Chapter 2: The Tissue Level of Organization PDF

Chapter 2 The Tissue Level of Organization  Types of Tissues  The human body contains > 200 types of cells classified into four types of tissues: 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Nervous tissue  Types of Tissues  Tissue Membra...

Chapter 2 The Tissue Level of Organization  Types of Tissues  The human body contains > 200 types of cells classified into four types of tissues: 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Nervous tissue  Types of Tissues  Tissue Membranes  Thin layer of cells that covers the outside of the body, the organs, internal passageways that lead to the exterior of the body, and the lining of the moveable joint cavities.  Two basic types of tissue membranes: 1. Connective membrane 2. Epithelial membrane  Embryonic Origin of Tissues  Epithelial Tissues Epithelial cells derived from all three major embryonic layers Its highly cellular, with little or no extracellular material present between cells Three basic types of connections 1. Tight junctions 2. Anchoring junctions 3. Gap junctions  Epithelial Tissues Three Classification of Epithelial Tissues:  Epithelial Tissues Glandular Epithelium Gland is a structure made up of one or more cells modified to synthesize and secrete chemical substances. Most glands consist of groups of epithelial cells. Gland can be classified into 1. Endocrine gland, a ductless gland that releases secretions directly into surrounding tissues and fluids 2. Exocrine gland whose secretions leave through a duct that opens directly, or indirectly, to the external environment  Connective Tissues  Classification of Connective Tissues  Muscle Tissues and Motion  Muscle tissue is characterized by properties that allow movement.  Muscle cells are: Excitable; they respond to a stimulus. Contractile, meaning they can shorten & generate a pulling force.  Muscle tissue is classified into three types:  Muscle Tissues and Motion  Muscle tissue classification: Skeletal muscle is attached to bones and its contraction makes possible locomotion, facial expressions, posture, and other voluntary movements of the body. Cardiac muscle forms the contractile walls of the heart Smooth muscle tissue contraction is responsible for involuntary movements in the internal organs. It forms the contractile component of the digestive, urinary, and reproductive systems as well as the airways and arteries.  Nervous Tissue  Nervous tissue is excitable cells that are capable of sending and receiving electrochemical signals that provide the body with information.  It mediates perception and response.  Two main classes of cells make up nervous tissue: 1. Neuron (Nerve cell) 2. Neuroglia (Supporter cells for the nerve cell)  Nervous Tissue  Neuroglia (Supporter cells for the nerve cell) - Astrocyte cells regulate ion concentration in the intercellular space, uptake &/or breakdown of some neurotransmitters, & formation of the blood-brain barrier (BBB). - Oligodendrocyte cells produce myelin in the central nervous system (brain and spinal cord). - Schwann cell produces myelin in the peripheral nervous system  Tissue Injury  Cell Death Apoptosis: is programmed cell death, a normal step-by-step process that destroys cells no longer needed by the body. Necrosis: accidental cell death, causes inflammation.  Inflammation is the standard, initial response of the body to injury Inflammatio n Squences  Tissue Injury  Injury repair