Chapter 4: Tissues

Tissue- a group of similar cells that combine to perform a common function Types of tissue: Epithelial Connective Muscle Nerve Membranes

Epithelial Tissue Cells that are closely packed with little intercellular material between them Avascular (without blood vessels)

Covering and Lining Epithelium Covers the body surfaces Lines the walls of cavities and organs Categorized on the basis of cell shape and arrangement

3 General Shapes: 1. Squamous- flat 2. Cuboidal- cube-shaped 3. Columnar- cylindrical Types of Arrangement: 1. Simple- a single layer 2. Stratified- multiple layers

Simple Squamous Single layer of flattened cells Lines inside wall of blood vessels Forms walls of capillaries and lung air sacs

Simple Cuboidal Single layer of cube-shaped cells Forms walls of ducts in skin glands and kidney tubules

Simple Columnar Single layer of cylindrical cells Lines inside walls of stomach and intestines

Stratified Squamous Multiple layers of cells, with cells along free edge flattened in shape Superficial layer of skin, mouth and throat

Pseudostratified Columnar Single layer of irregularly shaped cells that appear multiple, often with cilia Lines inside walls of larynx, trachea, and bronchi

Transitional Multiple layers of spherical or irregularly shaped cells Lines inside walls of urinary bladder and ureter

Glandular Epithelium Closely packed cells that are specialized to manufacture and secrete products Forms glands Categorized on how their products are distributed

Exocrine Glands Glands that empty their products into ducts, which channel secretions to the body surface or cavity Salivary, sweat and oil glands

Endocrine Glands Glands that secrete their products into the extracellular space, where they diffuse into the bloodstream. Pituitary, thyroid, and adrenal glands

Connective Tissue Highly vascular Composed of widely scattered cells that lie within a large amount of intercellular material which consists of : Interstitial fluid Protein fibers: Collagenous fibers Elastic fibers Reticular fibers

Connective Tissue Proper Intercellular material is produced by fibroblasts Dominated by protein fibers

Loose Connective Tissue (Areolar Tissue) Protein fibers arranged in a loose network, producing a gel-like material Contains all 3 types of fibers Macrophages (fight infection) Provides a structural anchor for body parts

Adipose Tissue Contains specialized fibroblasts called adipocytes or adipose cells which store fat

Dense Connective Tissue (Fibers are packed tightly together) Dense Regular Connective Tissue Fibers extend parallel to each other resists stress & is found in tendons and ligaments Dense Irregular Connective Tissue Fibers branch to form dense matting found in the deep layer of the skin

Dense Connective Tissue

Fluid Connective Tissue Blood and lymph – are collections of cells in a fluid matrix.

Supporting Connective Tissues Cartilage Produced and maintained by chondrocytes which lie in chambers called lacunae Matrix- firm, dense, intercellular material

Hyaline Cartilage Matrix is dominated by chondroitin sulfate Contain collagen Located in the upper respiratory tract tubes, ends of bones, and forms the skeleton of the fetus

Elastic Cartilage Matrix is dominated by elastic fibers Found in the ears, at the end of the nose, and in the epiglottis

Fibrocartilage Matrix is dominated by Collagenous fibers A component of certain joints (intervertebral discs)

Bone Matrix consists of mineral salts and collagen, which is maintain by osteocytes.

Types of Bone Compact Bone Spongy Bone dense matrix filled with mineral salts and collagen arranged in concentric layers called lamellae Osteonic canal located down the center, serves as a passageway for blood vessels Spongy Bone matrix consists of small plates of mineral salts and collagen called spicules that form a network with spaces in between - spaces are filled with blood forming tissue called red bone marrow

Blood-Forming Tissue 2 Types: Manufactures blood cells Contains stem cells, newly formed blood cells and protein 2 Types: Red bone marrow- found in spongy bone; initiates production of all blood cells Lymphoid tissue- found in lymph nodes, tonsils, spleen, and thymus; produces monocytes and lymphocytes

Membranes Simplest combination of tissues in the body that forms a functional unit Membranes divide areas of the body or organs, line hollow organs and cavities, and anchor organs

Mucous Membrane Lines internal walls of the digestive, reproductive and respiratory tracts Epithelium secretes mucus, which traps foreign particles, maintains a moist environment, and forms a protective layer over cells

Serous Membrane Lines the internal surfaces of the thoracic and abdominal pelvic cavities The epithelium secretes a watery fluid for lubrication

Cutaneous Membrane Also known as the skin Makes up the primary organ of the integumentary system

Synovial Membrane Lines inside walls of cavities that surround certain joints No epithelial layer Secretes a synovial fluid which lubricates the joints and nourishes joint cartilage

Muscle Tissue Consists of specialized cells to shorten or contract Produce movement of body parts 2 Main Proteins in the cytoplasm of the cells: 1. Myosin 2. Actin

Skeletal Muscle Attached to bones by bands of dense connective tissue called tendons Voluntary control Contains striations Provides body movement

Cardiac Muscle Forms the walls of the heart Involuntary control Contains striations Propels blood through the body’s system of vessels

Smooth Muscle Forms part of the walls of blood vessels and visceral organs Involuntary control No striations Propels material as it passes through body tubes Alters the sizes of organs

Nerve Tissue Characterized by the well-developed properties of conductivity and excitability Neurons- conduct electrochemical signals very rapidly Neuroglia- support and maintain the neurons

Tissue Injury, Repair, Aging Refer to page 114-115 in the textbook.