• The musculoskeletal system of the body is always in motion.

• Even when the body is resting, the lungs continue to breathe, the heart continues to beat, the intestines move around, and the skeletal muscles occasionally contract to move the body into a different position.

MUSCLE TEAMWORK

• Multiple muscle contractions are usually responsible for producing a movement.

• For example, there are twenty face muscles involved in smiling, while writing requires the use of more than sixty muscles in the arm, hand, and wrist.

• When one muscle contracts to pull on a bone and start a movement, the opposite muscle in the pair relaxes.

• Muscles function together in pairs.

• A continuous cycle of brief exchanges of give-and-take characterizes the action of the body.

POSTURE AND FEEDBACK

• The information that the brain receives about the posture and location of the body and limbs comes from the sensory systems that are built into the muscles.

• This ability, known as the proprioceptive sense, enables us to "know" that our fingers are clenched or that our knee is bent even though we do not need to look or feel for this information.

• When we are learning a new motor skill, we focus our attention on the movement itself while the brain makes adjustments to the control that the muscles have over the movement through a process of trial and error.

• After sufficient repetition, the motor nerve patterns and the proprioceptive signals associated with them become established, and finally the movement is able to be performed without conscious thought.

• In addition to this, the muscular and skeletal systems are protected from harm via sensory input.

• When bones or muscles are subjected to an abnormally high amount of stress, the nerves in those tissues send messages to the brain that reflect discomfort or pain.

• A conscious awareness of the discomfort prompts the body to take evasive or defensive action.

SENSORY FEEDBACK

• Sense organs, also known as spindle organs, are the terminal points of nerves found within muscles.

• These tissues react to strain by sending impulses through nerve fibers, which in turn relay the information to the brain.

STAYING SUPPLE

• Regular workouts that focus on building strength, stamina, and flexibility are essential to maximizing our ability for mobility as well as maintaining the health of our skeletal and muscular systems.

INFORMATION PROCESSING

• Inputs are required for information processing, followed by evaluation and decision-making, and then outputs are generated.

• The senses are the entry points for information into the body.

• The outputs of the brain's central processing unit, which govern the chemical reactions of glands and the physical movements of muscles, are produced by the brain.

• Data handling requires contributions from both the neurons and the hormones.

ELECTRICAL AND CHEMICAL PATHWAYS

• Tiny electrical impulses can be thought of as the "language" of the nervous system. In just one second, millions of nerve impulses travel through the nervous system of the body, carrying information to and from the brain.

• Information gleaned from one's senses is processed in the brain after making its way there.

• Following the formation of decisions, command signals, which also take the form of electrical impulses, are transmitted along the motor neurons to the muscles in order to trigger and coordinate the contractions of those muscles.

• In addition, microreceptors are responsible for monitoring conditions inside the body and sending data about those conditions to the unconscious part of the brain.

• The unconscious part of the brain then performs an automatic analysis of the data and sends impulses to various parts of the body in order to maintain an internal environment that is optimal for the body's functioning.

• Endocrine glands are responsible for secreting a variety of information carriers known as hormones into the bloodstream in order to trigger action in other tissues of the body.

• There are more than fifty hormones that travel through the bloodstream.

• Because each hormone has its own unique molecular structure, it can only stimulate those cells that already have the appropriate receptors on their surface.

• This causes the stimulated cells to carry out certain processes.

• In general, nerves perform their functions very quickly, usually within a few hundredths of a second.

• The majority of hormones have a larger window of time in which they are active, ranging from minutes to days to even months.

• In the case of growth hormone, for example, the continual secretion of the hormone over the course of several years is what causes the effects to be long-lasting, whereas the effects of a single dose would only persist for a few days.

SELECTIVE FOCUS

• The brain receives multiple streams of nerve signals referred to as "smell" from the nose.

• As part of the mind's selective awareness, we have the ability to choose whether or not to pay attention to certain things.