Histology and Cell Membrane Overview
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Questions and Answers

Which body system is primarily responsible for transporting oxygen and nutrients throughout the body?

  • Respiratory system
  • Nervous system
  • Digestive system
  • Cardiovascular system (correct)

    • What is the significance of using anatomical terminology in the study of human anatomy?

  • It provides a standardized way to communicate about body structures and their locations. (correct)
  • It allows for informal and subjective descriptions of body parts.
  • It is only necessary for advanced medical professionals.
  • It simplifies the complexity of anatomical structures.

    • Which organ system is responsible for the elimination of waste products from the body?

  • Endocrine system
  • Muscular system
  • Urinary system (correct)
  • Reproductive system

    • What characteristic is commonly compared across different types of tissues in anatomy?

    <p>Structural properties and function</p> Signup and view all the answers

    Which of the following organs is part of the muscular system?

    <p>Biceps brachii</p> Signup and view all the answers

    What is histology primarily concerned with studying?

    <p>The microscopic anatomy of biological tissues</p> Signup and view all the answers

    Which type of microscope offers the highest magnification capability?

    <p>Electron microscope</p> Signup and view all the answers

    Histology is most similar to which of the following fields?

    <p>Gross anatomy</p> Signup and view all the answers

    What are the typical dimensions of tissue sections examined in histology?

    <p>Several cm2 in area</p> Signup and view all the answers

    Which statement correctly describes the use of various microscopes in histology?

    <p>Light microscopes can magnify tissues up to approximately 1000 X.</p> Signup and view all the answers

    What topic is covered on the date 1 Nov?

    <p>Respiratory system</p> Signup and view all the answers

    Which two topics are covered in relation to the nervous system?

    <p>Nervous system 1 and Nervous system 2</p> Signup and view all the answers

    What is the scheduled time for assessments?

    <p>2pm to 2:30pm</p> Signup and view all the answers

    How many attempts are allowed for each assessment?

    <p>One attempt</p> Signup and view all the answers

    What is the pass mark required to succeed in assessments?

    <p>40%</p> Signup and view all the answers

    What format will the questions in assessments primarily take?

    <p>MCQ and fill-in-the-blanks</p> Signup and view all the answers

    On which date is the second lecture about the cardiovascular system scheduled?

    <p>25 Oct</p> Signup and view all the answers

    What is the frequency of online assignments throughout the course?

    <p>Five assignments total</p> Signup and view all the answers

    What comprises the cytoplasm of a cell?

    <p>Cytosol and organelles</p> Signup and view all the answers

    Which component is primarily responsible for the stability of the cell membrane?

    <p>Cholesterol</p> Signup and view all the answers

    Which function is NOT associated with membrane proteins?

    <p>Generating ATP</p> Signup and view all the answers

    What structural feature allows phospholipids to form a bilayer in aqueous environments?

    <p>Hydrophobic tails and hydrophilic heads</p> Signup and view all the answers

    Which of the following accurately describes integral membrane proteins (IMPs)?

    <p>Permanently attached to the membrane</p> Signup and view all the answers

    What is the primary role of glycolipids in the cell membrane?

    <p>Intercellular communication</p> Signup and view all the answers

    Which statement is true about the cell membrane functions?

    <p>It regulates exchange and provides structural support.</p> Signup and view all the answers

    What is the role of membrane proteins in relation to the extracellular matrix?

    <p>To attach cells to the extracellular matrix</p> Signup and view all the answers

    What is the primary function of membrane carbohydrates?

    <p>Lubrication and protection</p> Signup and view all the answers

    Which type of endocytosis involves the engulfing of large particles?

    <p>Phagocytosis</p> Signup and view all the answers

    What process is primarily responsible for the movement of small lipid-soluble molecules across cell membranes?

    <p>Diffusion</p> Signup and view all the answers

    Which cellular component is primarily packaged with DNA in eukaryotic cells?

    <p>Chromatin</p> Signup and view all the answers

    Exocytosis is best described as which of the following?

    <p>Transport of materials out of the cell</p> Signup and view all the answers

    What structure is formed when the cell membrane engulfs material during endocytosis?

    <p>Vesicle</p> Signup and view all the answers

    Which of the following statements is true regarding nuclear pores?

    <p>They facilitate communication between the nucleus and cytoplasm.</p> Signup and view all the answers

    What type of transport requires energy and can move ions against their gradient?

    <p>Active transport</p> Signup and view all the answers

    What distinguishes Haematoxylin from Eosin in the staining process?

    <p>Haematoxylin specifically stains nucleic acids.</p> Signup and view all the answers

    Which of the following statements about the electron microscope is accurate?

    <p>It operates using a beam of accelerated electrons.</p> Signup and view all the answers

    Which stain would be most appropriate for identifying carbohydrates in a tissue sample?

    <p>Periodic acid-Schiff (PAS)</p> Signup and view all the answers

    What is the characteristic color produced by Eosin when applied to cytoplasm?

    <p>Red/Pink</p> Signup and view all the answers

    Which of the following statements about the commonly used H&E stain is incorrect?

    <p>Eosin targets reticular fibres.</p> Signup and view all the answers

    What distinguishes histology from gross anatomy?

    <p>Histology examines tissues under a microscope.</p> Signup and view all the answers

    Which type of microscope can achieve subcellular resolution?

    <p>Transmission electron microscope</p> Signup and view all the answers

    What date is the first lecture about muscle tissue scheduled?

    <p>17 Oct</p> Signup and view all the answers

    What is the primary focus of histology in biological tissues?

    <p>To study the microscopic structure of tissues.</p> Signup and view all the answers

    Which lecture focuses on the topic of the urinary system?

    <p>1 Nov</p> Signup and view all the answers

    Why is the use of various stains important in histology?

    <p>To differentiate between various cellular components.</p> Signup and view all the answers

    How many continuous assessments are there in the course?

    <p>5</p> Signup and view all the answers

    What limits the areas that can be examined using a light microscope compared to an electron microscope?

    <p>Light microscopes are limited by lower magnification powers.</p> Signup and view all the answers

    What is the scheduled time for assessments unless otherwise indicated?

    <p>2pm to 2:30pm</p> Signup and view all the answers

    Which of these dates does not pertain to a lecture on the cardiovascular system?

    <p>22 Nov</p> Signup and view all the answers

    What is the minimum percentage needed to pass the assessments?

    <p>40%</p> Signup and view all the answers

    Which lecture is the second on the topic of joints?

    <p>11 Oct</p> Signup and view all the answers

    On which date is the first lecture on the reproductive system scheduled?

    <p>21 Nov</p> Signup and view all the answers

    What is the main component that stabilizes the cell membrane?

    <p>Cholesterol</p> Signup and view all the answers

    Which function is primarily associated with glycolipids in the cell membrane?

    <p>Intercellular communication</p> Signup and view all the answers

    Which statement correctly describes the nature of integral membrane proteins (IMPs)?

    <p>They are permanently attached to the membrane.</p> Signup and view all the answers

    How do membrane proteins assist in the process of chemical signaling between cells?

    <p>By acting as receptors</p> Signup and view all the answers

    What structural property of phospholipids allows them to form bilayers in aqueous environments?

    <p>Hydrophobic and hydrophilic regions</p> Signup and view all the answers

    What role do peripheral membrane proteins play in relation to the cell membrane?

    <p>They interact temporarily with membrane components.</p> Signup and view all the answers

    Which lipid type surrounds and anchors proteins in the cell membrane?

    <p>Phosphoglycerides</p> Signup and view all the answers

    What is the primary role of membrane carbohydrates in the cell membrane?

    <p>Serving as receptors for signaling</p> Signup and view all the answers

    What are the primary roles of membrane carbohydrates in cells?

    <p>Lubrication, protection, and recognition</p> Signup and view all the answers

    Which process involves the internalization of extracellular fluid along with dissolved particles?

    <p>Pinocytosis</p> Signup and view all the answers

    How does the nucleus communicate with the cytoplasm?

    <p>Via nuclear pores</p> Signup and view all the answers

    What is the purpose of the glycocalyx coating on the extracellular surface of the membrane?

    <p>To provide a protective and lubricating layer</p> Signup and view all the answers

    In which structural form does chromatin exist within eukaryotic cells?

    <p>A complex of DNA and proteins</p> Signup and view all the answers

    During exocytosis, which of the following statements is true regarding the energy requirements?

    <p>Exocytosis is an energy-dependent process.</p> Signup and view all the answers

    What type of membrane protein can penetrate the lipid bilayer and is involved in transport across it?

    <p>Integral membrane proteins</p> Signup and view all the answers

    Which of the following accurately describes the process of active transport?

    <p>It requires energy to transport substances against their gradient.</p> Signup and view all the answers

    Which of the following organ systems is not comprised of muscles and bones?

    <p>Respiratory system</p> Signup and view all the answers

    What is primarily emphasized when discussing the structure-function relationship of organs?

    <p>The correlation between the shape of an organ and its role in the body</p> Signup and view all the answers

    Which of these textbooks is not recommended for the study of human anatomy?

    <p>Human Physiology by Guyton &amp; Hall</p> Signup and view all the answers

    Which body system would be least involved in the process of waste elimination?

    <p>Nervous system</p> Signup and view all the answers

    In the study of anatomical terminology, which aspect is considered least important?

    <p>Understanding historical perspectives of terminology</p> Signup and view all the answers

    What is the primary role of an electron microscope in biological studies?

    <p>To provide subcellular resolution using a beam of accelerated electrons</p> Signup and view all the answers

    How does the resolution of an electron microscope compare to that of a light microscope?

    <p>It provides subcellular resolution.</p> Signup and view all the answers

    Which stain is typically used to highlight nucleic acids within a cell?

    <p>Haematoxylin</p> Signup and view all the answers

    How does Eosin function in histological staining?

    <p>It stains cytoplasmic structures in shades of pink or red</p> Signup and view all the answers

    What is a primary advantage of using stains in histology?

    <p>They enhance visibility of specific structures in tissues.</p> Signup and view all the answers

    Which of the following statements accurately describes the H&E staining system?

    <p>The combination allows for differentiation between nucleus and cytoplasm in tissue sections</p> Signup and view all the answers

    Which anatomical feature can histology not effectively study?

    <p>Organ systems visible to the naked eye.</p> Signup and view all the answers

    Which of these stains is specifically identified for staining acidic epithelial mucins in the extracellular matrix?

    <p>Alcian blue</p> Signup and view all the answers

    In what way does gross anatomy differ from histology?

    <p>Histology requires special stains to visualize structures.</p> Signup and view all the answers

    Which feature limits the light microscope's ability to examine structures compared to electron microscopy?

    <p>Limited magnification capabilities.</p> Signup and view all the answers

    What is the main function of the glycocalyx?

    <p>Lubrication and protection</p> Signup and view all the answers

    Which cellular process is specifically responsible for the engulfing of small particles suspended in extracellular fluid?

    <p>Pinocytosis</p> Signup and view all the answers

    What is a primary role of nuclear pores in the cell?

    <p>Transport of substances between the nucleus and cytoplasm</p> Signup and view all the answers

    Which statement accurately describes the role of chromatin in eukaryotic cells?

    <p>It packages DNA into a denser structure.</p> Signup and view all the answers

    In terms of transport mechanisms, which process requires energy to occur?

    <p>Active transport of ions</p> Signup and view all the answers

    What is the process called when a cell expels materials through vesicular transport?

    <p>Exocytosis</p> Signup and view all the answers

    What type of membrane protein can penetrate the lipid bilayer and is involved in ion transport?

    <p>Integral membrane proteins</p> Signup and view all the answers

    Which of the following statements about phagocytosis is true?

    <p>It can be used for the removal of pathogens.</p> Signup and view all the answers

    What is the main function of somatic cells in the human body?

    <p>To carry out specialized functions forming tissues and organs</p> Signup and view all the answers

    Which of the following statements correctly defines morphology?

    <p>Study of the form and shape of structures</p> Signup and view all the answers

    Which of these best describes the nucleus of the cell when stained?

    <p>Stained purple indicating presence of DNA</p> Signup and view all the answers

    What is the primary focus of cytology?

    <p>Study of cellular structure and function</p> Signup and view all the answers

    Which of the following accurately describes gametes?

    <p>They are specialized sex cells involved in sexual reproduction</p> Signup and view all the answers

    What distinguishes morphometry from morphology?

    <p>Morphometry deals with the measurement of shapes and sizes</p> Signup and view all the answers

    How many different types of somatic cells are generally found in the human body?

    <p>Approximately 220 types</p> Signup and view all the answers

    Which of the following is NOT a function associated with somatic cells?

    <p>Participate in genetic recombination</p> Signup and view all the answers

    What are the primary advantages of using an electron microscope over a light microscope in histology?

    <p>An electron microscope offers higher magnification up to ~ 100,000 X and provides subcellular resolution, allowing for detailed examination of small areas.</p> Signup and view all the answers

    Why is histology considered essential for understanding tissue function in the context of gross anatomy?

    <p>Histology provides insights into the microscopic structure of tissues, which is vital for understanding their function and relationships within larger anatomical contexts.</p> Signup and view all the answers

    How do the staining techniques differ in their applications for light and electron microscopy?

    <p>Light microscopy uses a wide range of stains for visualizing larger structures, while electron microscopy typically requires heavy metal stains to enhance contrast at a subcellular level.</p> Signup and view all the answers

    In what ways do the dimensions of tissue sections prepared for histological examination affect the quality of observation?

    <p>Thin tissue sections are essential for allowing light or electrons to pass through, which enhances clarity and resolution during microscopic examination.</p> Signup and view all the answers

    What limitations do the physical characteristics of light microscopes impose on histological studies compared to electron microscopes?

    <p>Light microscopes are limited by a maximum magnification of ~ 1000 X and cannot provide subcellular resolution, restricting the level of detail observed in tissues.</p> Signup and view all the answers

    What is the main source of illumination used in an electron microscope?

    <p>A beam of accelerated electrons.</p> Signup and view all the answers

    How does Eosin stain structures in a tissue sample?

    <p>Eosin stains structures red or pink, particularly cytoplasm.</p> Signup and view all the answers

    What specific cell components does Haematoxylin primarily stain?

    <p>It primarily stains nucleic acids in the nucleus.</p> Signup and view all the answers

    Which stain would you use to identify nerve and reticular fibers in a tissue sample?

    <p>Silver stain.</p> Signup and view all the answers

    What is the significance of using the H&E stain in histology?

    <p>H&amp;E stain provides a contrast between nuclear and cytoplasmic components.</p> Signup and view all the answers

    What color does the nucleus stain with the appropriate dye?

    <p>Purple</p> Signup and view all the answers

    Define cytology in the context of cell biology.

    <p>Cytology is the study of cellular structure and function.</p> Signup and view all the answers

    What are the two major divisions of cells in the human body?

    <p>Sex cells (gametes) and somatic cells.</p> Signup and view all the answers

    How many different cell types are there approximately in the human body?

    <p>Over 200 different cell types.</p> Signup and view all the answers

    What is the significance of homeostasis at the cellular level?

    <p>Homeostasis maintains optimal conditions for cellular functions.</p> Signup and view all the answers

    What does stereology contribute to cell biology?

    <p>Stereology examines 2D images to infer information about 3D structures.</p> Signup and view all the answers

    What roles do somatic cells play in the human body?

    <p>Somatic cells comprise all body cells except gametes and are responsible for forming tissues and organs.</p> Signup and view all the answers

    What is the primary function of morphometry in cell biology?

    <p>Morphometry involves the measurement of the shape of structures.</p> Signup and view all the answers

    What is the primary function of glycocalyx in cell membranes?

    <p>The glycocalyx mainly provides lubrication, protection, and specificity in binding.</p> Signup and view all the answers

    How do phagocytosis and pinocytosis differ in their processes?

    <p>Phagocytosis involves engulfing large particles, while pinocytosis is the intake of small particles suspended in fluid.</p> Signup and view all the answers

    Describe the role of nuclear pores in the nucleus.

    <p>Nuclear pores facilitate communication between the nucleus and the cytoplasm, allowing the transport of molecules.</p> Signup and view all the answers

    What is exocytosis and when is it typically employed by the cell?

    <p>Exocytosis is a process where cells expel molecules through energy-dependent secretion, commonly used for releasing hormones and neurotransmitters.</p> Signup and view all the answers

    Explain the concept of active transport and give an example.

    <p>Active transport is the movement of molecules against their concentration gradient using energy, such as the transport of Na$^+$ ions.</p> Signup and view all the answers

    What is chromatin, and why is it important in eukaryotic cells?

    <p>Chromatin is a complex of DNA and proteins that packages DNA into dense structures, essential for DNA organization and regulation.</p> Signup and view all the answers

    List two primary functions of membrane proteins.

    <p>Membrane proteins are involved in transport across the membrane and act as receptors for signaling.</p> Signup and view all the answers

    What distinguishes peripheral membrane proteins from integral membrane proteins?

    <p>Peripheral membrane proteins are loosely attached to the membrane's surface, while integral membrane proteins are embedded within the lipid bilayer.</p> Signup and view all the answers

    What is the optimal pH range for the enzymes in lysosomes, and why is this pH significant?

    <p>The optimal pH range for lysosomal enzymes is about 4.5–5.0, which is significant as it enhances the hydrolytic processes necessary for biomolecule breakdown.</p> Signup and view all the answers

    Describe the structure of mitochondria and its significance in energy production.

    <p>Mitochondria have an outer membrane, an inner membrane, and an intermembranous space, which are significant for ATP production through processes like the electron transport chain.</p> Signup and view all the answers

    What are the three main components of the cytoskeleton, and what functions do they serve?

    <p>The three main components are microfilaments, intermediate filaments, and microtubules, serving functions like cell shape maintenance, motility, and intracellular transport.</p> Signup and view all the answers

    Explain one role of lysosomes in cellular processes beyond digestion.

    <p>Lysosomes are involved in plasma membrane repair by fusing with damaged areas to help restore cellular integrity.</p> Signup and view all the answers

    How do microtubules contribute to intracellular transport?

    <p>Microtubules provide tracks along which motor proteins can transport organelles and vesicles within the cell.</p> Signup and view all the answers

    What are some examples of intermediate filaments and their importance?

    <p>Examples of intermediate filaments include keratin, desmin, and vimentin, which provide mechanical strength and structural support to cells and tissues.</p> Signup and view all the answers

    What is the role of mitochondrial DNA, and why is it important?

    <p>Mitochondrial DNA encodes some of the proteins essential for mitochondrial function, which is important for ATP production and cellular metabolism.</p> Signup and view all the answers

    Identify one mechanism through which lysosomes can protect cells from damage.

    <p>Lysosomes can engulf and digest damaged organelles through a process called autophagy, protecting cells from accumulated debris.</p> Signup and view all the answers

    Study Notes

    Histology

    • Histology, the microscopic study of tissues, examines thin tissue slices using a microscope.
    • Light microscopes allow for viewing wide areas, multiple stains, and magnifications up to 1000x.
    • Electron microscopes allow for detailed examination of smaller areas with magnifications up to 100,000x.

    Cell Membrane

    • Separates the cell's internal environment (cytoplasm) from the external fluid (interstitial fluid).
    • Consists of a phospholipid bilayer with embedded proteins and surface carbohydrates.
    • Functions:
      • Physical isolation.
      • Regulates exchange of substances with the environment.
      • Sensitivity to external stimuli.
      • Provides structural support.

    Structure of the Cell Membrane

    • Composed of a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.
    • Proteins are embedded within the membrane framework.

    Membrane Lipids

    • Three main types:
      • Phosphoglycerides: Form 50% of the membrane, anchor and surround proteins.
      • Cholesterol: Stabilizes the membrane.
      • Glycolipids: Involved in intercellular communication.

    Membrane Proteins

    • Function:
      • Connect cytoskeletal filaments to the cell membrane.
      • Attach cells to the extracellular matrix.
      • Transport molecules in and out of cells.
      • Act as receptors for intercellular communication.
      • Possess specific enzymatic activity.

    Membrane Carbohydrates

    • Located on the cell's outer surface as a coating called the glycocalyx.
    • Functions:
      • Lubrication and protection.
      • Anchoring and locomotion.
      • Binding specificity.
      • Recognition.

    Transport Across Cell Membranes

    • Diffusion: Movement of gases, lipophilic or small molecules across the membrane.
    • Active Transport: Requires energy to move substances against concentration gradients, like Na+ ions.
    • Bulk Transport:
      • Endocytosis: Brings substances into the cell.
        • Pinocytosis: Ingests small particles suspended in fluid.
        • Phagocytosis: Engulfs large particles, like pathogens and cell debris.
      • Exocytosis: Transports molecules out of the cell by secretion.

    The Nucleus

    • Enclosed by the nuclear envelope, which communicates with the cytoplasm through nuclear pores.
    • Contains:
      • Cellular DNA.
      • Nucleoli: sites of rRNA, mRNA, and tRNA synthesis.
      • Nucleoproteins.
    • Chromatin: complex of DNA and protein responsible for packaging DNA.

    Chromatin

    • DNA wraps around histone proteins, forming nucleosomes and the "beads on a string" structure (euchromatin).

    Histology

    • The study of microscopic anatomy of biological tissues
    • Examined by looking at thin slices of tissue under a microscope
    • Uses a light microscope for larger areas and wide range of stains
    • Uses an electron microscope for smaller areas with subcellular resolution

    Electron Micrograph

    • A micrograph prepared using an electron microscope
    • An electron microscope is a microscope that uses a beam of accelerated electrons to illuminate the specimen

    Stains

    • Stains are used to identify specific structures in the cell or tissues
    • Haematoxylin stains nucleic acids purple/blue
    • Eosin stains elastic and reticular fibers red/pink
    • Toluidine blue stains nucleus and cytoplasm blue
    • Silver stains nerve and reticular fibers black/brown
    • Periodic acid-Schiff reacts with carbohydrates to stain them purple/blue
    • Alcian blue stains acidic epithelial mucins blue
    • Cyanin stains myelin purple

    Haemotoxylin & Eosin Stain

    • The most commonly used staining system is called H&E
    • Eosin is an acidic dye that stains structures red or pink
    • Haematoxylin is a basic dye that stains structures blue or purple

    Cell Membrane

    • Separates the cell contents (cytoplasm) from the extracellular fluid
    • Cytoplasm consists of cytosol and organelles
    • Functions are physical isolation, regulation of exchange with the environment, sensitivity to the environment and structural support

    ### Structure of the Cell Membrane

    • Formed by a lipid bilayer with specialised proteins and surface carbohydrates
    • Lipid molecules are amphipathic with a hydrophilic end (phosphate) and hydrophobic end (lipid)
    • Forms a bilayer in water

    Membrane Lipids

    • Phosphoglycerides (phospholipids)
      • Make up 50% of membrane lipid
      • Surround and anchor proteins
      • Include phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine
    • Cholesterol
      • Stabilizes the membrane
    • Glycolipids
      • Involved in intercellular communication
      • Include sphingolipids and gangliosides

    Membrane Proteins

    • Attach cytoskeletal filaments to the cell membrane
    • Attach cells to the extracellular matrix
    • Transport molecules into and out of cells
    • Act as receptors for chemical signalling
    • Possess specific enzymatic activity

    Membrane Carbohydrates

    • Located on the extracellular surface as a coating called the glycocalyx
    • Functions include lubrication and protection, anchoring and locomotion, specificity in binding and recognition

    Transport across cell membranes

    • Diffusion for gases, lipophilic or small molecules
    • Active transport for Na2+ ions
    • Bulk transport for endocytosis, pinocytosis, phagocytosis and exocytosis

    Endocytosis

    • Cellular process in which substances are brought into the cell
    • The material to be internalized is surrounded by an area of cell membrane which buds off inside the cell to form a vesicle containing the ingested material

    Pinocytosis

    • Also known as fluid endocytosis and bulk-phase pinocytosis
    • Small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane, resulting in suspension of the particles within a small vesicle inside the cell
    • These pinocytotic vesicles subsequently fuse with endosomes to hydrolyze the particles

    Phagocytosis

    • Process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome
    • It is one type of endocytosis
    • In a multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris

    Exocytosis

    • Form of active transport and bulk transport by which a cell transports molecules out of the cell by secreting them through an energy-dependent process

    The Nucleus

    • Bounded by nuclear envelope
    • Communicates with cytoplasm through nuclear pores
    • Contains cellular DNA, nucleoli (rRNA, mRNA, tRNA) and nucleoproteins

    Chromatin

    • A complex of DNA and protein found in eukaryotic cells
    • Its primary function is packaging long DNA molecules into more compact, denser structures: DNA wraps around histone proteins, forming nucleosomes and the so-called "beads on a string" structure.

    Histology

    • The study of microscopic anatomy of biological tissues
    • Examines thin slices of tissue under a microscope
    • Light microscopy provides a wide range of stains for larger areas, up to ~ 1000 X magnification
    • Electron microscopy offers high magnification (up to ~ 100,000 X) for small areas, providing subcellular resolution
    • Electron micrograph is a micrograph prepared using an Electron Microscope

    Stains

    • Used to identify specific structures or molecules in the cell / tissue
    • Haematoxylin stains nucleic acids purple/blue
    • Eosin stains cytoplasm red/pink, elastic and reticular fibers
    • Toluidine blue is a general cell stain, staining nucleus and cytoplasm blue
    • Silver stains nerve and reticular fibers black/brown
    • Periodic acid-Schiff (PAS) stains carbohydrates purple/blue
    • Alcian blue stains acidic epithelial mucins and extracellular matrix of support cells blue
    • Cyanin stains myelin purple

    H&E Staining

    • Haemotoxylin and Eosin (H&E) is the most commonly used staining system.
    • Eosin, an acidic dye, stains structures red or pink, highlighting cytoplasm
    • Haematoxylin, a basic dye, stains structures purplish blue, highlighting the nucleus

    Definitions

    • Morphology is the study of the form and shape of structures.
    • Morphometry is the measurement of the shape of structures.
    • Stereology examines 2D images to gain information about 3D structures.

    The Cell

    • The fundamental building blocks of all animals and plants.
    • All cells arise from the division of pre-existing cells.
    • Perform all vital physiological functions.
    • Maintain homeostasis at the cellular level.
    • Cytology is the study of cellular structure and function.

    Types of Cells

    • Over 200 different cell types in the human body.

    • Each type is specialized for a specific function, often forming a particular tissue.

    • Tissues combine to form organs, where each cell type contributes to the organ's functionality.

      • Sex cells/gametes fuse during sexual reproduction (e.g., sperm, oocytes).
      • Somatic cells are all other cells in the body, including internal organs, skin, bones, blood and connective tissue.

    Membrane Proteins

    • Peripheral membrane proteins attach to integral membrane proteins or the peripheral regions of the lipid bilayer.
    • These proteins can function as regulatory subunits of ion channels or transmembrane receptors.

    Membrane Carbohydrates

    • Located mainly on the extracellular surface, forming a coating called the glycocalyx.
    • Functions include: lubrication and protection, anchoring and locomotion, specificity in binding, and recognition.

    Transport Across Cell Membranes

    • Diffusion: For gases, lipophilic or small molecules.
    • Active transport: For molecules like Na2+ ions.
    • Bulk transport:
      • Endocytosis: Substances taken into the cell.
        • Pinocytosis: Takes small particles suspended in extracellular fluid into the cell.
        • Phagocytosis: Engulfs large particles, forming a phagosome.
      • Exocytosis: Molecules are transported out of the cell by secretion.

    The Nucleus

    • Bounded by the nuclear envelope.
    • Communicates with the cytoplasm through nuclear pores.
    • Contains:
      • Cellular DNA
      • Nucleoli (rRNA, mRNA, tRNA)
      • Nucleoproteins

    Chromatin

    • Complex of DNA and protein found in eukaryotic cells.
    • Packages long DNA molecules into compact structures like nucleosomes (the "beads on a string" structure, also known as euchromatin).

    Histology

    • Histology is the study of the microscopic anatomy of biological tissues
    • It is performed by examining thin slices (sections) of tissue under a microscope
    • Light microscopes are used for examining large areas and offer a wide range of stains with up to 1000x magnification
    • Electron microscopes are used for examining small areas and offer subcellular resolution with up to 100,000x magnification

    Stains

    • Stains can be used to identify specific structures or molecules in the cell and tissue
    • Haematoxylin stains the nucleus purple/blue and specifically stains nucleic acids
    • Eosin stains the cytoplasm red/pink and specifically stains elastic and reticular fibers
    • Toluidine blue stains the nucleus and cytoplasm blue and is a general cell stain
    • Silver stains nerve and reticular fibers black/brown
    • Periodic acid-Schiff (PAS) stains carbohydrates purple/blue
    • Alcian blue stains acidic epithelial mucins and the extracellular matrix of support cells blue
    • Cyanin stains myelin purple

    Haemotoxylin & Eosin Stain (H&E)

    • Most commonly used staining system
    • Eosin is an acidic dye that stains structures red or pink, so the cytoplasm is stained pink in the picture
    • Haematoxylin is considered a basic dye and is used to stain structures a purplish blue, so the nucleus is stained purple

    Definitions

    • Morphology: study of the form and shape of structures
    • Morphometry: measurement of the shape of structures
    • Stereology: examination of 2D images to gain information about 3D structures

    The Cell

    • Cells are the building blocks of all animals and plants
    • All cells come from the division of pre-existing cells
    • Cells are the smallest units that perform all vital physiological functions
    • Each cell maintains homeostasis at the cellular level
    • Cytology: the study of cellular structure and function

    Types of Cells

    • There are over 200 different cell types in the human body
    • Each cell type is specialized to carry out a particular function
    • Cells form tissue which combine to form organs
    • Two major divisions of cells: Sex cells/gametes and somatic cells

    Sex Cells/Gametes

    • Cells that fuse during sexual reproduction
    • Examples: sperm and oocytes

    Somatic Cells

    • All other cells in the human body
    • Make up all the internal organs, skin, bones, blood and connective tissue
    • There are approximately 220 types of somatic cell in the human body

    Membrane carbohydrates

    • Mainly found on the extracellular surface as a coating called the glycocalyx
    • Functions include lubrication and protection, anchoring and locomotion, specificity in binding, and recognition

    Transport across cell membranes

    • Diffusion (gases, lipophilic or small molecules)
    • Active transport (Na2+ ions)
    • Bulk transport:
      • endocytosis
      • pinocytosis
      • phagocytosis
      • exocytosis

    Endocytosis

    • A cellular process in which substances are brought into the cell
    • The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material

    Pinocytosis

    • Also known as fluid endocytosis and bulk-phase pinocytosis
    • Involves small particles suspended in extracellular fluid being brought into the cell through an invagination of the cell membrane, resulting in a suspension of the particles within a small vesicle inside the cell
    • These pinocytotic vesicles subsequently fuse with endosomes to hydrolyze the particles.

    Phagocytosis

    • Process where a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome
    • It is one type of endocytosis
    • In a multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris

    Exocytosis

    • A form of active transport and bulk transport in which a cell transports molecules out of the cell by secreting them through an energy-dependent process

    The Nucleus

    • Bounded by a nuclear envelope
    • Communicates with cytoplasm through nuclear pores
    • Contains:
      • cellular DNA
      • nucleoli (rRNA, mRNA, tRNA)
      • nucleoproteins

    Chromatin

    • A complex of DNA and protein found in eukaryotic cells
    • Its primary function is packaging long DNA molecules into more compact, denser structures:
      • DNA wraps around histone proteins, forming nucleosomes and the so-called "beads on a string" structure (euchromatin)

    Lysosomes

    • Membrane-bound spherical organelle containing hydrolytic enzymes -break down many kinds of biomolecules engulfed by cell
    • Has a specific composition, of its membrane proteins, and luminal proteins
    • The lumen's pH (~4.5–5.0) is optimal for the enzymes involved in hydrolysis, analogous to the activity of the stomach
    • Involved in various cell processes-plasma membrane repair, cell signalling, and energy metabolism

    Mitochondria

    • Membrane-bound organelle
      • outer and inner membranes, separated by intermembranous space
    • Responsible for energy (ATP) production
    • Matrix contains many enzymes and small amounts of mitochondrial DNA

    Cytoskeleton

    • In eukaryotes the cytoskeleton is composed of three main components-all capable of rapid growth or disassembly dependent on the cell's requirements:
      • Microfilaments
      • Intermediate filaments
      • Microtubules

    Microfilaments

    • Long, thin filaments of actin (5nm diameter)
    • Functions include cytokinesis, amoeboid movement, cell motility, and changes in cell shape

    Intermediate filaments

    • Desmin, glial fibrillary acidic protein, keratin, lamin, neurofilaments, vimentin (10nm diameter)
    • Most stable component of the cytoskeleton-found in particularly durable structures such as hair, scales, fingernails.

    Microtubules

    •  and  tubulin (25nm diameter)
    • Provide platforms for intracellular transport and are involved in a variety of cellular processes, including the movement of secretory vesicles, organelles

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    Description

    This quiz explores the essential concepts of histology and the structure and function of cell membranes. It covers the microscopic examination of tissues and the characteristics of the phospholipid bilayer. Test your understanding of membrane functions, types, and the technology used in histological studies.

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