Introduction to Histology PDF

Introduction to Histology Suzanne M. Edenfield, RDH, EdD  Nature of Histology: Topics Definition How tissues are studied Components of a tissue Classification of Tissues Explanation of Tissues Magnifying glass  Definition of Histology...

Introduction to Histology Suzanne M. Edenfield, RDH, EdD  Nature of Histology: Topics Definition How tissues are studied Components of a tissue Classification of Tissues Explanation of Tissues Magnifying glass  Definition of Histology HISTO = Tissue LOGY = Science HISTOLOGY = The science or the study of tissues - microanatomy A tissue is any group of cells that are similar in structure and perform a specific function Anatomy and Physiology Anatomy = ana or apart; tome or a cutting. Anatomy means a cutting apart or dissection of. Physiology = function or study of all activities of living matter.  Definitions Cell: smallest living unit Tissue: Group of similar cells Organ: Group of tissues performing specific function System: Group of organs Cell interaction with extracellular environment: Exocytosis: transport of material from within cell to outside of cell Endocytosis: uptake of material from outside cell to inside cell  Cell Cell - unit of a living substance containing a nucleus; composed of protoplasm or the “physical basis of life” Characteristics: Excitability or irritability – capacity to respond to a stimulus Conductivity – ability to transmit a wave of excitation from point of stimulation to other parts of the body Contractility – ability to undergo shortening and change its form (muscle cells) Ingestion – taking in of food following digestion Respiration – use of O2 and production of CO2 Egestion – elimination of indigestible or unuasable material not used in metabolism Metabolism – all physical and chemical processes involved in the activities of life – most specifically conversion of food to energy Two phases: anabolism – building up Catabolism – breaking down  Components of a Tissue Group of cells which perform Fluid-plasma, can diffuse specific functions through capillary walls Are grouped together to form Organelles -specialized, organs to accomplish specific metabolically active structures functions with a genetic code found These groups of organs work within a cell together to form SYSTEMS: Cell Membrane – surrounds Skeletal, muscular, nervous, the cell; phospholipids serve digestive, respiratory, to allow for diffusion and circulator, excretory, receiving hormones, reproductive, endocrine antibiotics, and Intercellular substance- found neurotransmitters. It is the between cells, holds cells “gatekeeper” together, medium for passage of nutrients and waste  Tissue components continued Major Organelle examples Endoplasmic Reticulum - Mitochondria – most modifies, stores, numerous, power plants – segregates, and transports convert energy, energy proteins for use elsewhere source of ATP; extremely thru tiny canals vital to the cell DNA (deoxyribonucleic ATP-adenosine triphosphate acid) – cell blueprint – releases stored energy by contains primary hereditary diffusion out of the material for the cell; directs mitrochondria; powers the the formation of variety of metabolic processes; proteins to meet the Nucleus – largest, stores the enzyme needs of the body genetic code for cell- Ribosomes - make protein, chromosomes; has tend to be mobile and controlling influence over location changes depending the chemical reactions – on type of protein being “little factories” made; site where the genetic code is read; float freely within the cell  Tissue components continued Golgi Apparatus- 2nd largest, Lysomes- assist in phagocytosis Continues to further segregate, (sewer system) due to enzyme pack, and transport protein hyaluronidase, produced by Golgi compounds which are include App. Creates ingestion or hormones, enzymes, other “drinking by cells” or “eating by secretions which may be secreted cells” as mucous; It’s job is to export Centrosome – always located near substances produced by the cell. nucleus, plays role in forming Centrioles – located very near to mitotic spindle apparatus during the nucleus; function in cell mitosis. division Diagram of a Cell  Cell Division Cell division is created by way of mitosis: splitting of (46) chromosomes into replicas (chromatids) Growth of the body 4 phases of mitosis prophase –Centrioles separate and begin to move to opposite sides of cell; chromosome formation metaphase – Paired chromatids align in middle of cell and chromosomes migrate to equator of cell anaphase – Chromatids of each chromosome pull toward poles and become separated telophase – Separation and new nuclear membrane and nucleoli are formed Interphase – resting stage when not undergoing division  Intercellular Junctions Desmosome - similar to a “spot weld” holding cells together; cell to cell attachment; disc shaped Hemidesmosome – attachment of a cell to a noncellular surface, appearing to look like half of a desmosome hence, hemidesmosome; This type attaches the gingival epithelium to the tooth surface; nails to nail beds. Often connects epithelium to connective tissue. Used in securing gingival tissue to toot surface (epithelial attachment.  1st IT Guy https://youtu.be/9J9-Qr7oz-4 Link to Youtube film  Classification of Tissues 4 Groups Epithelial Connective Nervous Muscle Figure with Question Mark  Epithelial Tissue Composed of large number of cells and little intercellular substance, no blood supply of its own (avascular) Held together by tightly joined desmosomes (intercellular junctions) Joined to underlying connective tissue by Rete Pegs Lining, covering of body Occurs is sheets or membranes that are weak; support comes from the underlying basement membrane (basal lamina) known as connective tissue Functions: Protection – from bacterial invasion Secretion – from glands Absorption – from intestines and kidneys Filtration – from capillaries Found throughout body skin, mucous membranes of mouth stomach, intestines, pancreas and liver  Major Groups of Epithelial Tissue Surface Simple - one layer, found in areas of little friction Stratified - more resistant to Squamous - scale like, wear; consists of more than flat one layer of cells Lines blood vessels, heart, Stratified Squamous serous salivary glands compose most of the epithelium in body Functions to filter and diffuse fluids Types: Cuboidal - cube like, Psuedostratified Transitional rough Lines salivary ducts, Keratinized or becomes IEE (forms NonKeratinized ameloblasts Found in the thyroid, ovary, kidney Columnar - tall and  Major Groups of Epithelial Tissue continued Glandular - produces secretions (serous, mucous, mixed); removes materials from the blood and manufactures new substances Exocrine Glands – Contain ducts Endocrine Glands – “ductless glands” Figure of Epithelium Classifications  Connective Tissue Contains larger amounts of intercellular substance and fewer cells but are vascular Most common cell is the fibroblast: collagen fibers being the main fiber Produce intercellular substance, store fat, make new blood cells, perform phagocytosis, produce antibodies, make heparin Types and Classification of Connective Tissues; Can be classified according to texture  Solid Soft: (5 types) Fibrous - underlies epithelium of skin and mucous membranes (tendons & ligaments) Areolar - attaches skin to muscle Adipose - Fat - stores food Reticular - supportive framework for blood cells; found in embryonic tissues. Macrophages – Histiocytes; function in phagocytosis Mast Cells – Produce heparin and histamine Plasma – Produce circulating antibodies (gamma globulins) Elastic – stretchability, vocal cords; allow for tissue movement  Connective Tissue continued  Solid Firm Cartilage - gives support, permits skeletal growth, temporary skeleton  Solid rigid: Bone - calcified, supports body  Fluid: Hemopoietic - forms blood (marrow, lymph)  Red blood cells, RBC  White blood cells, WBC (neutrophils, lymphocytes, monocytes, eosinophils, basophils)  Neutrophil (polymorphnuclear – PMN)is most common  Lymphocyte: 2nd most common; 2 types – B cell, T cell, Natural Killer (NK)  Platlets: Clotting  Connective Tissue continued Soft connective tissue can also be classified as: Loose - forms “connective tissue proper” (dermis) along with dense connective tissue in layers; located deep to the epithelium and basement membrane of the skin Orally – known as the lamina propria Dense – Known as the “reticular layer” and is located deep to the epithelium and basement membrane of the skin or lamina propria Specialized: Cartilage, adipose bone, blood  Nervous Tissue Composed of nerve cells (neurons) Reacts to stimuli and transmits impulses Types:  Afferent - sensory (sight, smell, touch, hearing, taste)  Efferent - motor, autonomic nerves  Components:  Central Nervous System (CNS) - Brain and spinal cord  Peripheral Nervous System (PNS) - rest of body and extremities Autonomic - operates with no conscious control Somatic - operates with conscious control  Nervous Tissue Continued Autonomic - 2 divisions Sympathetic - fight or flight, get body ready for an emergency. Reach cranial tissues by traveling with arteries. Parasympathetic - rest or digest, example = digestion and release of saliva Cranial nerves III, VII, IX, X Flow Chart of Nervous System Components Diagram of Nerve Bundle  Muscle Tissue Cells are longer than they are wide Called fibers 3 Categories (voluntary or involuntary) Smooth Involuntary - reacts on own peristalsis Striated Voluntary - Skeletal muscle - moves arms, legs, soft palate, tongue, lips, cheeks, etc Striated Involuntary - reacts on own, heart Muscle Types Diagram Picture of Dancer