Histology Notes

HISTOLOGY Study of the tissues of the body & how they are arranged to constitute organs Organs 4 fundamental tissues Cells & extracellular matrix So histology dependent on microscopes.  THE CELL (eukaryotic) Cy...

HISTOLOGY Study of the tissues of the body & how they are arranged to constitute organs Organs 4 fundamental tissues Cells & extracellular matrix So histology dependent on microscopes.  THE CELL (eukaryotic) Cytoplasm Nucleus Hyaloplasm (cytosol) Suspended bodies Clear colloid solution Contains 1-enzymes 2- protein 3- nutrients Organelles Inclusions  Organelles (little organ) Living, organized & essential for the cell Membranous Non membranous 1. Cell membrane 1. Ribosomes 2. Mitochondria 2. Microtubules 3. Endoplasmic reticulum 3. Filaments 4. Golgi apparatus 5. Lysosomes  Inclusions Nonliving, nonorganized & nonessential Pigments Stored food Exogenous 1. Glycogen 1. Dust 2. Fat 2. Tatoo Endogenous 1. Hemoglobin 2. Melanin Cytoskeleton: 1- microtubules 2- microfilaments 3- intermediate filaments Molecular structure of cell membrane  Cell membrane (Plasma lemma) The thinnest layer surrounding the cell = 8- 10 nm L.M: Can’t be seen E.M: Trilaminar (unit membrane)…. Outer electron dense Inner electron dense intermediate electron lucent Filamentous layer on the outer aspect = cell coat Fluid mosaic model of cell membrane  Function of cell membrane Transport between intercellular & extracellular 1- Passive transport ( diffusion)… simple diffusion – facilitated diffusion ( channels) 2- Active transport … pump – against conc. gradient – need ATP 3- Bulk (vesicular) transport: endocytosis- exocytosis Endocytosis Note: Exocytosis Phagosome + lysosome Pinocytosis Receptor mediated endocytosis Endocytosis Receptor-mediated Phagocytosis Pinocytosis endocytosis  Exocytosis Fusion of vesicles with cell membrane & release of its content to ECF. Thank You Good Luck 