot desmosomes
* Tie cells together
* Allow bending and twisting
– Hemidesmosomes
* Attach cells to the basement membrane

21
Q

Identify the cell junctions on the cell

A
22
Q

What is attached to the basement membrane

A

– Basal lamina
* Closest to the epithelium
– Reticular lamina
* Deeper portion of basement membrane
* Provides strength

23
Q

Explain the epithelial maintenance and repair

A

– Epithelial cells are replaced by continual division of
stem cells
* Located near basement membrane

24
Q

Explain the classification of epithelia

A
  1. Based on shape
    * Squamous—thin and flat
    * Cuboidal—square shaped
    * Columnar—tall, slender rectangles
  2. Based on layers
    * Simple epithelium—single layer of cells
    * Stratified epithelium—several layers of cells
25
Q

Describe the simple squamous epithelia

A

– Simple squamous epithelia
* Absorption and diffusion
* Mesothelium
– Lines body cavities
* Endothelium
– Forms inner lining of heart and blood vessels

26
Q

Explain the function of Stratified squamous epithelia

A
  • Protect against mechanical stresses
  • Keratin adds strength and water resistance
27
Q

Describe simple cuboidal epithelia

A
  • Secretion and absorption
  • Glands and portions of kidney tubules
28
Q

Describe stratified cuboidal epithelia

A
  • Relatively rare
  • Ducts of sweat glands and mammary glands
29
Q

Describe the transitional Epithelia

A

– Tolerate repeated cycles of stretching without damage
– Appearance changes as stretching occurs
– Found in the urinary bladder

30
Q

Describe simple columnar epithelia

A
  • Absorption and secretion
  • Found in stomach, small intestine, large intestine
31
Q

Describe pseudostratified columnar epithelia?

A
  • Typically have cilia
  • Found in nasal cavity, trachea, bronchi
32
Q

Describe stratified columnar epithelia

A
  • Relatively rare
  • Provide protection in pharynx, anus, urethra
33
Q

Define Gland

A

Glands are collections of epithelial cells that produce secretions

34
Q

What are the two types of glands and describe

A

– Endocrine glands
* Release hormones that enter bloodstream
* No ducts
– Exocrine glands
* Produce exocrine secretions
* Discharge secretions through ducts onto epithelial surfaces

35
Q

Gland structure has

A

– Unicellular glands
– Multicellular glands

36
Q

Describe the unicellular glands

A

– Goblet cells are unicellular exocrine glands
* In epithelia of intestines
* Secrete mucin, which mixes with water to form
mucus

37
Q

Describe the multicellular glands

A

are classified by
1. Structure of the duct
* Simple (undivided)
* Compound (divided)
2. Shape of secretory portion of the gland
* Tubular (tube shaped)
* Alveolar or acinar (blind pockets)
3. Relationship between ducts and glandular areas
* Branched (several secretory areas sharing one
duct)

38
Q

State the three methods of secretion

A
  1. Merocrine
  2. Apocrine
  3. Holocrine
39
Q

Describe Merocrine secretion

A

Released by secretory vesicles (exocytosis)
– Example: merocrine sweat glands

40
Q

Describe Apocrine secretion

A

– Released by shedding cytoplasm
– Example: mammary glands

41
Q

Describe Holocrine secretion

A

– Released by cells bursting, killing gland cells
– Gland cells replaced by stem cells
– Example: sebaceous glands

42
Q

What types of secretions are produced by exocrine glands

A

– Serous glands
* Watery secretions
– Mucous glands
* Secrete mucins
– Mixed exocrine glands
* Both serous and mucous