Immune and Lymphatic System Flashcards
Pathogens: Bacteria
- No defined nucleus
- Small size
- Single-celled w/ single chromosome and cell wall
- Most harmless or beneficial e.g. probiotics
- E.g. diphtheria, pertussis, tetanus
Pathogens: Virus
- Small intracellular pathogens (only survive and reproduce in host cell)
- Contain DNA
- Protective protein coat
- E.g. influenza A (flu), adenovirus (common cold)
Pathogens: Fungi
- Eukaryotic
- Unicellular or multicellular
- Live on dead plant and animal material
- Dangerous if impaired immunity or systemic (opportunistic viruses attack)
- Has cell wall but no chlorophyll
- E.g. candida albicans, tine pedis
Pathogens: Prion
- Normal proteins that has mis-folded (wrong shape)
- Very stable and are hard for immune systems to attack
- Cause rare diseases e.g. Kuru, Creutzfeldt-Jacob disease
Parasites: Protozoa
- Single-celled eukaryote with no cell wall
- E.g. plasmodium (malaria), giardia lambia (diarrhoea)
Parasites: Helminths
- Worm-like parasites
- 2mm > 1m
- Reproduce sexually in definitive host
- E.g. tapeworms, roundworms, hookworms
Non-Specific Immunity: Physical Barriers - Skin
Skin:
- Skin cells fit tightly together to form a protective layer
- New cells regularly replace dead ones
- Unbroken skin secretes substances that kill bacteria in pores
- Microflora on skin creates an environment where pathogens can’t grow
Non-Specific Immunity: Physical Barriers - Mucous Membranes
- Sticky mucous traps pathogens and other particles
- The more pathogens present, the more mucous produced
Non-Specific Immunity: Physical Barriers - Cilia
Tiny hairs trap debris and beat to move mucous, pushing pathogens from lungs.
Non-Specific Immunity: Chemical Barriers
- HCl in stomach destroys pathogens by rupturing their membranes and DNA due to low pH
- Lysozyme: enzyme that destroys bacterial cell walls, found in secretions like tears
- Alkali in small intestine: destroys acid-resistant bacteria
Non-Specific Immunity: Phagocytosis
- Neutrophils and Monocytes (and macrophages): engulf and digest both small and large pathogens
- Pus consists of dead leukocytes from the body, especially neutrophils which indicates phagocytosis has occurred as part of a response to an infection
Non-Specific Immunity: Inflammation
- Damaged cells and surrounding cells release chemokines (cytokines); bradykinin, serotonin and prostaglandins
- Mast cells are triggered by cytokines or contact with bacteria/puncture weapon and release histamines, allowing more blood to move into affected area from blood vessel (diapedesis) through vasodilation and increased capillary permeability
- Fluid and plasma proteins leak out, causing oedema (swelling)
- Circulating WBCs attracted to area through chemotaxis (migration towards chemical signal)
- Phagocytes clean up area by digesting waste and pathogens
Non-Specific Immunity: Fever
- Phagocytic cells release cytokines (e.g. interleukin 1) causing a change in temp
- When people are febrile, the spleen and liver remove iron from the bloodstream as many pathogens need it to reproduce, so this inhibits their growth
- Fever and inflammation are protective mechanisms that can go out of control and cause harm
Interferons
- Interfere with virus replication
- Proteins produced by T-cells and cells infected by viruses
- Warn surrounding cells to prevention viral replication and spread
- Act as cytokines – boosting and stimulating the activities of natural killer cells, cytotoxic T cells and helper T cells
Complement
- Damage bacteria wall, attract phagocytes
- System of proteins found in the blood and tissues, normally in an inactive form
- Activated by antigen – antibody interactions and foreign sugars on bacteria
- Act by damaging bacterial cell wall, flagging bacteria for phagocytosis and attracts neutrophils and macrophages to the area
Immunoglobulins: IgA
- Defends against bacteria and viruses for short-term protection
- Found in exocrine gland secretions, e.g. saliva, sweat, tears
Immunoglobulins: IgE
- Promotes inflammation and allergic reactions
- May help protect against parasitic worm infections
- Exocrine gland secretions
Immunoglobulins: IgG
- Defends against bacteria viruses, and toxins and activates complement
- Plasma and tissue fluid
- Main antibody in circulation
Naturally Acquired Active Immunity
Natural exposure to live pathogens body builds up immune response with disease symptoms
Artificially Acquired Active Immunity
- Exposure to a vaccine containing weakened or dead pathogens or their components
- Immune response without symptoms
Naturally Acquired Passive Immunity
- Antibodies passed to foetus from pregnant woman with active immunity or to a newborn through breast milk from woman with active immunity
- Short-term immunity for new born without stimulating an immune response
Artificially Acquired Passive Immunity
- Injection of gamma globulin
- Containing antibodies or antitoxin
- Short-term immunity without an immune response
Autoimmune disease
- A failure of self-recognition, thus the body begins fighting itself by attacking its own antigens
- E.g. Celiac disease
Hypersensitivity
Excessive immune response to seemingly harmless antigens such as pollen, dust or to an animal, due to over-activity in one part of our immune defence.
