Chapter 4: The Tissue Level of Organization Chapter Objectives TISSSUES 1. Define tissue and histology. INTERCELLULAR JUNCTIONS 2. Describe an intercellular junction. 3. Describe the different types of intercellular junctions; include locations, types of proteins in the junction and what type of cytoskeleton they connect to. THE 4 BASIC TISSUES 4. List the four basic tissue types and their general functions. 5. List the epithelial tissues we are learning. 6. List the connective tissues we are learning. 7. List the muscle tissues we are learning. 8. List the two groups of nervous tissue cells. MEMBRANES 9. Describe an epithelial membrane general structure. 10. List the location and function of mucous membranes. 11. List the location and function of serous membranes. 12. List the location and function of cutaneous membranes. 13. List the location and function of synovial membranes.
Chapter Lecture Notes Tissues Tissues - a group of cells with a common embryonic origin that function together to carry out specialized activities Histology - the study of the microscopic anatomy of cells and tissues Each cell type has features particular to its function
Intracellular Junctions Tissues are formed by grouping cells together using a variety of Intercellular Junctions Intracellular Junctions connect adjacent cells mechanically at the cell membranes or through cytoskeletal elements within and between cells. (Fig 4.2) Tight Junctions are found where a leakproof seal is needed between cells. They keep materials from leaking out of organs. Found in the stomach, intestines and bladder Adherens Junctions make an adhesion belt (like the belt on your pants) that keeps tissues from separating as they stretch and contract. The adhesion belt is formed by a group of glycoproteins called Cadherins. The cadherins attach to microfilaments in the cytoplasm. Desmosomes act as “spot welds”. They also use cadherin glycoproteins. Attach to intermediate filaments in the cytoplasm. Found in epidermis and cardiac muscle Hemidesmosomes are half-welds that join cells to the basement membrane. Gap Junctions are pores (connexons) that allow small substances like ions to pass between cells. If one of the cells gets sick or dies, these seal like a hatch to prevent damage to other cells. Found in cardiac and smooth muscle, cornea and lens of eye The 4 Basic Tissues (Fig 4.1) Of all the cells in the body, they combine to make only 4 basic tissue types: Epithelial tissues Connective tissues
Muscular tissues Nervous tissues Epithelial tissues cover body surfaces and form glands and line hollow organs, body cavities, and ducts. (Fig 4.4, 4.5 & Table 4.1) Epithelial Tissue types we are learning Simple Squamous Epithelium Simple Cuboidal Epithelium Simple Columnar Epithelium Ciliated Pseudostratified Columnar Epithelium Nonkeratinized Stratified Squamous Epithelium Keratinized Stratified Squamous Epithelium Transitional Epithelium Connective tissues (CT) protect, support, and bind organs. (Fig 4.8 & Table 4.4 - 4.7) Connective Tissue types we are learning Areolar Connective Tissue Adipose Tissue Dense Regular Connective Tissue Dense Irregular Connective Tissue Hyaline Cartilage Elastic Cartilage Compact Bone Muscular tissues generate the physical force needed to make body structures move. They also generate heat used by the body. (Table 4.9)
Muscle Tissue types we are learning Skeletal Muscle Smooth Muscle Cardiac Muscle Nervous tissues detect changes in the body and respond by generating nerve impulses. (Table 4.10) Two groups of Nervous Tissue cells Neurons Conduct electrical impulses Neuroglia Support cells of nervous system Membranes (Fig 4.9) Epithelial membranes = epithelium + underlying connective tissue Mucous membrane – lines all cavities that open to outside Mucous membranes make mucus Locations respiratory system digestive system reproductive system urinary system Epithelium varies as you observed in lab Connective tissue - Areolar connective tissue
Lamina propria (propria = one’s own) is the specific name given to the connective tissue under a mucous membrane Serous membrane – Double membrane with fluid filled space between that lines all cavities that don’t open to outside: Locations Lung cavity = pleura Heart cavity = pericardium Abdominal cavity = peritoneum Construction Parietal layer - outer layer that lines outer body walls Serous cavity – middle fluid filled cavity Visceral layer – inner layer that covers organs (viscera) Epithelium = mesothelium = simple squamous epithelium (seen in lab outside the Necturus intestine) Connective tissue = thin layer of areolar CT Cutaneous membrane - Skin Epithelium = epidermis = keratinized stratified squamous epithelium Connective tissue = dermis = dense irregular connective tissue Synovial membranes - lines all joint cavities that are freely movable Mostly connective tissue and minimal epithelium Connective tissue cells secrete synovial fluid for lubrication Synovial membranes also line bursas and tendon sheathes
