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HUMAN BIOLOGY > Epithelial Tissues And Glands > Flashcards

Epithelial Tissues And Glands Flashcards

1. Define basic concepts of epithelium and glands 2. Describe and illustrate the histology concept of epithelium and glands

1
Q

Characterstics of epithelial Tissues

A
  1. Cellularity - composed almost entirelt of cells
  2. Avascular - no blood vessels
  3. High regenerative power
  4. Anchored to underlying fibrous basal lamina
  5. Able to generate surface polarity
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2
Q

Base membrane consist of

A

Basal lamina + reticular lamina

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3
Q

What is basal lamina and its components

A
  1. Ectracellular structure that separates basal surfaces from subjacent connective tissues
  2. Consist of lamina densa(delicate network of fine fibrils) and lamina rarae (electron layers)
  3. Components : 1. Type iv collagen
    2. Glycoprotein
    3. Proteoglycan
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4
Q

Function of basal membrane (basal lamina)

A 
Attachment
Barrier 
Compartmentalisation 
Polarity induction 
Tissue scaffolding
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5
Q

Function of epithelium

A
  1. Protection (mechanical)
  2. Transport (cilia)
  3. Secretion
  4. Excretion
  5. Lubrication (prevent friction)
  6. Sensory reception
  7. Reproduction
  8. Synthesis vit D with uv
  9. Absorption
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6
Q

What are intercellular joints and their types

A
  1. Cellular margins that contribute to adhesion or allow for communication btwn cells.
  2. 3 typesA. Occluding Junction : tight junctions / zonula occludens

B. Anchoring junction : I. Zonula adherens
II. Macula adherens ( desmosomes)
III. Hemidesmosome

C. Communicating junctions : gap junctions

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7
Q

Occluding junction

  • what
  • example
  • functions
A 
Junction that close off the intercellular space
Tight junction ( zonula occludent)
Functions : - acts as seal to prevent flow of materials between epithelial cells
- formation of functional compartments delimited by sheets of epithelial cells eg:for prevention of bacteria entering the intestinal lining
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8
Q

Anchoring junction

A

General function : to provide a firm adhesion among epithelial cells

1) zonula adherens
- cell to cell anchoring junction
- encircles the cell
- serves as adhesion sites between cell & another
- interacts with the network of actin filaments inside the cell

2) desmosome/macula adherens
- cell to cell anchoring junction
- interacts with intermediate filaments

3) hemidesmosome
- cell to extracellular matrix
- anchor cytoskeleton to basement membrane

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9
Q

Communicating junction

  • eg
  • characteristics
  • function
A

Eg: gap junction
Consist of CONNEXONS which form HEXAMERS with HYDROPHILIC PORE at the at the center.
-Allow exchange of hormones, GMP, Cyclic AMP
- Allow cells to act in coordinated manner (muscle tissue of heart, nervous tissue)

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10
Q

Types of epithelium tissue

A
  1. Covering epithelium (covers body n lines cavity of body)

2. Glandular epithelium (specialised cell that produce secretion like hormone, enzyme n mucus)

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11
Q

Specialisation of epithelial cell surfaces

A
  1. Cilia - respiratory epithelium
    - move material along cell surface
    - motile
  2. Microvilli - intestine, kidnet
    - tsa^
    - absorption n secretion
  3. Stereo cilia - x motile
    - TSA ^
    - ABSORPTION
    - EPIDIDYMIS
  4. FLAGELLA - Similar to cilia but longer
    - spermatozoa
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12
Q

What is gland and its basic function

A

An organ or group of cells specialised for synthesising & secreting certain substance

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13
Q

Development of glandular epithelium

A
  1. Develop during fetal life from covering epithelium
  2. Epithelium cells proliferate
  3. And invade into subjacent connective tissue
  4. Cell differentiate into glandular epithelium
  5. Located deep to the covering epithelium
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14
Q

What is endocrine gland?

A
  1. Glands whose connection with the surface is lost during development
  2. Lack of duct system
  3. Empty their secretion directly into blood vessels
  4. Eg: thyroid gland. Pituitary gland, adrenal gland
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15
Q

What is exocrine gland?

A
  1. Produce serous or mucous secretion that flow through a duct to the specific area where the secretion is used. (sweat & salivary gland)
  2. Classification based on secretion

I. Mucous gland
II serous gland
III mixed gland

  1. Classification based on modes of secretion

I. Merocrine / eccrine
II. Apocrine
III. Holocrine

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16
Q

Mucous glands

  1. Characterstics of secretion
  2. How the secretion is formed
  3. Function
  4. Example
A
  1. Viscous and slimy secretion
  2. Result of excessive glycosylation ( carbohydrate attached to OH group) of constituent proteins with oligosaccharides (carbohydrates with less monosaccharides) .
  3. Protects / lubricates the inner lining of organ
  4. Goblet cells, oesophageal glands, sublingual salivary glands
17
Q

Serous cells

  1. Characterstics of secretion
    2.
A
  1. Watery secretion
18
Q

Mixed/ seromucous / serous demilunes

  1. Formation
  2. Characteristics
  3. Example
A
  1. Mucous cell predominate, serous cell form a crescent over mucous cell
  2. Contains mucous acini and serous acini
  3. Eg: parotid gland, eccrine sweat gland
19
Q

Merocrine/eccrine secretion

  1. Describe the process
  2. Step by step
A
  1. Process of exocytosis
  2. Vesicles open onto cell surface
  3. Secretory product is discharged from cell
  4. Cell remains
  5. Example : salivary gland, pancreatic gland.
20
Q

Holocrine secretion

A
  • Breakdown & discharge of entire secretory cell
  • Cells become part of secretion
  • Does not require nerve supply to release its secretion
  • eg : sebaceous gland
21
Q

Apocrine secretion

A
  1. Releases product by pinching of apical portion of cytoplasm
  2. Cell is lost together with secretory product
  3. Eg: apocrine sweat gland, mammary gland
22
Q

Classification of epithelial cells based on no. of cells:

A
  1. Unicellular - made up of a single glandular cell (eg:goblet cell)
  2. Multicellular - clusters of cells
    ✔️ Simple exocrine gland(unbranched )
    🔵 Straight
    👉 Simple tubular (crypts of lieberkuhn in large intestine)
    👉Simple branched tubular ( gastric gland in stomach)
    👉 Simple branched acinar (sebaceous gland in skin)
    🔵 Coiled
    👉Simple coiled tubular ( sweat gland)

✔️ Compound exocrine gland(repeated branching pattern)
🔵 Compound tubular - Brunner’s glan in duodenum
🔵 Compound acinar - parotid gland, lactating mammary gland
🔵 Compound tubulo-acinar - submandibular & sublingual glands

HUMAN BIOLOGY (2 decks)

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