Nervous System Organization

Study Notes

The nervous system is the control and communication system of the body, sending and receiving messages, controlling thoughts and movements.
It has two major divisions: Central Nervous System (CNS) and Peripheral Nervous System (PNS).

Consists of the brain and spinal cord, acting as the command center, interpreting and responding to stimuli.
Functions:
- Sensation: delivers information from the outside environment to the brain.
- Integration: processes gathered information, generates thoughts, and retains memories.
- Motor Output: delivers messages from the brain to muscles or glands.

Cerebrum: largest part of the brain, associated with higher brain function, thought, and action.
- Divided into four sections (lobes):
  - Frontal Lobe: reasoning, planning, speech, movement, emotions, and problem-solving.
  - Parietal Lobe: movement, orientation, recognition, and perception of stimuli.
  - Occipital Lobe: visual processing.
  - Temporal Lobe: perception and recognition of auditory stimuli, memory, and speech.
Cerebellum: regulates and coordinates movement, posture, and balance.
Limbic System: often referred to as the "emotional brain," containing the thalamus, hypothalamus, amygdala, and hippocampus.
Brain Stem: responsible for basic vital life functions, such as breathing, heartbeat, and blood pressure.

Composed of gray matter and white matter.
Gray matter: contains cell bodies and short, non-myelinated fibers.
White matter: contains myelinated axons that run together in bundles called tracts.

Classified according to the number of processes extending from the cell body:
- Multipolar neurons: one axon and two or many dendrites.
- Bipolar neurons: one dendrite and one axon.
- Unipolar or pseudounipolar neurons: a single process that bifurcates, extending to a peripheral ending and the CNS.

Extends from the base of the brain through the foramen magnum.
Structure:
- Central canal
- Gray matter
- White matter
Functions:
- Controls body movements and functions
- Reports senses to the brain
- Manages reflexes

Collection of peripheral nerves, ganglia, and specialized sensory structures.
Carries sensory and motor information between the CNS and other organs and tissues of the body.
Divisions:
- Afferent (Sensory) Division: delivers information to the brain.
- Efferent (Motor) Division: carries impulses from the brain to muscles and glands.
- Autonomic Nervous System: controls involuntary actions.

Two divisions:
- Sympathetic Division: stimulates activity in body tissues not under conscious control.
- Parasympathetic Division: inhibits activity in body tissues not under conscious control.

Cell that detects the stimulus (sensory neuron) forms a synapse with a relay neuron in the spinal cord, which in turn synapses with a motor neuron, transmitting the signal to a skeletal muscle.