L 1 Cell Membrane Histology PDF

## Faculty of Medicine - Delta University for Science and Technology ### Level 1, Semester 1 - Module (Basic science) ### The Cell - Contact: prof. Dr. Samar Asker - Department: Histology - Official email: [email protected] - Academic hours: - Saturday: 9:00 AM - 3:00 PM - Wednesday...

## Faculty of Medicine - Delta University for Science and Technology ### Level 1, Semester 1 - Module (Basic science) ### The Cell - Contact: prof. Dr. Samar Asker - Department: Histology - Official email: [email protected] - Academic hours: - Saturday: 9:00 AM - 3:00 PM - Wednesday: 9:00 AM - 3:00 PM ### Learning Outcomes 1. Identify the histological structure of the cell. 2. Identify the histological structure of the membranous cell organelles at both light and electron microscope levels. 3. Recognize the functional significance of the membranous cell organelles. 3. Correlate the structure of the membranous cell organelles to their functions. ### Why Do We Study Histology? - A science which is concerned with the normal microscopic structure of cells (cytology) and tissues in relation to their functions. ### Histology Hierarchy - Cells → Tissues → Organs → Bodies ### What Is The Stain? - They are dyes or substances used for staining sections, to differentiate the various structures as they take different colors. ### Types of Stains | Stain Type | Stain Name | Color | |----------|-------------|---------| | Acidic | Eosin (E) | Pink | | Acidic | H&E | Purple | | Basic | Hematoxylin (H) | Blue | ### Special Stains for Organic Components - **Carbohydrates:** - (PAS): gives magenta color. - **Lipids:** - Frozen sections are used. - Sudan III → orange color. - Sudan black → black color. - Osmic acid → black color. ### The Microscope - The microscope is an instrument which magnifies the image & reveals fine details of the object. | Microscope type | Magnification | |-----------------|----------------| | Electron microscope | Up to 50.000 times | | Light microscope | 40, 100, 400, 1000 | - **Electron microscope Types:** - **Transmission EM** - **Scanning EM** ### Structure of the Cell - **Cell membrane** - **Cytoplasm** - **Nucleus** ### Cytoplasm - The cytoplasm = The cytosol = cytoplasmic matrix - **Cell organelles** - **Cell inclusion** ### Cell Organelles - Living components in the cytoplasm - Essential for the life of the cell - Perform important specific functions inside the cell. ### Cell Organelles Types - **Membranous:** - Cell membrane - Mitochondria - Endoplasmic reticulum (smooth & rough). - Golgi apparatus - Lysosomes - **Non-membranous:** - Ribosomes - Cytoskeleton - Microtubules (as centriole, cilia) - Filaments (Thin, intermediate, & thick). ### The Cell Membrane - The outer limiting membrane that surrounds the cell and regulates the passage of materials into or out of the cell. - **Light microscope (LM)** - Too thin to be seen - May stain its carbohydrate contents by PAS - **Electron microscope (EM)** - 3 parallel (trilaminar) lines, 2 dark (electron dense) separated by light one (electron lucent). - Called unit membranes ### Chemical Structure of the Cell Membrane - **Lipid:** - Phospholipid - Cholesterol - **Protein:** - Integral (intrinsic protein). - Peripheral (extrinsic protein). - **Carbohydrate:** - Cell coat - Glycocalyx ### Lipid Structure - **Phospholipid double layers** - Hydrophilic polar head (outwards) - Hydrophobic non-polar tail (center) - **Cholesterol** cytoplasmic side of the lipid bilayer give stability and rigidity to the membrane. - Channels for lipid-soluble substances. ### Integral Protein - In lipid bilayer not easily extracted. - Small particles: partially embedded in the lipid bilayer - Trans-membranous protein : large in size, completely embedded in the lipid bilayer and cross it. Act as channels through which water-soluble substances can pass through it. ### Peripheral Protein - Peripheral in position - Loosely attached to the outer surface of the cell membrane. - Easily extracted. ### Carbohydrate Component - Glycolipids and glycoprotein. - Projecting from the external surface of the membrane, forming the: - Cell coat or Glycocalyx. - PAS +ve - EM = fuzzy appearance. - Thick in the intestine. ### Functions of the Cell Membrane 1. Keep internal composition of the cell. 2. Cell coat: - Attachment to other cells. - Receptors. - Cell to cell recognition - Immunity ### Bulk Transport - **Exocytosis** - **Endocytosis** - Phagocytosis - Pinocytosis ### It's MCQ Time - The cell coat is - a) Rich in cholesterol. - b) Well developed and thick in the intestine. - c) Stained with Hx & E. - d) Present on the cytoplasmic side of the cell membrane. - How the cell membrane appears by EM? - a) Trilaminar. - b) Acidophilic. - c) Bilamellar. - d) thrown into incomplete folds. - e) formed of a reticulum. - Which substance of the following is responsible for decreasing lipid bilayer movement? - a) Phospholipids. - b) Extrinsic protein. - c) Glycocalyx. - d) Intrinsic protein. - e) Cholesterol molecule. - Which of the following stains is responsible for staining of cell membrane? - a) H&E. - b) Iron H. - c) Janus green. - d) PAS. - e) Mallory. ### Practical **Image:** An electron micrograph of 2 adjacent cell membranes. **Caption:** 2 adjacent cell membranes **Image:** A light micrograph of a cell stained with PAS. **Caption:** Cell membrane PAS stain ** Image:** An electron micrograph of the cell coat or glycocalyx of epithelial cells. **Caption:** Cell coat **Image:** A handwritten thank you note with a calligraphy pen **Caption:** Thank you