Lab 4

Histology

The study of tissue

Epithelial Function

• secretion
• protection
  • from: bacteria, dehydration, chemicals, etc…
  • multiple layers of physical protections
  • karatinization
  • tight junctions (sometimes desmosomes)
• excretion
  • voids wasste from tissue to external environment
  • C02 for example
• absorption
  • eg. intestines, lungs
• filtration
  • mostly occurs in kidneys and liver
• sensation
  • corpuscles
  • all special senses have epithelial tissues which support sensory function.

epithelia structure

• polarity (one side attaches to apical surface, other to basement membrane)
• basement membrane
  • basal lamina
  • reticular lamina
• avascularity
• apical specialization
  • microvilli in GI tract
  • cillia in lungs create movement of materials

Epithelial Classification

• Cell Shape
  • squamous
  • cuboidal
  • columnar
  • transitional
• Layering
  • simple
  • stratified
  • pseudostratified

what are pryors patches? patches that survive stomach get sent here as part of lymph system of develop immunity

Here’s a table organizing epithelial tissues by cell shape (squamous, cuboidal, columnar) and layering (simple, pseudostratified, stratified). Each cell includes a description and examples:

Layering	Squamous	Cuboidal	Columnar
Simple	Description: Single layer of flat, thin cells.	Description: Single layer of cube-shaped cells.	Description: Single layer of tall, rectangular cells.
	Function: Diffusion, filtration.	Function: Secretion, absorption.	Function: Secretion, absorption.
	Examples: Alveoli of lungs, blood vessels (endothelium).	Examples: Kidney tubules, ducts of glands.	Examples: Lining of stomach, intestines, gallbladder.
Pseudostratified	Description: Not applicable (pseudostratified is only columnar).	Description: Not applicable (pseudostratified is only columnar).	Description: Single layer of cells with nuclei at different heights.
	Function: N/A	Function: N/A	Function: Secretion, movement of mucus (often ciliated).
	Examples: N/A	Examples: N/A	Examples: Lining of trachea, upper respiratory tract.
Stratified	Description: Multiple layers of flat cells; surface cells are squamous.	Description: Multiple layers of cube-shaped cells.	Description: Multiple layers of rectangular cells; surface cells are columnar.
	Function: Protection against abrasion, pathogens, and chemicals.	Function: Protection, secretion.	Function: Protection, secretion.
	Examples: Skin (epidermis), lining of mouth, esophagus, vagina.	Examples: Sweat glands, salivary glands (rare).	Examples: Male urethra, ducts of some glands (rare).

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