Cells Handout PDF

Cells  Learning Objectives Describe the structure of the cell membrane Understand the different types of cell organelle Describe how the three dimensional structure of the cell is maintained Identify and understand the functions of different cell organelles Understand that t...

Cells  Learning Objectives Describe the structure of the cell membrane Understand the different types of cell organelle Describe how the three dimensional structure of the cell is maintained Identify and understand the functions of different cell organelles Understand that the health of the individual depends on the normal functioning of cells in the body The cell membrane is a bilayer of phospholipids molecules arranged so that hydrophobic parts are orientated to the water based solutions inside and outside the cell. The hydrophobic lipid parts are orientated towards each other – away from the water based cellular fluids.  Cell Membrane Marieb & Hoehn, 2018 Intracellular Organelles Marieb & Hoehn, 2018 Cytoskeletal Elements Marieb & Hoehn, 2018 Structure of a cilium Marieb & Hoehn, 2018 Cell Junctions Marieb & Hoehn, 2016 p87 Tight junctions – forming an impermeable continuous seal around the cells. This prevents molecules passing through the intercellular space. Desmosomes – anchoring junctions binding adjacent cells. Also part of an internal tension reducing network of fibres. Gap junctions – communicating junctions allowing ions and small molecules to pass through. Very important in heart cells and embryonic cells. Tissues – collections of cells to perform a function Example Cell type Nervous brain, spinal cord and nerves neurons tissue Muscular all cells with contractile properties myocytes, muscle fibres tissue Epithelial all sheets or layers of cells covering described by layer tissue or lining surfaces thickness and cell shape Connective everything else. Cells which linked or free cells which make tissue support the other tissues, bones extensive extracellular tendons matrix Fibroblast - makes extracellular matrix and collagen, has a role in wound healing. Marieb & Hoehn, 2018  Cells with special functions Cell Example Cell type ‘Germ’ cells those that give rise to the ova and sperm oocytes, spermatozoa Blood cells red and white blood cells erythrocytes, leucocytes Immune cells white blood cells involved in protecting T and B the body against infection lymphocytes, macrophages Endocrine cells which secrete hormones and are Pancreatic islet cells cells involved in indirect cell communication Endocrine cells – e.g. Pancreatic islet cells Marieb & Hoehn, 2018 An epithelium is a tissue formed by cells joined together to form a sheet. they have polarity - they know which way up they are; they have juxtaluminal junctional complexes - cell junctions they secrete a basal lamina - an extracellular product which is placed beneath the cells Marieb & Hoehn, 2018 Epithelial cells have three types of cell surface the apical surface faces the ‘outside’ may show cell specialisations like microvilli or cilia lateral surfaces join with other similar cells - cell junctions define how close the cells are the basal surface anchors the cell to extracellular elements - produces and maintains the basal lamina Copyright Notice Students are reminded that copyright subsists for illustrations and photographs in this presentation. The digital copies have been made under the terms of a CLA licence which allows you to: access and download a copy and print out a copy. The digital copy and any digital or printed copy supplied to or made by you under the terms of this licence are for use in connection with this course of study. You may retain such copies after the end of this course, but strictly for your own personal use. All copies (including electronic copies) shall include this copyright notice and shall be destroyed and/or deleted if and when required by the AECC. Except as provided for copyright law, no further copying, storage or distribution (including by e-mails) is permitted without the consent of the copyright holder. The author (which term includes artists and other visual creators) has moral rights in the work and neither staff not students may cause, or permit the distortion, mutilation or other modification of the work, or any derogatory treatment of it, which would be prejudicial to the honour or reputation of the author.