Transcript Topic 6.4 Tuberculosis Powerpoint File

The Body’s Response to
Tuberculosis
Topic 6.4
Specification- topic 6
 11 Explain how bacterial and viral infectious
diseases have a sequence of symptoms that may
result in death, including the diseases caused by
Mycobacterium tuberculosis (TB) and Human
Immunodeficiency Virus (HIV).
Meet the PathogenMycobacterium tuberculosis
Features of bacterium
 List the features of a bacterium
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Peptidoglycan cell wall
Cell membrane
Cytoplasm
Mesosomes
ribosomes
Circular chromosome
capsule
Plasmids
Flagella
Pili
 What do the ones in yellow have in common?
Infection
 Infection:
 The invasion and multiplication of microorganisms such as
bacteria, viruses, and parasites that are not normally
present within the bodyhttp://www.medicinenet.com/script/
 With TB, the site of the primary infection in the alveoli in
the lungs
 Watch the following animation:
 https://www.youtube.com/watch?v=202hkf43HXQ
Transmission
 Contagious: can be transmitted from person to
person.
 How is it transmitted?
 carried in droplets of mucus or saliva spread while
talking, sneezing, coughing, etc.
Primary Infection
 Describe the steps involve in the primaryinfection starting from the mode of
entry to the body.
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Infection starts when bacteria in droplets of mucus or saliva are inhaled
Bacteria implants in the lungs
Presence of bacteria triggers an immune response
Inflammatory responseInflammation is
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Triggered by histamine released by cells
This increases the amount of tissue fluid, more white blood cells in the area
Macrophages engulf bacteria and move into lymph nodes in the lungs
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and the M.Tuberculosis may be destroyed
Or a granuloma forms, a mass of tissue composed of immune cells, to contain the infection
and prevent spreading.
 Bacteria and immune cells in the centre of granuloma may die due to lack of oxygen,
this is now called a tubercule or bacteria may remain in a dormant state contained
inside tubercule- Q 6.37
 Heals after several weeks, most people don’t have any symptoms
 Can be diagnosed with a blood test for T-cells specific for M.tuberculosis
antigens or possibly with chest X-rays. (gas filled spaces are black)
Evasion of immune system
 The bacterium can survive in macrophages and
evade the immune system.- lie dormant. Why?
 They have a very thick, waxy cell wall which protects
them from the enzymes in the macrophages.
 The waxy cell wall contains peptidoglycan, but is over
60% lipids, mainly mycolic acid, this affects
permeability of the lysozymes
 T cells are suppressed so fewer or no antibodies can
be produced by B cells
 Explain the point above T helper cells are needed to produce cytokines and
activate B cells
Active TB
 https://www.youtube.com/watch?v=IGZLkRN76Dc
 Read p110-Active tuberculosis
 Which two conditions lead to primary infection resulting in active
TB?
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Dormant TB becomes active due to suppressed immune system.
The number of bacteria are too great.
 Who might have a compromised immune system?
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Very young, old, other infections or diseases (HIV positive)
 What is an opportunistic infection:
 takes opportunity when one’s immune system is weak.
Active TB
 What happens during respiratory pulmonary
tuberculosis?
 Bacteria can multiply and cause cavities to form in lung
tissue.
 Untreated it will lead to death.
 Q 6.33
 What are the symptoms?
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Coughing or coughing up blood
Trouble breathing
Lethargy
Fever
Weight loss or loss of appetite
Fever
 What is the role of the thermoregulatory center in
the hypothalamus of the brain? Describe in detail
how it does this.
 Being too warm leads to sweating, hairs lie flat due
to relaxation of the hair erector muscles,
vasodilation to increase blood flow to the skin.
 Too cold causes the hair to stand up and trap more
air, insulation, no sweating, vasoconstriction to
decrease blood flow near the skin, shivering,
increase in metabolic rate.
Fever- explained
 Caused by pyrogens, chemicals released by some white blood cells
 Raises the thermostat- the temperature our body is set to remain at
a higher temperature than 37 degrees Centigrade
 Inhibits growth of some microbes
 Speeds up reactions, may speed up repair of tissues
 Can facilitate phagocytosis
 Q 6.34
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The enzymes denature
Tertiary structure is altered.
Active site does not fit the substrate
All metabolic reactions are enzyme driven.
Glandular TB
 What is a secondary infection?
 When the TB bacteria spread from lungs to other
parts of the body like the lymph nodes, bones and
CNS
 What is glandular TB?
 When TB bacteria are present mainly in the lymph
nodes which are a type of gland.
 What is a common symptom?
 Swollen lymph nodes in neck or armpits
Diagnosis
https://www.youtube.com/watch?v=XBFCsglP2Xo
 Describe Skin test: tuberculin injected,
swelling shows presence of
antibodies
 Blood test: detect T cells specific to
antigen found on TB
 X-rays: can show damage to lungs or
other areas
Treatment and
Prognosis
 What is the treatment?
 Combination of at least three antibiotics over 6
months
 Rest and healthy diet advised
 Why have cases decreased during 20th century:
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Improved living conditions
Better hygiene
Antibiotics
Pasteurization
Refrigeration
 Activity 6.9