Stimulus is something that causes a psychological response. It can be internal or external. The stimulus is the contact with the hot pan. It is an external stimulus. Sense organs, such as the sensory receptors in the skin are sensitive to external stimulus. The quickly pull of your hand is a reflex action.
The contact causes a nerve impulse that will travel to the spinal cord via the sensory neurons.<span>To respond to the stimulus of the reflex arc, the muscle needs to contract to pull the hand quickly away from the hot pan.</span>
<span>Cell membrane needs to allow and exit the materials that enter the cell because the cell needs nutrients and these nutrients are converted into molecules that aid in many cellular activities like repair, divide and form structures and biomolecules.
Also to excrete wastes and other harmful materials for the cell.
This continues because the cell wants to attain homeostasis.
Homeostasis is the state where the internal and external part of the body maintains and establishes balance and equilibrium. This is achieved through cellular processes in the body, the integumentary system regulates the body temperature, the hypothalamus –hunger and thirst of the individual and other interrelated organ systems that make the body healthy and in the state of equilibrium. Now, when diseases or disorders appear they disrupt the organ systems in the body thus, causing imbalance state –high fever, inability to focus and etc.<span>
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DNA stores the instructions (genetic information) used to build proteins.
We can’t see the picture :(
Maybe post another question but with the picture
