Structure of the Nervous System

Study Notes

Central Nervous System (CNS)

The CNS serves as the main processing center for the entire nervous system.
It consists of two main components: the brain and the spinal cord.
The brain functions as the organizer and distributor of information for the body.

Brain

The brain has three main parts: the cerebrum, cerebellum, and brain stem.
The cerebrum controls activity and thought, and is divided into four lobes:
- Frontal lobe: responsible for personality, facial expressions, and interpreting the environment.
- Parietal lobe: processes information related to taste, temperature, and touch.
- Occipital lobe: responsible for processing visual information from the eyes.
- Temporal lobe: responsible for processing auditory information from the ears.
The cerebellum controls posture, balance, and coordination, and is divided into three lobes:
- Posterior lobe: plays an important role in motor coordination.
- Anterior lobe: plays an important role in balance or equilibrium.
- Flocculonodular lobe: plays an important role in balance and eye movements.
The brain stem connects the brain to the spinal cord and controls breathing, digestion, heart rate, and blood pressure.
The brain stem is divided into three parts:
- Midbrain: associated with sleep and wake cycles, and temperature regulation.
- Pons: conducts signals from the cerebrum down to the cerebellum and medulla.
- Medulla oblongata: controls autonomic functions and connects the higher levels of the brain to the spinal cord.

Thalamus and Hypothalamus

The thalamus relays information from sensory receptors to proper areas of the brain for processing.
The hypothalamus synthesizes and secretes certain neurohormones to stimulate or inhibit the secretion of hormones from the pituitary gland.

Spinal Cord

The spinal cord serves as a channel for signals between the brain and the rest of the body.
It controls simple musculoskeletal reflexes without input from the brain.

Peripheral Nervous System (PNS)

The PNS connects the CNS to the organs and limbs.
It has two main divisions: the somatic nervous system and the autonomic nervous system.

Somatic Nervous System

The somatic nervous system is associated with the voluntary control of body movements.
It has two main parts:
- Spinal nerves: carry motor and sensory signals between the spinal cord and the body.
- Cranial nerves: carry information into and out of the brain stem.

Autonomic Nervous System

The autonomic nervous system is associated with the involuntary control of body movements.
It has two subdivisions:
- Sympathetic: activated when the body is in a dynamic role or stress, and causes increased heart rate and breathing, dilation of pupils, sweating, etc.
- Parasympathetic: maintains body functions and restores the body to normal or relaxed mode.

Description

Explore the major divisions and parts of the nervous system, including the Central Nervous System (CNS) and Peripheral Nervous System. Learn about the components of the CNS such as the brain and spinal cord, and their respective functions.