CENTRAL NERVOUS SYSTEM (CNS)

CENTRAL NERVOUS SYSTEM (CNS)

Composed of the brain and the spinal cord

BRAIN

·         The master integrator of the nervous system.

·         Responsible for thought, decision-making, behavior, and all life processes.

MEDULLA

·         Regulates vital involuntary processes like breathing, heart rate, and blood pressure.

·         Controls reflexes: sneezing, coughing, swallowing, vomiting.

·         Acts as a relay center for nerve signals between spinal cord and brain.

·         Houses cranial nerves that control sensations in the throat and mouth.

MEDULLA OBLONGATA

·         Extends from the spinal column to the pons.

·         Controls vital functions:

o    Heart rate     

o    Constriction of blood vessels (affecting blood pressure)

o    Respiration

·         Contains reflex centers for coughing, vomiting, swallowing, and sneezing.

·         Severe trauma to this area is life-threatening.

PONS

·         Located above the medulla and below the midbrain.

·         Serves as a bridge between the cerebrum and cerebellum.

·         Helps regulate respiratory patterns with the medulla.

·         Controls breathing rhythm and sleep.

MIDBRAIN (Mesencephalon)

·         Connects the pons and cerebellum.

·         Integrates visual and auditory reflexes.

·         Maintains balance and equilibrium.

Regulates sleep and wakefulness.

HYPOTHALAMUS

·         Small area above the pituitary gland.

·         Coordinating center for the autonomic nervous system.

·         Secretes releasing and inhibiting hormones affecting the pituitary gland (e.g., growth-hormone-releasing factor).

·         Regulates:

o    Body temperature

o    Food intake

o    Visceral responses (e.g., increased heart rate with anger).

CEREBELLUM

·         Coordinates body movement at an unconscious level.

·         Allows smooth muscle activity by inhibiting unnecessary impulses.

·         Regulates:

o    Muscle tone

o    Coordination of goal-directed spontaneous movements

o    Posture and balance

o    Eye movements

o    Motor learning

o    Some cognitive functions

·         Each hemisphere influences motor activity on the ipsilateral side of the body.

·         Compares motor plan (intent) with motor performance (feedback from periphery).

·         Functions to smoothen and coordinate movements.

·         Works by forming synaptic contacts with brainstem motor centers and cerebral hemispheres.

CEREBRUM

·         The largest part of the human brain.

·         Divided into lobes named after the cranial bones they lie under.

·         Functions contralaterally:

o    Left lobes → control right side of the body.

o Right lobes → control left side of the body.

CONTRALATERAL

·         Frontal Lobes

o    Voluntary motor activity

o    Judgment, planning, organization, problem-solving

o    Behavior regulation

o    Broca’s area: controls movements related to speech (left frontal lobe in right-handed individuals).

Parietal Lobes

o    Interpret impulses and sensations from the skin and muscles.

o    Responsible for facial, shape, and color recognition.

o    Taste sensation overlaps with parietal and temporal lobes.

·         Temporal Lobes

o    Receive auditory (hearing) and olfactory (smelling) impulses.

o    Involved in new memory formation, learning, music, and emotions.

·         Occipital Lobes

o    Handle vision.

o    Responsible for depth perception and three-dimensional perception.