Tissues Group of cells that are similar in structure and perform a common or related function.
The study of tissues is called Histology.
Connective Tissue Found everywhere in the body Abundant and widely distributed
Amount in particular organs vary
Cartilage Stands up to both tension and compression Qualities like dense connective tissue and bone Receives nutrients through diffusion by blood vessels
Include chondroblasts that produce a new matrix until the skeleton stops growing at the end of adolescence.
Hyaline Most abundant cartilage type in the body Contains large numbers of collagen fibers Matrix appears glassy and amorphous Provides firm support and some pliability Covers ends of bones as articular cartilage Supports tip of nose, connects ribs to sternum, supports most of the respiratory system passages
Embryonic skeletons are mostly made up of this cartilage
Elastic Nearly Identical to Hyaline cartilage More elastin fibers in elastic cartilage Strong and exceptional stretchability
Used in external ear and epiglottis (covers the opening to the respiratory passageway when we swallow, preventing foods and fluids from entering the lungs.)
Fibrocartilage Intermediate between Hyaline and Dense Regular Connective Tissue Compressible and resists tension well Found where strong support and the ability to withstand heavy pressure are required
Used between vertebrae and is the spongy cartilage of the knee
Bone Also called osseous tissue Protects and supports body structures Provide cavities for fat storage and synthesis of blood cells Have bone matrixes similar to cartilage but it is harder and more rigid
Also has osteoblasts, which produce the organic portion of the matrix
Blood Fluid within blood vessels Atypical connective tissue It does not connect things or give support Classified as connective tissue because it develops from mesenchyme and consists of blood cells and blood plasma Consists mostly of red blood cells and some white blood cells Fibers of blood form clotting
Carries nutrients, wastes, respiratory gases and other substances throughout the body
Connective Tissue Proper Contains two subclasses, loose and dense
All mature connective tissue (except for bone, cartilage and blood) belong to the dense class
Consists of three types: Areolar, Adipose and Reticular
Areolar Supports and binds other tissues, holds bodily fluids, defends against infection and stores nutrients as fat Loose arrangements of fibers Provides a reservoir of water and salts for other tissues Contains hyaluronic acid which hinders movements of cells through it Soaks up excess bodily fluid when a body region is inflamed
Present in all mucous membranes
Adipose Similar to areolar in structure and function, has greater nutrient storing capabilities Adipocytes or fat cells make up 90% of the tissue Looks like chicken wire in appearance Mature adipocytes are some of the largest cells in the body Acts as a shock absorber, insulation and storage site. Found behind eyeballs, hips around heard and lymph nodes. Sometimes called white fat
Also found in bone marrow and some muscles
Forms internal framework that support free blood cells in lymph nodes, spleen and bone marrow
Consists of two types, Regular and Irregular
Regular Referred to as fibrous connective tissue Loosely packed bundles of collagen fibers running parallel to the direction of pull Great resistance to tension Slightly wavy and contain fibroblasts forming fibers and scant ground substance
Forms tendons and aponeneuroses, as well as fascia that wraps around muscles, groups of muscles, blood vessels and nerves
Irregular Same structural elements as regular variety, but have bundles of collagen fibers that are much thicker and arranged in different directions
Found in the skin as dermis, forms joint capsules, and fibrous coverings that surround organs such as kidneys, bones, cartilages, muscles and nerves.
Simple Concerned with absorption, secretion and filtration
Usually very thin so it does not protect.
Epithelial Sheet of cells that covers a body surface or lines a body cavity. Occurs in body as covering and lining epithelium and glandular epithelium Form boundaries between different environments Forms many functions like protection, absorption, filtration, excretion, secretion, and sensory reception Special characteristics: polarity, specialized contacts (fit close together to form continuous sheets), supported by connective tissue, avascular but innervated (it is supplied by nerve fibers but contains no blood vessels) and an ability to regenerate Classified by shapes and cell layers Cell layers: Stratified and Simple
Shapes: Squamous, Cuboidal and Columnar
Simple Squamous Epithelium Filters or exchanges substances Located in the kidneys, in the lungs and forms the walls of air sacs
2 types: Endothelium which is slick, friction reducing lining, allows efficient exchange of nutrients and wastes between the bloodstream and surrounding tissue cells. Mesothelium which is found in serous membranes which line the ventral body cavity and covers its organs.