Nervous System

BrainSpinal Cord

NervesNeurons

Neurons

Communication between cells through nerve signals.

Parts of a Neuron• Soma – cell body• Dendrite – receive messages• Axon – send messages out• Myelin – help speed up

messages, made up of Schwann cells

Types of Neurons• Sensory – incoming signals• Motor - movement• Interneurons – in brain and

spinal cord only (processors/relay terminals)

Neural Connections• Synapse – space between axon of

neuron A and dendrite of neuron B• Neurotransmitter – chemicals

that diffuse across synapse to change polarity of neuron B’s dendrite membrane

• Nerve cells contain receptor molecules for neurotransmitters

Synapses

Neurotransmitter being released into synapse and attaching to receptors on dendriteBased on Harvard Medical School

Family Health Guide

Central Nervous System• Brain• Spinal Cord

Control center, coordinates body functions

Peripheral Nervous System Carry messages to and from

CNS

Motor and sensory neurons found here.

No interneurons here!

BrainCerebrum

Corpus Callosum

Pituitary Gland

HypothalamusBrain Stem: Pons, Midbrain, Medulla Oblongata

Cerebellum

Thalamus

Autonomic Nervous System• Involuntary• Two divisions

–Sympathetic – fight-or-flight responses

–Parasympathetic – body at rest

Somatic Nervous System• Cranial and spinal nerves• Reflexes – automatic

responses to stimuli

Senses• Chemoreceptors – chemicals• Photoreceptors – light• Mechanoreceptors – pressure,

vibration

Chemoreceptors• Taste – taste buds

–Sweet–Salty–Bitter–Sour

• Olfaction - smell

Photoreceptors• Vision• Retina

–Cones – color–Rods – black & white

Mechanoreceptors• Hearing – vibration in cochlea• Balance – semicircular canals

in ears• Touch – pressure, pain, heat,

cold