6.4 The body’s response to TB Flashcards
what is TB?
a contagious disease cause by the bacterium Mycobacterium tuberculosis
what conditions encourage the rapid spread of the disease?
poverty and cramped living conditions
why have the number of TB cases fallen?
better living conditions and the development of antibiotics
what are the two phases of TB?
primary infection and active tuberculosis
how does the immune system respond to the primary infection of TB?
macrophages engulf the bacteria. a granuloma forms. these tissue masses are anaerobic and have dead bacteria and macrophages in the middle and are called tubercules
what allows TB to survive the immune response?
the bacteria can survive inside macrophages due to the thick waxy cell walls
how do TB bacteria suppress the immune system?
it can suppress T cells which reduces antibody production and attack by T killer cells
in what circumstances does active TB occur?
compromised immune system
what does active TB do in the lungs?
bacteria multiply and destroy the lungs tissue
what are the symptoms of active TB?
coughing blood, shortness of breath, weight loss and fever
what causes a fever?
fever-causing substances are released from neutrophils and macrophages. these chemicals affect the hypothalamus
what is the benefit of a fever?
it enhances immune function and phagocytosis
what is glandular TB?
when lymph nodes become infected
what is the main symptom of glandular TB?
enlarged lymph glands
what can be used to diagnose TB?
skin and blood tests
why is a skin test not always reliable?
it can give a negative result if the person has latent TB or if the person has had a BCG anti-TB vaccination
how are bacteria identified?
a sample of sputum is taken and cultured to see what bacteria are present. different bacteria can be identified using staining techniques
what does x-raying the chest of a TB patient show?
the extent of the damage and disease in the lungs
