Pathophysiology and Stages of Life


Pathophysiology and Stages of Life

Pathophysiology and Stages of Life

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  • Human physiology is the science of the mechanical, physical and biochemical functions of humans in good health, their organs and the cells of which they are composed
  • Pathophysiology is the study of the changes of normal mechanical, physical and biochemical functions, either caused by a disease or resulting from an abnormal syndrome (a collection of signs and symptoms that occur together in response to a certain condition)
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Non-Specific Resistance

  • Offers immediate protection against a wide variety of pathogens and foreign substances
  • Lacks specific responses to specific invaders
  • First line defence - skin and mucous membranes
    • Both mechanical and chemical barriers discourage pathogens and foreign substances from penetrating the body and causing disease
  • Second line defence - internal defences
    • Antimicrobial proteins
      • blood and interstitial fluids contain antimicrobial proteins that discourage microbial growth
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Non-Specific Resistance

  • Natural killer cells and phagocytes
    • if microbes penetrate the skin and mucous membranes and survive the action of antimicrobial proteins in blood, they may be attacked by natural killer T cells or phagocytes
  • Inflammation
    • Initiated by cells damaged by microbes, physical agents or chemical agents
    • Redness, pain, heat, swelling
    • Can cause loss of function in injured area
    • Traps microbes, toxins and foreign material at site of injury and prepares site for tissue repair
    • Helps restore homeostasis
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Non-Specific Resistance

  • Fever
    • An abnormally high body temperature that occurs because the hypothalamic thermostat is reset
    • Commonly occurs during infection and inflammation
    • Many bacterial toxins elevate body temperature
    • Elevated body temperature:
      • inhibits the growth of some microbes
      • speeds up body reactions that aid repair
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Specific Resistance (Immunity)

  • The ability of the body to defend itself against specific invading agents such as bacteria, toxins, viruses and foreign tissues
    • Substances that are recognised as foreign and provoke immune responses are called antigens
  • Two properties distunguish immunity from non-specific defences:
    • Specificity for particular foreign molecules (antigens), which also involves distinguishing self from non-self molecules
    • Memory for most previously encountered antigens such that a second encounter prompts an even more rapid and vigorous response
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Stages of Life

  • A patient's age is important in relation to health and disease
    • neonate (newborn, 0-28 days)
    • infant (baby, 1-11 months)
    • toddler (1-2 years)
    • prepubescent (4-12 years)
    • adolescent (puberty, 13-19 years)
    • adult (20+ years)
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Prenatal Development and Pregnancy

  • Prenatal development: the process in which a baby develops from a single cell after conception into an embryo and later a foetus
  • Embryonic stage: begins after implantation and lasts until 8 weeks after conception
  • Embryonic stage: 3 distinct laters differentiate into different tissues and structures
    • Ectoderm (outer)
      • skin, nails and hair, brain, nervous tissue and cells
    • Mesoderm (middle)
      • muscles, bones, heart, lungs, reproductive organs, lymph
    • Endoderm (inner)
      • lining of lungs, bladder, digestive tract
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Pregnancy and Medication

  • Sometimes medicine a pregnant woman is taking can enter the foetus causing damage or birth defects
  • Risk of damage to a foetus is greatest in the first few weeks of pregnancy when major organs are developing
  • We don't know if taking medicines during pregnancy will have negative effects on the baby later
  • No medicines have been proven absolutely safe to take when pregnant
  • Example: Thalidomide tragedy
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Children and Medication

  • Children (particularly neonates) differ from adults in their response to drugs
  • Risk of toxicity is increased in children by:
    • inefficient renal filtration
    • relative enzyme deficiencies 
    • differing target organ sensitivity 
    • inadequate detoxifying systems causing delayed excretion
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Children and Medication

  • Children may experience adverse drug reactions because:
    • The action of drugs in children may be different from that in adults
    • Drugs are not extensively tested in children
    • Suitable formulations may not be available to allow precise dosing in children
    • Many drugs are not specifically licensed for use in children
    • The nature and course of illness and adverse drug reactions may differ between adults and children
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Childhood Diseases

  • Nearly all the diseases in this list can also be contracted by adults, and children can contract diseases not categorised as childhood diseases
  • Asthma
  • Chicken pox
  • Croup
  • Measles
  • Mumps
  • Whooping cough
  • ADHD
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Ageing (Senescence)

  • Senescence or biological aging is the change in the biology of an organism as it ages after its maturity
  • In general, aging is characterised by the declining ability to respond to stress, increased homeostatic imbalance, and increased risk of aging-associated diseases
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Ageing - Biological Changes

Aging-Associated Diseases

  • Aging-associated disease: a disease that is seen with increasing frequency with increasing senescence
  • Aging-associated diseases are to be distinguished from the aging process itself because we all age but we do not all experience aging-associated diseases
  • Cardiovascular disease - common cause of death in the elderly
  • Cancer
  • Arthritis
  • Cataracts
  • Osteoporosis
  • Type 2 diabetes
  • Alzheimer's disease
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The Elderly and Medication

  • Elderly patients often receive multiple drugs for their multiple diseases, which increases risk of drug interactions, adverse reactions and non-compliance
  • Balance of benefit and harm of some medicines may be altered in the elderly
  • Elderly patients may have difficulty swallowing tablets
  • Normal ageing may be mistaken for disease 
  • Ageing systems = increased susceptibility to drugs
  • Aged patients excrete drugs slowly
  • Drug dosage is commonly started at 50% of adult dose
  • Some drugs should be avoided altogether in the elderly
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Pathophysiology Terminology

  • A disorder is any derangement or abnormality of function
  • Disease is a more specific term for an illness characterised by a recognisable set of signs and symptoms
    • a local disease affects one part or a limited region of the body
    • a systemic disease affects either the entire body or several parts of it
  • Diseases alter body structures and functions
  • A person with a disease may experience
    • symptoms: e.g. headache or nausea
    • signs: e.g. swelling, rash, fever, paralysis
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Diagnosis of Disease

  • Diagnosis is the science and skill of distinguishing one disorder or disease from another
  • A diagnosis is made on:
    • the patient's signs and symptoms
    • his/her medical history
    • a physical examination
    • laboratory tests
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Medical History

  • Taking a medical history consists of:
    • Collecting information about events that may be related to a patient's illness, including:
      • the chief complaint
      • history of present illness
      • past medical problems
      • family medical problems
      • social history
      • review of symptoms
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Physical Examination

  • A physical examination is an orderly evaluation of the body and its functions
  • This process includes:
    • inspection
    • palpitation
    • auscultation
    • percussion
    • measuring vital signs
    • laboratory tests
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  • Pathology is the laboratory study of cell and tissue changes associated with a disease
    • Biopsy: surgical speciman
    • Autopsy: exam after death
  • Idiopathic - cause of disease is unknwon
  • Etiology: causative factors of a disease
    • congenital
    • genetic
    • microorganism
    • metabolic dysfunction
    • burns
    • nutritional deficiency
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Predisposing Factors and Prevention

  • Predisposing factors
    • are tendencies that promote development of a disease in an individual
    • they indicate a risk, not certain development
    • include age, gender, diet, occupational exposure, genetic
  • Prevention of a disease may include
    • vaccine
    • dietary and lifestyle modifications, e.g. stop smoking
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  • Pathogenesis: the development of a disease or sequence of events involved in tissue changes related to a disease process
  • Acute: sudden short term illness with marked signs
  • Chronic: milder condition but persists for a long time
  • Sub-clinical: pathological change occurs but no obvious manifestations are exhibited by the patient
  • Latent: silent, no clinical signs, incubation period
  • Prodromal: the time in early development of the disease where the patient is aware of some changes but the signs are non-specific, e.g. fatigue, loss of appetite
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  • Manifestation: clinical evidence or effects of a disease
  • Local: found at site of problem
  • Systemic: general indication of disease, e.g. fever
  • Lesion: specific tissue change
  • A lesion can be: a microscopic change or things like a blister
  • Diagnostic test is a laboratory test that can assist in diagnosis, measuring progress of recovery and confirm that a patient is free from a disease
  • Remission: manifestations of disease subside
  • Exacerbations: manifestations of disease increase
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  • Precipitating factor: something that triggers an accute episode, e.g. pollen
  • Complication: additional problems that arise after the original disease begins
    • disease can become worse or show more signs, symptoms or pathological changes, become widespread throughout the body or affect other organ systems
    • a medical treatment may produce adverse effects itself
    • a new disease may also appear as a complication
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  • Therapuy/therapeutic intervention: measures that promote recovery or slow disease progress
  • Types of therapy:
    • preventative/prophylactic therapy - intended to prevent a medical condition, e.g. vaccines
    • abortive therapy - intended to stop a medical condition from progressing any further, e.g. treatment at beginning of migraine headache
    • supportive therapy - increases patient's comfort
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  • Convalescence - period of recovery and return to normal state
  • The later stage of an infectious disease or illness when the patient recovers and returns to normal, but may continue to be a source of infection even if feeling better
  • Prognosis: probability of recovering from a disease
  • Morbidity: disease rates within a group
  • Mortality: relative numbers of deaths resulting from a particular disease
  • Epidemiology: the science of trafficking pattern and occurrence of diseases, e.g. flu
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  • Epidemic: many cases of infectious disease in a given area
  • Pandemic: high number of cases over several areas/worldwide
  • Incidence: number of new cases within a given stated time period
  • Communicable disease: infections that can be spread from one person to another
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