Immune System Flashcards
Pathogen
Disease-causing agent
Antigen
Specific surface marker on pathogens that can be detected by WBC
Self
Surface marker detected as belonging to the human body
Non-self
Surface marker detected as foreign to the human body
Name 5 types of WBC involved in the immune response
Neutrophils, basophils, eosinophils, lymphocytes, monocytes (differentiate into macrophages and dendritic cells)
Role of neutrophils
First responder to an infection; recognise, engulf and destroy bacteria through phagocytosis
Role of basophils
Release histamine to initiate an allergic response
Role of eosinophils
Destroy parasites as well as assist in allergic response
Role of lymphocytes
Specialised WBC, B & T lymphocytes defend against specific pathogens
Role of macrophages
- NON-SPECIFIC immune response: recognise, engulf and destroy pathogens through phagocytosis and recruit other immune cells to help fight off an infection
- SPECIFIC immune response: present antigens from pathogens to T-helper cells to initiate a specific immune response
What is the main function of the immune system and what are the 3 ways in which this is achieved?
To protect the body against infection
- Prevent entry of pathogens (1st line, innate)
- Trap and destroy any pathogens (2nd line, innate)
- Destroy specific pathogens (3rd line, adaptive)
Describe how the 3 components of the first line of defence protect the body from infection
- Physical barriers: physical structures which prevent entry of pathogens
- Chemical barriers: secreted chemicals which prevent entry of pathogens or destroy pathogens which have entered the body
- Microbiological barrier: presence of natural bacteria (e.g. skin, stomach, vagina) prevent colonisation of pathogenic bacteria due to lack of space and resources
State 5 physical barriers
Intact skin, hairs, ear wax, mucociliary escalator, mucous membranes
Describe 3 ways in which the integumentary system acts as a physical barrier
- Intact skin prevents entry of pathogens, keratin in epidermis makes it waterproof
- Dead cells constantly fall off, removing bacteria
- Hair in nose and other places prevents pathogens from entering respiratory/genitourinary tract
Explain the role of the cardiovascular system in ensuring the skin barrier remains intact
Blood clot formation
1. Blood vessel gets damaged and leaks
2. Vasoconstriction reduces blood flow to the area to prevent blood loss
3. Platelets activate and stick to each other, forming a platelet plug to stop bleeding
4. Coagulation: fibrinogen is converted to fibrin which strengthens clot by trapping platelets and erythrocytes
Explain how ear wax acts as a physical barrier
Ear wax traps pathogens, preventing them from entering into the ears
Explain how the mucociliary escalator acts as a physical barrier
Cilia (hair-like projections) on the walls of the bronchi works together with mucus to trap pathogens and sweep them out of the respiratory system
Explain how mucous membranes act as a physical barrier, including where they are found
They produce mucus which traps pathogens and prevent them from further entering into the respiratory, alimentary and genitourinary tracts
State 5 chemical barriers
Saliva, tears, sweat, sebum, HCl in stomach