The Neurological System
The branches of science that will help you understand the body parts and functions are anatomy and physiology. Anatomy deals with the study of the human body (the component parts, structure and position) and physiology the study of how the body functions.
Body Systems
The body comprises of a number of systems including the: Cardiovascular system, Digestive system, Endocrine system, Muscular system, Neurological system, Respiratory system and the Skeletal system.
The Neurological System
All of our body systems work in conjunction with each other and none are capable of working in isolation. The nervous system controls and coordinates the functioning of all other systems in response to our surroundings. Each stimulus or change in our environment is detected by our senses and messages are interpreted by the brain that in turn, sends directions to the various organs to respond and adapt according to the external conditions which affect our body.
The function of the Neurological System is to transmit and receive a constant series of messages via electrical impulses to and from the control centre situated in the brain. These messages are either those receiving "information" from various body tissues via the sensory nerves, or those initiating the function of other tissues such as organs, muscles, etc.
The nervous system is divided into the central nervous system (CNS) that includes the brain and spinal cord, and the peripheral nervous system (PNS) comprising cranial nerves and spinal nerves. The PNS includes nerves emerging from the brain (cranial nerves) and nerves emerging from the spinal cord (spinal nerves). These nerves are divided into sensory nerves that conduct messages from various parts of the body to the CNS, whilst motor nerves conduct impulses from the CNS to muscles and glands. The PNS is further divided into the Somatic System (SNS) and Autonomic System (ANS), depending on the area of the body these messages are transmitted to and from.
The SNS consists of sensory neurons from the head, body wall, extremities, and motor neurons to skeletal muscle. The motor responses are under conscious control and therefore the SNS is voluntary. Certain peripheral nerves perform specialised functions and form the autonomic nervous system; they control various activities that occur automatically or involuntarily such as the contraction of smooth muscle in the walls of the digestive system. The autonomic system is further divided into the sympathetic and parasympathetic systems. These two systems provide nerve stimuli to the same organs throughout the body, but bring about different effects.
The Sympathetic Nervous System helps prepare the body for "fight or flight" and create conditions in the tissues for physical activity. It is stimulated by strong emotions such as anger and excitement and will therefore speed up heart rate, increase the activity of sweat glands, adrenal glands, and decrease those of the digestive system. It also produces rapid redistribution of blood between the skin and skeletal muscles.
Conversely, the Parasympathetic Nervous System slows down the body and helps prepare for a more relaxed state, ready for digestion and sleep. It will therefore increase peristalsis of the alimentary canal, slow down the heart rate, and constrict the bronchioles in the lungs. The balance between these two systems is controlled to create a state of homeostasis that is where the internal stability of the bodily systems are maintained in response to the external environment.
Effect of exercise on the neurological system
Good coordination and balance is vital to the sports person. The quicker the reactions, the more chance the individual has of having "the edge" over the opposition, or of improving his or her personal best. As with most of the Systems, the neurological system can be trained and improved with repetitive exercises. New and extended movements may be progressively attempted, practiced and perfected involving action with the musculoskeletal systems and, as importantly, the voluntary nervous system to initiate those actions.
It is also important to realise that to some extent nerves serving muscles under our conscious control work in pairs and therefore when rehabilitating an injured part it is often beneficial to exercise and stimulate the symmetrically uninjured part as well.
We have already noted how other systems may benefit from exercise and these improvements take place with the help of the neurological system. Like other systems, the neurological system may be adversely affected by smoking, lack of sleep, poor diet and stress.
The nervous system is adversely affected by age. As we grow older neurons are lost and not replaced. There is also a decreased capacity for transmitting impulses to and from the brain and both voluntary and reflex actions become slower.
The Neurological System
The Skeletal System
The branches of science that will help you understand the body parts and functions are anatomy and physiology. Anatomy deals with the study of the human body (the component parts, structure and position) and physiology the study of how the body functions.
Body Systems
The body comprises of a number of systems including the: Cardiovascular system, Digestive system, Endocrine system, Muscular system, Neurological system, Respiratory system and the Skeletal system.
The Skeletal System
The skeletal system comprises of 206 bones and provides four basic functions:
Support for tissues and muscle
Protection for vital organs
Movement through bones and attached muscles
Storage for minerals and immature blood cells
Growth
Ossification is the process by which bone is formed. Some bones (e.g. the flat bones of the skull) are formed in one stage from the connective tissue. This process is known as intramembranous or direct ossification.
Other bones (e.g. short bones) are formed from the cartilaginous model of the future bone developed in the embryo, being dissolved and replaced by bone cells. This process is known as endochondral or indirect ossification - most bones are formed this way.
Support
Bones and cartilage that make up the skeleton are the only rigid materials in the body. The 206 bones of the skeleton provide a framework and points of attachment for many of the soft tissues of the body. The five main classifications of bones are : Long (e.g. femur), Short (e.g. tarsal bones of the foot), Flat (e.g. frontal bone of the skull), Irregular (e.g. vertebrae) and Sesamoid (e.g. knee cap)
Protection
These structures protect some of the vital tissues and functional organs of the body. Typical examples are:
Skull - protects the brain
Vertebrae - protects the spinal cord
Thoracic cage - protects the heart and lungs
Movement
Bones act as levers during movement and provide solid structures to which muscles are attached. The joints allow movement between bones and these movements are directly related to the type of joint and range of motion. Joints fall into one of three categories: Fixed fibrous or Synarthroses (e.g. bones of the skull), Slightly moveable or Amphiarthroses (e.g. symphysis pubis) and Freely movable or Diarthroses.
Freely Movable joints comprises of four main groups: Ball and Socket (e.g. hip), Hinge (e.g. elbow), Pivot (e.g. radius and ulna) and Gliding (e.g. carpal joint of the wrist)
Component parts of a synovial joint
A fibrous capsule surrounds the joint and is strengthened by ligaments. The stability of these joints is dictated by the shape of articulating surfaces, their surrounding ligaments and muscles. For example, the knee is given great strength from 2 cruciate and 2 collateral ligaments. Whilst one of the hardest joints to dislocate is the hip. It is formed with the head of femur fitting neatly into the socket or acetabulum in the pelvis.
Articular or hyaline cartilage covers and protects the ends of bones which meet to form a joint and therefore allows freedom of movement. It is a very hard, smooth material which does not repair itself when damaged.
Tendons connect muscle tissue to bone and although more elastic than ligaments, have a far greater tensile strength than muscle.
Synovial membrane lines the joint cavity and covers the tendons and ligaments which pass through it. The membrane produces synovial fluid which lubricates the joints
Shoulder Joint
Ligaments are tough fibrous bands of tissue which connect bone to bone and help stabilise a joint, the strongest ligament in the body being situated at the front of the hip capsule, preventing excessive backward movement of the legs. Ligaments, although stronger than muscle tissue, have fewer nerve endings and less blood supply , and therefore take longer to repair when damaged. Whilst these strong fibrous bands offer great stability to a joint in preventing excessive movement, if they are stretched or torn through injury, they do not necessarily return to their former length and therefore may remain stretched, therefore offering reduced stability to that particular joint.
A bursa is a small sac formed in connective tissue lined by a synovial membrane and containing a small amount of synovial fluid. It is situated between moving parts, often between tendon and bone, to prevent rubbing.
Storage
In some bones, there is red marrow which produces red blood cells, some white cells and platelets. Minerals, especially calcium and phosphorous are also stored in bones and can be distributed to other parts of the body.
Effect of exercise on the skeletal system
The condition of bone may be improved by exercise as it responds to mechanical stresses. These mechanical stresses usually take the form of skeletal muscle pulling at their points of attachment being their origins and insertions. Where these mechanical stresses are applied, most it has been shown that more mineral salts are deposited and more collagenous fibres are produced. Therefore, both the density and size of bone in these areas may be increased and these changes in bone structure are stimulated by increased loads being placed on the skeleton. This has been borne out by greater bone mass being observed in weight lifters than in other lighter endurance athletes such as joggers. Other examples include racquet players who have been shown to have greater bone density in their playing arms. It has even been shown that if a leg is immobilised by being placed in plaster, due to a fracture, that even after a few weeks the bone becomes decalcified from lack of mechanical stress.
Whilst it may therefore be considered beneficial to utilise exercise to maintain healthy bones, great care must be taken with children whose bones and muscles are still developing. They should not be subjected to forms of sport involving high degrees of mechanical stress, partly because of the weaknesses that still exist within the bones, and also because of adverse effects on the development of these bones before maturity.
There are two main effects on bones as we grow older. Bones begin to lose calcium and this is one of the factors contributing to the condition called osteoporosis. Secondly, with age less protein is produced which alters the make-up of bone and sometimes creates brittle bones.