8th Grade Science Mrs. Christopherson Mrs. Goede The Nervous System 8th Grade Science Mrs. Christopherson Mrs. Goede

Parts of the Nervous System Central Nervous System Brain Spinal Cord Peripheral Nervous System Nerves

Central Nervous System Brain: Divided into two hemispheres: Left: Analytical Right: Creative Divided into 4 lobes, each responsible for different functions. Frontal: complex thinking Temporal: hearing, memory retrieval Parietal: contains the sensory and motor cortexes Occipital: vision

Central Nervous System Spinal Cord: Thin bundle of nerves running down the spinal column Surrounded by a fluid that protects it from banging into the vertebrae Function: transmits messages between the brain and the peripheral nervous system

Central Nervous System Spinal Cord cont: 4 main groups of spinal nerves: Cervical nerves: supply movement and feeling to the arms, neck, and upper body Thoracic nerves: abdomen Lumbar nerves: lower back Sacral nerves: buttocks, genitals

Peripheral Nervous System “Peripheral”: relating to an outer boundary The nervous system extending from the spinal cord out to the body Consists of: Sensory neurons: body  the central nervous system Motor neurons: the CNS  body

Peripheral Nervous System Sub-divided into 2 parts: Somatic Nervous System: controls nerves that go to the skin and muscles; conscious activities (i.e.-activities you are aware of) Autonomic Nervous System: controls internal organs; unconscious activities (you don’t think about these functions)

Peripheral Nervous System The neuron: Dendrites: Receive messages from other neurons Cell Body: Contains the nucleus-the control center of the neuron Axon: Sends messages to other neurons

Central Nervous System Peripheral Nervous System Consists of 2 parts: Central Nervous System Peripheral Nervous System Which includes these organs: Which is composed of 2 parts: Brain Spinal Cord Somatic nervous system Autonomic nervous system

The Nervous System & Our Senses Everything we know about the world around us comes from our senses. Touch Vision Hearing Taste Smell

The Nervous System & Our Senses The brain receives sensory messages from different parts of our body Touch: skin Vision: eyes Hearing: ears Taste: taste buds Smell: nose

The Nervous System & Our Senses Our nervous system responds to change; we only react to something if it is different from what we’ve previously experienced. Objects or sensations that remain the same tend to blend into the background; we don’t notice them For example: our touch receptors notice the feel of our clothes when we get dressed in the morning but we soon “forget” that we have clothes on!

The Nervous System & Our Senses Brain Map of the Senses

The Nervous System & Our Senses As the diagram showed, when the nerves of our body sense something, a message is sent from that nerve back to the brain. The message travels to a specific portion of the sensory cortex to be decoded In this way, our brain tells our body what to do about the sensory situation. E.g.: We react differently to a fly landing on our arm vs. boiling water landing on our arm!

The Nervous System and Our Senses