Tissue Types Overview Tissue Definitions Epithelial Tissue • Simple and Stratified Connective Tissue • Characteristics • Bone, Cartilage, Loose Conn. • Dense Connective Blood Muscle Tissue • Skeletal, Cardiac, and Smooth Nervous Tissue Tissue Repair Tissue Development and Aging Table 4.1 Connective Tissue: Cartilage Three types of cartilage: • Hyaline cartilage • Elastic cartilage • Fibrocartilage Connective Tissue Types: Cartilage Hyaline cartilage Found in larynx, joints, connecting ribs, tip of nose Connective Tissue Types: Cartilage Elastic cartilage Found in the external ear, auditory tube, larynx Connective Tissue Types: Cartilage Fibrocartilage Found between vertebrae in the spine Figure 3.19c Connective Tissue Types: Dense Dense connective tissue Found in tendons, ligaments, lower layers of skin (d) Connective tissue proper: dense connective tissue, dense regular Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Collagen fibers Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Location: Tendons, most ligaments, aponeuroses. Nuclei of fibroblasts Shoulder joint Ligament Photomicrograph: Dense regular connective tissue from a tendon (500x). Tendon Figure 4.8d (e) Connective tissue proper: dense connective tissue, dense irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast. Nuclei of fibroblasts Function: Able to withstand tension exerted in many directions; provides structural strength. Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract. Fibrous joint capsule Collagen fibers Photomicrograph: Dense irregular connective tissue from the dermis of the skin (400x). Figure 4.8e (f) Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Elastic fibers Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Aorta Heart Photomicrograph: Elastic connective tissue in the wall of the aorta (250x). Figure 4.8f Connective Tissue Types: Adipose Adipose tissue Found around organs (e.g. kidneys), eyballs, hips, and breast A signet ring Figure 3.19f Connective Tissue Types: Reticular Reticular connective tissue Found in spleen, bone marrow, and lymph nodes Connective Tissue Types: Blood Blood Tissue Types Overview Tissue Definitions Epithelial Tissue • Simple and Stratified Connective Tissue • Characteristics • Bone, Cartilage, Dense • Connective, Loose Connective Blood Muscle Tissue • Skeletal, Cardiac, and Smooth Nervous Tissue Tissue Repair Tissue Development and Aging Muscle Tissue Function is to produce movement Three types • Skeletal muscle • Cardiac muscle • Smooth muscle Muscle Tissue Types: Skeletal Skeletal muscle Found in all muscle connected to bones Figure 3.20a Muscle Tissue Types: Cardiac Cardiac muscle Found exclusively in the heart Figure 3.20b Muscle Tissue Types: Smooth Smooth muscle Found in walls of hollow organs like stomach, bladder, uterus, blood vessels, intestines Tissue Types Overview Tissue Definitions Epithelial Tissue • Simple and Stratified Connective Tissue • Characteristics • Bone, Cartilage, Dense • Connective, Loose Connective Blood Muscle Tissue • Skeletal, Cardiac, and Smooth Nervous Tissue Tissue Repair Tissue Development and Aging Nervous Tissue Found in brain, spinal cord, and extensions all over the body Tissue Repair Types of Repair • Regeneration Replacement of destroyed tissue by the same kind of cells • Fibrosis Repair by dense fibrous connective tissue (scar tissue) Determination of method • Type of tissue damaged • Severity of the injury Events in Tissue Repair 1. Inflammatory Reaction sets the stage • Mast cells release histamines • Release of histamines cause vasodilation • temperature, swelling • Clotting proteins • Walling-off of injured area, scab • Leukocytes: neutrophils, macrophages 2. Organization restores blood supply • Formation of granulation tissue • Fibroblasts bind with collagen • Phagocytosis by macrophages 3. Regeneration of surface epithelium • Fibrosed area matures, contracts • Scar tissue forms Regeneration of Tissues Tissues that regenerate easily • Epithelial tissue • Fibrous connective tissue and bone Tissues that regenerate poorly • Skeletal muscle Tissues that are replaced largely with scar tissue • Cardiac muscle • Nervous tissue within the brain and spinal cord Development of Tissues Regenerative Non-regenerative (amitotic) 3 Primitive Germ Layers: • Endoderm: Forms gut tube, digestive system • Mesoderm: Forms muscle, mesenchyme (embryonic connective tissue) -> osteoblasts, fibroblasts, chondrocytes -> bone, blood, other connective tissue • Ectoderm: Forms nervous tissue, skin Aging of Tissues Normal tissue changes • Hyperplasia (enlargement) • Atrophy (reduction) Abnormal tissue changes • Neoplasms Some Tissue Changes in Aging • Skin loses elasticity, epithelia membranes thin • Exocrine glands less active; skin dries • Decreased endocrine function and slowing of metabolism • Bones become porous • Muscles atrophy Summary Tissue Definitions Epithelial Tissue • Simple and Stratified Connective Tissue • Characteristics • Bone, Cartilage, Dense • Connective, Loose Connective Blood Muscle Tissue • Skeletal, Cardiac, and Smooth Nervous Tissue Tissue Repair Tissue Development and Aging