Lesson 4: The Tissue PDF

LESSON 4: THE TISSUE MARY FRANCES BAUDIN TOLEDO, RN, MAN C LI N IC AL I N STR U C TOR  TISSUE Tissue-is used to describe of group of cells functioning together in the body. Histology- is the microscopic study of tissue appearances, organization, and function. Four Major Types of Tissues 1....

LESSON 4: THE TISSUE MARY FRANCES BAUDIN TOLEDO, RN, MAN C LI N IC AL I N STR U C TOR  TISSUE Tissue-is used to describe of group of cells functioning together in the body. Histology- is the microscopic study of tissue appearances, organization, and function. Four Major Types of Tissues 1. Epithelial 2. Connective 3. Muscle 4. Nervous  Four Major Types of Tissues Epithelial tissue- are sheets of cells that cover the exterior surfaces of the body, line internal cavities and passageway, and form certain glands. Connective tissue- are most diverse category of tissue, binds the cells and organs of the body together and function in the protection, support, and integration of all parts of the body. Muscle tissue- it provides movement, whether that means moving the skeleton, as in walking, or moving the blood through the body as the heart muscle contracts. Nervous tissue- is capable of short-and long- distance communication throughout the body inorder to wiggle the toes. General Features of Tissues Extracellular matrix (ECM)— Cellular connections— material found outside of a attachments between cells tissue Tight junctions—allow no movement of substances between cells Major components: Desmosomes—flexible connections Collagen—tough, protective protein that allow some movement of fibers but flexible allowing substances between cells movement Gap junctions—passageways that Proteoglycans—large negatively allow movement of certain charged protein/carbohydrate substances between the cells molecules Epithelial tissue Characteristics of Epithelia Form coverings, linings, and glands Two surfaces of epithelia: Basal surface—attached to basement membrane Apical surface—exposed to external environment or internal space Avascular Highly regenerative Anatomy of Epithelia Epithelia are: Highly cellular Polar (apical and basal surface) Avascular Innervated Bound to basement membrane The Epithelial Cell Apical surface modifications Cilia – move materials across surface Microvilli – increase surface area Cells of Epithelia Epithelial tissue is named after its shape and number of layers of cells on the apical surface Based on shape: Squamous—flat cells Cuboidal—box-shaped cells Columnar—column-like cells Based on number of layers: Simple—one layer of cells Stratified—two or more layers of cells Pseudostratified—one layer of cells that appears like more Epithelia That Defy Naming Convention Pseudostratified columnar epithelium May appear stratified All cells touch basement membrane because there is only a single layer Transitional epithelium Stratified tissue Cells stretch and change shape Goblet Cells Common feature of simple and pseudostratified epithelia Secrete mucus Stratified Epithelia Contain more than one layer of cells Cells of basal layer are stem cells that regenerate cells into apical layers Basal layer cells may be different in shape from apical layer cells Tissue is named based on shape of cells in apical layer Simple Squamous Epithelium Consists of a single layer of flat cells Found in the air sacs of lungs, the lining of the heart, blood vessels, and lymphatic vessels Allows materials to pass through by diffusion and filtration Secretes lubricating substances Simple Cuboidal, Simple Columnar, Pseudostratified Columnar Epithelia Simple cuboidal epithelium Lines kidney tubules Secretes and absorbs substances (Na+, K+, glucose, etc.) Simple columnar epithelium Lines digestive and reproductive tracts Secretes and absorbs various materials Pseudostratified columnar epithelium Lines trachea and respiratory tract Secretes and moves mucus Stratified Squamous, Stratified Cuboidal, and Stratified Columnar Epithelia Stratified squamous epithelium Lines esophagus, mouth, vagina Protects against abrasion Stratified cuboidal epithelium Found in sweat glands, salivary glands Secretes and protects Stratified columnar epithelium Found in male urethra Secretes and protects Transitional Epithelium Transitional epithelium Lines bladder, urethra, and ureters Allows urinary organs to expand and stretch Glands of Epithelia Endocrine glands secrete hormones into the blood Examples: Thymus, pituitary gland, adrenal glands Are ductless Exocrine glands secrete substances locally through a duct Examples: Sweat glands and glands of digestive system Secrete mucus, sweat, saliva, and breastmilk Exocrine Gland Structure Unicellular – single cells Multicellular – single layer of cells that fold into surrounding tissue Tubular glands form tubes Acinar glands form pockets Simple glands have one duct Compound glands combine formats  Exocrine Secretions Merocrine secretion: accomplished by exocytosis Apocrine secretion: material accumulates near apical surface of gland Holocrine secretion: involves rupture and destruction of entire gland cell Serous glands produce watery secretions Mucous glands produce watery to thick secretions Connective tissue Anatomy of Connective Tissue Connective tissue consists of cells and the extracellular matrix (ECM) Cells rarely touch each other Ground substance is between fibers Vascularized Classification of Connective Tissues three categories: Connective tissue proper Areolar, adipose, reticular, dense regular, and dense irregular connective tissue Supportive connective tissue Hyaline cartilage, fibrocartilage, elastic cartilage, compact bone, spongy bone Fluid connective tissue Blood and lymph Cells and Fibers of Connective Tissues Fibroblasts produce fibers in the ECM Collagen—strongest fibers Elastic—provide elasticity Reticular—branching fibers that support internal organs Adipocytes—store energy and provide cushioning White blood cells—provide immune function Red blood cells—carry gases such as oxygen and carbon dioxide Connective Tissue Types Connective tissue proper Loose connective tissue Areolar Reticular Supportive connective tissue Hyaline cartilage Fibrocartilage Elastic cartilage Fluid connective tissue Blood Application: The Ribcage The ribcage merges two supporting connective tissue types Bone makes up most of the ribcage Protects lungs and heart Cartilage allows for expansion during breathing The Perichondrium Made of dense irregular connective tissue Encapsulates cartilage within the body Connective Tissue Types Connective tissue proper Dense regular connective tissue Dense irregular connective tissue Adipose tissue Supportive connective tissue Bone Fluid connective tissue Lymph Bone The most rigid of the connective tissues Provides protection and support for internal organs Compact bone Solid with greater strength than spongy bone Spongy bone Empty spaces contain red bone marrow Fluid Connective Tissues Blood and lymph Transport molecules and cells throughout the body Blood contains cells: Erythrocytes, leukocytes, and platelets Lymph is primarily acellular Loose Connective Tissues Areolar connective tissue Subcutaneous layer Supports nearby tissues Adipose tissue Subcutaneous layer Energy storage, cushioning Muscle tissue Anatomy of Muscle Tissue Muscle tissue is responsible for movement Shortens to generate pulling force Cells are tightly packed Differs in location and manner of control ◦ Skeletal muscle, cardiac muscle, smooth muscle Characteristics of Muscle Tissue The major function of muscle tissue is movement Contracts in response to stimuli Voluntary muscle—conscious control Skeletal muscle Involuntary muscle—unconscious control Cardiac and smooth muscle Skeletal Muscle Attached to bone Allows body movement and maintains posture Contains striations—alternating light and dark bands under light microscope Voluntarily controlled Cells are multinucleated Cardiac Muscle Found in the walls of the heart Contains striations Involuntarily controlled Cells attached by intercalated discs Smooth Muscle Found within internal organs Associated with digestive, respiratory, urinary, and reproductive systems Lacks striations Involuntarily controlled Nervous tissue Anatomy of Nervous Tissue Nervous tissue makes up the brain, spinal cord, and peripheral nerves Neurons conduct action potentials to communicate with other cells Glial cells support neuronal functioning Neurons generate action potentials Anatomical structure of neurons: Dendrites—short branches that receive signals Cell body—houses nucleus and organelles Axon—long projection used to send action potentials Synapse—gap between neuron and its target cell membranes MEMBRANES Membranes - means cell membrane or tissue membrane. - a thin sheet of cells that covers the outside of the body(skin), organs (heart muscle), internal passageway (abdominal mesentiries), or the lining of moveable joint cavities. Four types of tissue membranes mucous serous cutaneous synovial FOUR TYPES OF TISSUE MEMBRANE Mucous membrane- are composites of connective and epithelial tissues. These membranes line the body cavities and hollow passageways that open to the external environment. Serous membrane- are epithelial membranes that line the cavities of the body that do not open to the outside. Cutaneous membrane- it is stratified squamous membrane resting on top of the connective tissue. Synovial membrane-is a type of connective tissue membrane that lines the cavity of a freely movable joint. Synovial fluid release from the synovial membrane lubricates the joint and nourishes the cells of the cartilage within joints. Tissue growth and healing TISSUE INJURY Inflammation- is the standard, initial response of the body to injury. Acute or short-term, inflammation resolve overtime by the healing of tissue. Chronic an inflammation that goes too long. Resulted to devastiting effects on homeostasis (arthritis, tuberculosis). Note; the suffix “itis” denotes inflammation of a specific organ or type. (tendinitis is the inflammation of the tendons, and pericarditis refers to the inflammation of the pericardium, the membrane sorrounding the heart. TISSUE INJURY ( Vasodilation is the widening of the blood vessels. Increased blood flow to the area of inflammation allows more leukocyte (white blood cell), the cell of the immune system,to reach the area. Because of the resulting increase in blood flow, the area becomes warmer to touch, and may be noticeably redder, then nearby uninflammed tissue. Histamine- is an immune cells commonly found in the connective tissue it make the lining of the local blood vessel “leaky” to enable white blood cells to move from the blood to the interstitial tissue spaces. Blood plasma also enters the tissue. Edema- a condition characterized by an excess of watery fluid collecting in the cavities or tissue of the body.  TISSUE INJURY Pain is a signal in your nervous system that something maybe wrong. It is an unpleasnt feeling, such as prick, tingle, sting, burn or ache. It is an usual response that has evolved for protection. Why there is pain? Pain helps to prevent further injury by keeping us from using ( walking) the injured tissue. Pain also keeps us from touching the affected area, preventing the possible introduction of bacteria. TISSUE INJURY The INFLAMMATORY PROCESS begins when damaged cells and/or resident leukocyte of the tissue release signaling molecules, including histamine, to signal danger. These signaling molecules have many effects, including local vasodilation and leakiness of the blood vessel that forms edema and the usual response which is pain on the injured site. Tissue Healing Begins with removal of debris and toxins Clotting stops the bleeding Granulation tissue forms to allow epithelial cells to regenerate lost tissue Scar tissue may form due to rapid repair and replacement of collagen fibers The Process of Tissue Healing/Repair Platelets and clotting factor form a clot, which blocks further blood loss. Epithelial cell are able to grow and cover the wound because they can migrate over the granulated tissue. The epithelium is restored to its typical thickness.  TISSUE AND AGING Biology confirms that many body structure change with age, and as a consequence, most functions of the body decline overtime.Of course, genetic make up and life style play a huge role in how the aging proceeds. Two major changes (cellular and tissue) Rate of Mitosis all cells, including stem cells, lose the ability to replicate as the body ages. Tissue healing takes longer. Fewer fibroblasts to spin collagen and fewer epithelial tissue exist to replicate and cover the wound. Elastic Fiber the decrease in production by the time a human reaches 50, their body contains just 70% of the elastic fiber that they had at the age of 20. By the time they reach 80 , they have less than 50 percent. The tissue becomes thinner and less likely to snap back to their original shape after movement, contributing to wrinkles. The most elastic place in the body is our blood vessel, where elasticity allows for the fluctuation in blood pressurethat occur with the heart contraction and relaxation. The decrease in elasticity leads to higher blood pressure as we age. The lens, a structure in the eye, become less flexible ,leading to the nedd for reading glasses. Tendons and ligaments lose the small amount of elasticity they had. leading to joint stiffness and inflexibility. Tissues and Cancer Mutations may alter the regulatory signals cell receives Altered signals lead to uncontrolled replication of cells Mass of cells is a tumor Malignant tumors are cancerous, cause disease, and can spread to other areas of the body Benign tumors do not cause disease in the body or metastasize (spread to other areas of the body) Tumor Growth Tumor growth is typically limited by physiological constraints Tumors that grow “trick” tissues into supporting their growth