Essentials of Human Anatomy Body Tissues Chapter 3 Dr Fadel Naim Ass. Prof. Faculty of Medicine IUG 1

Tissue Level of Organization Group of similar cells common embryonic origin common function Histology study of tissues

4 Basic Tissues (1) Epithelial Tissue Connective Tissue covers surfaces because cells are in contact lines hollow organs, cavities and ducts forms glands when cells sink under the surface Connective Tissue supports and binds structures together stores energy as fat provides immunity to disease

4 Basic Tissues (2) Muscle Tissue Nerve Tissue cells shorten in length producing movement Nerve Tissue cells that conduct electrical signals detects changes inside and outside the body responds with nerve impulses

Biopsy Removal of living tissue for microscopic examination Useful for diagnosis, especially cancer Tissue preserved, sectioned and stained before microscopic viewing

Epithelial Tissues General characteristics - cover organs and the body line body cavities line hollow organs have a free ( apical ) surface have a basement membrane avascular cells readily divide cells tightly packed cells often have desmosomes classified according to cell shape and number of cell layers

Epithelial Tissue Functions Protection Sensory functions Secretion Absorption Excretion Slide 7 7

Types of Epithelium Covering and lining epithelium epidermis of skin lining of blood vessels and ducts lining respiratory, reproductive, urinary & GI tract Glandular epithelium secreting portion of glands thyroid, adrenal, and sweat glands

Classification Cell Shapes Arrangement Squamous Cuboidal Collumnar Simple Stratified Pseudostratified

Simple Epithelial Tissues Simple squamous Simple cuboidal Simple columnar Pseudostratified columnar

Epithelial Tissues Simple squamous – single layer of flat cells substances pass easily through line air sacs line blood vessels line lymphatic vessels

Simple Squamous

Epithelial Tissues Simple cuboidal – single layer of cube-shaped cells line kidney tubules cover ovaries line ducts of some glands

Simple Cuboidal

Epithelial Tissues Simple columnar – single layer of elongated cells nuclei usually near the basement membrane at same level sometimes possess cilia sometimes possess microvilli often have goblet cells line uterus, stomach, intestines

Simple Columnar Epithelium

Simple Columnar Epithelium with cilia

Epithelial Tissues Pseudostratified columnar – single layer of elongated cells nuclei at two or more levels appear striated often have cilia often have goblet cells line respiratory passageways

Pseudostratified Columnar Epithelium

Stratified Epithelial Tissues Stratified squamous Stratified cuboidal Stratified columnar

Epithelial Tissues Stratified squamous – many cell layers top cells are flat can accumulate keratin outer layer of skin line oral cavity, vagina, and anal canal

Stratified Squamous Epithelium

Epithelial Tissues Stratified cuboidal – 2-3 layers cube-shaped cells line ducts of mammary glands, sweat glands, salivary glands, and the pancreas

Stratified Cuboidal Epithelium

Epithelial Tissues Stratified columnar – top layer of elongated cells cube-shaped cells in deeper layers line part of male urethra and part of pharynx

Stratified Columnar Epithelium

Epithelial Tissues Transitional – many cell layers cube-shaped and elongated cells line urinary bladder, ureters, and part of urethra

Transitional Epithelium

Glandular Epithelium Composed of cells that are specialized to produce and secrete substances

Endocrine Glands Lack ducts and secrete their products directly into the interstitial fluid and bloodstream. Hormones act as chemical messengers to influence cell activities elsewhere in the body.

Exocrine Glands Usually maintain their contact with the epithelial surface by means of a duct. Duct secretes materials onto the surface of the skin or onto an epithelial surface lining an internal passageway.

Connective Tissues General characteristics - most abundant tissue type many functions bind structures provide support and protection serve as frameworks fill spaces store fat produce blood cells protect against infections help repair tissue damage have a extra-cellular matrix have varying degrees of vascularity have cells that usually divide

Extra-Cellular Matrix Cells rarely touch due to extracellular matrix Matrix(fibers & ground substance secreted by cells Consistency varies from liquid, gel to solid

Connective Tissue Major Cell Types Fibroblasts fixed cell most common cell large, star-shaped produce fibers Macrophages wandering cell phagocytic important in injury or infection Mast cells fixed cell release heparin release histamine

Connective Tissue Fibers Collagenous fibers thick composed of collagen great tensile strength abundant in dense CT hold structures together tendons, ligaments Elastic fibers bundles of microfibrils embedded in elastin fibers branch elastic vocal cords, air passages Reticular fibers very thin collagenous fibers highly branched form supportive networks

Connective Tissues Connective tissue proper loose connective tissue adipose tissue reticular connective tissue dense connective tissue elastic connective tissue Specialized connective tissue cartilage bone blood

Connective Tissues Loose connective tissue Adipose tissue mainly fibroblasts fluid to gel-like matrix collagenous fibers elastic fibers bind skin to structures beneath most epithelia blood vessels nourish nearby epithelial cells between muscles Adipose tissue adipocytes cushions insulates store fats beneath skin behind eyeballs around kidneys and heart

Connective Tissues Dense connective tissue Reticular connective tissue composed of reticular fibers supports internal organ walls walls of liver, spleen, lymphatic organs Dense connective tissue packed collagenous fibers elastic fibers few fibroblasts bind body parts together tendons, ligaments, dermis poor blood supply

Connective Tissues Elastic connective tissue Bone (Osseous Tissue) abundant in elastic fibers some collagenous fibers fibroblasts attachments between bones walls of large arteries, airways, heart Bone (Osseous Tissue) solid matrix supports protects forms blood cells attachment for muscles skeleton osteocytes in lacunae

Cartilage Connective Tissue Characteristics: Weaker than bone More flexible than bone Cells in an abundant matrix. Cell Types Chondroblasts Chondrocytes in lacunae Avascular

3 Major Functions of Cartilage Supporting soft tissues. Providing a gliding surface at articulations (joints) Providing a model for the formation of most of the bones in the body.

Types of Cartilage Three types of cartilage: Hyaline cartilage Most abundant kind Has a perichondrium (membrane) Associated with synovial joints Most bones first modeled in hyaline cartilage Fibrocartilage Has collagen fibers Intervertebral discs, pubic symphysis Elastic cartilage Has elastic fibers Ear, respiratory tubing

Types of Epithelial Membranes Mucous line tubes and organs that open to outside world lining of mouth, nose, throat, etc. secrete mucus Serous line body cavities that do not open to the outside reduce friction inner lining of thorax and abdomen cover organs of thorax and abdomen secrete serous fluid Cutaneous covers body skin Synovial composed entirely of connective tissue lines joints

Muscle Tissues Skeletal muscle General characteristics Smooth muscle attached to bones striated voluntary General characteristics muscle cells called muscle fibers contractile three types skeletal smooth cardiac Smooth muscle walls of organs skin walls of blood vessels involuntary not striated Cardiac muscle heart wall involuntary striated intercalated discs

Muscle Tissues Skeletal Muscle Smooth Muscle Cardiac Muscle

Nervous Tissue Sometimes termed neural tissue. Found in brain, spinal cord, and peripheral nerves Consists of neurons, or nerve cells, and glial cells that support, protect, and provide a framework for neurons.

Neurons Detect stimuli, process information quickly, and rapidly transmit electrical impulses from one region of the body to another. Prominent cell body functions in control; information processing, storage, and retrieval; internal communication.

Neurons Processes extend from the nerve cell body. Dendrite Axon

Wound Healing: Mechanisms Contraction - amputation Epithelialization - ulcer Connective tissue deposition - laceration

Tissue Repair: Restoring Homeostasis Worn-out, damaged tissue must be replaced Fibrosis = replacement with stromal connective tissue cells (scar formation) Regeneration = replacement with original cell types (parenchymal cells) some cell types can divide (liver & endothelium) some tissues contain stem cells that can divide bone marrow, epithelium of gut & skin some cell types can not divide & are not replaced muscle and nervous tissue

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