Ch.25 Body defence mechanisms
Terms
Body defence
Protective function of our body against diseases
Non-specific defence mechanisms
Physical barriers
Skin: tough, impermeable barrier
Inner wall of the respiratory tract: closely-packed cells, cilia & mucus
Chemical barriers
Tears and saliva: lysozyme
Sebum (sebaceous gland): antiseptic
Gastric juice: HCl
Vaginal secretion: acidic
Blood clotting
Blood platelets, fibrinogen--> fibrin, trap blood cells-->blood clot
Phagocytosis
Phagocytes engulf, digest pathogens
Inflammatory responses
Arteriole dilation, blood flow and permeability of capillaries increase, more phagocytes squeeze out
red and hot, swollen, pain
Specific defence mechanisms
Lymphocytes
B cells
T cells
Plasma cells
Memory B cells
Antibodies
Lysis of pathogens
Agglutination
Antitoxin: neutralize toxins
Helper T cells
Killer T cells
Memory T cells
lymphokines-->lymphocyte
Kill infected cells directly
Activate other B cells and T cells
Primary vs Secondary response
Vaccination: specificity and immunological memory
Artificial vs Natural Active vs Passive