Tissues Karen Malt, MSN, RN

Tissues Groupings of cells are called “tissues.” Tissues are known as the “Fabric of the Body.” Each tissue of an organ specializes in performing unique functions that help the organ do its job. Tissues differ in size and shape, in the amount and kind of material between the cells, and in the function of the cells.

Tissues The Four Main Types of Tissues Epithelial- forms sheets that cover or line the body Connective- Provides structural/ functional support Muscle- Contracts to produce movement Nervous- Senses, conducts, and processes information

Tissues Matrix- the fluid environment that fills the space between the cells. Matrix is similar to “jelly” and varies in amount and its composition among the various types of tissue. Example: Epithelial tissue has very little matrix due to the fact that the cells are so tightly connected to each other. Connective tissue on the other hand is made up mostly of matrix with the cells very far apart.

Tissues Collagen- a protein within the matrix of many tissues. Collagen gives tissues flexibility and strength. Elastin- present in some tissues, gives tissues the ability to stretch and rebound easily.

Tissues Epithelial Tissue- covers and lines various parts of the body. Classified according to shape: Squamous- flat and scale-like Cuboidal- Cube shaped Columnar- higher than they are wide Transitional- varying shapes that can stretch Classified by Arrangement of Cells Simple- single layer of cells of the same shape Stratified- many layers of cells; named for the shape of the cells in the outermost layer

Tissues Squamous Epithelium- Simple Squamous Epithelium- single layer of very thin, irregularly shaped cells. Substances can pass through readily making transport its special function. Example: Absorption of O2 into the blood takes place through the simple squamous epithelium that forms the tiny air sacs in the lungs.

Squamous Epithelium- (continued) Stratified Squamous Epithelium-Several layers closely packed cells. An arrangement that makes this types of tissue adept at protection. Example: these types of cells protect the body against invasion by microorganisms. The skin is an example of stratified squamous cells.

Tissues Simple Columnar Epithelium Lines the inner surface of the stomach, intestines, some areas of the respiratory tract, and reproductive tracts. These cells are taller than they are wide, and the nuclei are located toward the bottom of the cell. The open spaces within these cells are called “goblet cells” which are mucus producing.

Tissues Stratified Transitional Epithelium Found in areas of the body prone to stress and must be able to stretch. Example: wall of the urinary bladder

Tissues Pseudostratified Epithelium Lines the trachea or windpipe moving mucus along the lining affording protection against dust or foreign particles in the lungs. NOTE: The cells actually touch the glue-like membrane that lies under all the epithelial tissue

Tissues Cuboidal Epithelium Simple Cuboidal Epithelium- forms tubules for secretory activity. Example: Salivary glands, digestive juices, perspiration (sweat). Glands are classified: Exocrine- release their secretions through a duct Endocrine- release their secretions directly into bloodstream

Tissues Connective Tissue- Most abundant and widely distributed tissue in the body. Found in the skin, membranes, muscles, bones, nerves, and all internal organs. This tissue is delicate, paper thin webs that holds organs together and gives them shape. It also, exists as strong and tough cords, rigid bones, and even in the form of a fluid (blood).

Tissues Types of Connective Tissue Areolar Adipose (fat) Fibrous Bone Cartilage Blood Hematopoietic Tissue

Tissues Areolar Tissue Most widely distributed of all connective tissue types. Known as the “glue” that helps keep the organs of the body together. Some of the fibers are made of Collagen, a strong, but flexible fibrous protein. Some are stretchy fibers made of Elastin which is rubbery. Helps tissues return to a shorter length after having been stretched. Fascia helps bind the skin, muscles, bones and other organs together.

Tissues Adipose Tissue- when areolar tissue begins to store lipids it can turn into adipose tissue. Numerous vesicles have formed inside the adipose cells where large quantities of triglyceride lipids accumulate. Called the “white fat.” The type of adipose tissue called “brown fat” actually burns its fuel to produce energy when the body is cold to produce heat. ALL adipose tissue secretes hormones, which helps regulate metabolism and fuel storage in the body.

Tissues Reticular Tissue- reticular means “net-like” and aptly describes the net-like structure of this type of tissue. This tissue id found in bone marrow, spleen, and lymph nodes where it supports developing cells of the immune system.

Tissues Dense Fibrous Connective Tissue- Consists mainly of thick, strong, white collagen fibers that are packed very close together. Regular Dense Fibrous Connective Tissue- Bundles are arranged in roughly parallel rows. This makes up tendons, the straps that connect muscles to bones. Irregular Dense Fibrous Connective Tissue- Collagen arranged in a chaotic swirl of tangled bundles. This forms the tough sheets in the deep layer of the skin. Overstretching of this tissue results in “stretch marks.”

Tissues Bone- bone matrix is hard because of its dense packing of collagen bundles encrusted with mineral crystals containing calcium. Bones store calcium and support and provide protection for the body. Compact Bone- The solid form of bone that makes up the outer walls of the bone. Compact bone is made up of “osteons” or “haversian systems.” Cancellous Bone or Spongy Bone – Found on the inside of the bone. This bone is a chaotic lattice of branches (this adds strength).

Tissues Three types of Cartilage: Cartilage – has the consistency of a hard “plastic” or “gristle-like” gel. Cartilage cells are called chondrocytes , these cells give cartilage the appearance of “Swiss-cheese.” Three types of Cartilage: Hyaline- Most common type, found in support rings of respiratory system and covers the ends of bones that form joints. Fibrocartilage- strongest, most durable. Found in vertebral discs and in the knee joint. Elastic Cartilage- This cartilage has a high degree of flexibility. Found in the external ear, voice box and larynx.

Tissues Blood Tissue – Blood is probably the most unusual form of connective tissue, because of its matrix “Blood Plasma.” Blood Plasma- Functions: Transportation of cells Protective Functions in the body

Tissues Hematopoietic Tissue- This tissue is responsible for formation of blood cells and lymphatic system cells important in the defense against disease. Bloodlike connective tissue found in the red marrow cavities of bones and organs such as: Spleen Tonsils Lymph Nodes

Tissues Muscle Tissue – The Movement specialists of the body. Skeletal Muscle- attached to bones and, when contracted, produce voluntary and controlled muscle movements. Cardiac Muscle Tissue- Forms the walls of the heart Smooth Muscle Tissue- Forms involuntary muscle movement. Helps forms the walls of blood vessels and hollow organs such as the intestines.

Tissues Nervous Tissue - Provides rapid communication between the body structures and control of body functions. Nervous Tissue Consists of two kinds of Cells: Neurons- Conducting units Glia or Neuroglia- supporting cells Neuron consists of: Cell Body; two types of processes; axon (transmits nerve impulse away from the cell body), and dendrite (carries impulse toward the cell body).