Dealing with Diseases

First line of defence

Physical, chemical and microbial barriers against pathogens

Second line of defence

Innate immune response which detects and takes action against pathogens.

Third line of defence

Adaptive immune response, involves targeted action by lymphocytes against pathogens

The skin

Largest organ in the body, made of epithelial cells. Acts as a physical barrier, seperate a internal and external environment

Epithelial cells

Cells that create and secrete mucus, lining all points of entry to the body.

Flushing out Pathogens

Preventing pathogens from entering the body through mucus, urine, poop, tears etc

Epidermis

External layer of skin, made of keratinised dead cells

Dermis

Tissue containing blood vessels, hair follicle, nerves and muscle

Phagolysosome

a vasicle within a phagocyte containing an encased pathogen which has infused with a lysosome

Phagosome

A vesicle within a phagocyte which has trapped a pathogen

Sub cutaneous

Third layer of skin containing fat and major blood vessels like arteries and veins

Chemical Defences

Break down pathogens and bacteria to prevent colonization, Lysozymes in the tears, saliva and mucus breaks down bacteria and pathogens

Microbiota Barriers

Bacteria that prevent pathogen colonization through outcompeting them for nutrients, and producing and secreting antimicrobial chemicals.

Plant Physical barriers

Hairs preventing vector transfer, and thick bark and waxy cuticle on leaf surface preventing entry and water formation for pathogen growth.

Stomata

Points of entry which facilitate gas exchange, many plants contain hairs and sunken stomata to make pathogen entry difficult

Plant Chemical Barriers

Chemicals inside the plant or secreted into soil that inhibit growth and development of pathogens

Innate immune response

Second line of defense which gene expression of specific proteins rapidly occurs to assist the immune response. non specific, does not change depending on the pathogen

Plant Innate Immune response

Second line of defense in plants, a localised response within cells as most plant cells have the capacity for antimicrobial defenses

Adaptive immune Responses

Third line of defense. Specific, specialised responses to different pathogens, retain memory from previous experiences with specific pathogens

Cells in Innate Immune Response

Antigen presenting cells

Cells which present a part of a pathogen to the innate immune response for action

Phagocytes

Leukocyte (white blood cells) cells such as Neutrophils, Macrophages and Dendric cells which destroys and digests foreign materials via phagocytosis

Phagocytosis

Engulfing a pathogen via endocytosis and breaking it down using digestive enzymes (lysosomes). phagocyte engulfs bacteria, trapping bacteria in cell (phagosome), which fuses with the lysosome and breaks down.

pathogen recognition receptors

receptors shaped to connect with PAMPS, occurs as an innate response to pathogens

PAMP

Molecules in pathogens that do not occur in host cells, allowing it to be identified by PRR. (not antigenic)

Macrophages

Large phagocyte cells distributed in all body tissues which presents pathogens to the adaptive immune response, and clear up apoptotic cells and damaged tissue.

MHC1

a receptor on all cells except rbc which present our proteins to distinguish we are self

MHC2

A receptor on APCs specicially for presenting antigens, only found on macrophages, dendritic cells and B- lymphocytes

Antigen Presenting Cells (APC)

Cells with MHC2 which present antigens to the adaptive immune system. includes macrophages, dendritic cells and b- lymphocytes

Neutrophils

phagocyte cell which circulates the blood stream, dying after phagocytosing a pathogen. non antigen presenting cells

Complement System

The activation of a dormant protein, having cascading effect, stimulating the activation of other complement proteins which will defend the body.

opsonisation

complement proteins bind to and tag yeast and bacteria pathogens for phagocytes to more easily detect and destroy.

Induce chemotaxis

Complement proteins create a concentration gradient to attract phagocytes and other white blood cells to an infected or damaged area

Membrane attack Complex

Complement Proteins pierce a hole in pathogen’s membrane, disrupting the phospholipid bilayer and killing it.

Mast Cells

Granulocyte cells in skin and respiratory system that stimulate the inflammatory response by releasing histamine.

Degranulation

Mast cell releases granules which release histamines, cytokines and heparin, stimulating an inflammatory response

Natural Killer Cells

MAC- inhibitory Proteins

Proteins on all body cells which ensure inactivation of unbound activated complement proteins .

interferons

A type of innate cytokine secreted by an infected cell which signals to surrounding cells to induce resistance. Instructs cells to destroy rna, restrict protein production, and self destruct if infected.

cytokine

an immune system signalling molecule for body to defend