Chapter2 cellmarieb
- 1. Goals: •Anatomy of a typical cell •Cell Membrane •Discussion of internal structure of a cell with emphasis on the various organelles Developed by John Gallagher, MS, DVM
- 2. Some Terminology: 1. Cells are the smallest living structure 2. Cell = functional unit of the body 3. Cytology = The Study of Cells 4. Ultrastructural Cytology = Cytology at the Electron Microscopic level 5. Histology = the study of tissues (next meeting)
- 3. Anatomy of a typical cell 1. Cell membrane 2. Cytoplasm = cytosol + organelles 3. Organelles •Smallest: •Granule cell in cerebellum: 4 μ Fig. 2.1 •RBC: 5-7 μ = 0.005-0.007 mm •Largest: •Anterior horn cell in spinal cord: 135 μ •Ovum: 120 μ = 0.12 mm •Longest: •Pseudounipolar cell (CNS to toe)
- 4. Anatomy of a typical cell, cont’d _ Shapes: – Squamous (scale) - flat, capillaries, lungs – Cuboidal - lines ducts – Columnar - length > width, digestive tract – Stratified - many layers – Many others will be covered in histology (next two lectures)
- 5. Cell Membrane = phospholipid bilayer _ Physical isolation of the cell contents from the environment (interstitium) _ Regulation of exchange of materials with the environment _ Sensitivity to changes in the environment _ Structural support of the cell – Organelles, too!
- 7. Membrane Permeability _ Diffusion – Concentration Gradient of Solutes _ Osmosis – Water (solvent) through semipermeable membrane _ Filtration – Hydrostatic Pressure » Capillaries! _ Active Transport – Requires energy (ATP)
- 8. Endocytosis = into the cell _ Pinocytosis – Extracellular Fluid _ Phagocytosis – Solid Objects, e.g., bacteria _ Receptor-mediated Endocytosis – Special membrane proteins required
- 9. Exocytosis = out of the cell _ Secretory vesicles (e.g. hormones) – Fluid and waste removal
- 10. Cytosol vs. cytoplasm Cytosol = The thick fluid inside any cell Often synonymous with cytoplasm (protoplasm) Cytoplasm = cytosol + organelles Suspends organelles
- 11. Organelles _ Structures INSIDE a cell that have specific functions wrt cellular structure, maintenance, or metabolism – Membranous » Nucleus » Golgi apparatus » Endoplasmic reticulum » Mitochondria » Vesicles and lysosomes – Nonmembranous » Ribosomes » Microtubules (cytoskeleton) » Actin/Myosin in muscle cells
- 13. Nucleus (= center) _ Visible with LM _ Membrane bound – Many pores _ DNA – 23 Pairs of Chromosomes » Except gametes _ Nucleolus – Most active DNA
- 14. Nucleus
- 15. Golgi Apparatus •Packaging and shipping of proteins (secretory granules and transport vesicles) •Membrane renewal •Synthesis of Lysosomes
- 17. Golgi Apparatus
- 18. Endoplasmic Reticulum Synthesis, Storage, transport Smooth ER Lipid synthesis Rough ER Ribosomes make it rough ER Protein synthesis
- 19. Mitochondrion / -a •Energy Conversion for cellular activities •Formation of ATP •Double membrane •Glycolysis and TCA cycle •More prevalent in active cells, e.g., rods and cones •Their own genome •Self-replicating
- 20. Lysosomes
- 21. Ribosomes - RNA 60% RNA + 40% protein Protein Factories Fixed vs. free ribosomes
- 22. Cytoskeleton 4 major components: 1. Microfilaments (mostly actin) 2. Intermediate filaments 3. Microtubules (composed of tubulin subunits) Function: support & movement of cellular structures & materials
- 23. Cilium – Cilia (pl.) In 9+2 array Compare to microvilli and flagella
- 24. Actin/Myosin _ The contractile proteins in muscle cells _ Striations Skeletal muscle
- 25. Intercellular Attachments Chapter 4, pp 74-76 Act as: 1. Seals betw cells 2. Intercellular communication 3. Added strength to resist separation 1. Gap Junctions 2. Tight Junctions 3. Desmosomes 4. Basement Membrane Fig 4-7
- 26. 1) Gap Junctions Channel proteins (connexons) interlock and form pores Abundant in cardiac and smooth muscle Allows efficient intercellular communication
- 27. 2) Tight Junctions Interlocking membrane proteins Found near surface of cells lining the digestive tract. Explain! Adhesive Belt Junctions deep to tight junctions reinforce the seal
- 28. 3) Desmosomes Proteoglycan layer reinforced by transmembrane proteins (cell adhesion molecules or CAMs) Belt, button and hemidesmosomes Found in superficial layers of skin
- 29. 4) Basement Membrane _ Reticular fibers + Basal Lamina _ Between epithelium and deeper connective tissue _ Acts as a filter, and helps epithelial regeneration
- 30. Fig 2.19 a
- 32. Mitosis (vs. meiosis) _ Cell Division – Interphase – Between mitosis – Prophase – Chromosomes become bunched – Metaphase – Chromosomes gather at equator – Anaphase – Chromosomes move to poles – Telophase – The two new nuclei form – Cytokinesis – Actual cell separation – Two new diploid cells
- 33. Mitosis
- 35. Some cells Fat cells (adipocytes) Cartilage cells (chondrocytes)
- 36. More cells Neutrophil Plasma cell
- 37. Still more cells Columnar cells Sperm cells (spermatozoa)
- 38. River Cullenagh, Ennistymon, Co Clare, Ireland