Defence against diseases (c3.2.1)

Apuntes

BODY SYSTEMS IMMUNE SYSTEM Pathogens C3.2.1 Pathogens as the cause of infectious disease A pathogen is a disease-causing agent that disrupts the normal physiology of the host body • Pathogens can be either cellular (living organisms) or non-cellular (infectious molecules) Cellular (living) Acellular (non-living) Parasites Protozoa Fungi Bacteria Viruses Prions Immune System The function of an immune system is to provide protection against pathogenic infections • The immune system is structured into three fundamental lines of defence that work to prevent pathogens from damaging tissues and restore normal health following infection NON-SPECIFIC DEFENCES 1. SURFACE BARRIERS 2. INNATE IMMUNITY • Intact skin • Mucous membranes • Chemical secretions • Phagocytic leukocytes • Inflammation • Fever SPECIFIC DEFENCES 3. ADAPTIVE IMMUNITY • Lymphocytes • Antibodies • Memory cells Surface Barriers C3.2.2 Skin and mucous membranes as a primary defence The first line of defence against infection are the surface barriers that prevent pathogen entry • These can include physical barriers (skin and mucous membranes) and chemical barriers Skin • Protects external st...