Chapter 5 Flashcards
What is histology?
The study of tissues
What are the four types of tissues?
Epithelial, connective, muscle, nervous
Epithelial tissue:
Composed of one or more layers of closely packed cells
*Covers body surfaces/ lines body cavities/forms majority of glands
Characteristics of epithelial tissue:
- Cellularity ( entirely tightly packed)
- Polarity
- Basal surface
- Attachment to basement membrane
- Nutrients obtained from apical surface or basil surface
- Continual replacement of lost cells
Functions of epithelial tissue:
- Physical protection
- Selective permeability
- Some cells are specialized to secrete
- Supply information to nervous system
Classification of epithelial tissue by number of cell layers:
Simple - one cell layer thick, all cells contact basement membrane
Stratified - two or more layers, only one layer in contact with basement membrane
Psuedostratified - appears layered, all cells reach basement membrane but may not reach the surface
Epithelial tissue classified by cell shape:
- Squamous - flat, wide
- Cubodial cells - as tall as they are wide. Cube like.
- Columnar cells - slender and taller than they are wide.
- Transitional cells - change shape depending on stretch of epithelium
Function of simple squamous epithelium:
Allows rapid movement of molecules across surface.
Lines part of the lungs, vessel walls and serous membranes
Function of simple cuboidal epithelium:
Absorption and secretion
- Ideal for atructural components of glands
Function of simple columnar epithelium:
Ideal for secretion and absorption/ two forms
- Nonciliated
- Ciliated
Characterisitics of Nonciliated simple columnar epithelium
- Contains microvilli
- Unicellular glands - goblet cells
Forms mucus when mixed w water. - Lines most of digestive tract from stomach to anal canal
Characteristics of Cilitated simple columnar epithelium:
- Goblet cells interspersed
- Lines the bronchioles and the uterine tubes - cilia help mold oocyte from over to uterus.
Characteristics of pseudostratified columnar epithelium:
- Appears as multiple cell layers
- Not really Stratified
Two forms:
Ciliated
Nonciliated
Functions of Ciliated pseudostratified columnar epithelium:
Protective functions
Goblet cells secrete mucin
Traps large particles moved by cilia
Located in large passageways of respitory system
Characteristics of Noncilated pseudostratified columnar epithelium:
Rare
Lacks cilia and goblet cells
Occurs mainly in the male urethra and epididymis
Stratified squamous epithelium
Multiple cell layers, only deepest in contact w basement membrane
Protects against abrasion and friction
Exist in keratinized and nonkeratinized forms
Keratinized Stratified squamous epithelium
Superficial layers of dead cells
Cells lack nuclei, filled w keratin
Filled w Keratin and die
Found in epidermis
Nonkeratinised Stratified squamous epithelium
All cells live
Kept moist w secretions (saliva, mucus)
Lines oral cavity, part of pharynx, esophagus, vagina and anus
Stratified cuboidal epithelium
Forms tube and coverings
Protection and secretion
Forma walls in most exorcize glands
Transitional epithelium
limited to urinary tract
Binucleated cells ( 2 nuclei)
Allows for stretching as bladder fills
Glands
Individual cells or multicellular organs composed of epithelial tissue
Ex: endocrine or exocrine
Endocrine vs Exocrine
Endocrine - lack ducts and secrete hormones into the blood
Exocrine examples: sweat glands, mammary glands, salivary glands
Unicellular exocrine glands
Do not contain a duct
Most common is the goblet cell
Multicellular exocrine glands
Acini- cell clusters that produce secretions
Ducts transport secretions to epithelial surface
Merocrine glands
Package secretions into vesicles released by exocytosis
Apocrine glands
Apical membrane pinched off and becomes secretion
Holocrine glands
Ruptured cell becomes secretion
Characteristics of connective tissue:
All CT shares three basic components: cells, protein fibers, ground substance
NeXT slide 41
