What is it?The system that senses the environment and coordinates responses. The nervous system controls both voluntary responses (those we consciously control) and involuntary responses (automatic processes that keep our body alive). The nervous system consists of two parts:

1. Central nervous system- brain and spinal cord2. Peripheral nervous system- nerves that connect the body to the central nervous

system.

Organization of nervous system Central Nervous System -consists of brain and spinal cord

Peripheral nervous system a) receives sensory information from environment and relays to brainb) relays instruction FROM brain TO other body parts and organs

StructuresPeripheral nervous system has three groups of nerves

1) Motor nerves - nerves that control voluntary muscles 2) Sensory Nerves - nerves that carry information from sensory organs to the brain 3) Nerves that control involuntary function such as breathing, heartbeat and digestion

Nervous System – 3.10

__Cerebrospinal fluid_________ is fluid that helps protect the brain and spinal cord from damage and injury, helps remove wastes from the brain and transports chemicals.

Nerve TissueNerves are made up of cells called neurons. Neurons are cells specialized for receiving and transmitting chemical and electrical signals.

Structure of a nerve Label the following diagram.

The myelin sheath is a special insulating layer that helps electrical signals conduct by preventing them from passing to other neurons.

Diseases or injury to the Nervous System

Multiple Sclerosis ___destruction of insulating sheath (myelin sheath) on axons in neurons. This leads to difficulty transmitting electrochemical signals leading to symptoms such as slurred speech, muscle weakness, difficulty walking and in some cases difficulty breathing or speaking.

Physical trauma. Falls, hits or whiplash can cause trauma to the brain or spinal cord. Depending on the location and severity of the impact, trauma can disrupt the transmission and reception of signals in the nervous system, leading to impaired function of sight, sensation, or impaired motor function (paralysis).

Nervous System – 3.10