Ch 5 Powerpoint1a Flashcards
What are the primary types of tissues?
Epithelial, connective, muscle, nervous
These tissues work together to meet the needs of the animal as a whole.
What is histology?
The microscopic study of tissues
Also referred to as microanatomy.
What are the main functions of epithelial tissue?
- Protects, covers, and lines
- Filters biochemical substances
- Absorbs nutrients
- Provides sensory input
- Manufactures secretions
- Manufactures excretions
What are the characteristics of epithelia?
- Vary in size and shape
- Organized into tightly packed groups
- Polar cells with apical and basal surfaces
- Avascular
- Most cells are innervated
What are the major types of cellular junctions?
- Tight junctions
- Desmosomes
- Gap junctions
- Basement membrane
What is the function of tight junctions?
Prevent leaks between adjacent cells
Found in the urinary bladder and digestive tract.
What is the role of desmosomes?
Connect plasma membranes of adjacent cells for strong mechanical coupling
Important in tissues that undergo tension and stretching.
What are gap junctions?
Cells linked by tubular channel proteins allowing exchange of ions and nutrients
Found in intestinal epithelial cells, heart, and smooth muscle tissue.
What is the basement membrane?
Foundation of epithelial cells, a nonliving network of fibers
Helps prevent cells from being torn off.
What are the types of epithelial cell shapes?
- Squamous
- Cuboidal
- Columnar
What characterizes simple squamous epithelium?
Delicate, thin, flat cells lining surfaces involved in gas or liquid passage
Examples include mesothelium and endothelium.
What is simple cuboidal epithelium?
A single layer of cube-shaped cells with round, dark-staining nuclei
Found in areas where secretion and absorption occur.
Describe simple columnar epithelium.
Elongated cells closely packed together, nuclei aligned at the base
Found in many excretory ducts and the digestive tract.
What is the function of stratified squamous epithelium?
Protects underlying tissues in areas subject to mechanical and chemical stress
Examples include the mouth, esophagus, and vagina.
How is stratified cuboidal epithelium characterized?
Generally occurs in two layers, protects underlying tissues
Found along large excretory ducts.
What is pseudostratified columnar epithelium?
Layer not truly stratified, nuclei at varying levels, most are ciliated
Located in respiratory tract and male reproductive tract.
What is transitional epithelium?
Basal layer of cuboidal or columnar cells with a superficial layer of squamous cells
Found in regions that expand and contract like the bladder.
What are the classifications of glands?
- Presence or absence of ducts
- Number of cells composing them
- Shape of secreting ducts
- Complexity of glandular structure
- Type of secretion produced
- Manner of secretion storage and discharge
What distinguishes exocrine glands?
Possess ducts and discharge secretions directly into local areas
Examples include sweat, salivary, and liver glands.
What is a unicellular exocrine gland?
Only example is the goblet cell, which secretes mucin
Found in respiratory and digestive tracts.
What are multicellular exocrine glands composed of?
A secretory unit and a duct
Surrounded by connective tissue rich in blood vessels.
What type of ducts do simple exocrine glands have?
Unbranched ducts
In contrast, compound glands have branched ducts.
What are the shapes of secretory portions in exocrine glands?
- Tubular
- Alveolar (acinar)
- Tubuloalveolar (tubuloacinar)
How are secretions classified in exocrine glands?
- Merocrine: secretory cells remain intact
- Apocrine: top part of cell is released
- Holocrine: entire cell is destroyed
