The Nervous System and the Control of Movement

The Nervous System The nervous system is the body's way of gathering information, storing it, and responding to it Main role is to assemble information about conditions external and internal to the body Analyze this information Initiate responses that may be necessary to satisfy certain needs

Two Components of the Nervous System Brain + spinal cord = central nervous system (CNS)‏ Peripheral nervous system (PNS) = responsible for other things i.e. Heart Digestive system Muscular control All voluntary and involuntary neuromuscular controls

The Brain Control centre or “computer” of the body Incapable of performing physical tasks, therefore it sends commands to other parts of the body to perform them 6 main parts: cerebrum, cerebellum, brain stem, diencephalon, limbic system, reticular activating system

Cerebrum Largest part of the brain Contains nerve centres that control sensory and motor activities Can be divided into two halves or “hemispheres” Each hemisphere is divided into 4 lobes (named after the bone that they lie over Frontal lobe, temporal lobe, parietal lobe, occipital lobe

Cerebellum Second largest region Lies behind and below the cerebrum Main function is to coordinate muscle movement and control balance

Brain Stem Below cerebrum and in front of cerebellum Links the cerebrum with the spinal cord Houses brain centres responsible for autonomic functions, postural control, muscle tone, and eye movement

Diencephalon Consists of thalamus and hypothalamus Thalamus relays most sensory stimuli to the cerebral cortex Controls awareness of pain, screening of incoming signals, focusing attention Hypothalamus controls body temperature, appetite, emotions and various automatic functions

Limbic System Composed of a collection of structures within the cerebral hemispheres that regulate basic drives i.e. Hunger, aggression, emotional drives Screens information going to the cerebral cortex

Reticular Activating System Network of neurons Fans out through the cerebral cortex Directs information to appropriate centres for interpretation Crucial for maintaining consciousness

Vertebral Column and the Spinal Cord Main pathway for information connecting the brain and peripheral nervous system Spinal cord runs through the vertebrae Starts from the the base of the brain stem and travels down to the second lumbar vertebra Spinal nerves carry sensory information towards the CNS and motor commands away from the CNS

Peripheral Nervous System Consists of the parts of the nervous system that lie outside the CNS (everything but the brain and spinal cord)‏ Carries information in and out of the CNS Motor Nerves – aka efferent nerves carry information from the CNS to the body's organs Sensory Nerves – aka afferent nerves carry information from sensory receptors to the CNS

Autonomic Nervous System Subsystem of the PNS Controls involuntary actions (i.e. Heart beat)‏ Comprised of two branches which act as opposing systems Sympathetic system Parasympathetic system

Sympathetic System Causes localized bodily adjustments to occur (i.e. Sweating)‏ Prepares bodies for emergencies This involves release of adrenaline, increased heart rate, widening of blood vessels, and “fight or flight” responses

Parasympathetic System Helps to return the body to normal after it has been altered by the sympathetic system i.e. Sympathetic system will increase heart rate, parasympathetic system will decrease heart rate to bring it back to its resting state.

Somatic Nervous System Another subsystem of the PNS Responsible for our awareness of the external environment Contains both afferent and efferent nerve fibres Through this system, the PNS receives and processes information from receptors in the skin, voluntary muscles, tendons, and joints Gives us the sensations of touch, pain, heat, cold, balance, body position, and muscle action

Cont... Handles the muscles in our extremities Allows us to move