<span>Refractory period is the period after an initial stimulus when a neuron is not sensitive to another stimulus.</span><span>
During the relative refractory period of an action potential, a larger than normal stimulus is needed to cause another action potential. This is due to the fact that t</span>he voltage gated potassium ion channels remain open long enough to hyperpolarize the axon membrane.
Answer:
Both C and E are reasonable answers.
Explanation:
Homeostasis describes the body's ability to maintain a stable equilibirum. In other words, if the body experiences a stress, it will generate a response that works to counteract that stress and restore itself to how it was prior to the stress.
A. This describes a cause and effect (BP down --> venous return down). It does not describe an active physiological response to counteract the BP drop such as an increase in heart rate. Not homeostasis.
B. Again, a cause and effect is described. Blood vessel walls becoming thinner is not a response to counteract increased BP. Not homeostasis.
C. Here a response to a stress is described. Men are drinking more water. The body responds by getting rid of that water, restoring the body to its former state. This describes homeostasis.
D. This sounds like homeostasis, but it's actually the opposite of what happens. Dilation of peripheral blood vessels is a way for the body to get rid of heat. This is the opposite of what you would want if the body got colder - it would make the stress worse, which is the opposite of homeostasis. In actuality the response to cold temperature is constriction of blood vessels to preserve heat.
E. This deescribes homeostasis. The stress is increased glucose. The body's response to manage it is to release insulin, which helps remove the glucose from circulation.
The function of the lens is that it allows light rays to focus into the retina. They are composed of fluids that contains lots of nutrients for the lens to gain from it and cleanses dirt if it comes in contact the eye. Overtime, this lens, will slowly degrade as its fluid will start to lose.
