Platelets, Which Have Negatively Charged Cell Membranes, Adhere to the Positively

question 19

Multiple Choice

Platelets, which have negatively charged cell membranes, adhere to the positively charged surface of a torn blood vessel.As they do so, they release substances that attract more platelets to the damaged area and change the charge on their cell membranes to positive.More platelets adhere to the damaged are a.The cycle repeats until the damaged area is sealed.What sort of feedback loop is formed, and why

• A)positive-feedback loop: the response reinforces the initial change
• B)negative-feedback loop: the response opposes the initial stimulus
• C)negative-feedback loop: having too many platelets in one area blocks blood flow
• D)positive-feedback loop: the response prevents a person from haemorrhaging to death

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Definitions:

Blood Vessels

Tubes in the body through which blood flows, including arteries, veins, and capillaries.

Hemolymph

The fluid that bathes the tissues in animals with an open circulatory system (e.g., arthropods and most mollusks).

Hemocoel

Blood cavity characteristic of animals with an open circulatory system.

Hemocyanin

A hemolymph pigment that transports oxygen in some mollusks and arthropods.