Always in motion is the future.

Week 7: Neural

Nervous System Organization

The nervous system is a rapid controller. It processes millions of bits of information from many sensory organs, filters incoming stimuli, discards unimportant data, and integrates those inputs to control the body's responses to relevant stimuli.

General Design

Two major divisions:

Sensory: sensory experiences from sensory receptor stimulation, including visual, auditory, tactile and others. Can cause immediate rxn or memory. Information enters CNS through peripheral nerves.
Motor: controls bodily activities in effectors (target cells) such as skeletal muscle contraction, smooth muscle contraction in internal organs, gland secretions.

Three Functional Levels of the Central Nervous System (CNS):

Spinal Cord: Not just a conduit for signals, but also contains control centers and neuronal circuits for walking movements, withdrawal reflexes (pain response), gastrointestinal and local vascular reflexes, etc. Can store small amounts of information.
Lower Brain: lower brain areas, including pons, medulla, cerebellum, thalamus, hypothalamus, etc. Controls subconscious activities such as equilibrium, emotional patterns, feeding reflexes.
Higher Brain (Cortical Level/Cortex): acts in association with lower nervous system centers. Large memory storehouse, storing most information for future use, helping coordinate brain functions into precise operations. Essential for most thought processes.

Organization

Central Nervous System (CNS): brain and spinal cord
Incoming signals to the brain are afferent
Outgoing signals are efferent
Peripheral Nervous System (PNS): peripheral & cranial nerves
Nerves: axons -- myelinated (insulated) or unmyelinated.

Stroke

Most elderly persons have some arterial blood supply blockage to the brain. As many as 10 per cent eventually have enough blockage to cause damaged brain function called a stroke. Most strokes are caused by arteriosclerotic plaques, which activate the blood clotting mechanism. The clot causes blockage and decreased local function. High blood pressure can also burst a vessel, causing hemorrhage which compresses brain tissue. The effects of a stroke depend on the area of the brain damaged.