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Cells and their Components 1st Adaptation: Reagan Lee & Joseph Coong (2022) Slides Created By: Cuchulainn Liam Gent (2021)Format •MCQ! •Open questions! •Quick recaps! •Audience participation encouraged!Learning objectives •Explain what the cell is and its microanatomy •How the cell maintains homeostasis and interacts with the environment •How cells become tissues Disclaimer •You may not have been taught some of these things at this stage! •That is okay! •Most questions can be answered by an educational guess! •We learn more from mistakes than not! •All relevant information can be found in the slide notes! •I take no credit of any photos or diagrams or slides used in this presentationQ1: Who is this? A. Charles Darwin B. Robert Koch C. Louis Pasteur D. Robert HookeQ1: Who is this? A. Charles Darwin B. Robert Koch C. Louis Pasteur D. Robert Hooke • How many cells do we have in the average human body? And what is the commonest cell type? What is a cell? • What does “cell” mean? • What is the broad definition of a cell? • What defines a eukaryotic cell? • How many cells do we have in the average human body? And what is the commonest cell type? On average, humans have 37.2 trillion cells! What is a The most abundant cell type is by, no doubt, red blood cells! RBCs comprise as much as 84% of all the cells in our body. cell? • What does “cell” mean? organism, that is able to function independently, which isn typically microscopic and consists of cytoplasm and a nucleus enclosed in a membrane. • What is the broad definition of a cell? Broadly, a cell can be defined as the basic building blocks of broad categories consisting of - prokaryotes & eukaryotes.two • What defines a eukaryotic cell? Eukaryotic cells are defined by the following: Membrane bound mitochondria (powerhouse of the cell!), e.t.c.A, presence of Q2: What does the cell membrane NOT contain? A. Phospholipids B. Chromatin C. Cholesterol D. Channel proteins Q2: What does the cell membrane NOT contain? A. Phospholipids B. Chromatin C. Cholesterol D. Channel proteinsThe Plasma Membrane • Phospholipids! • Cholesterol! • Glycoproteins and glycolipids! • Many specialised transport proteins! • Etc …Q3: How do ions MOSTL Y cross the membrane? A. Simple diffusion B. Channels C. Endocytosis D. Carrier proteinsQ3: How do ions MOSTL Y cross the membrane? A. Simple diffusion B. Channels C. Endocytosis D. Carrier proteinsMembrane transport •How do molecules cross membranes? •(a) Lipophilic, small, uncharged molecules •(b) Ions •(c) Larger, water-soluble moleculesExtra Question: Which of these conditions do NOT involve a faulty channel protein? A. Cystic fibrosis B. Congenital long QT syndrome C. Myasthenia GravisExtra Question: Which of these conditions do NOT involve a faulty channel protein? A. Cystic fibrosis gene Involves mutation in chloride channel Most genetic types of LQTS involve B. Congenital long mutation in potassium or sodium channel QT syndrome gene, or associated proteins. Immunologic abnormality against C. Myasthenia nicotinic ACh receptors (Still ion channel, Gravis but involves an immune reaction against it. Not an inherently faulty channel) Q4: What is happening in the diagram? A. Phagocytosis B. Receptor mediated endocytosis C. Constitutive secretion D. Pinocytosis Q4: What is happening in the diagram? A. Phagocytosis B. Receptor mediated endocytosis C. Constitutive secretion D. Pinocytosis EXTRA POINTS: What are the particles lining the cytoplasmic face of the vesicle? And what do they do?Transport by Vesicles •Endocytosis; •Phagocytosis •Pinocytosis •Receptor-mediated endocytosis (follow-up on next slide) EXTRA POINTS: What does vesicle from a vacuole?is the differenceTransport by Vesicles •Exocytosis; •Constitutive secretion •Regulated secretion Q5: What is chemical signalling from nerve to muscle an example of? A. Endocrine B. Paracrine C. Autocrine Q5: What is chemical signalling from nerve to muscle an example of? A. Endocrine B. Paracrine C. AutocrineSignal Reception & Transduction: How do cells communicate? •Autocrine •Paracrine •Endocrine EXTRA POINTS: What is juxtacrine signalling?Signal Reception & Transduction; how do cells communicate? •Channel-linked receptors - Ionotropic receptors (ACh, voltage-gated calcium channels •Enzymatic receptors - Insulin and growth factor receptors •G-protein-coupled receptors - Adrenaline Q6: What is the cause of pseudohypoparathyroidism? A. Growth hormone defect B. Parathyroid hormone defect C. Growth hormone receptor defect Shortening of the 4th Metacarpal Bones D. Parathyroid receptor defect EXTRA POINTS: How does this cause Q6: What is the cause of tetany? How would you treat this condition pseudohypoparathyroidism? ? A. Growth hormone defect B. Parathyroid hormone defect C. Growth hormone receptor defect D. Parathyroid receptor defect Extra Question: What happens if the Ras signalling pathway is permanently switched on? A. You become stressed due to fight or flight signal B. Your cells stop dividing C. You develop acidosis D. You have uncontrolled cell proliferation Extra Question: What happens if the Ras signalling pathway is permanently switched on? A. You become stressed due to fight or flight signal B. Your cells stop dividing C. You develop acidosis D. You have uncontrolled cell proliferation exactly?INTS: Meaning whatSignalling pathways: • Phwhich signals are carried. Don’t get bogged down on the details too much.amples of pathways along •binds adenylyl cyclase; increases cAMP; activating PKA; activates phosphorylase kinase; activates; glycogen phosphorylase •Phospholipase C pathway; ligand binds GPCR; subunit activates PLC; breaks inositol phospholipid into DAG and inositol 1, 4, 5 triphosphate; latter opens Ca channels in the ER causing Ca increase in cytoplasm, which can have multiple effects •Ras pathway; ligand binds receptor tyrosine kinase; dimerization and kinase activation follows; cytoplasmic tyrosine phosphorylates creating binding sites for signalling proteins; adaptor protein phosphorylation involving MAP kinases, changing protein activity and gene expressionde of Membrane A B Organelles C Vesicle D Membrane Q7: What are A the structures labelled A? B A. Golgi B. Centrioles C C. Nuclei D. Mitochondria Vesicle D Q7: What are the structures labelled A? A. Golgi B. Centrioles C. Nuclei D. Mitochondria EXTRA POINTS: What cells might have many of these? What happens if they don’t work? Is it treatable? Q8: What is the structure below the mitochondria? A. Smooth endoplasmic reticulum B. Centrosome C. Rough endoplasmic reticulum D. Lysosomes Q8: What is the structure below the mitochondria? A. Smooth endoplasmic reticulum B. Centrosome C. Rough endoplasmic reticulum D. Lysosomes Endoplasmic reticulum •2 types •Smooth • Makes lipids and steroid hormones • Drug detoxification •Rough • Dotted with ribosomes • Makes proteins for export Q9: Which antibiotics target the bacterial ribosome? A. Streptomycin B. Doxycycline C. Chloramphenicol EXTRA POINTS: if you can explain D. All of the above this picture! Q9: Which antibiotics target the bacterial ribosome? A. Streptomycin B. Doxycycline C. Chloramphenicol Aminoglycosides; binds 30S, baEXTRA POINTS: D. All of the above Tetracyclines; binds 30S, bacteriostatic resistance Binds 50S, bacteriostatic develop? Membrane Q10: Where Mitochondria are ribosomes made? to visualise here** B A. Golgi B. Nucleolus C C. Centrioles D. Lysosomes Vesicle D Membrane Q10: Whereare Mitochondria ribosomes made? sER & rER difficult to visualise here** B A. Golgi B. Nucleolus C C. Centrioles D. Lysosomes Vesicle DNucleus and nucleolus •Nucleus: •Largest •Enveloped •Nuclear pores •Contains DNA (Chromosomes) •Contains nucleolus •Most of your cell types are nucleated Membrane Q11: What is Mitochondria the function of the structure labelled C? B A. Cell movement B. Cell division C C. Respiration D. Protein export Vesicle NucleusQ11: What is the function of the structure labelled C? A. Cell movement B. Cell division C. Respiration D. Protein export Membrane Q12: What is the Mitochondria function of the structure labelled B? B A. Organisation of microtubules B. Breakdown of cell waste GA C. Produce ATP D. Excrete waste Vesicle Nucleus Membrane Q12: What is the Mitochondria function of the structure labelled B? B A. Organisation of microtubules B. Breakdown of cell waste GA C. Produce ATP D. Excrete waste Vesicle NucleusCytoskeleton •A network of protein filaments and motor proteins allowing cell movement and more •Composition: • Microfilaments; small, structural support and contractions • Intermediate filaments; support • Microtubules; larger, movement • exists as a pair of centrioles, and are, important in cell division • Motor proteins: Kinesis, dyneins, myosinsChest X-Ray from a patient with Kartagener Syndrome (Primary Ciliary Dyskinesia with Situs Inversus) - The main notable finding is the presence of dextrocardia (heart on the Right s instead of the Left). This is due to situs inversus. Primary Ciliary Dyskinesia is due to the inheritance/mutation of autosomal recessive genes, which code for the dynein arm. Pathophysiology: Dynein Arm Defect → Immotile Cilia → Dysfunctional ciliated epithelium. Often leads to bronchiectasis due to impaired clearance of bacteria by dysfunctional cilia. The presence of situs inversus can be explained through the following mechanism: “It has been suggested that cilia are important for proper organ orientation during embryonic development and that dysfunctional cilia make organ orientation a random event, leading to situs inversus 50% of the time.” Link: https://www.sciencedirect.com/science/article/abs/pii/B9780323065610000173 Clinical Correlate: What happens when Dynein Arms fail to work? → Note: This is a very in-depth topic for Year 1. Main takeaway is “pathologies can arise from the smallest of genetic defects.” Have a read through, if you’re interested, but feel free to skip forward as well. :D Chest X-Ray from a patient with Kartagener Syndrome (Primary Ciliary Dyskinesia with Situs Inversus) - The main notable finding is the presence of dextrocardia (heart on the Right instead of the Left). This is due to situs inversus. Primary Ciliary Dyskinesia is due to the inheritance/mutation of autosomal recessive genes, which code for the dynein arm. Pathophysiology: Dynein Arm Defect → Immotile Cilia → Dysfunctional ciliated epithelium. Often leads to bronchiectasis due to impaired clearance of bacteria by dysfunctional cilia. The presence of situs inversus can be explained through the following mechanism: “It has been suggested that cilia are important for proper organ orientation during embryonic development and that dysfunctional cilia make organ orientation a random event, leading to situs inversus 50% of the time.” Link:https://www.sciencedirect.com/science/article/abs/pii/B9780323065610000173 Membrane That’s Mitochondria the cell! Centrioles Not everything is labelled*** But cells come together and make tissues, that make up GA organs! Let’s explore that next… Vesicle NucleusQ12: What is NOT a type of epithelial tissue? A. Simple Squamous B. Transitional C. Reticular D. PseudostratifiedQ12: What is NOT a type of epithelial tissue? A. Simple Squamous B. Transitional C. Reticular (Found in lymph nodes) D. PseudostratifiedTissues: Q13: Where is simple squamous epithelium found? A. Bronchi, uterus, digestive tract B. Oesophagus, mouth, vagina C. Bladder, urethra, ureters D. Alveoli, blood vessels, lymphaticsQ13: Where is simple squamous epithelium found? Simple columnar; absorbs, and secretes A. Bronchi, uterus, digestive tract mucous and enzymes B. Oesophagus, mouth, vagina Stratified squamous: protects against abrasion C. Bladder, urethra, Transitional: Allow urinary organs to expand ureters stretch D. Alveoli, blood vessels, lymphatics Simple squamous: Allows materials to pass through by diffusion and filtration, and secretes lubricating substancesForm fits function! •Epithelial tissue •Simple – single layer (absorption, secretion) • Squamous (flat) • Cuboidal • Columnar • Pseudostratified (respiratory tract) •Stratified – multiple (protection) • Squamous • Keratinised (dry) • Non-keratinised (moist) • Transitional Q14: What is the most abundant tissue in the body? A. Muscle B. Connective C. Nervous D. Epithelial Q14: What is the most abundant tissue in the body? A. Muscle B. Connective C. Nervous D. Epithelial EXTRA POINTS: What is the tissue type in the aboveConnective tissue •Types of connective tissue: Type out some! •Cells are embedded in ECM •Main functions: •Binding/structural support •Protection •Transport •InsulationConnective tissue •Cells are embedded in ECM •Main functions: •Binding/structural support •Protection •Transport •InsulationConnective Tissue Summary: •Loose: most abundant; connects other tissues, e.g. under skin and between muscles. •Adipose: areolar matrix with adipocytes; white or brown tissue. •Reticular: lymphatic system, matrix of reticular fibres. •Dense: Fibrous or elastic; tendon, ligaments, periosteum vs blood vessels and lungs. •Cartilage: chondrocytes in collagen and proteoglycan matrix; hyaline,fibrocartilage and elastic fibrocartilage •Bone: Osteocytes embedded within a mineralised collagen matrix; contains osteoblasts, -clasts and -cytes Q15: What type of connective tissue does the arrow point to? A. Loose B. Adipose C. Reticular D. Dense E. Cartilage F. Bone Q15: What type of connective tissue does the arrow point to? A. Loose B. Adipose C. Reticular D. Dense E. Cartilage F. Bone Q16: What type of connective tissue does the arrow point to? A. Loose B. Adipose C. Reticular D. Dense E. Cartilage F. Bone Q16: What type of connective tissue does the arrow point to? A. Loose B. Adipose C. Reticular D. Dense E. Cartilage F. Bone Q17: What type of connective tissue does the arrow point to? A. Loose B. Adipose C. Reticular D. Dense E. Cartilage F. Bone Q17: What type of connective tissue does the arrow point to? A. Loose B. Adipose C. Reticular D. Dense E. Cartilage F. Bone Q18: Which are connectivetissue diseases? A. Rheumatoid arthritis B. Systemic Lupus erythematosus C. Osteoarthritis D. All of the above Q18: Which are connectivetissue diseases? A. Rheumatoid arthritis B. Systemic Lupus erythematosus C. Osteoarthritis D. All of the above Main Point: abundant, and many debilitatingis conditions affect it. Q19: Which statement is TRUE? A. Cardiac is striated, skeletal is not B. Skeletal cells are mononucleated, cardiac are not C. Cardiac cells have intercalated discs D. Skeletal muscles are under involuntary control Q19: Which statement is TRUE? A. Cardiac is striated, skeletal muscle is not B. Skeletal muscle cells are mononucleated, cardiac are not C. Cardiac cells have intercalated discs D. Skeletal muscles are under involuntary controlMuscle tissue •Smooth: •Non-striated, involuntary, peristalsis Gut & Ureter •Skeletal: •Striated, multinucleated, voluntary •Cardiac: •Striated, involuntary, mononucleated, intercalated discsExtra Question: Why are skeletal muscle cells multinucleated? Write down your best guess in the chat, or turn on your microphone!Extra Question: Why are skeletal muscle cells multinucleated? •Skeletal muscle cells are big! •Multiple nuclei mean multiple copies of genes, allowing large amounts of proteins and enzymes needed for contraction •To control long cells with many structural and functional units, a single nuclei might not cut it! Q20: Which of the following is TRUE? A. Glial cells are excitable B. Neurons are supportive cells C. Glial cells are more numerous than neurons D. An oligodendrocyte is a type of neuron Q20: Which of the following is TRUE? A. Glial cells are excitable B. Neurons are supportive cells C. Glial cells are more numerous than neurons D. An oligodendrocyte is a type of neuron Nervous tissue •Neurones •Excitable & initiate, receive and transmit information •Cell bodies within CNS, axons found within PNS •Glial cells •Non-excitable, supportive, more numerous •Examples: astrocytes, oligodendrocytes, ependymal cells and microglia Q21: Which junction mechanically attaches cells to adjacent cells or the ECM? A. Anchoring junctions B. Communicating junctions C. Occluding junctions D. T junctions Q21: Which junction mechanically attaches cells to adjacent cells or the ECM? A. Anchoring junctions B. Communicating junctions C. Occluding junctions D. T junctionsCellular junctions For tissues to form, cells need to stick together. •Occluding: seal together, preventing leaks - Forms tight junctions •Anchoring: mechanically attach cells to adjacent cells or the ECM •Some junctions involve actin filaments, and others intermediate filaments. • Includes Desmosomes, Hemidesmosomes and Adherens junctions •Communicating: control signals from one cell to another, most are linked via gap junctions Have a think about which junctions might be found where! Junction Type Components Function + Clinical Correlate Occluding Occludins “Seals cells tightly.” Paracellular (Tight) Junction Claudins movement of solutes are prevented. Anchoring Adherens Junction Connects actin cytoskeletons of Junction neighbouring cells with cadherins. Loss of cadherin (Type E) → promotes metastasis Desmosome Structural support through interactions w/ intermediate filament. Autoantibodies to desmosome proteins → causes Pemphigus Vulgaris Hemidesmosome Adjoins keratin in basal cells to basement membrane. Autoantibodies to hemidesmosomes → causes Bullous Pemphigoid Communicating Connexons Connexons are channel proteins which (Gap) Junction enable chemical & electrical signalling between cells. First Aid for the USMLE Step 1 2023, Page 482Feedback Please take a minute now before you leave to fill in a quickfeedback form: https://app.medall.org/feedback/feedback-flow? keyword=7a296e2866682df1ac5aabc5&organi sation=accessibility-in-medicine (I’ll post the link in the chat :D) AIM Facebook Give our Facebook page a like for updates and opportunities, just search @AIMEdinburghThank you for coming! :D Email: accessibilityinmedicine@gmail.com Resources: Junqueira’s Basic Histology: Text and Atlas, 15e (online access via library) First Aid for the USMLE Step 1 2023 (personal subscription)