Blood Fluid 2 Flashcards
What are pathogens?
Infecting causing organisms
Example of bacteria + what it causes?
Staphylococcus aureus which causes sepsis
E.g. of fungus and what it causes?
Epidermophyton floccosum causes athlete’s foot
E.g. of virus?
Polio
E.g. of parasite?
Tapeworm
3 major mechanisms of defense:
Protective surfaces, innate immune system and adaptive immune system
What do protective surfaces do?
They secrete antibacterial substances (lysozyme) and they have acidic pH that inhibits the growth of pathogens
Where are these protective surfaces?
Skin and mucosal linings: Gastrointestinal tract, Respiratory tract, Urinary tract and Reproductive tract
What is the innate immune system?
Cells, complement proteins and peptides in blood and tissue beat trivial infections
What does the innate immune system consist of? hint 6
Cells in Blood/Tissue
(1) Neutrophils
(2) Eosinophils
(3) Basophils
(4) M’cyte/Macrophage
(5) Mast cells
(6) Natural killer cells
What is the adaptive immune system?
Cells with the ability to learn, i.e. subsequent infections produce greater response
What does the adaptive immune system consist of?
T-lymphocytes: T cells (7) and B-lymphocytes: B-cells (8)
What do the T-cells do?
Cellular response, T cells interact with
APCs (macrophage & dendritic cells)
What do B-cells do?
Humoral response - Involves production of antibodies by B cells
Constituents of blood are?
RBCs - erythrocytes, platelets - thrombocytes, plasma, WBCs -leukocytes: granulocytes (Neutrophils, eosinophils and basophils) and agranulocytes (lymphocytes and monocytes)
5 steps of pagocytosis?
- Engulf by endocytosis
- Form an internal phagosome
- Delivered & fusion with lysosome
- Degraded in lysosome
- Released via exocytosis
Why is phagocytosis used?
To acquire nutrients and remove pathogens and cell debris
What has phagocytosis as their primary function?
Macrophages and neutrophils are primary phagocytes
Primary function of eosinophil?
Attack parasites for example worms
Primary function of basophil?
Release heparin, elastase
Primary function of neutrophil?
1st to encounter pathogens - They contain antibacterial and digestive enzymes (eg myeloperoxidase) involved in
destruction of invading organisms.
% of WBCs that granulocytes are:
60-70%: neutrophil
1-5%: eosinophil
1-5%: basophil
Secondary function of neutrophil?
Contain lyzozymes; involved in phagocytosis
Teritary function of neutrophil?
Cntain gelatinase; granules involved in insertion of glycoproteins into cell membrane for cellular adhesion
How many lobes is the nucleus composed of?
Nucleus of neutrophils has 2-5 lobes
What do eosinophils look like? in terms of lobed nucleus
Bilobed nucleus & granules (stain acidic dyes; eosin)
What granulocyte can kill by granule release ?
Eosinophils
Where do eosinophils enter?
Enter mucosal surfaces of respiratory, lower urinary
and GI tracts
Eosinophils - what do they phagocytose?
Phagocytose IgE opsonised parasites
What is the least common white cell type?
Basophils
What do basophils look like - in terms of nucleus lobes?
Large granules - basophilic, dark blue staining & bilobed nucleus
When are basophils and eosinophils increased?
Increased in parasitic/allergic disease
What does histamine do to blood vessels?
Histamine dilates blood vessels - inflammation redness
How do basophils exocytose granules?
They exocytose granules (histamine) via contact
with IgE complexed allergen
What is a mast cell?
A type of white blood cell that is found in connective tissues all through the body, especially under the skin, near blood vessels and lymph vessels, in nerves, and in the lungs and intestines
What are basophils similar to and what do they contain?
Similar to mast cells and they have histamine
% of lymphocytes of WBC?
20%
B-lymphocytes - what do they do?
Antibody production (plasma cells) - antigen presentation
T-lymphocytes - what do they do?
Priming of innate responses (T-helper 1, TH1), priming of antibody responses (T-helper 2, TH2) and Direct cell lysis (cytotoxic T’s)
% of monocytes (macrophages) in WBCs?
5% of WBCs
What are monocytes attracted by?
Histamine and cytokines
What do monocytes secrete?
They secrete enzymes, complement proteins and interleukins
Where are monocytes made and where do they go?
They emerge from bone marrow while immature; 1-
2 days later mature into macrophages
How long do macrophages last and what do they do before they do?
They last months & digest 100’s bacteria before
they die
What do macrophages present at their cell surfaces?
They present pathogen antigens at cell surface
Where are fixed macrophages?
Fixed macrophages are stationed at strategic
points
6 Types of fixed macrophages?
- Dust/Alveolar type (lungs)
- Histiocytes (connective tissue)
- Kupffer cells (liver)
- Microglial cells (nervous)
- Osteoclasts (bone)
- Sinusoidal lining cells (spleen)
What do mast cells express?
They express Fc receptor, binds Fc of IgE (made by B-cells)
What do allergens bind on mast cell surface?
IgE
What do mast cells stimulate the release of?
Histamine and heparin
What does histamine do?
It dilates venules by increasing blood permeability
5 steps of mast cells as innate immune cell:
- DILATION OF BLOOD VESSELS, INCREASED BLOOD FLOW, INCREASED VESSEL PERMEABILITY: Redness/Swelling/Heat/Pain
- ATTRACTION OF PHAGOCYTES
- RELEASE OF CYTOKINES
- PATHOGEN REMOVAL
- TISSUE REPAIR
What does histamine cause?
Histamine causes edema (swelling), warmth, redness, attracts inflammatory cells, activates nerves (itching & pain)
What are natural killer cells?
They are cytotoxic lymphocytes
What do natural killer cells release and what does this cause?
Release perforin which forms pores in cell membrane and causes apoptosis.
What do natural killer cells play a role in?
They play a role in rejection of tumours and cells infected by viurses
What are patients deficient in NK cells susceptible to?
Patients deficient in NK cells are susceptible to herpes virus infection
What cell activity is tightly regulated in regards to natural killer cells?
NK cell activity is tightly regulated (prevents auto-reactivity, killing own cells)
What is cytotoxic activity regulated by?
Cytotoxic activity is controlled by surface expressed “activating receptors” and “inhibitory receptors“
What is the disease neutropenia?
Neutropenia disease consists of low numbers of neutrophils during anaemia, leukaemia, chemotherapy, which results in increased infections
What disease is eosinopenia?
Eosinopenia (low numbers in eosinophils) during stress, glucocorticoid treatment, Cushing’s disease
What disease is basopenia?
Basopenia (low numbers in basophil) causes itching (autoimmune urticaria)
What disease is eosinophilia?
Eosinophilia (high numbers of eosinophils) during infection, arthritis, malignancy, dermatitis, drugs (penicillin)
What is basophilia?
It is high numbers of basophils in some forms of leukaemia or lymphoma
What diseases do mast cells excessively release histamines in? what can be helpful?
Mast cell excessively release histamine in Asthma, Arthritis, Eczema, Itch, Rhinitis, Anaphylaxis. Antihistamines can be helpful.