Ch. 3 - Tissues and Early Embryology Flashcards
(105 cards)
Tissue
Collections of specialized cells and cell products that perform a relatively limited number of functions
Primary Tissue Types
- Epithelial
- Connective
- Muscle
- Neural
Epithelium
A sheet of cells that covers an exposed surface or lines an internal cavity or passageway
Basal lamina
Complex structure produced by the epithelium and cells of the underlying connective tissue where typical epithelium is bound to
Avascular
Do not contain blood. Nutrients are obtained by diffusion or absorption across the apical or basal surfaces
Neuroepithelium
Specialized sensory epithelium found in special sense organs that provide the sensations of smell, taste, sight, equilibrium, and hearing
Gland Cells
Epithelial cells that produce secretions
Glandular epithelium
Most or all epithelial cells produce secretions
Characteristics of Epithelial Tissue
- Cellularity, polarity
- Attachment
- Avascularity
- Arranged into sheets or layers
- Regeneration
Functions of Epithelial Tissue
- Provide physical protection
- Control permeability
- Provide sensation
- Produce specialized secretions
Apical Surface
Where the cell is exposed to an internal or external environment
Basolateral Surface
Where the epithelium contacts the basal lamina and neighboring epithelial cells
Simple Epithelium
Only a single layer of cells cover basal lamina
Stratified Epithelium
Two or more layers of cells above the basal lamina
Squamous Epithelium
The cells are thin, flat, and somewhat irregular in shape. In a sectional view the nucleus occupies the thickest portion of each cell, and has a flattened shape similar to that of the cell as a whole; from the surface, the cells look like fried eggs laid side by side.
Simple Squamous Epithelium
Locations: mesothelia lining ventral body cavities; endothelia lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli of lungs
Functions: reduces friction; controls vessel permeability; performs absorption and secretion
Components: cytoplasm and nucleus
Stratified Squamous Epithelium
Locations: surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina
Functions: provides physical protection against abrasion, pathogens, and chemical attack
Components: connective tissue, basal lamina on top w/ stem cells, and squamous superficial cells on top
Keratinized
A protein that occurs where mechanical stress and dehydration are potential poblems. Located on apical layers of epithelial cells to make superficial layers both tough and water resistant
Non-Keratinized
Provides resistance to abrasion to epithelial, but epithelial will dry out and deteriorate unless kept moist
Cuboidal Epithelium
Resemble little hexagonal boxes; they appear square in typical sectional views. Each nucleus s near the center of the cell, which the distance between adjacent nuclei roughly equal to the height of the epithelium.
Simple Cuboidal Epithelium
Locations: glands; ducts; portions of kidney tubules; thyroid gland
Functions: limited protection, secretion, absorption
Components: basal lamina w/ cuboidal cells on top and nucleus in center
Stratified Cuboidal Epithelium
Locations: lining of some ducts (rare)
Functions: protection, secretion, absorption
Components: lumen of duct, stratified cuboidal cells w/ nucleus in center and connected to basal lamina
Columnar Epithelial
Like cuboidal cells, they’re also hexagonal in cross section. In contrast to cuboidal cells though, their height is much greater than their width. The nuclei are crowded into a narrow band close to the basal lamina, and the height of the epithelium is several times th distance between two nuclei.
Simple Columnar Epithelium
Locations: lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys
Functions: protection, secretion, absorption
Components: microvilli, cytoplasm, nucleus close to basal lamina, loose connective tissue