ChiaiEpithelial2GuaranteedTest

Question 1

Epithelial Tissue
KEY POINTS (First Slide and my extra comments in parenthesis)

What is Common Structure?
Embryological Origin?
Seven functions?

Answer 1

COMMON STRUCTURE (Epithelial Tissue)

• Predominantly cellular contiguous sheet of cells (contiguous sheets of cells that forms a layer or membrane)
• Numerous intracellular junctions (Holds cells together to form single, continuous layer)
• Free surface
• Polar cells with apical and basolateral domains (cell membranes differ in the two regions)
• Sits on basal lamina of connective tissue (sits on basement membrane)
• Avascular (receives all nutrients from the connective tissue it sits on)

EMBRYOLOGICAL ORIGIN: Derived from all three germ layers (ectoderm, mesoderm, and endoderm)

SEVEN FUNCTIONS: Selective permeable barriers, protection, secretion, absorption, transport, sensory surface, and repair itself

Question 2

APICAL DOMAIN SPECIALIZATIONS (of epithelial tissue)

1) Microvilli
2) Sterocelia
3) Celia
4) Flagella

Answer 2

1) MICROVILLI (Brush-border)
- Non-motile
- Actin filament core
- Increases surface area for absorption/secretion

2) STEREOCELIA
- Structurally similar to microvilli
- Non-motile
- Increases surface area for absorption/secretion

3) CELIA
- Motile
- Microtubules arranged as “axoneme”
- Move fluid and particles along surface

4) FLAGELLA
- Motile
- Structurally similar to celia
- Moves sperm through reproductive structures

Question 3

POLARITY (of epithelial tissue)

Answer 3

-TWO DOMAINS with different proteins in membranes of respective domain/different functions

-Apical Domain has:
*Free Surface
*Surface specializations:
Non-motile: Microvilli and Stereocelia
Motile: Celia and Flagella

• Basolateral Domain contains:
  1) Junctional Complex consisting of 3 junctions:
  * Zona occludens, Zona adherins, and Macula adherins
  2) Gap junctions open passages for communication
  3) Basal Domain contains:
  - Membrane enfolding for increasing surface area
  - Basal Lamina to hold cell to connective tissue
  - Hemidesmosomes to hold cell to connective tissue

Question 4

GLANDS (epithelial tissue)

Four different ways of classifying each gland, the first two of them are listed on this slide

Answer 4

• All derived as outgrowths of epithelium
• Each gland can be classified four different ways:1) Presence or absence of ducts:
  * EXOCRINE have ducts - secrete on to surface
  * ENDOCRINE have no ducts - secrete into surrounding connective tissue2) Structure/Morphology:
  *Unicellular - single cell in epithelial sheet
  *Multicellular - all exocrine glands have two parts: Ducts and Secretory units
  *Name based on these two parts of gland
  ^Branching of ducts - simple vs branched
  ^Shape of secretory unit - acinar vs tubular

Question 5

GLANDS (epithelial tissue)

Four different ways of classifying each gland, the last two of them are listed on this slide

Answer 5

3) Mode of secretion: Mechanism of release of secretions -
* Holocrine-Whole cell and secretions-dead
* Merocrine-Exocytosis
* Apocrine-Secretory product and part of cytoplasm
* Cytocrine-Whole living cell

4) Types of secretion: Different substances released
* Mucous - slippery and viscous
* Serous - watery
* Mixed - combination of mucous and serous
* Sebum - oily
* Ceruminous - waxy