Divisions of the Nervous System Central Nervous System

Divisions of the Nervous System

Central Nervous System n n CNS– relays messages, processes information, and analyses information The two parts are n n Brain Spinal Cord

Outer Protection of CNS n n Meninges- three layers of connective tissue that surround the brain and spinal cord Cerebrospinal fluid- fluid surrounding the brain that acts as a cushion. n Spinal tap – samples cerebrospinal fluid to test for bacteria or protein

Parts of the Brain n Cerebrum n n n Largest portion of the brain The wrinkles increase the surface area which increases the number of neurons Contains areas of higher reasoning and sensory interpretation

Parts of the Brain n Cerebrum con’t n n The left half analyzes the information from the right side of the body and vice versa. Made of two layers n n Grey matter – tightly packed cell bodies White matter – tightly packed axons with myelin sheathes

Parts of the Brain n Cerebellum n n Located at the back of the skull Coordinates and balances muscle movement

Parts of the Brain n Brain Stem n n Connects the spinal cord and the brain Controls most important involuntary actions like blood pressure, heart rate, breathing and swallowing.

Parts of the Brain n Thalamus n n Receives information from the body and relays the information to the correct section of the brain. Hypothalamus n Control center for hunger, thirst, fatigue etc.

Spinal Cord n n A thick bundle of nerve axons that connect the brain to the rest of the body Reflexes – a quick, automatic response – is controlled by the spinal cord

Peripheral Nervous System n All nerves and cells located outside of the spinal cord n Somatic Nervous system n n Controls skeletal muscles Autonomic Nervous System n Controls involuntary responses.

Reflex Arcs n Five parts: n n n Sensory Receptor – takes in stimulus Sensory Neuron- relays impulse to spinal cord Interneuron-relays impulse to motor neuron Motor neuron- carries impulse to muscle Effector – the muscle that moves.