Determinants of Health and Disease

1
Determinants of Health and Disease
2
What Determines Good Health?

• Good physical health
• Mental health if you believe
• that youre not healthy you are
• more susceptible to getting sick.
• Spiritual people who are
• religious/spiritual tend to be
• more upbeat, positive, optimistic
• etc

3
Terms Associated with Disease

• Pathogenic disease causing
•  
• Opportunistic pathogen is
• generally harmless in its normal
• habitat but can become pathogenic
• in a host who is seriously
• debilitated or has a weak immune
• system.
• Ex. pneumocytsis carnii will cause pneumonia
  in AIDS patients
•  
• Virulent Has a very high degree
• to cause infection
• Ex. Ebola (80 mortality)

4
Virulent Application

• Which is more virulent?
•  
• E. coli 0157H7 pathogen
• (found in burgers at Jack-
• in-the-Box)
• or
• E. coli in Felixs gut
• Note E. coli in Felixs gut is an
• opportunistic pathogen. Has the ability
• to cause an infection but it has to be in
• the right conditions/environment like a
• sterile site.

5
Portal of Entry

• The area in which a
• microorganism enters the
• body. They may be cuts,
• lesions, injection sites, or
• natural body orifices
• Four major pathways
• Skin
• Mucous membranes
• Placenta
• Parenteral route

6
Exposure to Microbes Contamination and
Infection

• Contamination the mere presence of microbes in
  or on the body
• Infection results when the organism has evaded
  the bodys external defenses, multiplied, and
  become established in the body

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Portals of Entry

• Skin
• Outer layer of packed, dead, skin cells usually
  acts as a barrier to pathogens
• Some pathogens can enter through openings or cuts
  
• Others enter by burrowing into or digesting the
  outer layers of skin

8
Portals of Entry

• Mucous membranes
• Line the body cavities that are open to the
  environment
• Provide a moist, warm environment that is
  hospitable to pathogens
• Respiratory tract is the most common site of
  entry entry is through the nose, mouth, or eyes
• Pathogens able to survive the acidic pH of the
  stomach may use the gastrointestinal tract as a
  route of entry

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The Movement of Microbes into Hosts Infection
INSERT TABLE 14.4
10
Differentiate Disease and Infection

• Diseases
• Cystic fibrosis
• Cancer
• Diabetes
• Cardiovascular heart disease (CHD)
• Mental diseases (depression)
• Alcoholism
• Autoimmune (Lupus)

• Infection
• Cellulitis (pyoderma)
• pharyngitis
• conjuctivitis
• pneumonia
• cystitis
• otitis media
• vaginitis
• Colitis
• Gastritis
• encephalitis

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Disease

• A harmful alteration
• of host tissues (arthritis) or
• metabolic processes
• (Diabetes/hyperglycemia.)

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The Nature of Infectious Disease

• Causation of Disease Etiology
• Study of the cause of disease
• Germ theory of disease disease caused by
  infections of pathogenic microorganisms
• Robert Koch developed a set of postulates one
  must satisfy to prove a particular pathogen
  causes a particular disease

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The Nature of Infectious Disease
INSERT TABLE 14.7
14
The Nature of Infectious Disease
INSERT TABLE 14.6
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Infection

• Entry, manifestation,
• proliferation of an
• infectious agent within a
• host.
• Infectious agent has to
• enter, begin to grow and
• continue grow in host
• tissues.

16
Infectious Agents Linked to Malignancies

• Infectious diseases have
• been linked to other
• Diseases
• HPV ? cervical cancer
• H. Pylori ? gastric cancer
• Hepatitis B ? liver cancer

17
Infectious process

• Microorganism must enter host
• tissues.
• Microorganism must establish itself
• and begin to propagate (grow)
• Microorganism must have access to
• Nutrients
• If one of these three processes is not
• met an infection will not manifest
• In host tissues.
• Ex. HIV needs nutrients (T4 helper) in order to
  propagate.

18
Intoxication

• Effects on the body by a
• toxin produced by a
• biological agent.
• Enterotoxin F is produced by
• Staphylococcus aureus,
• causes toxic shock syndrome.

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Intoxication Versus Infection

• Difference Between food Poisoning and Foodborne
  Infecton
•  
• Condition
  Time until sick Length (process)
  Symptoms  
• Intoxication by S. aureus 4 hours
  24 hours
  Vomiting
• food poisoning)
•  
• Infection by Salmonella 3-14
  days until treated
  Cramps
• (food borne illness)
  
  Fever Diarrhea
• Dehydration
• Tenesmus
• Stool sample is taken to look for infectious
  agent then treated with antibiotics.
• 
  

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Attack of the Pathogens

• A pathogen (infectious agent) or
• (more commonly) germ, is a
• biological agent that causes disease
• or illness to its host.
• There are several molecules that
• microorganisms produce that allows
• invasion into tissues or a means to
• exert its pathological affect on the
• body.

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Virulence Factors

• Virulence factors are molecules
• expressed and secreted by pathogens
• (bacteria, viruses, fungi and protozoa)
• that enable them to achieve the
• following
• colonization of a niche in the host (this
  includes adhesion to cells)
• evasion of the host's immune response
• entry into and exit out of cells (if the pathogen
  is an intracellular one)
• obtain nutrition from the host.

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Virulence Factors of Infectious Agents

• Pathogenicity ability of a microorganism to
  cause disease
• Virulence degree of pathogenicity
• Virulence factors contributing to an organisms
  virulence
• Adhesion factors
• Biofilms
• Extracellular enzymes
• Toxins
• Antiphagocytic factors

23
Virulence Factors

• Virulence factors are very
• often responsible for causing
• disease in the host as they
• inhibit certain host functions.
• Pathogens possess a wide
• array of virulence factors.
• Some are intrinsic to the
• bacteria (e.g. capsules and
• endotoxin) whereas others
• are obtained from plasmids
• (e.g. some toxins).

24
Virulence Factors
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The Role of Adhesion in Infection

• Process by which microorganisms attach themselves
  to cells
• Required to successfully establish colonies
  within the host
• Uses adhesion factors
• Specialized structures
• Attachment proteins

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Virulence Factors of Infectious Agents

• Toxins
• Chemicals that harm tissues or trigger host
  immune responses that cause damage
• Toxemia refers to toxins in the bloodstream that
  are carried beyond the site of infection
• Two types
• Exotoxins
• Endotoxins

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Endotoxins

• The endotoxin is the lipopolysaccharide
• (LPS), which is part of the bacterial cell
• wall of Gram-negative bacteria.
• It is the Lipid A component of the
• LPS that has the toxic properties.
• The LPS is a very potent antigen and,
• as a result, stimulates an intense host
• immune response. As part of this
• immune response cytokines are
• released which cause the fever and
• other symptoms seen during disease.
• If a high amount of LPS is present then
• septic shock (or endotoxic shock) may
• result which, in severe cases, can lead
• to death.)

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Exotoxin

• Exotoxins, on the other hand, are
• actively secreted by some bacteria and
• have a wide range of affects including
• inhibition of certain biochemical
• pathways in the host.
• The two most potent exotoxins known to man
• are the tetanus toxin (tetanospasmin) secreted
• by Clostridium tetani and the botulinum toxin
• secreted by Clostridium botulinum.
• Exotoxins are also produced by a range of
• other bacteria including Escherichia coli
• Vibrio cholerae (causative agent of cholera)
• Clostridium perfringens (causative agent of
• food poisoning as well as gas gangrene) and
• Clostridium difficile (causative agent of
• pseudomembranous colitis).

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The Nature of Infectious Disease
INSERT TABLE 14.8
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Comparison of Toxins
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Enzymes

• Microorganisms can producenumerous
• enzymes (proteins that break down
• substances)
• Lipase breaks down oleic acids which has many
  antimicrobial properties and protects our skin.
• Produced by Staphylococcus
• Coagulase coagulates plasma
• produced by Staphylococcus aureus
• Hyaluronidase known as spread factor.
  Hyaluronic acids holds cells together and
  Hyaluronidase destroys the cement that holds the
  tissues together.
• Produced by Streptococcus pyogenes and
  Staphylococcus aureus

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Virulence Factors of Infectious Agents

• Extracellular enzymes
• Secreted by the pathogen
• Dissolve structural chemicals in the body
• Help pathogen maintain infection, invade further,
  and avoid body defenses

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The Body Fights Back

• The body contains many natural
• orders of defense against some of
• the common pathogens in the form
• of the human immune system and by
• some "helpful" bacteria present in the
• human body's normal flora.

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Defense Mechanisms of the Host
Figure 14.1
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Non specific physical barriers

• Skin (largest organ of the body)
• Mucous membranes openings to body (ears, mouth,
  anus, urethra)

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Barriers at the Portal of Entry A First Line of
Defense
Figure 14.2
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Flushing Mechanism

• Sneeze
• Cough
• Lacrimation (tears)
• Sweat
• Ear wax
• Salivation
• Defecation
• Peristalsis movement of food material in the
  intestinal tract

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Figure 14.3
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Nonspecific Chemical Defenses

• Sebaceous secretions and specialized glands-
  antimicrobial
• Lysozyme in tears
• Lactic acid and electrolyte concentrations of
  sweat
• Skins acidic pH and fatty acid content
• HCl in the stomach
• Digestive juices and bile in the intestine
• Semen- antimicrobial chemical
• Acidic pH in the vagina

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Complement

• Complement cascade
• entire immune system is
• turned on
• Functions neutralizes
• viruses, enhances
• phagocytosis, damages
• plasma membrane, can
• destroy (lyse)
• microorganism

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Complement A Versatile Backup System

• At least 26 blood proteins that work in concert
  to destroy bacteria and certain viruses
• Cascade reaction
• Three different pathways that all yield similar
  end results
• Classical pathway
• Lectin pathway
• Alternative pathway

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Interferon

• Antiviral properties good in
• fighting cancer and viruses
• Body produces minute amounts
• Interferes with transcription
• and translation of mRNA

43
Interferon Antiviral Cytokines and Immune
Stimulants

• Interferon (IFN) involved against viruses,
  other microbes, in immune regulation and
  intercommunication
• Three major types
• Interferon alpha
• Interferon beta
• Interferon gamma
• All three classes produced in response to
  viruses, RNA, immune products, and various
  antigens
• Bind to cell surfaces and induce changes in
  genetic expression
• Can inhibit the expression of cancer genes and
  have tumor suppressor effects

44
Figure 14.18
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Non specific biological barriers

• Normal flora bacteria or
• plants. These organisms are
• with you for your entire life.
• They keep infectious
• pathogens in check.
• Natural resistance resistance
• youve acquired throughout
• your life (adult) Resistance
• acquired from mother (child.)

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The Immune System

• Immunology the study of all features of the
  bodys second and third lines of defense
• Healthy functioning immune system is responsible
  for
• Surveillance of the body
• Recognition of foreign material
• Destruction of entities deemed to be foreign

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Self and Nonself

• White blood cells must distinguish self from
• nonself cells
• Evaluates cells by examining markers on their
• surfaces

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Figure 14.4
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Blood components

• White blood cells
• B lymphocytes
• T lymphocytes