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Platelets . Appearance . Irregular shape Colourless Sticky Very very tiny! . What do they do? . Maintain homeostasis Preventing blood loss Homeostasis = ability to maintain a balanced internal environment in response to the environmental changes around them . How? .
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Appearance • Irregular shape • Colourless • Sticky • Very very tiny!
What do they do? • Maintain homeostasis • Preventing blood loss • Homeostasis = ability to maintain a balanced internal environment in response to the environmental changes around them
How? • Adhesion: platelets attach to the rip or tear in the blood vessel • Activation: platelets change shape, turn on receptors and secrete chemical messages to other cells • Aggregation: they connect to each other through receptor bridges
Definitions • Coagulation cascade = combination of proteins activated by the chemical messages from the platelets. At the end of the coagulation cascade fibrinogens have become fibrin. • Fibrin = product of fibrinogens which are blood clotting proteins
How? (cont’d) • As the platelet plug forms it activates the coagulation cascade which uses fibrin deposits to form the clot. • A “white clot” is made up mostly of platelets, while a “red clot” is made up of mostly fibrin. • Typically our clots are a mixture of both
Good vs. Bad • What would be an example of a good blood clot? • A bad one? • What might be the results of a bad blood clot?
Blood Clots inside the Blood Vessels • Can be caused by: • Cancer, pregnancy, lupus, rheumatoid arthritis, certain medications • Sticky blood • Damage to the inside of blood vessels • Can lead to: • Heart attack, stroke, embolism
Factors • Smoking • Physical inactivity
Blood clots and Aspirin • What do you think will happen to a blood clot if you take aspirin? Does it make it make it better or worse?