Disease & Disease-Producing Organisms
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Transcript of Disease & Disease-Producing Organisms
Disease & Disease-Producing Organisms
Chapter 5Anatomy & Physiology I
• Any abnormality of the structure or function of a part, organ or system
• Diseases fall into 7 different, but often overlapping categories
• 7 Predisposing factors increase the probability of a person becoming ill
• The study of disease
Disease
• Infection: • Degenerative diseases• Nutritional disorders• Metabolic disorders• Immune disorders• Neoplasms• Psychiatric Disorders
Categories of Disease
Infection
• Believed to play a part in at least 50% of all human illnesses
• Cause:– Many diseases are
caused by infectious organisms
• Example– cold, AIDS, tuberculosis
etc
Degenerative Diseases• Involve degeneration
(breaking down) of tissues in any system of the body
• Causes– Hereditary– Wear and tear– Infection– No known causes
• Example: – Alzheimer,
osteoporosis, and arthritis
Nutritional Disorders• Caused by:– dietary lack (deficiency) of
essential vitamins, minerals, proteins, or other substances
– Excess alcohol, caloric intake• Example– Scurvy – lack of Vitamin C– Rickets – lack of Calcium– Beriberi- lack of thiamine– Kwashiorkor- lack of protein– Goiter: lack of iodine
Nutritional Excesses
Metabolic Disorders• A disturbance in the buildup, breakdown, or excretion
of substances• Causes– Disruption in the reactions of cellular metabolism– Hormone imbalance regulate many metabolic activities– Hereditary errors of metabolism
• Examples– diabetes, – gout (a disorder of the joints), >> uric acid– digestive disorders, and – hereditary dysfunctions.
Immune Disorders• Caused by– Immune deficiencies: The decreased ability of the
body to fight infection and disease. Caused by genetic or infection• Example: AIDS
– Hypersensitivity – overactive immune system• Allergies–Animals, pollen, medicine, nuts etc
• Autoimmune disorders–Example: rheumatoid arthritis, multiple
sclerosis (MS), and systemic lupus erythematosus (SLE)
Neoplasms
• The word neoplasm means “new growth” and refers to cancer and other types of tumors.
• An abnormal and uncontrolled growth of tissues– Benign– Metastatic
Psychiatric Disorders
• A health condition that changes a person’s thinking, feelings, or behavior (or all three) and that causes the person distress and difficulty in functioning
Predisposing Factors
• May not cause a disease, but does increase the probability of a person becoming ill
• Age: measles is more common in children, Alzheimer in elders
• Gender: heart disease to men, diabets to women• Heredity: diabetes, allergies, and certain forms of cancer.• Living conditions & habits: sleep, exercise, diet, drugs,
alcohol, and tobacco • Emotional disturbance: stress, anxiety, anger, sensitivity• Physical & chemical damage – Injuries & chemical exposure• Preexisting illness: high blood pressure or diabetes,
increases one's chances of contracting another disease.
• Pathophysiology:– Is the study of close relationship of each
disease's pathologic and physiologic aspects and the understanding of these fundamentals in treatment.
The Study of Disease
Disease Terminology • Etiology – study of the
cause of disease• Epidemiology: the study of
diseases in populations. Epidemiology statistics include:
• Incidence – The number of new disease cases, occurence and tendency to affect certain groups of individuals more than other groups
• Morbidity – the proportion of a population with a specific disease
• Mortality – the proportion of a population that dies from a given disease
Disease Terminology Cont.• Diseases are classified
based on severity and duration as:– Acute – relatively severe
but last a short time– Chronic – may be less
severe but likely to be continuing or recurring
– Subacute – between acute and chronic diseases
Disease Terminology Cont.• Based on origin:• Idiopathic – disease without known cause• Iatrogenic – disease caused by adverse effects
from medical treatment• Communicable – disease that can be transmitted
from one person to another– Epidemic – many people from a certain region
acquire a certain disease at the same time– Endemic – a disease found to a lesser extent, but
continuously in a particular region– Pandemic – a disease prevalent throughout the world
Example of Endemic Disease: The Goiter Belt in the US
• Medical process – History, including signs and symptoms
• Sign – objective evidence (observed by physician or other healthcare professional
• Symptoms – subjective evidence (conditions noted by the patient). For example: imaging studies, blood tests, and study of tissues removed in biopsy.
• Syndrome – a characteristic set of signs and symptoms that accompany a disease; PMS, AIDS
– Diagnosis – a conclusion as to the nature of the illness– Prognosis – prediction of probable outcome of disease– Therapy – course of treatment
Treatment and Prevention of Disease
Methods of disease prevention or treatment that can be used along with or
instead of traditional modern medical practices
Treatment: Complementary and Alternative Medicine
Alternative Medicine
• Naturopathy: healthy life style• Chiropractic: correcting
misalignment for treatment of musculoskeletal disorder
• Acupuncture: insert needle to relief pain
• Biofeedback: electronic devices monitor changes and feed info back to a person
• Herbal medicine
Disease Prevention
• Modern medicine’s major focus is on treating patients who currently have a disease
• Wellness movement focuses on preventing the occurrence of disease by promoting health
• Health – an optimal physical, mental and emotional state of being, not merely the absence of disease
• Health-promoting practices– Massage– Diet– Exercise– Stress management
Infectious Disease• Invasion of the body by disease-producing
microorganisms• Microorganisms – – Aka microbes, germs– A tiny living thing too small to be seen by the naked eye– Most are harmless, many are beneficial, a few cause illness
(are pathogenic)• Parasite – a living organism that lives on or in a living
host at the host’s expense• Pathogen – disease-producing organism
Types of Infection• Infection – pathological state resulting from
the invasion of the body by pathogenic microorganisms
• Local – infection restricted to a small area• Systemic – infection throughout the whole
body• Opportunistic infection – an infection that
takes hold because the body has been weakened by disease or injury
Modes of Transmission• Direct Contact– Touching – Sexual activity
• Indirect Contact– Touched objects
• Vector – an insect or animal that transmits a pathogen from one host to another (mosquito)
• Atmosphere
Portals of Entry & Exit
• Skin• Respiratory
tract• Digestive
system• Urinary
system• Reproductive
system
The Common Cold• 1 billion Americans “catch” a cold
every year• Leading cause of doctor visits &
missed days of work & school• Caused by over 200 different
types of viruses• One sneeze can send hundreds of
thousands of particles several feet, where they live for 3-6 hours
• To prevent– Avoid close contact– Wash hands– Do not touch your face– Clean surfaces frequently
• Microorganisms- simple, microscopic, usually single-cell, forms of life. The group includes bacteria, viruses, fungi, protozoa, and algae. Book: table 5.1
• Microbiology – The study of these microscopic organisms • Bacteria – single-celled organisms which grow in many
environments• Viruses- composed of nucleic acids & protein; can only multiply
inside of living cells• Fungi – plantlike organisms
– Single celled – yeasts– Filamentous - molds
• Protozoa – single-celled animals – Aka parasites– Includes worms
Microbiology
Microorganisms
• Most are harmless to humans and are essential to all of life on earth
• Normal flora – population of microorganisms that normally grow on or within our bodies – Beneficial – If normal flora are destroyed it can cause
overgrowth of normally harmless bacteria, rendering them pathogenic
Bacteria
• Single celled organisms• One of the most primitive
forms of life on earth• Their genetic material is not
enclosed by membrane• Do not have a true nucleus • Lack most organelles
Bacteria Cont.
• Classification– Aerobic – require oxygen to grow– Anaerobic – grow in the absence of oxygen– Facultative anaerobes – use oxygen if present but are also
able to grow without oxygen – e. coli• Endospores – resistant forms of bacteria that can
tolerate long periods of dryness or other adverse conditions. Endospores can be become airborne– Resistant to ordinary methods of disinfection– Particularly dangerous – tetanus, botulism, anthrax
Bacteria Movement
–Flagella: helps them to swim rapidily–Pili – short “hairs”
that help bacteria to glide across solid surfaces & anchor it to surfaces
Bacteria Cont.
• Largest group of pathogens to humans
• Can divide every 20 minutes or every 24 hours
• Cause damage to humans in 2 ways– Produce toxins– Growing in human
tissues
• Physical barriers – skin, mucus membranes
• Immune system
Human defence mechanism
• Cocci– Diplococci– Streptococci– Staphylococci
• Bacilli• Curved rods– Vibrios– Spirilla– spirochetes
Shape & Arrangement of BacteriaThree groups of bacteria based on their shape
Cocci & Bacilli• Cocci – round – Diplococci – in pairs – causes
gonorrhea, and meningitis – Streptococci – in strings – strep
throat– Staphylococci – in clusters -
pneumonia and fever.• Bacilli – straight rods– All endospore-forming bacteria
are bacilli– TB, typhoid fever, Legionnaire’s
disease
Curved Rods
• Vibrios – short curved rods, like a comma – cholera
• Spirilla – resemble a corkscrew
• Spirochetes – similar to spirilla but capable of waving & twisting motions. Casues syphilis
Obligate Intracellular Parasites
• Bacteria that are much smaller than normal• Also include viruses, which are not bacteria• They only grow within the cells of their hosts • Chlamydia• Ricksettia – Transmitted through insect bites– Rocky Mountain spotted fever, typhus
Viruses• Extremely small in comparison to bacteria: seen by electron
microscope• Have some characteristics of living matter but not all
– Contain genetic material & are able to reproduce• Contain only DNA OR RNA
– Generally made of genetic material surrounded by a protein coat– Are not cellular– Do not have enzyme systems
• Can only grow within a host’s cell (obligate)
Virus size comparison. A chlamydia and a staphylococcus are shown for reference
Viruses
Classifying and naming Viruses
• Classified according to:– type of nucleic acid they have: DNA or RNA– whether that nucleic acid is single stranded (ss) or double
stranded (ds).– The diseases they cause: common cold, hepatitis, measles – where they were isolated : West Nile– the symptoms they cause: yellow fever– the host : Chickenpox, HIV, Swine influenza
Other Agents Smaller than Viruses
• Prions (proteinaceous infectious )-made solely of proteins– Slow growing and hard to destroy– Mad cow disease
• Viroids – Composed solely of RNA with no protein coat– So far have only been discovered to cause plant
diseases
Fungi
• Types – Yeast – single celled– Molds – long &
filamentous• Simple plant-like
organisms– Do not contain
chlorophyll – Grow in dark, damp
places• Very few cause
diseases
Mycotic (Fungal) Infections
• Diseases caused by fungi are called mycotic
• Can affect skin– Ringworm – tinea
corporis or capitis– Athlete’s Foot
• Can affect those with compromised immune systems– Candidiasis
Protozoa• Single-celled animal-like
organisms• Amebas – a “blob” that can move• Ciliates – tiny hairs propel this
organism• Flagellates – a tail propels this
organism• Sporozoa – cannot propel
themselves– Obligate parasites, unable to grow
outside host– Carried by mosquitos– malaria
Protozoa Movement
Parasitic Worms (Helminths)
• Roundworms– Ascaris – intestinal; hard to
control & eliminate– Pinworm – intestinal; hard to
control & eliminate– Hookworms – intestinal; suck
blood & cause anemia; larvae enter body through foot
– Trichinea – live in muscles of animals & people; enter body through undercooked meat
– Filaria – live in lymphatic system
Hookworm
Roundworms Ascaris & Filaria
Filaria Infection
Parasitic Worms (Helminths) Cont.
• Flatworms – Tapeworms – can
be 50 feet long in intestines, spread through undercooked meat
– Flukes – can infect many body parts
Tapeworm
Microbial Control
• Infectious diseases are increasing– Increased population, travel, food processing
• Public health measures help control microbes– Sewage/garbage disposal– Water purification– Prevention of food contamination– Milk pasteurization
Aseptic Techniques & Methods
• Sterilization – kills EVERY living microorganism on an object
• Disinfection – kills all pathogens (except spores) but does not necessarily kill harmless microbes
• Antisepsis – pathogens not necessarily killed but prevented from multiplying
Universal Precautions to Control Infection
• Healthcare workers MUST use barriers for any contact with moist substances, non-intact skin, & mucous membranes –REGARDLESS of whether or not blood is visible & REGARDLESS of a patient’s diagnosis
• Soiled linen and trash are treated as contaminated
• Needles are not recapped after blood draws• Handwashing – goal of 100% compliance
Handwashing
• The single most important measure to prevent the spread of infection in ALL settings
• Gloves are not a substitute for handwashing
Areas Missed During Handwashing
Antimicrobial Agents
• Antibiotics– Penicillin– Danger of opportunistic infections developing due
to loss of normal bacteria– Danger of resistant strains of pathogens developing
• Antiviral agents – very few and they have a limited range of effectiveness– Viruses mutate rapidly to become resistant– Antiviral agents are often used in combinations
Antibiotics