Transmission and the Immune System

tRANSMISSION & tHE IMMUNE SYSTEM

Read & write about blood clotting, transmission of viruses like HIV, and phagocytic blood cells. Share in cooperative groups about blood clotting, transmission of viruses like HIV, and phagocytic blood cells.

Language Objective

Explain the process of blood clotting, transmission of viruses like HIV, and the function of phagocytic blood cells.

Content Objective

Blood Clotting

Blood clotting, also known as coagulation, is the process by which blood changes from a liquid to a gel in the walls of damaged blood vessels.

Each step

• Prothrombin: inactive precursor molecule into the activated thrombin
• Thrombin: only lasts a few seconds limiting cloting to the damaged area
• Thrombin triggers the conversion of soluble plasma into insoluable
• Soluble: circulates blood without sticking. Insoluble: forms long sticky fibers
• The fibrin strands form a mesh of fibres around the platelet plug and traps blood cells to form a clot.

Phagocytic White Blood Cells

White blood cells (leukocytes) that move from the bloodstream into tissues. Once at the site of inflection, they: Engulf and digest non-human material Display molecules from the pathogens (“antigens”) on their own cell surface (to activate adaptive immunity) Release chemicals that summon more white blood cells to the scene.

Transmission

Vehicle

Indirect through non-living carrier ex: food, water, feces, surface

Direct Contact

skin to skin, fluid to fluid, worm to skin

Aerosols

Small particles that linger & drift in the airex; breathing, talking

Droplets & Vectors

Droplets: large particles pulled to ground with gravity (coughing & sneezing)Vectors: via living carrier (mosquito, tick, flea)

How it works

Clotting factors are proteins that are made and secreted from the liver. They circulate in the blood plasma in an inactive form until activated by platelets at the site of blood vessel damage. Activated platelets trigger a cascade of reactions that ends with the activation of CLOTTING FACTORS.