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Questions and Answers

Which mechanism allows cytotoxic T cells to induce apoptosis in infected cells?

  • Engulfment by autophagy
  • Engagement of MHC molecules
  • Release of perforin and granzyme (correct)
  • Release of interleukins

    • What role does autophagy play in managing viral infections?

  • Enhances MHC presentation
  • Engulfs and degrades parts of the cytoplasm (correct)
  • Increases cytokine production
  • Destroys viral RNA directly

    • What is a characteristic feature of chronic viral infections?

  • Long silent period before disease manifests (correct)
  • Constant high levels of immune response
  • Immediate severe symptoms upon infection
  • Rapid viral replication resulting in cell lysis

    • How do natural killer (NK) cells identify cells for destruction during infections?

    <p>By detecting low MHC expression</p> Signup and view all the answers

    Which receptors are primarily responsible for recognizing viral RNA or DNA in cells?

    <p>Pattern Recognition Receptors (PRRs)</p> Signup and view all the answers

    What are the main effects of cytokine release during a viral infection?

    <p>Amplifying the immune response</p> Signup and view all the answers

    What is the primary function of type I interferons released by infected cells?

    <p>Signal neighboring cells to activate antiviral defenses</p> Signup and view all the answers

    How do antiviral proteins produced in response to interferons affect viral replication?

    <p>Degrade viral RNA and inhibit protein synthesis</p> Signup and view all the answers

    During which phase do early, nonspecific symptoms of a viral infection typically appear?

    <p>Prodromal phase</p> Signup and view all the answers

    What is NOT a factor affecting the length of the incubation period for viral infections?

    <p>Host's lifestyle choices</p> Signup and view all the answers

    What role does apoptosis play in the response to viral infections?

    <p>Prevents further virus replication by sacrificing the infected cell</p> Signup and view all the answers

    Which protein is known to regulate the apoptotic response in infected cells?

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

    What is the primary function of major histocompatibility complex (MHC) molecules in viral infections?

    <p>Presenting viral peptides on cell surfaces</p> Signup and view all the answers

    What is one consequence of the long silent period associated with chronic viral infections?

    <p>Potential for neoplastic changes</p> Signup and view all the answers

    Which cytokine is specifically known for amplifying the immune response during viral infections?

    <p>Interleukin-1</p> Signup and view all the answers

    What is the primary effect of cytokine release during a viral infection?

    <p>Activation of immune responses in nearby cells</p> Signup and view all the answers

    What is a common characteristic of silent viral infections?

    <p>The viral genome remains dormant in host cells.</p> Signup and view all the answers

    Which immune system component is primarily responsible for recognizing viral patterns?

    <p>Pattern recognition receptors</p> Signup and view all the answers

    What role do interferons play during a viral infection?

    <p>They modulate the host immune response and inhibit virus replication.</p> Signup and view all the answers

    What is the primary consequence of cytokine release during a viral infection?

    <p>They can lead to tissue damage and severe symptoms.</p> Signup and view all the answers

    What process is induced by viral infections to eliminate infected cells?

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

    Which of the following is an example of a virus that can establish persistent infections?

    <p>Hepatitis B virus</p> Signup and view all the answers

    Which cells play a critical role in the rapid response to a viral infection after a previous encounter?

    <p>Memory T and B cells</p> Signup and view all the answers

    During which phase can viral reactivation occur due to stress or immune suppression?

    <p>Latent phase</p> Signup and view all the answers

    What is the appropriate timing for primary lip repair in a child with a cleft lip?

    <p>Around 3 months of age</p> Signup and view all the answers

    What is a common psychosocial issue faced by individuals with cleft lip and palate?

    <p>Low self-esteem and social withdrawal</p> Signup and view all the answers

    What anatomical structure is primarily implicated in the development of unilateral cleft lip?

    <p>Maxillary process</p> Signup and view all the answers

    Which syndrome is associated with multiple anomalies, including cleft palate and micrognathia?

    <p>Pierre Robin anomaly</p> Signup and view all the answers

    What is the aim of alveolar bone grafting in cleft palate management?

    <p>To create a bony bridge for canine eruption</p> Signup and view all the answers

    At what stage of prenatal development does the fusion failure leading to cleft lip typically occur?

    <p>Week 9-10</p> Signup and view all the answers

    Which characteristic is NOT typically associated with a submucous cleft palate?

    <p>Fusion of palatal processes</p> Signup and view all the answers

    Which of the following is NOT a specialist included in the CLP team?

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

    What is the approximate time frame for palate repair?

    <p>6 months</p> Signup and view all the answers

    Which of the following conditions is related to orthodontic implications following CLP?

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

    Which viral structure component is primarily responsible for the attachment of the virus to host cells?

    <p>Viral attachment proteins</p> Signup and view all the answers

    During which phase of the lytic cycle does the host cell burst to release new virus particles?

    <p>Lysis and Release</p> Signup and view all the answers

    What does the term 'pleomorphism' refer to in viruses?

    <p>Diverse shapes exhibited by virions</p> Signup and view all the answers

    In the lysogenic cycle, what occurs during the dormancy phase?

    <p>Viral DNA remains inactive and is propagated.</p> Signup and view all the answers

    What is a defining characteristic of obligate intracellular parasites?

    <p>They cannot survive without a host.</p> Signup and view all the answers

    Which of the following accurately describes the virion?

    <p>A complete infectious form of the virus.</p> Signup and view all the answers

    What is the function of Pattern Recognition Receptors (PRRs) in the innate immune response?

    <p>To recognize viral components and trigger early immune responses</p> Signup and view all the answers

    Which type of T cells is responsible for secreting cytokines that coordinate the immune response?

    <p>Helper T Cells (CD4+ T Cells)</p> Signup and view all the answers

    What is the main role of interferons (IFNs) in the immune response to viral infections?

    <p>To enhance the activity of natural killer (NK) cells and activate other immune cells</p> Signup and view all the answers

    In the context of the adaptive immune response, what is the function of B cells?

    <p>To differentiate into plasma cells that produce specific antibodies</p> Signup and view all the answers

    How does inflammation contribute to the immune response during viral infections?

    <p>It attracts additional immune cells to the site of infection</p> Signup and view all the answers

    What primarily occurs during the acute phase of a viral infection?

    <p>High-rate viral replication with the onset of specific symptoms.</p> Signup and view all the answers

    What is a common outcome of the host immune response during the resolution phase of a viral infection?

    <p>Symptoms completely resolve as the immune system eliminates the virus.</p> Signup and view all the answers

    Which factor distinguishes latent viruses from those in the active infection phase?

    <p>Dormancy of the viral genome without active replication.</p> Signup and view all the answers

    What is the primary result of reactivation of latent viruses under stress or immune suppression?

    <p>Recurrent symptoms or viral shedding occur.</p> Signup and view all the answers

    In chronic viral infections, the virus may establish long-term presence primarily by:

    <p>Rapidly mutating to avoid detection by T cells.</p> Signup and view all the answers

    What type of immune cells remains after the resolution of a viral infection to provide long-lasting immunity?

    <p>Memory T and B cells.</p> Signup and view all the answers

    During the acute phase of a viral infection, which mechanism contributes significantly to tissue damage?

    <p>Inflammatory cytokines produced by the immune response.</p> Signup and view all the answers

    Which of the following describes the role of interferons during a viral infection?

    <p>To activate natural killer cells and enhance the immune response.</p> Signup and view all the answers

    What can result from a successful immune response to a viral infection?

    <p>Restoration of health and immunity against future infections.</p> Signup and view all the answers

    Which of the following viruses is most likely to establish a latent infection?

    <p>Herpes simplex virus.</p> Signup and view all the answers

    Which mechanism involves cytotoxic T cells recognizing infected cells?

    <p>MHC molecule interaction</p> Signup and view all the answers

    What is the function of NK cells in response to viral infections?

    <p>To target cells with low MHC expression</p> Signup and view all the answers

    Which cytokines are primarily involved in amplifying the immune response during a viral infection?

    <p>Interleukin-1 and interferons</p> Signup and view all the answers

    Which phase is characterized by the onset of early, nonspecific symptoms of a viral infection?

    <p>Prodromal phase</p> Signup and view all the answers

    How does the autophagy process help in combating viral infections?

    <p>By degrading viral particles within cells</p> Signup and view all the answers

    What is a consequence of the cytokine release during a viral infection?

    <p>Enhanced tissue damage</p> Signup and view all the answers

    Which of the following is true regarding the MHC presentation of viral peptides?

    <p>It facilitates recognition by immune cells</p> Signup and view all the answers

    During which event do viruses typically enter the body?

    <p>Mucosal surface contact</p> Signup and view all the answers

    Which factor can influence the length of the incubation period for viral infections?

    <p>Type of virus</p> Signup and view all the answers

    What role does perforin play in the immune response to viral infections?

    <p>Destroys the membranes of infected cells</p> Signup and view all the answers

    What is the role of the intermaxillary process during facial development?

    <p>Contributes to the primary palate and pre-maxilla</p> Signup and view all the answers

    Which type of ossification is responsible for the formation of the calvarium and facial bones?

    <p>Intramembranous ossification</p> Signup and view all the answers

    What primarily determines the shape and size of bones according to the functional matrix theory?

    <p>Soft tissue matrices</p> Signup and view all the answers

    During which weeks do the palatine shelves fuse with the primary palate and nasal septum?

    <p>Weeks 8 and 9</p> Signup and view all the answers

    What is a key difference in growth patterns between the maxilla and mandible after the age of 7?

    <p>Mandible continues to grow while maxilla growth slows dramatically</p> Signup and view all the answers

    Which growth prediction method is deemed more effective for assessing jaw growth?

    <p>Cervical vertebrae analysis</p> Signup and view all the answers

    Which statement about postnatal craniofacial growth is accurate?

    <p>Maxillary growth aligns closely with neural growth patterns</p> Signup and view all the answers

    What cellular mechanism is primarily responsible for clearing viral infections during the resolution phase?

    <p>Cytotoxic T cell activity</p> Signup and view all the answers

    What is a defining feature of the acute phase of viral infections?

    <p>Rapid replication of the virus and symptom onset</p> Signup and view all the answers

    Which statement accurately describes the latency phase of certain viruses?

    <p>The viral genome remains dormant in specific cells.</p> Signup and view all the answers

    Which of the following best describes chronic infections caused by some viruses?

    <p>They can lead to long-term health issues due to immune evasion.</p> Signup and view all the answers

    What is the role of memory T and B cells after viral resolution?

    <p>To provide a quick immune response upon re-exposure</p> Signup and view all the answers

    Which specialist is NOT typically part of the CLP team?

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

    What is the main consequence of compromised muscles surrounding the inner auditory meatus in children?

    <p>Potential hearing impairment</p> Signup and view all the answers

    During which stage of the lytic cycle does the viral genetic material utilize the host's machinery?

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

    In the lysogenic cycle, what happens to the viral DNA during the integration phase?

    <p>It becomes dormant within the host DNA.</p> Signup and view all the answers

    What is the typical time frame for lip repair in children with cleft conditions?

    <p>6-12 weeks</p> Signup and view all the answers

    Which of the following conditions is NOT typically associated with orthodontic implications in children with CLP?

    <p>Increased caries susceptibility</p> Signup and view all the answers

    Which viral structural feature is primarily responsible for its pleomorphic characteristics?

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

    Which factor characterizes a virion in its complete form?

    <p>Viral genome with a complete envelope</p> Signup and view all the answers

    What defines the main role of viral attachment proteins during infection?

    <p>To attach to host cell receptors</p> Signup and view all the answers

    What is the primary role of obligate intracellular parasites like viruses?

    <p>To utilize the host's cellular machinery</p> Signup and view all the answers

    What role does autophagy play in viral infections?

    <p>It degrades viral particles to present to the immune system.</p> Signup and view all the answers

    Which statement correctly describes the function of MHC molecules during viral infections?

    <p>They present viral peptides to activate immune cells.</p> Signup and view all the answers

    What is the main function of cytokines released during a viral infection?

    <p>To enhance the immune response and recruit more immune cells.</p> Signup and view all the answers

    During which phase of viral infection do early, nonspecific symptoms first appear?

    <p>Prodromal phase</p> Signup and view all the answers

    How do natural killer (NK) cells contribute to the immune response against viral infections?

    <p>They recognize and destroy cells with low MHC expression.</p> Signup and view all the answers

    What is typically observed during the incubation period of a viral infection?

    <p>The virus replicates without causing noticeable symptoms.</p> Signup and view all the answers

    Which cytokine is primarily known for attracting immune cells to the infection site?

    <p>Interleukin-1 (IL-1)</p> Signup and view all the answers

    What is a common characteristic of the prodromal phase in viral infections?

    <p>Appearance of nonspecific early symptoms.</p> Signup and view all the answers

    Which of the following are common problems associated with cleft lip and palate?

    <p>Hearing difficulties</p> Signup and view all the answers

    Which process is primarily responsible for the cell's ability to recognize and respond to viral infection?

    <p>Antigen presentation via MHC</p> Signup and view all the answers

    What is the primary aim of alveolar bone grafting in managing cleft palate?

    <p>To create a bony bridge to support canine eruption</p> Signup and view all the answers

    Cytotoxic T cells primarily induce apoptosis in infected cells through the use of which molecules?

    <p>Cytotoxic molecules like perforin and granzyme</p> Signup and view all the answers

    Which statement best describes the 'rule of 10' in cleft surgery?

    <p>Surgical correction should occur around 10 weeks of age with a hemoglobin level of at least 10 g/dL</p> Signup and view all the answers

    How does excessive vertical growth in dental development relate to orthodontic treatment?

    <p>It can result in open bite formation</p> Signup and view all the answers

    What is a principal consideration when planning orthodontic surgery for patients with cleft lip and palate?

    <p>Orthodontic interventions should be delayed until growth is complete</p> Signup and view all the answers

    What is a notable feature of a submucous cleft palate?

    <p>Presence of a bifid uvula</p> Signup and view all the answers

    Which syndrome is commonly associated with cleft lip and palate anomalies?

    <p>Pierre Robin anomaly</p> Signup and view all the answers

    At what stage of foetal development does the failure of fusion leading to cleft lip typically occur?

    <p>Week 9-10</p> Signup and view all the answers

    What is the prevalence ratio of cleft lip and palate between males and females?

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

    Study Notes

    Facial Growth

    • Facial growth begins around week 4-5 with swellings around the primitive mouth (stomodeum).
    • Maxillary and mandibular swellings develop from the first pharyngeal arch, appearing laterally on each side of the stomodeum.
    • Mandibular swellings define the lower border, and the frontonasal process forms the upper border of the stomodeum.
    • Maxillary swellings also form the upper border of the stomodeum.
    • Maxillary swellings grow forward and fuse at the midline.
    • The nasal placode forms two thickenings on the frontonasal process.
    • Failure of maxillary swelling fusion results in unilateral or bilateral cleft lip.
    • Fusion of maxillary and mandibular swellings forms the cheeks, reducing mouth width.

    Palate Formation

    • The intermaxillary process gives rise to the primary palate and the anterior part of the palate (including four incisors).
    • The nasal septum also forms part of the palate.
    • Thin extensions form in the inner wall of the maxillary process, leading to the palatine shelves.
    • Palatine shelves initially appear on either side of the tongue.
    • The palatine shelves rotate upwards to the midline as the tongue lowers.
    • Palatine shelves fuse to each other and to the primary palate.
    • The lower border of the nasal septum fuses with the palate.

    Bone Formation and Growth

    • Bone can form through two methods: intramembranous and endochondral ossification.
    • Intramembranous ossification forms bones like the calvarium, facial bones, and most of the mandible, and clavicle.
    • Endochondral ossification involves replacement of cartilage by bone, and occurs in structures like the condylar cartilages of the mandible.
    • Bones of the face and skull join together via sutures.
    • Bony growth within sutures responds to forces that separate bones.
    • Growth can cause bone mass to shift relative to neighboring bones, leading to displacement.
    • Remodelling and displacement often occur simultaneously in the same bone.
    • Cartilage in the mandibular condyle differs from other body cartilage; it is susceptible to changes as related to other facial structures.

    Control of Craniofacial Growth

    • Genetic factors play a significant role in anteroposterior growth compared to vertical growth.

    Growth Theories

    • Sutural theory (Sicher): Sutures have inherent growth potential and push bones apart.
    • Cartilaginous theory (Scott): Cartilage is the primary determinant of growth. Transplanting nasal septum cartilage to other tissues results in some growth which would further suggest that growth is a cartilage-driven process.

    Functional Matrix Theory

    • The functional matrix theory (Moss) suggests growth involves a mechanism related to capsular and periosteal matrices.
    • Genetic control in soft tissues drives the size and shape of bones.
    • Periosteal matrices include features such as teeth, muscles, blood vessels, and nerves.
    • Capsular matrix includes organs.

    Postnatal Craniofacial Development

    • As the face enlarges, growth progresses forward and downward.
    • The calvarium (skull), cranial base, and facial bones (maxilla and mandible) grow at different rates, completing growth by approximately age 7.
    • Facial growth slows down during puberty.
    • Maxillary growth displays a growth pattern that is similar to neurally-driven growth, with a noticeable decline by age 12.
    • The maxillary complex generally grows downward and forward until age 7.
    • Changes are caused by drift and remodeling of the hard palate, as well as vertical development of the alveolar process as teeth erupt and root development.
    • Palatal sutures exhibit displacement of maxillary halves, with growth basically ceasing at age 12

    Growth in Children

    • Facial growth continues from birth until 12 years old.
    • The mandible often follows somatic growth (overall body growth), impacting vertical height.
    • The mandible's position is influenced by tongue, causing growth in width and length.
    • Growth occurs in children in a 2-3mm manner in the mandibular body that doubles in puberty.
    • Facial growth doesn't fully stop.
    • Bone maturation in hand-wrist radiographs correlates poorly with jaw growth, but assessment via cervical vertebrae improves this correlation.

    Cleft Lip and Palate

    • Cleft lip and palate develops between 6 and 12 weeks.
    • Fusion of palatal shelves, development from both frontonasal and pharyngeal arches is involved
    • The primitive palate arises from the intermaxillary process.
    • Muscles of the soft palate originate from the 4th pharyngeal arch.
    • Failure in fusion of palate processes results in cleft palate (unilateral or bilateral).
    • Incomplete clefts are limited to hard or soft palate, or exhibit a bifid uvula.
    • Cleft lip represents a failure of the fusion of medial nasal processes and maxillary processes.
    • Nasal processes may fail to properly fuse with each other, or with lateral nasal processes.

    Cleft Epidemiology

    • Cleft lip and palate occurs in 1 in 700 UK births.
    • Cleft palate is more common in females than males.
    • Cleft lip prevalence is slightly higher in males than females
    • Non-syndromic clefts are more common than syndromic/genetic cases (81% of lip cases, 70% of palate)

    Cleft Diagnosis and Management

    • Prenatal diagnosis of cleft lip can be observed in 81% of cases before birth, however cleft palate is much harder to detect
    • Treatment involves lip repair (6-12 weeks), and palate repair (6 months).
    • The timing of treatment involves intervention via alveolar bone grafting (10 years old), definitive orthidontic treatment (12-14 years old), and orthognathic surgery (17-20 years old), followed by nasal revision surgery, if necessary.
    • Orthodontic procedures are planned following lip and palate repairs.

    Clinical Cleft

    • Cleft lip and palate is an anatomical anomaly arising from fusion failure in the dentofacial development process.
    • It frequently contributes to 65% of oral anomalies occurring among a broader range of issues in the head and neck region.
    • This occurrence has a high prevalence in Asian communities.
    • Family history is a relevant factor, increasing risk.

    Viral Infections

    • Viruses are infectious at all stages of disease development.
    • Viral taxonomy is crucial in categorizing and understanding viruses.
    • Viral structures encompass helical, spherical, and complex geometries.
    • Viruses are reliant on cellular structures for replication.
    • Examples of common childhood viral infections include common colds, influenza, COVID-19, measles, mumps, rubella, chickenpox, and herpes simplex virus.
    • Some viral infections can transform into a chronically active state (e.g., CMV, influenza).

    Viral Pathogenesis

    • Viruses attach to specific receptors on host cells to initiate infection.
    • Viral genetic material enters the host cell's machinery, overriding cellular processes to reproduce viral components.
    • Newly assembled viral components gather within the host cell.
    • Host cells rupture, releasing virions that can infect other cells.
    • Viral DNA can integrate into the host cell's DNA to cause a latent or chronic carrier state.
    • The body's immune responses involve both innate and adaptive responses to infection.
    • Cellular responses to infection include production of interferons, antiviral proteins, apoptosis, autophagy, and cytotoxic T cell activation.
    • Viral replication can take place promptly, sometimes causing immediate acute symptoms (e.g. fever, rash, cough).
    • In some cases, viral infections may lead to chronic infections and/or complications (i.e., pneumonia, encephalitis).
    • Common viral infections may sometimes cause a post-viral state (e.g., fatigue, memory impairment, etc).

    Viral Infection Course

    • Viral entry into the body commonly occurs through mucosal surfaces such as the respiratory, digestive, or urogenital tract, or through skin breakage, or through direct injection.
    • The incubation period marks the time between viral entry and the onset of symptoms. During this time the virus is replicated within host cells.
    • The prodromal phase is characterized by nonspecific symptoms, such as fever, malaise, and body aches.
    • The acute phase is marked by the development of specific, virus-related symptoms which are dependent on the strain of virus (i.e., measles cough, respiratory distress etc).
    • Once the infection has resolved, there's either an eventual recovery or the chronic persistence of the virus within the host.

    Immunity and Memory

    • Adaptive immunity, including B and T cells, provides long-lasting immunity to specific viral threats via memory responses.
    • Recognition of pathogens triggers early immune responses via receptors such as Toll-like receptors (PRRs).
    • Infected cells release interferons, which activate nearby cells to produce factors that inhibit viral replication.
    • Natural killer (NK) cells identify and destroy infected cells based on surface marker changes.

    Other Genetic and Medical Conditions

    • These notes explore genetic disorders such as cystic fibrosis.
    • Other conditions are duchenne muscular dystrophy, sickle cell disease and different genetic disorders.
    • Pharmacogenomics is implicated in drug metabolism and effects (how the body processes drugs dependent on genes).

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    Facial Growth PDF

    Description

    This quiz explores the processes of facial growth and palate formation, focusing on the development stages starting from the primitive mouth. Key concepts include the roles of maxillary and mandibular swellings, as well as the implications of fusion failures. Test your understanding of embryology in the context of facial structure.

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