Tissues
Groups of cells similar in structure and function
The four types of tissues are
- Epithelial
- Connective
- Muscle
- Neural
Functions of Epithelial Tissue are
- Protection
- Control permeability
- Secretion
- Sensory reception
Characteristics of Epithelial Tissue are
- Cellularity
- Connections
- Polarity
- Supported by connective tissue
- Avascular but innervated
- Regenerative
Cellularity is
composed almost entirely of cells
Connections are
cells held together by tight junctions and desmosomes
Polarity
apical and basal surfaces
Supportive connective tissue is
basement membrane
Regenerative
rapidly replaces lost cells by mitosis
Two apical modifications are
- Cilia
2. Microvilli
Classification of Epithelia
- # of cell layers
2. Shape of cells
Stratified tissues are named by
the shape of the apical layer of cells
Endothelium and mesothelium are both
Simple Squamous Epithelium
Endothelium lines the
inside of the heart and blood vessels
Mesothelium lines the
pericardial cavity and the peritoneal cavity
Simple Cuboidal Epithelium
Single layer of cube like cells with large,spherical, centralized nuclei
Function of Simple Cuboidal Epithelium
Secretion and absorption
Location of Function of Simple Cuboidal Epithelium
Kidney tubules;ducts and secretary portions of small glands; ovary surface
Simple Columnar Epithelium
Single layer with tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus secreting unicellular glands
Function of Simple Columnar Epithelium
absorption; secretion of mucus, enzymes,and other substances; ciliated type propels mucus by ciliated action
Location of Simple Columnar Epithelium
Non ciliated type lines most of the digestive tract , gallbladder and excretory ducts of some glands; ciliated variety lines small bronchi,uterine tubes and some regions of the uterus
Pseudostratified (ciliated) Columnar Epithelium
Single layer of cells differing heights, some not reaching the free surface; nuclei seen at different levels; may contain goblet cells and bear cilia
Function of Pseudostratified (ciliated) Columnar Epithelium
Secretion particularly of mucus; propulsion of mucus by ciliary action
Location of Pseudostratified (ciliated) Columnar Epithelium
Non ciliated type in males sperm carrying ducts and ducts of large glands; ciliated variety lines the trachea most of the upper respiratory system
Stratified Squamous Epithelium
Thick membrane composed of many cell layers; basal cells are cubodial or columnar and metabolically active;;surface cells are flattened
Stratified Squamous Epithelium function
Protects underlying tissue in areas subjected to abrasion.
Stratified Squamous Epithelium location
Nonkeratintized type forms the moist lining of the esophagus mouth and vagina; keratintized variety forms the epidermis of the skin a dry membrane
Transitional Epithelium
Resembles both stratified squamous and stratified cuboidal; surface cells dome shaped or squamous like depending on degree of organ stretch
Transitional Epithelium function
Stretches readily and prevents distension of urinary organ by contained urine
Transitional Epithelium location
Lines the ureters, bladder and part of the urethra
Glands are
epithelial tissue
Secrete product into duct
Exocrine glands
Examples of exocrine glands
Ex: mucous, sweat, oil, and salivary glands
Goblet (mucous) cell- unicellular gland
No ducts: secretions picked up by bloodstream
Endocrine glands
Exocrine glands are characterized by
their mode of secretion
secretes product outside of cell without harming cell
Merocrine
Part of cell breaks off
Apocrine
Cell explodes
Holocrine
Examples of merocrine
sweat & salivary glands
Examples of apocrine
mammary glands
Examples of holocrine
oil glands
- Cutaneous – skin
- Mucous – lines body cavities open to the exterior
- Serous membrane
Epithelial Membranes
Inflammation of visceral/parietal membrane of the pleural cavity
Pleurisy
Inflammation of visceral/parietal membrane of the peritoneal cavity
Peritonitis
