MAHSA University MBBS Year 1 (BMS Block) - The Cell PDF

MAHSA UNIVERSITY FACULTY OF MEDICINE MBBS YEAR 1 (BMS BLOCK) THE CELL Prepared by: Mr Yusuf  LEARNING OUTCOMES 1. Describe the microscopic structures of the cell, cell membrane, cytoplasmic organelles, cytoskeleton and nucleus 2. State the functions of each...

MAHSA UNIVERSITY FACULTY OF MEDICINE MBBS YEAR 1 (BMS BLOCK) THE CELL Prepared by: Mr Yusuf  LEARNING OUTCOMES 1. Describe the microscopic structures of the cell, cell membrane, cytoplasmic organelles, cytoskeleton and nucleus 2. State the functions of each organelle  Components and shapes of the cells Cytoplasm Cell Nucleus Membranous Organelles Nucleolus Non-membranous Cell inclusions Chromatin Cytoplasmic matrix Nucleoplasm  List of organelles Membranous Non-membranous Plasma membrane Ribosomes Rough Endoplasmic Reticulum Cytoskeleton: Microfilaments, microtubules, intermediate filaments Smooth Endoplasmic Reticulum Centriole Golgi Apparatus Nucleolus Mitochondria Lysosomes Perixosomes Nucleus  Plasma membrane - it is called the unit membrane composing of: 1) Phospholipid component - a hydrophilic 2) Fatty acid component - a hydrophobic - function: 1) Maintains the structural integrity of the cell 2) Allow selective materials to pass through (permeable) 3) Contains the identification markers e.g. receptor sites for certain hormones and antigens  Ribosomes - it is produced in the nucleolus - it is made up of protein and RNA - located in cytosol of all cells except RBCs - ribosomes usually occurs in clusters called polysomes - polysomes are categorized into 2 forms: 1) free polysomes in cytosol 2) attached to the rough endoplasmic reticulum(rER) - ribosomes are basophilic(dark blue in H&E stain) due to its RNA components - f(x)- site for protein synthesis  Endoplasmic reticulum - a membranous organelle - a series of continuos and interconnecting channels - the lumen of the channel called as cisternae - it is categorized into 2 types: 1) Rough endoplasmic reticulum 2) Smooth endoplasmic reticulum  Rough Endoplasmic Reticulum Morphology - cisternae are parallel to one another, flattened, and elongated - covered by ribosomes - appear basophilic(bluish in H&E stain) in cytoplasm of protein secretory cells f(x)- synthesis, modify, and transport of certain protein molecules  Smooth Endoplasmic Reticulum Morphology - cisternae appear tubular or vesicular in-shape - no ribosomes - stained poorly - found in lipid/steroid manufacturing cells f(x)- glycogen breakdown, detoxification, synthesize steroid hormones  Golgi apparatus Morphology - stacks of cisternae with small vesicles budding-off from the sac - not stained with H&E - appear as clear area in H&E section surrounded by basophilic cytoplasm of secretory cells f(x)- receives secretory materials like protein synthesized from rER - assembling and packaging of the secretory materials - transport the products in vesicles to outside of the cell or to lysosomes  Mitochondria Morphology - rod-shaped, flexible organelle, fluid-filled - about the size of bacterium - contain its own DNA - bounded by 2 unit membranous sacs: 1) Outer membrane sac- it is thin and smooth 2) Inner membrane sac- form shelf-like folds called cristae - the 2 membranous sacs forming 2 fluid-filled spaces: 1) intermembranous space 2) intercristal space- it contains the matrix - not visible in H&E preparation f(x)- produce Adenosine Triphospates(ATPs)  Lysosomes Morphology - spherical, membrane-bound vesicles - contain more than 50 types of hydrolytic enzymes - found abundance in cytoplasm of macrophages f(x)- play a role in defense - remove the damage cells fragment during tissue repair  Peroxisomes Morphology - spherical, membrane-bound organelle - contain peroxidases, catalases - found abundance in liver and kidney cells f(x)- breakdown of H2O2 (detoxifixation)  Cytoskeleton - there are 3 types: 1) Microfilaments 2) Microtubules 3) Intermediate filaments - f(x) of cytoskeleton: 1) Framework 2) Anchoring and support the organelles 3) Movements 4) Role in muscle contraction  Microfilaments Morphology - fine solid strands of 7nm in diameter - compose of protein actin - located in most types of cells but mostly in muscle cells - form structural core of microvilli  Microtubules Morphology - hollow cylinders of about 24nm in diameter - compose of protein tubulin - found in cilia, flagella, axons - form basal bodies of cilia, mitotic spindle, centrioles  Intermediate filament - functions of intermediate filament 1) Anchoring a cell to extracellular matrix 2) Anchoring a cell to other cell 3) Anchoring a cell to organelle  Centriole Morphology - Rod-shaped - occurs as pair at rights that lie at right angle to each other - found in the centrosome near the nucleus in most interphase cells - f(x) of centriole: 1) As microtubule organizing center 2) Help organize the mitotic spindle during cell division 3) Give rise to basal bodies  Cytoplasmic Inclusions - temporary structures that accumulate in the cytoplasm of certain cells - it is a non-living substances that unable to carry out any metabolic activity and not bound by membranes - examples of cytoplasmic inclusions: 1) Glycogen granules in the liver and muscle cells 2) Lipid droplets in fat cells, 3) Pigment granules in certain cells of skin and hair 4) Crystals