Summary of Infections and Immune Responses

Infections and Pathogenic Biota

• Infections Occur: When infectious agents invade host tissues.
• Pathogenic Biota: Microorganisms that can cause disease.

Endogenous Infectious Agents

• Source: They originate from the host's own microbiota.

Normal Biota Colonization

• Colonization Timing: The human body is colonized by normal biota at birth.
• Location: Resident biota is commonly found in various body sites, including the skin, gut, and mucosal surfaces.

Microbial Antagonism

• Definition: The effect where normal microbiota protects against pathogens by competing for resources and habitats.

Pathogens

• Opportunistic Pathogens: Pathogens that cause disease when the host's defenses are compromised.
• True Pathogens: Microorganisms capable of causing disease in healthy hosts.

Pathogen Entry Points

• Common Entry Points: Most pathogens enter the body through mucous membranes, skin breaks, or respiratory tract.

Infectious Agents

• Types: Agents can be endogenous (from inside) or exogenous (from outside).

Phagocytosis

• Definition: A process where cells engulf and digest microorganisms as a part of the immune response.

Symptoms and Disease Evaluation

• Symptom: A subjective indication of disease experienced by the patient.
• Objective Indications: Observable signs of disease assessed by a healthcare provider.

Disease Transmission

• Vectors of Transmission: Animals or people who carry and transmit a disease to others.

First Line of Defence

• Components: Physical barriers (skin), chemical barriers (secretions), and normal flora that prevent pathogen entry.