Non-specific Immune Response

Hiya,

Today's blog is on non-specific immune response. The human body has a variety of adaptations that help prevent the contraction of disease, these are the body's primary, non-specific responses;

(Marliese Brandsma)

The Skin; the skin acts as the primary barrier to foreign invaders. The epidermis is the outer most layer. Kertainocyte cells make up the epidermis and are formed underneath this epidermis and migrate to the surface. At this surface, the cells dry out (and die) and the cytoplasm is replaced by keratin in a process called keratinisation. These dead cells can shed off.

Blood Clots; when the skin's epidermis (a primary defence) is broken e.g by a cut, blood clots form in order to close the wound and prevent anything entering or leaving the body via this opening. Blood clots are complex and carefully controlled by calcium (Ca 2+ ions) and 12 clotting factors;

• Damaged tissues and platelets release clotting factors which trigger an enzyme cascade. This produces necessary proteins to produce the clot
• The wound is sealed and sides are drawn together
• Fibrous collagen is deposited 
• Epidermal stem cells divide (mitosis) and move to the edges of the cut where the differentiate into the needed cells
• Tissues contract and new blood vessels form to supply the new tissue. 

The enzyme cascade is pictured below. You need to know;

• Thromboplastin breaks down prothrombin to produce thrombin
• Thrombin breaks down fibrinogen to produce fibrin

Mucous membranes; at sites of diffusion/ gas exchange, mucous membranes help to trap dust, matter and pathogens and prevent them from passing further and potentially entering the body's bloodstream. Mucous membranes work with ciliated epithelium to move the produced mucous out of the body, e.g in the trachea, ciliated epithelium wafts mucous to the top of the trachea to be swallowed to enter the oesophagus and be digested by the enzymes in the stomach (if pathogens are present, the strong pH of the HCl will kill it).

Expulsive reflexes; reflex actions such as sneezing, coughing and vomiting are caused by allergens, spores, dust and microorganisms (and their toxins). By reflexing, the body can immediately expel the dust and perhaps microorganisms within it.

Inflammation; when an environmental stimuli is detected by the Mast cells (found in areas in close contact with the environment), release chemicals called histamines are released. Histamines cause natural vasodilation (widening of the lumens of blood vessels) and increased capillary wall permeability. This causes more tissue fluid to form and pass into the lymphatic system, therefore more pathogens come into contact with lymphocytes. Inflammation causes swelling, redness, heat and pain.