George is lifting weights. He starts by doing biceps curls
which involves flexing his
elbows. His elbow is able to bend
because the humero-ulnar joint is a hinge
joint. Sam is doing leg presses, extending his knees as he pushes
against the weights. Meanwhile, Jane is doing "lat pulls" by pulling
downward on a weighted bar. This movement involves adduction of her arms.
Her shoulder joint is a ball-and-socket joint, allowing
a wide range of movements.
Answer:
c) receptor; control center; effector.
Explanation:
Homeostasis maintains the internal body conditions almost constant. It includes specific cells that sense any deviations of internal or external conditions from the normal range. These cells are called receptors. The sensory information from the receptors is delivered to the control center. The central nervous system mainly serves as a control system wherein sensory information from the receptors is processed. The control center commands muscles and/or glands to perform desired responses to restore the homeostasis. Here, muscles and glands serve as effectors.
For example, thermoreceptors sense the rise of body temperature and the brain (control center) commands sweat glands (effectors) to produce sweat.
