Chapter 5 Tissues. Intercellular Connections . Individual cells connect to form tissues 3 ways: Tight junctions- prevents permeability of ions through junction. Desmosome- adhesion between cells in spots. Allows from some permeability.
A tissue is a group of cells with a common structure & function
The human body is composed of four main tissue types:
May occur in layers:
Simple Squamous- Thin, flattened cells. Allow for diffusion and filtration. Line air sacs of lungs and walls of capillaries.
Simple cuboidal-single layer of cube shaped cells. Lines follicles of thyroid gland, kidneys and ducts of certain glands. Used for secretion and absorption
Simple columnar- single layer of elongated cells. Can contain cilia, used for protection and absorption in digestive tract. Can contain goblet cells.
Stratified squamous-Layers of squamous cells. Make up epidermis and line cavities exposed to external environment. Outer layer die and accumulate keratin.
Stratified columnar- Several layers of columnar cells overlying cuboidal cells near the basement membrane. Found in male reprod. System and pharynx
Pseudostratified ciliated columnar- Appear stratified but are not. Often contain cilia and goblet cells which secrete mucus. Line respiratory passages.
Transitional tissue- Changes in response to change in tension (stretching). Line urinary bladder and urethra. Larger cells at surface, smaller cells deeper.
products; ex. – sebaceous (oil) glands
1. Fixed cells – stay in one place & have stable numbers; 2 types:
allergic reactions &
usually located near
blood vessel walls
2. Wandering cells –
(Purple cells – macrophages,
Green cells – T-lymphocytes)
Areolar tissue-binds the skin to underlying organs and under epithelium to provide bloodflow. Binds and protects. A- fibroblast, B-collagen, C- elastin
Regular dense connective- strong fibers bind body parts together. Found in ligaments and tendons. Poor blood supply so slow healing. A- fibroblasts. B- collagen and elastin
Hyaline cartilage- Most common, found on ends of bones, nose cavity and supporting rings of resp. system. A- chondrocytes, B- Matrix (fine collagen fibers), C- Lacunae
Fibrocartilage- tough tissue containing collagenous fibers. Shock absorbers between vertebrae and pubic girdle. A- Chondrocyte, B- Collagen fibers