Nervous System Introduction

Introduction to the Nervous System

• The nervous system is a complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body.

Divisions of the Central Nervous System

• The central nervous system (CNS) consists of the brain and spinal cord.
• The CNS receives sensory information from the nervous system and controls the body's responses.

Organization of the Central Nervous System

• The brain plays a central role in the control of most bodily functions, including awareness, movements, sensations, thoughts, speech, and memory.
• Some reflex movements can occur via spinal cord pathways without the participation of brain structures.
• The spinal cord is connected to a section of the brain called the brainstem and runs through the spinal canal.

Protection of the Central Nervous System

• The CNS is protected by the skull and vertebrae, and three protective layers called meninges: Dura Mater (outer layer), Arachnoid Layer (middle layer), and Pia Mater (inner layer).
• Cerebrospinal fluid, a clear watery liquid, separates the middle and inner layers, acts as a shock absorber, and facilitates the exchange of nutrients between the blood and nervous system.

Parts of the Brain

• The brain is the control center of the body, accounting for 2% of body weight and using 20% of the body's oxygen.
• The brain is divided into three parts: Cerebrum, Cerebellum, and Brain Stem.

Cerebrum

• The Cerebrum is the largest part of the brain, responsible for learning and senses, and is divided into two hemispheres (Right and Left) connected by the Corpus Callosum.
• Each hemisphere controls the opposite side of the body.
• The Cerebrum is further divided into four sections or LOBES:
  • Frontal Lobe: prospective memory, decision making, personality, movement control, speech, and language.
  • Parietal Lobe: interpreting simple somatosensory signals, learning, language, motor planning, and stereognosis.
  • Temporal Lobe: auditory processing and perception, object perception and recognition, language recognition, and declarative memory.
  • Occipital Lobe: visual processing and interpretation.

Gray Matter vs. White Matter

• Gray Matter: absence of myelin in masses of neurons, found in the Cerebral Cortex.
• White Matter: myelinated neurons, found in the inner layer of the cerebrum.

Cerebellum

• The Cerebellum is the second-largest part of the brain, located below the cerebrum at the back of the skull.
• The Cerebellum is responsible for balance and muscle coordination, and is involved in certain cognitive functions, such as language.

Brain Stem

• The Brain Stem connects the brain to the spinal cord and has two regions that act as a "switchboard".
• The Medulla Oblongata controls heart rate, breathing rate, and blood flow through blood vessels.
• The Pons relays signals between the cerebrum and the cerebellum.

Other Structures inside the Brain

• Thalamus: receives messages from sensory receptors and relays information to proper regions of the cerebrum.
• Hypothalamus: regulates hunger, thirst, fatigue, anger, etc., and controls the pituitary for endocrine function.
• Hypothalamus is the main visceral control center and regulates the autonomic nervous system.

Learn about the central and peripheral nervous systems, their divisions, and functions in animals. Understand how they coordinate actions and sensory information.