May 17, 2012

Health Minute With CASI

The Amazing Work of Our Central Nervous System, Part 1

The Nervous System is divided into two parts: The Central nervous system includes the brain and spinal cord. The Pheripheral nervous system includes the 12 pairs of cranial nerves, and 31 pairs of spinal nerves, and all their branches. The Pheripheral nervous system carries sensory messages to the CNS from sensory receptor, motor messages from the CNS out to muscles and glands, as well as autonomic messages that govern the internal organs and blood vessels.

Central Nervous System:

The Cerebral Cortex is the cerebrum’s outer layer of nerve cell bodies, which looks like “gray matter.” It is the center for the human’s highest functions, thought memory, reasoning, sensation, and
voluntary movement. Each half of the cerebrum is a hemisphere: the left hemisphere is dominant in most people, including those who are left-handed.

Each hemisphere is divided into four lobes: frontal, parietal, temporal and occipital. The lobes have certain areas that direct certain specific functions.

Frontal Lobe: areas concerned with personality, behavior, emotions and intellectual function. The precentral gyrus of the frontal lobe initiates voluntary movement.

Parietal Lobe: postcentral gyrus is the primary center for sensation.

Occipital Lobe: is the primary visual receptor center.

Temporal Lobe: behind the ear has the primary auditory reception center.

Wernicke’s area: in the temporal lobe is associated with language comprehension. When damaged in the person’s dominant hemisphere, receptive aphasia will result. The person hears sound, but it has no meaning like hearing a foreign language.

Broca’s area: in the frontal lobe mediates motor speech. When injured in the dominant hemisphere, expressive aphasia results: The person cannot talk. The person can understand language and knows what he or she wants to say, but can produce garbled sound.

Damage to any of these specific cortical areas produces a corresponding loss of function: Motor weakness, paralysis, loss of sensation, or impaired ability to understand and process language. When damage occurs the neurological cells are deprived of their blood supply, such as when a cerebral artery becomes occluded, or when vascular bleeding or vasospasm occurs.

Basal Ganglia: buried deep within the two cerebral hemispheres that form the subcortical associated motor system( the extrapyramidal system). They control such movements of the body, the arm swing alternating the legs during walking.

Thalamus: the main relay station for the nervous system. Sensory pathways of the spinal cord and brain stem form synapses( sites of contact between two neurons on their way t the cerebral cortex.

Hypothalamus: major control center with many vital functions. Temperature, heart rate, and blood pressure control, sleep center, front and back pituitary gland regulator, and coordinator of autonomic nervous system activity and emotional status.

Cerebellum: Is a coiled structure located under the occipital lobe that is concerned with motor coordination of voluntary movements, equilibrium and muscle tone. It does not initiate movement but coordinates and smooths it, the complex and quick coordination of many different muscles needed in playing a keyboard, swimming, or juggling. It is able to adjust and correct the voluntary movements, but operates entirely below the conscious level.

Continue to follow up on next month’s article to continue to learn the fascination of our brain.