Embryo Quiz Today 1 PDF

DH 255 Oral Histology and Embryology Instructor: Suhila Beitelmal, BDS, BDSc (DH), RDH honors, ALE REQUIRED TEXTS AND MATERIALS Chiego, Jr, D.J. (2018). Essentials of oral histology and embryology: A clinical approach (5th ed.). St. Louis, MO: Elsevier....

DH 255 Oral Histology and Embryology Instructor: Suhila Beitelmal, BDS, BDSc (DH), RDH honors, ALE REQUIRED TEXTS AND MATERIALS Chiego, Jr, D.J. (2018). Essentials of oral histology and embryology: A clinical approach (5th ed.). St. Louis, MO: Elsevier. REFERENCE TEXTS AND MATERIALS Bowen, D.M. & Pieren, J.A. (2020). Darby and Walsh dental hygiene: Theory and practice. (5th ed.). Philadelphia, PA: Elsevier Brand, R.W., Isselhard, D.E., & Erdman, K. (2019). Anatomy of oral facial structures; A comprehensive approach. (8th ed.). St. Louis, MO: Elsevier Fehrenbach, M., & Popowics, T. (2015). Illustrated dental embryology, histology, and anatomy. (4th ed.). St. Louis, MO: Elsevier Saunders National Dental Hygiene Certification Board. (2018). National dental hygiene certification exam; English- French lexicon. Ottawa, ON: Author. Retrieved from https://docs.wixstatic.com/ugd/fe76ee_2169eae7f7df409387353e82e 7735fee.pdf  LO 4: Histology and study of human tissues Chapter 1&2  Learning Objectives Describe and explain the following terms: histology, organelles, microtubules, microfilaments, cytoplasmic inclusions, teratogens List the uses of the light microscope, electron microscope, scanning microscope Describe cell structure and function  Histology: Definition Histio: relating to tissue Logia(ology): the study of CNIH  Histology : A Science 18th century Histology became a separate branch of science :establishing the normal structure of tissues and cells in relationships to their function Based upon the examination of samples of cells and tissue CNIH  Use of microscopes Human eye has resolution of about 100 um Plant cell only structure listed below that is visible with human eye CNIH  Methods of Histological examination Light microscope: cells observed under a light microscope can be alive or fixed and stained Light microscope can magnify up to 1000 times the size of an object CNIH Fall 2011  Preparation of tissue Histological sections: thin sections Study by transmitted light through the prepared slide compound lenses in sequential magnification CNIH Slide preparation, magnification CNIH  Light Microscope Preparation of Tissue Staining tissues: most tissues are colorless and indistinguishable under the LM Staining is based on the pH of cellular constituents Chemically preserved tissues reveal the biochemical composition of tissue CNIH Staining tissues: H & E stain Acid containing structures :nuclei Hematoxylin = blue stain (purple) Alkaline substances: cytoplasm Eosin = red stain CNIH  Methods of Histological examination Electron Microscope: Invented in the first half of the 20th century distinguish individual molecules of biological importance. In effect, it can magnify objects up to 1 million times. CNIH  Electron microscope Nm= 1 billionth of a meter Angstrom=.1 nanometer Electrons are transmitted through a thin specimen in a vacuum Images are projected onto a fluorescent screen CNIH  Transmission Electron Microscope Limitations of the EM Since no living specimen can survive under their high vacuum, they cannot show the ever-changing movements that characterize a living cell. CNIH  Methods of Histological examination Scanning EM: Specimen must be fixed, dried and coated with a thin layer of heavy metal (gold or platinum) Electron beam is reflected from the surface of the coated specimen As tissue is scanned by a focused beam of electrons, the electrons are converted into a image onto a screen CNIH  Cell Project There are about 210 known distinct human cell types, body is composed of 100 trillion cells. Pair-share: – Individually think of 5 distinct human cell types – Partner: write down 3 distinct human cell types CNIH Micro-Anatomy of a Cell and it’s function CNIH  Organelles: subunits of the cell & functions Nucleus Plasmalemma Endoplasmic reticulum (rough & smooth) Mitochondria Golgi complex Lysosomes Microvilli Cellular transport mechanisms Mitosis Microtubules Microfilaments CNIH CNIH  Nucleus of a cell All human cells except RBC Double layered nuclear membrane with pores Contains 1 or more nucleoli: DNA< RNA and protein, ribosomal RNA: protein synthesis 46 chromosomes: DNA + protein CNIH  Plasmalemma: Thin, flexible, dynamic barrier between the organized, living particles within the cell and the outside the cell Selective barrier: responsible for maintaining the difference between the external and internal environment of the cell(homeostasis) CNIH  Plasmalemma: Visible with Electron microscope CNIH  Plasmalemma: trilaminar Outer surface: glycoproteins: receptors for hormones & neurotransmitters Inner surface: proteins: 60-70% of total mass, structural reinforcement Central layer: phospholipids: barrier for diffusion CNIH  Plasmalemma: trilaminar It is the site of transport of molecules and particles in and out of the living cell – For example: hormone receptors Exchange of information between adjacent cells CNIH  Rough Endoplasmic reticulum Structure: Series of interlocking membrane- bound canals in a pattern of flattened long, branching tubules with ribosomes on their cytoplasmic face CNIH Rough Endoplasmic reticulum CNIH  Rough Endoplasmic reticulum Function: synthesis & distribution of proteins for export (dependent on the number of ribosomes) ie: – Collagen from fibroblasts – Digestive enzymes from pancreas CNIH  Smooth Endoplasmic reticulum Function: Is a tubular network free or ribosomes Major function: synthesis of steroids Degradation of hormones and drugs CNIH  Mitochondria EM microscope reveals:Structure: Trilaminar Membranous structure CNIH  Mitochondria Function:Obtains energy by enzymatic action and then converts it into ATP for cellular use CNIH  Golgi complex Structure: EM 6 – 8 smooth surface membranes Cavities filled with fluid and expand during secretory activity Function: protein formation and secretion CNIH  Lysosomes Structure is related to Function Shape & density vary greatly Budding vesicle on the maturing face of the Golgi body Contains digestive enzymes Digestion of worn out cells (autophagocytic) CNIH  microvilli Specialized structures that appear on the free surface of some epithelial cells, extensions of the plasmalemma Microscopic,fingerlike projections increase the absorptive surface area up to 30X – Part of a tastebud: taste hairs – Modification to increase surface area of the intestines CNIH  Cellular Transport Mechanisms Exocytosis: active transport from a vesicle within the cell to the extracellular environment, fusion of the vesicle membrane with the cell membrane  Cellular Transport Mechanisms Endocytosis: uptake of material from the extracellular environment Phagocytosis: moving cell engulfs/digests material from EE – Ie: WBC engulf bacteria Pinocytosis: stationary cell engulfs/digests material from EE – Ie:kidney tubules reabsorb proteins Mitosis: Cell Division  Microtubules Structure Formed from proteins Slender, hollow, cylindrical structures Diameter about 25nm Nonmembranous cellular organelles CNIH  Microtubules Function: Act as scaffold to determine cell shape, building block of the cell Guidance system in intracellular transport: Provides a set of "tracks" for cell organelles and vesicles to move on CNIH  Microtubules cont. Function/location – cytoskeleton to maintain shape of cell – Framework of centioles (mitosis) – Mitotic spindle fibers for separating chromosomes in mitosis – Support of cilia – Geometric patterns inside flagella and cilia, they are used for locomotion/support movement CNIH Defects in the cilia and flagella of human cells are associated with some notable medical problems. Kartagener’s syndrome: portions of the microtubules are not connected properly, this is characterized by recurrent respiratory infections related to the inability of cilia in the respiratory tract to clear away bacterial and other materials. CNIH Defects in the cilia and flagella of human cells are associated with some notable medical problems. Damage to respiratory cilia may also be acquired rather than inherited and is most commonly linked to smoking cigarettes. Bronchitis, for instance, is often triggered by a build-up of mucus and tar in the lungs that cannot be properly removed due to smoking-related impairment of cilia. CNIH  Microtubules Microtubules: framework of Centrioles (9 sets of triplets) Microtubules: Mitotic spindle fibers spindle fibers for separating chromosomes during mitosis CNIH  Microfilaments Structure Thin threadlike proteins: filamentous cytoplasmic structures diameters vary from 5 – 7nm CNIH  Microfilaments Structure: Predominantly composed of contractile protein: actin most abundant cellular protein carry out cellular movements including gliding and contraction CNIH  Microfilaments Function: Contraction & support all cells except RBC Cellular movements including gliding and contraction CNIH  Microfilaments : :contraction & Microfilaments support all cells except RBC Actin & myosin filaments: most highly organized and concentrated in skeletal muscle Involved in muscle contraction CNIH  Microfilaments Microfilaments: tonofilaments of hemidesmosomes and desmosomes, mechanical and structural function (attachment apparatus) CNIH Microfilaments of the microvilli CNIH  Microtubules vs Microfilaments Predominantly Formed from composed of proteins contractile protein: actin Thin (filamentous) Slender, hollow, threadlike proteins cylindrical structures Diameters from 5– Diameter about 25nm 7nm Nonmembranous most abundant cellular organelles cellular protein CNIH  Microtubules vs Microfilaments Function Function Cytoskeleton to maintain Cellular movements shape of cell Contraction Locomotion Support Structures Structures Centrioles Actin & myosin filaments Mitotic spindle – Microvilli – Muscular contractions Tonofilaments of hemidesmosomes Neurofilaments CNIH  CYTOPLASMIC INCLUSIONS In addition to organelles, there is a wide variety of cellular inclusions – Endogeneous inclusions – Exogeneous inclusions Not present in all cells, maybe present in specific cells during certain physiological activities CNIH  Endogeneous inclusions Generally essential to life, arise from within the cell – Lipid droplets (fat storage) – some pigments CNIH  Melanin Most abundant and important pigment Origin: neural crest cells produced by melanocytes Pigment transferred to basal epidermal cells to screen out harmful overexposure to ultraviolet light CNIH Malignant melanoma CNIH  Exogenous inclusions transitory and often harmful, arise outside the cell – Incorporated by phagocytosis, pinocytosis, absorption: heavy metals, lead poisoning, asbestos, carbon CNIH  Organelles of the Cell http://www.cellimagelibrary.org/ CNIH Fall 2011 CNIH