TISSUES- BEYOND KLEENEX What is a tissue?? Groups of cells that are similar in structure and function 4 Types: epithelium, connective, nervous, muscle EPITHELIAL TISSUE covering Function= protection, absorption, secretion, excretion Location= body surfaces Cells fit closely together No blood supply Divides quickly Basement membrane Apical surface Types of Epithelial Tissue Characterized by shape & # of layers Simple (1 layer) Stratified (many layers) Simple Squamous Epithelium Single, flat, thin, fish-like Alveoli (lungs), capillaries Simple Cuboidal Epithelium Single, cube-shaped Nucleus in center Glands, kidneys, ovaries Simple Columnar Epithelium Single, long Nuclei near basement membrane Thick Goblet cells- produce mucus Digestive tract Pseudostratified Columnar Epithelium Appear layered, but NOT cilia Respiratory tract Stratified Squamous Epithelium Many layers, thick & flat Protection Esophagus, mouth, outer skin Stratified Cuboidal Epithelium Layers, cubed Protection Sweat ducts Rare Stratified Columnar Epithelium Layers, columns Rare Male urethra Transitional Epithelium Modified stratified squamous Stretchable Only in urinary system Glandular Epithelium Cells produce and secrete substances Endocrine Glands- secrete into body fluids or blood (hormones) Exocrine Glands- secrete onto surface (sweat) QUIZ Epithelial Quiz Histology CONNECTIVE TISSUE support, protection, binding together Most abundant tissue in the body Extracellular matrix- nonliving, liquid, gel-like, or hard Collagen fibers (white -tendons) Elastic fibers (elastic -yellow- vocal chords) Reticular fibers (very fine) Bone Tissue Rigid & hard (hard matrix) Support & protection Osteocytes (bone cells) in lacunae (cavities) Blood supply good, heals fast CARTILAGE- Hyaline Cartilage More flexible Chondrocytes (cells) in lacunae Nose, larynx, bone ends, fetus skeleton CARTILAGE- Elastic Cartilage Ear Elastic fibers CARTILAGE- Fibrocartilage Shock absorber Knee caps, vertebrae Dense Connective Tissue Closely packed collagen fibers Tendons, ligaments Blood supply low; heals slow Loose Connective Tissue- Areolar tissue Delicate, thin, more matrix Cushions organs LOOSE CONNECTIVE TISSUE- Adipose Tissue FAT cells Stored oil pushes nuclei to side Insulation & protection LOOSE CONNECTIVE TISSUSE- Reticular Connective Tissue Lymph nodes, spleen, bone marrow Reticular fibers Blood Cells/ nonliving plasma Transportation WBC, RBC, platelets, plasma Skeletal Muscle Specialized to contract Attached to bones Voluntary Striations, many nuclei Cardiac Muscle Striated, 1 nucleus, intercalated disks Involuntary Heart only Smooth Muscle No striations 1 nucleus, cells pointed at ends Involuntary Stomach, bladder Nervous Tissue Cells = neurons Tissue Repair Wound Healing 2 ways: Regeneration: replacement of destroyed tissue by cells Fibrous: scar tissue Depends on type of tissue damaged & severity wound healing animationwound healing animation Granulation tissue Good regeneration: Skin, bone Poor regeneration: Cardiac & nervous tissue NEOPLASMS- Cancerous or Benign Cell divides rapidly (cancerous or benign) Hyperplasia Tissues enlarge because of a stimulus that irritates the cells Atrophy