University:
High School
Course:
High School Biology
Academic year:

2019
Views:

342

Pages:

9
Author:

StellarStrategist

Nonspecific Defenses Infectious Disease • A disease caused by a pathogen – Pathogen – a biological agent that causes disease • Types of Pathogens – – – – – Viruses (H1N1 – influenza) Bacteria (streptococcus) Protists (giardia) Fungi (athlete’s foot) Animal parasites (tape worm) Disease Transmission • How diseases are passed from one to another – Airborne – travels through the air & enters through respiratory system – Direct contact – transferred by touch or contact with objects – Bodily fluids – contact with the saliva, blood, mucus or other fluids of infected person – Food borne – transferred in food – Vector – an organism that directly transfers pathogens (mosquitoes) The Human Immune System • Functions: – Fights off invading pathogens – Prevents the spread & growth of cancers • Parts: – – – – – – White Blood Cells Bone marrow Thymus Lymph nodes Tonsils & adenoids Spleen • Organized into two sections – Non-specific and specific Non-Specific Defenses • Protects body against any pathogen • 2 Types of Nonspecific Defenses: – First Line of Defense (External) – Barriers that keep pathogens out – Second Line of Defense (Internal) – Prevents infection from spreading 1st Line of Defense (External) • Types : – Skin – covers the outside of the body – Skin secretions – contain toxic chemicals that kill pathogens • Sweat, oil, wax – Mucous membranes – line the surface of all openings into the body – Mucus – traps pathogens • secretions of the mucous membranes – Cilia – hair like structures on cells that can trap pathogens 2nd Line of Defense (internal): White Blood Cells • Phagocytic cells – WBCs that “eat” pathogens (through endocytosis) – *Macrophages – consume & destroy any pathogen and cellular debris – Neutrophils – consume & destroy any pathogen – Natural Killer cells – attack cells that have already been infected 2nd Line of Defense (Internal): Inflammatory Response Inflammation – brings more blood to the location of entry (therefore, more WBC) 2nd Line of Defense (Internal): Fever • Increase in overall body temperature – Stimulates body’s immune defenses – Slows growth of bacteria – Promotes actions of WBCs • Note: Extremely high fevers can damage tissues & enzymes