Histology Presentation PDF

MEMBRANOUS presentation of histology  TABLE OF CONTENTS 01 02 03 Cell membrane Mitochondria Lysosomes 04 05 04 Golgi Mitochondria RER & SER  1-Cell Membrane :Controls what enters...

MEMBRANOUS presentation of histology  TABLE OF CONTENTS 01 02 03 Cell membrane Mitochondria Lysosomes 04 05 04 Golgi Mitochondria RER & SER  1-Cell Membrane :Controls what enters and leaves the cell. 2-Cytoplasm :Jelly-like substance filling the cell, holding organelles. 3-Nucleus :Cell's control center, contains DNA. 4-Organelles :Tiny structures with specialized functions.  INTODUCTION WHAT IS A CELL? Basic Building Block. Cells are the smallest unit of life. Independent Unit. Each cell can do everything it needs to live, like taking in food and making more cells._ Many Different Types : There are many kinds of cells, each with its own special job Structure of cell membrane Protein Lipids Carbohydrates  - Function: Provide energy and structural support. - Location: Found in the cell membrane, connective tissues, and extracellular matrix. LIPIDS - Staining: Periodic acid- Schiff (PAS) stain is used  PHOSPHOLIPIDS - Structure: Consist of a hydrophilic (water- attracting) head and two hydrophobic (water-repelling) tails. - Function: Form the basic structure of the cell membrane, creating a bilayer that acts as a barrier to protect the cell. - Role: Provide fluidity and flexibility to the membrane, allowing for the movement of proteins and other molecules within the membrane.  - Function: Provides stability and fluidity to the cell membrane. - Location: Interspersed between the phospholipids in the membrane. - Role: Helps maintain membrane integrity and assists in the formation of lipid rafts, which are essential for cell signaling.  PROTEINS Proteins are embedded in the phospholipid bilayer. some are combined with lipids (lipoproteins) and some are combined with carbohydrates (glycoproteins). and appear on both outer and inner surfaces. Provide structural channels (or pores). Act as carrier proteins These are only attached to the surfaces of cell membrane (both from outside and inside) but they don’t penetrate. oats mainly as enzymes. Binds to substances to be transported. Transmembrane or integral proteins: Peripheral proteins: Types of protein  Membrane receptors: relay signals between the cell and the external environment.‫‏‬ Transport proteins: for transport of water and ions either through active (pumps) or passive transport (passive channels ).‫‏‬ Membrane enzymes: catalyze reactions on inner and outer surface of the‫‏‬ membrane‫‏‬. Adhesion molecules: that give the cell its label of identity. So that the cell can identify each other and interact, they are glycoproteins or glycolipids.  CARBOHYDRATES - Function: Provide energy and structural support. - Location: Found in the cell membrane, connective tissues, and extracellular matrix. - Staining: Periodic acid-Schiff (PAS) stain is used to highlight carbohydrates in tissue sections. The mitochondria are organelles found in most living cells and are considered one of the most essential parts of the cell. Often referred to as the "powerhouses" of the cell, they are responsible for producing the energy necessary for cellular functions. 1. Structure: A- With light microscope: They appear as rods,granules or threads when stained with Iron Hx or Janus green.(Centeriol stained with iron Hx too) B- With electron microscope: Mitochondria have a double-membrane structure. The outer membrane is smooth , while the inner membrane has folds called "cristae," which increase the surface area and aid in energy production.  2. Function: The main function of mitochondria is cellular respiration, a process where glucose and oxygen are converted into energy in the form of ATP (adenosine triphosphate). ATP is the primary energy currency that cells use for various biological processes. 3. Genetic Material: Mitochondria contain their own DNA, known as mtDNA (mitochondrial DNA), which is separate from the DNA in the cell’s nucleus, so they can form proteins for themselves not for the cell. and this DNA is inherited only from the mother. 4. Other Roles: Beyond energy production, mitochondria have several additional roles, such as: 1- Controlling calcium levels within the cell 2-Heat production in the brown fat of newborn. Mitochondria are essential for life, as they provide the energy needed for numerous biological functions. Any disruptions in mitochondrial function can lead to health issues that affect the entire body.  Definition: Lysosomes are membrane_bound organelles that contain enzymes to break down biomolecules Origin: Lysosomes may originated from The Endoplasmic Reticulum and Golgi body From the prossess of budding off Importance: They play a key Role in cellular waste processing and Recycling  structure a_Light microscope (LM) can be demonstrated by special histochemical methods b_Electron Microscope(EM) 1_primary lysosomes: appear as homogeneous vesicles, surrounded by a single membrane 2_secondary lysosomes: *Heterolysosomes: fusion of primary lysosome with phagosomes (exogenous) as bacteria (Heterophagic vacuole) **Autolysosomes: fusion of primary lysosomes with phagosomes (endogenous) as mitochondria (Autophagic vacuole) ***Multivesicular bodies: fusion of primary lysosomes with pinocytic vesicles 3_Residual bodies: contain remains of indigestible material or debrid  Enzymes: Hydrolases , Including proteases, lipases , Nucleases, and carbohydrases, optimized to function at an acidic PH "function of lysosomes" 1_Digestion of nutrients 2_Digestion of fluid droplets 3_Defensive mechanism against bacterial and viruses 4_Autophagocytosis 5_In the thyroid gland 6_During fertilization 7_Residual bodies play important role in the aging process  Lysosomes have vital Function in cell homeostasis and Metabolic Regulation as well as in the immune system, Including Roles in phagocytosis , Antigen processing and inflammation ;disruption of these functions can lead to Metabolic , Autoimmune and kidney disease Role in Disease 1_Lysosomal storage disorders: Mutations in lysosomal enzyme gene lead to Disease like Tay_Sachs and Gaucher's Disease 2_phagogenesus : these Diseases occure due to the accumulation of undigested molecules inside the lysosome  GoLGI Body Site : It is a membrane cytoplasmic organelle , golgi body is considered as the secretory apparatus of the cell. It is always located between the nucleus and periphery of cell. "Structure" Light microscope(LM) It appears as a network of fibrils ,after staining with SilVer.In Hx and E  Electron microscope (E/M) is formed of 3 shapes of membranous components. 1-flattened vesicles (cicternae)(saccule) saccules➡stacks ( 3-10saccules) Each has an inner ,concave surface(trans, mature),facing the cell surface and an outer convex surface(cic,forming, immature ),facing the cell base. They are the sites of protein concentrations. 2-Transfer er transport vesicles (microvesicles):They carry the protein from the RER to outer convex (immature surface)of the flatted vesicles (cic face) 3-Macrovesicles (condensing vacules):They are large distended vesicles that separate from the mature face of flattened vesicles. They discharge their enzymes outside the cell (Zymogen granules) or remain in the cell as *lysosomes.  important Function : (secretory apparatus) Secretory proteins and glycoproteins, cell membrane proteins, lysosomal proteins, and some glycolipids all pass through the Golgi apparatus at some point in their maturation. In plant cells, much of the cell wall material passes through the Golgi as well.  important NB: Where are the Golgi bodies located ? -Golgi bodies are found in many types of vertebrate cells with the exception of reproductive cells in the form of a network structure. As for reproductive cells, All invertabrate cells and plant cells.Golgi bodies are found in the form of curved bodies. The are called *dictyosomes *  The Rough Endoplasmic Reticulum (RER) It is a cell organelle found in eukaryotic cells that plays a vital role in protein synthesis. It has ribosomes on its outer surface, giving it a “rough” appearance. These ribosomes translate mRNA into proteins. Location: Found throughout the cytoplasm but is more concentrated near the cell nucleus and Golgi apparatus. structure: (L/M) Ribosomes are attached to its outer surface and appear as basophilic areas. (E/M) A system of cavities (cisternae) bounded by membranes.  Function 1. Segregation of the protein, formed by the ribosome on the surface. 2. Transfer of the protein to the Golgi vesicles. 3. Protection of the cytoplasm from the effect of the contained enzymes.  SMOOTH ENDOPLASMIC RETICULUM The smooth endoplasmic reticulum functions in many metabolic processes. It synthesizes lipids, phospholipids as in plasma membranes, and steroids. Cells that secrete these products, such as cells of the testes, ovaries, and skin oil glands, have an excess of smooth endoplasmic reticulum. The smooth endoplasmic reticulum also carries out the metabolism of carbohydrates and steroids. In muscle cells, the smooth endoplasmic reticulum regulates calcium ion storage. The smooth endoplasmic reticulum like the rough endoplasmic reticulum is connected to the nuclear envelope. The smooth endoplasmic reticulum comprises tube-like structure located near the cell periphery. These tubules or tubes sometimes branch forming a network that is reticular in appearance. The network of smooth endoplasmic reticulum allows for an increased surface area to be devoted to storage of key enzymes.