Immunology Flashcards
The ability of the body to resist damage from microbes (foreign substances) and internal threats, e.g., cancer.
- It is all over the body but acts as one team.
Immunity
The immune system consists of 2 mechanisms.
a. innate mechanisms (Non specific)
b. adaptive response (Specific)
Mechanisms that confer a nonspecific defence against pathogens. Respond immediately to any threat. Composed of epithelial cells, mucous membrane, etc. It protects against agents.
Innate mechanisms (Non specific)
Reponse that provides defence against specific molecular agents and antigens (pathogens).
Adaptive response (Specific)
The immune system includes all _____ & _____ that defend the body against pathogens.
structures and processes
_____ include infectious organisms, toxic chemicals, radiation and other agents that damage tissue
Pathogens
Humans have _____ lines of immune defence against pathogens:
Three
Line of defence that includes skin and mucous membrane; these are impenetrable to most pathogens.
First line of defence (Mechanical)
Line of defence that include leucocytes and macrophages, antimicrobial proteins, immune surveillance, inflammation and fever. All of these defences are present at birth and are highly effective against a wide range of pathogens
Second line of defence (Cellular)
Line of defence that include adaptive (specific) immune defence – which arises from prior exposure to a pathogen, and provide future protection to the body via memory cells.
3rd line of defence. (Chemical)
Dry and porous. It doesn`t allow bacteria to grow.
Skin
Bacteria that can cross the stomach because it is more acidic than the stomach.
H. Pylori
Decreased acid in the stomach causes ____ in bacteria that may cause them to go up to the lungs and cause pneumonia.
Increase
Mucous, tears and saliva contains ____ that kills bacteria.
Lysosyme
WBC leaves blood vessels
Diapedesis
Immune system structures include those of the (4)
lymphatic system, skin, mucous membrane, and specialised proteins.
Components of Innate Immunity
- Epithelial and mucous membrane
- Acid, cell secretion and enzymes
- Phagocytic cells
- Complement protein
- Inflammation
- Fever
Function of Innate Immunity: (3)
Non-specific Resistance
i) Responds immediately
ii) Protects against all foreign substances
iii) Protects against agents which may have enter the body
- They are the first line of defence against pathogens
- Block any pathogen or chemical entry into the body.
Physical Barrier = Epithelial and Mucous membranes
____ is too dry and poor in nutrition to support microbial growth, except for the axillary and pubic areas.
Skin
The skin surface is composed mainly of _____, a tough protein that only few pathogens can penetrate.
keratin
Digestive, reproductive, respiratory and urinary tract get protection from(3).
mucous membrane, mucus and cilia
Microbes trapped in respiratory mucus and cilia are removed by ____ to the pharynx and are often swallowed.
cilia
Areolar tissue beneath epithelial tissue of the skin and mucous membrane contain ______ (a kind of stick gel), which blocks microbes from migrating across it.
hyaluronic acid
Only microbes that secrete ______, which breaks down this gel (hyaluronic acid) can penetrate this layer easily and cross into the body. (Snake venoms, bacteria toxins and some protozoan contain hyaluronidase, and so these substances can cross this layer.)
hyaluronidase
____ kills ingested microbes
Stomach
____ on the skin block bacteria growth
Sebum
Skin is coated with antimicrobial chemicals such as _____ - a peptide that kills
micro-organisms by creating holes in their membrane.
defensins
Skin is also coated with a thin film of ____ from sweat that inhibit bacteria growth
lactic acid
Mucus, tear and saliva have enzymes (lysozyme) that destroy bacteria by dissolving their _____.
cell walls
Those pathogens that get pass the physical and chemical barriers are often attacked by ______ and _____.
leucocytes and macrophages.
Five types of leucocytes contribute to resistance and immunity
i. Neutrophils.
ii. Eosinophils
iii. Lymphocytes
iv. Monocytes are leucocytes
WBC that wander in connective tissues and kill bacteria by phagocytosis. They also release potent chemicals that surround the pathogens and the neutrophils, and the chemicals digestives both the pathogens and the neutrophils.
Neutrophils
WBC found in mucous membrane- act against allergens (antigens that cause allergies) and produce superoxide, hydrogen peroxide, and toxic proteins to destroy worms
Eosinophils
Cells have the ability to kill pathogens and tumour cells. These cells do not have selective action as neutrophils. Eliminate a variety of infected or cancerous cells that lack self-surface markers. Are NOT phagocytes; they induce cells to undergo programmed cell death (apoptosis). Secrete potent chemicals the aid the inflammation process
Leucocytes - NK cells. (Natural Killer)
Leucocytes that have migrated from the blood into connective tissue and transform themselves into macrophages. They are phagocytes. They are widely distributed in connective tissue and have specialized forms and names (.e.g., microglia in neural tissue and hepatic macrophage in the liver)
Monocytes
Programmed cell death.
Apoptosis
Chemical released by cells (5)
i. Histamine
ii. Prostaglandins
iii. Pyrogens
iv. Kinins
v. Interferon
Chemical released by Basophils, Mast cells and Platelets that causes vasodilation, vascular permeability, mucus secretion, smooth muscle contraction e.g., bronchoconstriction
Histamine
A group of lipids from cells that cause smooth muscle relaxation, increased permeability and attract neutrophils and eosinophils.
Prostaglandins
Chemicals released by neutrophils and monocytes that stimulate fever production.
- cause body to increase hypothalamus setting (resets body temperature)
Pyrogens
Proteins in the plasma that stimulate pain receptors and attract macrophages.
Kinins
Protein secreted by when certain cells of the body (including leucocytes) when they are infected with viruses.
Interferon
Interferon’s function.
To alert neighbouring cells and help to prevent them from becoming infected.